Chaffoteaux & Maury CORVEC Series Manual

SYSTEMS

MANUAL

for

CORVEC

DOMESTIC

BOILERS

chaffoteaux~

et llhury

AA

INTRODUCTION

1

W

1.

INTRODUCTION

Chaffoteaux et Maury is one of the largest producers
of gas water heaters and boilers in Europe and one
of the oldest established manufacturers of these
appliances. Chaffoteaux et Maury have been design-

ing and making water heaters since 1919 and low

water content boilers since 1952.
The principle of the weil known instantaneous

water heater is not so different from that of the
central heating boiler - THEY BOTH HEAT
WATER - the former for direct use, the latter as
the medium for transmitting heat.

Comparing the functions of the two appliances it

is apparent that the water heater operates in less
favnlrrable conditions than the central heating
bc

The boiiers made by Chaffoteaux et Maury use a
row water content finned copper heat exchanger.

Why copper? - Why low w.ater content?

+

Copper is universally known and used as the best
material for conveying water, in addition it is both

easily worked and durable. Most important, it is
one of the best conductors of heat.

In the conventional boiler of cast iron or steel, the

boiler probably weighs 80 -. 100 Ibs. with a water
content of probably 20 1 40 Ibs. and it is evident
that there will be a delay whilst all this mass is
heated before the system responds. At the end of

a cycle the boiler dissipates the heat of this mass
some of it to atmosphere, through the flue, before
the thermostat responds and starts the cycle once
ag:

Low water COP+~

,&&nt coupled with light weight means
that we have a low mass resulting in a flexible and
responsive appliance, having efficiencies of 78% -

80%.

Since a boiler providing central heating is designed
to maintain room temperatures at an adequate
level when the outside temperature is - l°C -

(30°F) it follows that the boiler will only be
working under its design conditions for a few days
in the year, for the rest of the time it will cycle due
to its output being greater than the demand. With a
high mass boiler it is necessary on each cycle to heat
not only the water content, but the whole surround­ing mass of metal. High mass boilers show a marked
drop in efficiency when working under part load
conditions. Low mass boilers, like the Chaffoteaux
boiler, show only a very small drop in efficiency
between full load and half load, between 3% and

4%. In a high mass boiler the drop in efficiency is

more usually about 20%. It has been suggested that

a domestic boiler works 80% of the time at about
30% of load, part load efficiency is therefore
vitally important.

Today with the continual raising of fuel prices and
the depletion of natural resources, it makes sense
to use low water content boilers.

Our boilers are suitable for either open or sealed
systems but because of their construction must be
used on fully pumped systems. All commonly used

external system controls can be used.
This Guide is not a substitute for Installation and

Servicing Instructions which accompany each
boiler. Before going ahead with your first installa­tions please study that booklet.

This publication is not intended to be a text book
on central heating but, it is hoped that the informa­tion it contains will help the reader understand our
appliances and that the tables and data will be of
daily use.

2 PRINCIPLES OF OPERATION OF

CHAFFOTEAUX ET MAURY APPLIANCES

2.

PRINCIPLES OF OPERATION OF
CHAFFOTEAUX ET MAURY APPLIANCES

The operation of all Chaffoteaux domestic range
boilers is the same, the units depend on water flow
through the appliance for their operation. It is a
safety feature of the boiler that it will not fire
unless there is a sufficient flow of water.
The minimum flow rates for all models are such
that the boilers can only be used on fully pumped

systems and not with gravity systems.
Water enters the boiler via the return pipe and flows
through the heat exchanger. It then enters the
vent’4 (1 ), across the thermostat (2) and out of
the w pipe (3). When the boiler is firing the

the

stat capsule (2) closes a by pass (5) and the
venturi creates a pressure difference in the water
section which lifts the diaphragm (6) against the
gas valve spring (7) pressure. When the temperature
of the water reaches the pre-set value of the
thermostat capsule the capsule lifts off its seat (2a)
and allows the by pass (5) to open. The pressure
difference across the diaphragm is equalised and
the gas valve spring closes the gas valve. The shapes
of the gas valve and thermostat capsule ensure a
modulation of the burner flame.
The thermostat capsule operates at a pre-set
temperature of 82°C and no adjustment is necessary.
The range of boilers utilise a non-electric multi­functional control that provides all the necessary
interlock features required by current Standards.

With the consumer’s control in the ‘off’ position

(A) no gas can reach the pilot or main burner
i;res,

:ive of the operation of the water section.

Wht

;ie consumer’s gas control is turned to pilot

position (B) gas is allowed to flow to the pilot head
and simultaneously a spark is produced

to

ignite
the pilot flame. The pilot flame heats the thermo­couple (8) which energises the electromagnet (9)
holding open the thermoelectric valve. When the
pilot is established the consumer’s gas control can
be turned from the pilot to the main gas position
(C) allowing gas to flow to the underside of the
main gas valve (10). The operaticn of the water
section will now determine when gas is allowed
to flow to the burner.
The boilers incorporate standard safety features
throughout the range:-

i) The water section only allows the gas valve

to operate when the correct flow of water is
passing through the appliance.
NO WATER FLOW MEANS NO GAS.

ii) The thermocouple and thermoelectric valve

ensure that no gas can pass to either the
pilot or main burner in the event of pilot
failure.

iii) A high limit temperature overheat is provided

in the form of a fusible link (11) which, if
ruptured, interrupts the circuit to the thermo­electric valve and isolates gas from the pilot
and main burner.

iv) An interlock is provided so that, if the pilot is

extinguished for any reason, the boiler can
only be refired by repeating the lighting
sequence. The relighting sequence can only be
attempted after a delay of about one minute.

VENTURI

FROM HEAT
EXCHANGER

THERMOELECTRIC VALVE

GAS & WATER SECTION

TO BURNER

t.

FLOW TO SYSTEM

DIAGRAMATIC ONLY
NOT TO SCALE

HEAT LOSSES

3. HEAT LOSSES
Before a central heating system can be designed it

is necessary to define the parameters on which the
design is to be based.
The consumer should be made aware that once

installed it will not be possible to increase the

internal ‘temperatures without the installation of
additional heating media.
Generally, in the UK, domestic heating provides
agreed internal temperatures at an external tempera-

ture of - 1°C (30” F).

It may be necessary to consider a lower design
temperature in Northern England and Scotland, or
if the property is on the coast or exposed to high
L

k.

I. * current recommended internal temperatures
and air change rates are given in Table 2. Where
bedrooms are likely to be used as a study or play­room it is as well to provide a higher temperature
of, say, 18°C (65°F).

TABLE 1.

(BS 5449 Pt. 1: 1977)

Temperatures and rates of air changes on which

heat loss calculations should be based.

* These temperatures will only apply for whole

house central heating and for heated rooms
with part house central heating.

t Local building regulations may require a specific

rate of air change for particular rooms.

tt When used part time as bedsitting rooms or for

study purposes additional means should be
provided for maintaining a higher room tempera­ture.

9 Where continuous mechanical ventilation is

provided due allowance for the greater change

should be made.

Perhaps at this stage it is as well to remember that

mar’, of the mechanical aids available and the ‘rule

Of

lb’ methods are less than accurate and could

result in user dissatisfaction and in the final analysis

*

there is no substitute for proper heat loss calcula­tion. This has the added advantage of highlighting
the areas of greatest heat

loss

and gives the designer

the opportunity to consider additional insulation.

It also brings to the designer’s attention, by high-

lighting areas of greatest loss, the positions for
radiators.
The heat loss of a room is based on three criteria:-

1) Area of components of the structure - walls,
windows, floor, ceiling.

2) The conductivity of the component (expressed
as a ‘U’ value).

3) The temperature difference between the two
faces of the structure.

Common ‘U’ values are set out in Table 5. and
worked example is shown.
An alternative to using a lower external temperature
for properties in exposed positions is to use a per­centage addition as set out in Table 2.

TABLE 2.

I

Orientation

I

Normal

1 Exposed 1

NORTH

10%

20%

EAST

10%

15%

WEST

5%

10%

SOUTH

-

5%

Before commencing the calculation carefully note:-

1) Orientation N. S. E. W. facing.

2) The construction of the building component.

3) The measurements of the component.

4) The temperature of adjacent areas.
In semi-detached and terraced houses the prudent
designer cannot assume that the adjoining building
will be heated to a certain standard and it is
customary, in these circumstances, to assume a
temperature in adjoining areas of 4O (40°F).
As well as the losses through the structure, heat
is lost through the air changes in the room. Air
change rates are given in Table 1.
To obtain the heat loss by ventilalation multiply:-

Volume of room in m3 or it3
by

number of air changes/hour (from Table 1)
by

factor given in Table against the temperature
difference fI T external to internal air.

TABLE 3.

TABLE 4.

I

Temp difference A t 1 Factor 1

I

12 I

0.0036 1

t

I

19 1

0.0057 I

I

22

I

0.0066
I

Temp. difference A t

Factor

in “F

20 0.386
25 0.460
30 0.552

1

I

40

I

0.736

I

EXAMPLE
(based on Table 3.)

Room 3 m x 4 m x 2.4 m = 28.8m3

2 Air changes - 22°C t

28.8 x 2 x 0.0066 = 0.380 kW

EXAMPLE
(based on Table 4.)

Room 9.84 ft x 13.12 ft x 7.87 ft = 1016 ft

2 Air changes - 40” F t

1016 x 2 x 0.736 = 1495 btu/h

TABLE

5. Building Heat Losses

HVCAhHVE Guide to Good Practice

Usi = The number of watts that will flow through

Uimp = The number of btu/h that will flow through

each square metre for each degree C.

each square foot for each degree F.
difference between the internal and ex­ternai temperatures in the case of external
walls, or in the case of partition walls
between the temperatures on either side
of the wail.

I‘ 351 ” (13% ” )

Cavity (two leaves brick, air space

and 16 mm. plaster)

Both leaves brick (11” nominal)

As 5, outer leaf 220 mm.

(9” nominal) brick

Cavity as 5, inner leaf 100 mm.

(4”) insulating concrete

As 7, outer leaf 220 mm.

These U values are
average figures and
apply to most suburban
and country dwellings.

For North and North-

East exposures on hill
sites, at the coast or
at riversides, however,

Single glazed, wood frames

105 mm. brick, plastered 16 +

16 mm. (4%” nominal)

220 mm. brick (9” nominal)

! Item

19

20
21

22

23
24

25
26
27

28
29

30
31
32

33
34

35
36

L-

37
38

CONSTRUCTION

Usi

Uimp

Remarks

Plaster ceiiing, asphalte on

100 mm. (4”) concrete

ROOFS (pitched)
Tiles on boards and felt
Plaster ceiling, roof space above,

tiles on battens

tiles on boards and felt

Plasterboard ceiling, roof space

above

3.41 0.60

2.75

0.48

2.98 0.52

1.92 0.34

tiles on battens and felt

No insulation between joists
25 mm. (1”) glass fibre between

joists

50 mm. (2”) glass fibre between

joists

A

The full difference
between internal and
external temperature
should be taken.
Allowance has been
made for the fact

that the underside

temperature will be
higher than the
external temperature.

75 mm. (3”) glass fibre between

joists

50 mm. (2”) vermiculite between

joists

2.50

0.44

0.90

0.16

0.55

0.10

0.39

0.07

0.88

0.15

GROUND FLOORS
Ventilated wood floor on ioists,

air brick on one side

bare boards
parquet, lino or rubber

Air brick on more than one side

bare boards
parquet, lino or rubber

Solid floors in contact with earth

0.61

0.11

0.59

0.10

0.82.

0.14

0.68

0.12

0.36

0.06

These heat losses are
for a medium 15 x 7.5
metre (1000 ft.2 1 plan
detached house.
Decrease by 50%
for a terraced house.
Increase by up to 25%
for a small house of
5 x 10 m. (500 ft.2) plan.

INTERMEDIATE FLOORS
Wood floor on joists, plaster
ceiling

downward transmission
upward transmission

Concrete 150 mm. (6”) with

100 mm. (2”) screed

downward transmission
upward transmission

Concrete 150 mm. (6”) with

wood flooring

downward transmission
upward transmission

1.50

0.26

1.70

0.30

2.20

0.39

2.70

0.48

1.70

2.00

0.30

0.35

Effect of Fabric insulation

The following tableshows examples of the approxl-

mate reduction in heat flow resulting from insula-

tion:-

IFabric/ Type of 1 Reduction of 1

Ceilings

Cavity wails

Insulation

3” glass

fibre

foam

heat flow

80%

Susoended

insulation

2

,I

-EXAMPLE OF HEAT LOSS CALCULATIONS

-A

N

W

E

I 3 *..m I I

Temperature in
adjoining area

16°C (60” F)

Temperature in

5 I I 0

I

0 0

I’

0 0 0 2.59 m

- I I I--I------II- IS.5 ft)

‘U’ value S.I.

‘U’ value Imp.

SEE TABLE 5

w/m2 /“C btu/ft2 /” F

I

External walls 11” cavity

(un-ventilated)

1.50 0.26
,

I

Internal walls 3” breeze plastered both sides

2.25

Window - single glazed, wood frame

4.30

0.79

Ceiling - wood floor above ceiling, plastered

1.70 0.30

I

I

I

Floor - solid

I

0.36

I

0.06

I

Exposure - Normal.

internal temperatures 21 “C (70°F) @ - 1 “C (30°F) external.

EXAMPLE
Heat loss - SI units

Component

Area

A t

Construction

‘U’

Loss

from Table

Wall N 4.26 m x 2.59 m 11.03m2 22 4 (1.5+ 10%) 400

1.65

Wall W (3.66 m x 2.59 m) -(window) 7.29m2 22 4 (1.5+ 5%) 252

(2.19 m2)

1575

Heat Loss - IMP. units

Component

Area

A t Construction

‘U’

Loss

from Table

Wall N

14’ x 8.5’ 1 19 ft2

40

4

(0.26 + 10%)

1333

A 90

Wall W

(12’ x 8.5’) - (window)

78 ft2 40

4

ICI . A’\

1 U.LO

I

1 (0.26 + 5%) 1

842

I

.

IO x41

0.27

Wall E 12’

x 8.5’

102 ft2

Nil

- -

Wall S 14’

x 8.5’

119 ft2

5

15 0.40

238

,O

9 0.79

758

168 it2

1 40 32

0.06

403

16Rft2

I lfl .34

0 30

wM

Glass 6’ x

4’

24 ft2

1 4

Floor

14’x 12’

Ceiling

14’x 12’

.-- --

- -

.

t

-.--

I

V”T

Air change 14’

x 12’ x 8.5’

1428 ft3

1 40 1

- 1 Factor from

1 1052

I

lx

I I I

(Table4 0.736

5129

btu/h

‘JB The very small discrepancy is due to ‘U’ values & dimensions being worked to 2 places only

SYSTEM DESIGN

4

4.1 RADIATOR SELECTION

Having determined, by calculation, the heat losses
it is the time to select a radiator/heat emitter

to

satisfy the heat loss.

Radiator manufacturers, in their catalogues,
generally show an emission based on mean water
temperature 170” F.
On full load the temperature difference across a
Chaffoteaux boiler is 20°C (36°F) i.e. a flow
temperature of 82°C (180” F) and a return tempera­ture of 62°C ( 144” F). The mean water temperature

is therefore

‘F = 72°C (162°F)

It is, therefore, necessary to adjust the radiator size

in order to achieve the required output and the

multiplying factors are shown in Table 6 and a
worked example is also given.

TABLE 6.

1

21°C

I

1.08

J

EXAMPLE

Room Heat loss

for 21 ‘C/70” F
7018 x 1.08

=

7018 btu/h

7579

Select radiator with output of 7579 btu/h. @ 55°C

(100°F) AT.

are taken to the source of the greatest heat loss. See

Fig. 1. By so doing one can avoid col’d draughts at
low level. The word ‘radiator’ is a misnomer, for a

radiator is, in the main, a convector, approximately
70% of the output is in convected heat and only
30% in radiant heat.

Radiators should be placed on wallswith a minimum
distance beneath them of 4 in. No shelf, sill or
other obstruction should be closer than 2 in. above
and should not protrude more than half the width
of the radiator. If it does an additional 10% should
be added to the output to allow for this. Ensure
there is no obstruction to the passage of air over the
rear surface of the radiator, i.e. protruding skirting
board, mouldings etc.
Where full length curtains are likely to be closed in

front of a radiator it must be remembered that a
space of 4 in. should be left in front of the radiator

to allow passage of air across the front surface.

Likewise there should be a 4 in. space between the

bottom of the curtain and the .floor and a similar
space at the top. See Fig. 2.

To obtain the best entrainment it usually, but not

invariably, means that radiators are placed under,

or adjacent to, windows.
When a shelf is used because a radiator is on an

inside wail and it is

necessary

to make a provision
to prevent ‘pattern staining’ (dust entrained in the
rising air stream which is deposited on and discolours
walls above radiators) recommendations are shown
in Fig. 3.
We have also shown various types of radiator
enclosure and the suggested additional output for
which allowance should be made. See Fig. 4.

In large or irregular shaped rooms two or more
radiators should be considered to provide the best
comfort conditions.

Radiator Positioning

The best air ‘entrainment’ is achieved if the radiators

HEATED AIR

/

DISCOMFORT

f

FULL LENGTH

RADIATOR SHELF + 5% to 10%

WINDOW

RADIATOR

FOAM SEAL
BETWEEN

SHELF &WALL

FIG. 2.

FIG. 3.

ENCLOSED RADIATOR + 20% to 30%

tici.

4.

ACCESS FOR AIR

GRILLE

NB. Make provision for access to valves.

Provide access for venting radiator.

4. 2 PIPE

SIZING

Chaffoteaux boilers are suitable for either one pipe
or two pipe systems but, in each case, the pipework
must be correctly sized.

1)

So that there is sufficient volume of water

passing through the radiators compatible

with their output.

2)

So that there is a sufficient flow of water

through the boiler so that the boiler achieves
full flame.

3)

So that the total system resistance falls
within the range of the domestic circulators
(pumps) available.

The deficiency with a one pipe system is that there
is a temperature drop as the circuit progresses. The
last radiators on the loop will receive cooler water
than the first and, therefore, the mean water tem­perature will be lower so it will be necessary to in­crease the radiator size to achieve output. Generally
a one pipe loop in 15 mm should not be designed
to carry more than approximately 20,000 btu/h.

A one pipe circuit is illustrated in Fig. 5.
There are available single entry radiators which are
suitable for one pipe systems when used in conjunc­tion with a special radiator valve which incorporates

4)

So that the water velocity in any part of the
system does not exceed 1 m/set, (3ft/sec) for
small boreand 1.2m/sec, (4ft/sec), for micro­bore.

a by-pass.

FIG. 5.

P

ONE PIPE SYSTEM

I

J

RADIATOR

BOILER
ISOLATING

. ..-

VALVt m

7

BOILER

%AX 150 mm

(6 ins)

-

‘rn

TAILS SHOULD BE AS
SHORT AS POSSIBLE

I

RADIATOR

RADIATOR

A

\

I

PREFERRED ARRANGEMENT SWEEP 7’
IN DIRECTION OF WATER FLOW

BETWEEN Ts SHOULD BE AT LEAST
EQUAL TO THE

LENGTH OF THE RADIATOR

FIG. 6. FIG. 6.

TWO PIPE SYSTEM

TWO PIPE SYSTEM

FIG. 7.

RADIATOR RADIATOR

BOILER

I

I

SECTION 1

SECTION 2

I

I

SECTION 3

I

i

TWO PIPE - REVERSED RETURN

RADIATOR

RADIATOR RADIATOR RADIATOR RADIATOR

I I I I I

lllll

1

A

\

-

I

I

-

\

I

-

NE. In a revened return wstem the pipe resistance to each

radiator is the same. No balancing is usually required.

The preferred layout is a two pipe system. It will

be seen that the volume of water which flows in

Section 1 is greater than that in Section 2 which

itself is greater than in Section 3. The size of the
pipes should take this, into account. Two pipe

systems are illustrated in Figs. 6 & 7.

This would seem an appropriate time to remind
ourselves that pipework should be graded towards
the radiators and the open vent. Any inverted loops,
which should be avoided are provided with an air
vent and provision is made at any low point to

drain the system.
Where practicable pipes should be fitted clear of
timber joists. If a joist is notched it should not
exceed 15% of the depth of the joist. (10” joist

maximum depth of notch 1 Y’z”).

Notches in the same joist shall be at least 4” apart
horizontally. Notches should be lined with pads of
felt to minimise noise. Consideration should be
given to the inclusion of protective saddles to
prevent damage by nails.
Pipe fixings and supports should be fitted at

intervals not exceeding 1.8 m (6 ft.), in exposed
or vulnerable positions the interval between pipe
fixings should not exceed 1.2 m. (4 ft.).
Pipework passing through structure should not be
built in but should be provided with a sleeve.
All pipes not emitting useful heat should be
insulated.

Before the pressure drop (resistance) of the system
can be calculated it is necessary to establish the
volume of water required in the various circuits.

The flow in Ibs/h is derived from the following

formula:-

Circuit heat output (btu/h)

= Water flow in Ibs/h.

Temperaturedifference (36°F)

When working in S.I. units the flow rate is expressed

in kg/set and is derived from the tollowing:-

Circuit heat output in kW x 0.238 = kg/set
Temperature difference (20°C)

The velocity in small bore copper pipes should not
exceed 1 m. set (3 ft. set).
The resistances for straight pipes are given in Tables
9 & 10. It is also necessary to know the resistance
for fittings. The best way of calculating this is in
terms of equivalent length of straight pipe.
Some of the more usual fittings are shown in Tables

ll& 12.

The equivalent length for reduced ‘T’s motorised

valves, radiators etc. can be obtained from the

manufacturer’s literature.
There are two worked examples, one for a one pipe

system and one for a two pipe system.

Velocity

in

excess

of3m

secretary

Velocity

in

excess

of1m

secretary

Size

RESISTANCE OF PIPE FITTINGS

TABLE 11
Expressed in equivalent length of straight pipe in metres

I

Equivalent length

in feet

I

Type of fitting

TABLE 12
Expressed in equivalent length of straight pipe in metres

Valves

Equivalent length in metres

Type

of fitting 15

22 28

Straight

0.30

0.30 0.60

Angle 1.6

4.3 6.00

Copper elbow

Capillary

0.60

1 .oo

1.30

Compression 0.30

0.30 0.60

Tee branch

Square
Sweep

I I

1 .oo

1.60

2.00

0.60

‘1 .oo

1 .oo

EXAMPLE

ONE PIPE SYSTEM

5000 btulh

A one pipe system has load of 17,000 btu/h.

Temperature difference is 36°F.
System has 80’ of 15 mm pipe.
Heat emission from 15 mm pipe assuming 90°F
above room temperature is 36 btu/h per ft. ­Table 7.
Therefore heat load = 17,000 btu/h + (80 x 36
(pipes)) = 19,880

From table by interpolation resistance at

552 lb/h = 0.29 in p.ft.

Fittings 6 sweep Ts Eq. L

12 ft of pipe

12 elbows

#I

24 ft of pipe

6 angled valves

”

30 ft of pipe

3 straight valves

” 3 ft of pipe

Equivalent length of fittings

69 ft of pipe

Actual lencth of oioe

80 ft.

Water flow =y = 552 Ibs,h

Total pipe & Fittings

149 ft

Resistance = 149 x 0.29

= 43.5 in or 35

ft 7.5 in head.

’ TWO PIPE SYSTEM

8 ft.

q

I

I

4 .8000 btulh

I I

SECTION 6

Consider layout and determine the index circuit.
The index circuit is the circuit with the highest
resistance which often means the circuit with the
highest load.

Index circuit is ground floor circuit to rad. 3.

Section A - (Rad. 3 to junction Rads. 4/5)

Load for rad . . . _ . . . . . . . . . . . . . . . 16,000 btu/h

! d for pipes 30 ft of unpainted 15 mm pipe

Room 70” F - mean water 162“ F

Therefore temp. difference

A t =

92:

F

Emission from pipes from Table 7.

(90°F

At

= 36 btu/h/ft)

(99OF

A t

= 41 btu/h/ft)

By interpolation

92°F

At

= 37 btu/h/ft

30 ft x 37 btu/h/ft . . . . . . . . . . . . . 1,110 btu/h

Total Load for section . . . . . . . . . . . 17,110 btu/h

Convert to Ibs/h 17,110 btu/h = 475 Ibs,h

36”FAt

From Table 9. resistance of 15 mm pipe=0.22

in.w.g. per ft.

Length of pipe = 30 ft

(Equivalent length of fittings)

4 elbows = 8ft
2 L valves = 2ft

c

/alent length of pipe

I section

= 40 ft

Resistance in section = 40 x 0.22 in = 8.8 in.w.g.

Section B

Load - Previous Section

. . . . . . . . . 17,110 btu/h

Rads4 & 5 . . . . . . . . . . . _. . . . . . . . 11,000 btu/h

Pipes46 ft. x 37 btu/h . . . . . . . . . . . . 1,702 btu/h

29,812 btu/h

Convert to Ibs:- 29812 btu/h = 828 Ibs

36At

15 mm pipe resistance 0.58” per ft.
Length of pipe

= 24 ft. (No fittings).

Resistance = 24 x 0.58 = 13.92 in.w.g.

Section C

Load -

Previous sections . . . . . . . . . 29,812 btu/h

Load for 1st floor:-

Rads . . . . . . . . . . . . . . . . . . . . . _ . . . . 7,000 btu/h

Pipes - 76 ft. x 43°F per ft. . . . . . . . . 3,268 btu/h

Since room temperature is lower

At

is higher.

Therefore pipe emissiokhigher.

Room 60°F - Mean water 162°F

At=

102°F

Load for section . . . . . . . . . . . . . . . . 40,080 btu/h

Convert to Ibs:- 40080 btu/h

36At

= 1 l 1 3 Ibs

(Max. load in 15 mm 1100 Ibs use 22 mm pipe)
22 mm pipe resistance at 1113 Ibs/h = 0.17 in.w.g./ft.

Length of pipe 10 ft x 0.17 = 1.7 in.w.g.

. .

Section D

Load - previous sections . . . _ . . . e . 40.080 btu/h

Hot Water. . . . . . . . . ; . . . . . . . . . . . . 8,000 btu/h

Pipes 15 mm 20 ft x 37 btu/ft. . . . . . . . -740 btu/h

Pipes 22 mm 14 ft. x 34 btu/h/ft.

. . . ; -630 btu/h

49,450 btu/h

Convert to Ibs 49,450 btu/h = , 373 ,bs

36.At ’

Length of pipe ‘14 ft. x 0.21 in.w.g./ft. = 2.9 in.

SUMMARY
Total flow 1373 Ibs/h.

1 gal. weighs 10 Ibs.
Flow in system = 137.3 gph

= 2.28 gpm

Resistance =

8.8 in.

13.92 in.

1.7 in.

2.9 in.

17.32 in. = 2.27 ft.

Minimum required flow through Maxiflame boiler
is 2.6 gpm at which the head loss = 5.5.ft.

.

Required pump duty = 2.6 gpm against head loss.

of 7.77 ft.

FIG. 8.

.

MICROBORE SYSTEM

BOILER

L

e

.:,.:

-.

ZAX
15Omm
(6 ins)

SMALL EORE PIPES
MICROBORE PIPES

Chaffoteaux boilers are suitable for use with micro- housing. The pipework can be laid in the screed,
bore systems. The essential feature of a microbore

with proper provision for insulation, lateral and

system is that each radiator is connected in parallel

linear expansion and of course draining. The advan-

back to a central manifold using 6 mm, 8 mm, or

tages are that lengths can be laid without there

10 mm soft copper pipes.

being joints in the screed.
A typical system is illustrated in Fig. 8. Pipe losses
and resistances are given in tables 13, 14 & 15. A
worked example is also provided.

The velocity in the pipesshould not exceed 4 ft/sec.

- 1.2 m/set.

The advantage of microbore systems is more evident

in new housing with solid floors than in older type

TABLE 13

TABLE 14

Microbore

Flow of

water

at

150°F

through

copper pipes.

Microbore

’ Flow Rate
1 kc/s

Bminal pipe size OD

8mm 10mm 12mm

182 46 21
210 55 28
245 68 34
285 81 40
325 94. 47
360 107 53
405 120 60

1 ~4485

1325 536

1670 665
2030 795
2410

925
2830 1080
3280 1235
3780

1408

­1710 ’
1860

T.. 2030

: 2220

2365
2540

r 2785

Velocity

1.5 m/s .

Loss of head

:__

per 1 foot run in inches :

Flow Rate

WG (62°F)

lb/h

Pipe size -

6mm o.d. 8mm

o.d.

IlOmm o.d.

50

0.86

0.20 I n 05

-.’

60

1.10

0.24 0.06
70 1.38 0.29 0.08 m,
an

171

0.10.

90’

2.08 0.41 012

100 2.51

0.47 : 0:“14.

110 2.98

0.55 1 Of16

120 3.48 0.65 1 0.110
130 4.02 0.76 I IT91

In the absence of data

I

this table can be used

for light gauge steel

pipes
If an approximation,
based on velocity, is

TABLE 15
Microbore

I

Type of fitting Equivalent length

6mm 8mm 10mm

Two angle valves or one twin angle vaive

5.00 6.00 9.00

Minimum radius smooth bend

0.25 0.25 0.50

Manifold connection

2.00 2.00 3.00

r

\

EXAMPLE

MICROBORE

7,000 btu/h

“PPElA FL!OOFl

IIIlI[

;.

--

- EQihV. OF 20 ft.

EQUIV. OF 40 ft.

OF 22 mm TUBE. OF 22 mm TUBE.

Section 1

Load - Rad & pipe losses 7,000 btu/h

Flow in Section 4 7 000

L = 194 Jbs/hr

36OFAT

Resist, 0.4 in.w.g. per ft.

60 x 0.4 = 24

in.

Section 2

Load - Rads & pipework

22,000 btu/h

Flow in

section 22,000 = 611 Ibs,h

36”FAT

Resist. 0.034

in.w.g. per ft.

40 x 0.034 = 1.36

in.

Section 3

Load - Rads & pipework

30,000 btu/h

Flow in section 30,000

- = 833 Ibs/h

36OFAT

Resist. 0.09 in.w.g. per ft.

20

x 0.09 = 1.8 in.

System requirement 1.38 g.p.m. against 27.16 in.

4.3 PUMP SELECTION

Having designed your circuits and selected the pump

by reference to the pump manufacturer’s graphs,
the pump position relative to the cold feed and
open vent must be decided.

it is essential that the designer ensures that:-

1) Water is not expelled over the open vent.

2)

No part of the system is under sub-atmospheric

pressure.
The point at which the cold feed enters is called
the neutral point.
At this point the pressure is constant and is not
affected by the flow of water round the system. At

all other parts of the system the pressure is a
combination of the pump head plus the static head.

By reference to the pump manufacturer’s graph

against the flow rate for the system, the available

head will be indicated. This is the head available on
the outlet to the pump. This head is gradually
reduced by the resistance of the system until one

arrives at the inlet side of the pump. Most pump
manufacturers require a minimum of 6 ft. static
head at the pump inlet.

PUMP PERFORMANCE AT 240V 82’C

1

(180°F) >

Q)-

-7-F
E

t

t;’
~~

LITRES SEC 0.5

1.0

_ 1.6;~

I

GPM

)” 8

I I

I

12.

16r;

‘i&g

_‘.

1.2 gpm

; :

FIG 9.

Fig. 9 shows the graph for a typical domestic pump.
Let us assume that the heating load is 26,000 btu/h.

The volume of water we will require the pump to

pass will be:-

Flow rate:

26,000

btu/h = 722 ,bs,h

36°F temp. diff.

72

Ibs/h

-1 .i;iats per
‘.

10 (Ibs in gal) x 60 (minutes)

.fnin. (GPM).

~ “- I -.

At ,I .2 .GPM available head on setting-4 :is approx.

14ft.

.: . .

At .1.2 GPM the head loss

through

the boiter is 4 ft.

of head.

Let us also assume that the system resistance is
5 ft. of head.
Figs. 10 to 13 show the pump in various position ,..
relative to the cold feed and open vent.

Since the temperature at which water boils is’
directly dependent upon pressure - the-higher the
pressure the higher the boiling point..See*Tabte 16.

If -the water in the heat exchanger approaches’

boiling point or actually boils the results are boiler
noise (kettling) or possible damage to-the heat.
exchanger. It is, therefore, important. to obtain
the highest possible pressure in the boiler.

System 1 The pressure at the open vent is always

higher than the static head so the system
will always pump over.

System 2 Pressure in boiler is always less than the

static head. The open vent will suck in
air when the static head is 4 ft. or less.

System 3 Open vent pressure is always the same

as the static head so no pumping over or
air sucked in.

System 4 Preferred position - Highest pressure in

boiler. Open vent pressure always the
same as the static head - no:pumping
over or air sucked in.

.

--H-==-l

Ii-7

mwr------ ----

I-

FIG. 10.

‘1 PRESSURE AT

&- BOILER OUTL,ET

1

j *-

I

I

! ,I

I _ _.. .I.
1

_..

I

I

(~+p==y

801 LER OUTLET

FIG. 11.

, FIG. 12.

FIG. 13.

TABLE 16

Atmospheric pressure 14.7 psi.

4.4 COLD FEEDS AND OPEN VENTS

The movement of water in the open vent is relative
to the circuit resistance between the cold feed and
open vent - the lower the resistance the lower the
risk of introducing aerated water into the system
when the pump starts and stops. For this reason
Chaffoteaux recommend that the cold feed and
open vent are placed within 6 in. of each other on

the inlet side of the pump. The .order in which
connections are made is not critical but the pre­ferred order is cold feed, open vent, pump.

Preferred layouts are shown in Figs. 14 to 16.
Since one of the functions of the open vent pipe is
to vent to atmosphere air circulating with the water,

it is recommended that a low velocity point is
formed. It should be appreciated that, if the open
vent connection is made horizontally into the side
of a pipe, then it is unlikely that the air will be
vented. See Fig 18. The open vent pipe MUST rise
throughout its entire length from its junction with
the system to atmosphere over the expansion tank.

1

Boiling “C ’

113.4

116.2

118.7

It is strongly recommended that an arr separatoc
is used. Their efficiency is due to the reduction in

the water velocity and to the special,

movement.

given

to the

water.

They are

most:.efficient in

reducing commissioning time and

pump failures

and adding to the life of the boiler.

.‘- J

1 ..a- ., ‘.

,. v

As a minimum an expanded ‘T’ should

be

used.as

Fig. 17.

“. g:.,< ..,

Chaffoteaux recommend that the pump is- placed
in the return. In this position, with” the-. cold
feed and open vent entering on the low pressure

side of the pump as illustrated, one achieves the

following:-

1) Avoids pumping over and air entrainment.

2) Pump in coolest water-for better performance.

3) All the system will be under positive pressure.

4) Highest pressure in the boiler.
The effect of high pressure in the boiler is to ir
crease the boiling point of the water and avoib

kettling.

.

COLD FEED AND OPEN VENT CONNECTIONS

ARATOR

22 mm OPEN VENT

-a

22 mm OPEN VENT

i

FIG. .14.

i-

FIG. 16.

-7

._

MAXIMUM DISTANCE 150 mm

(6 ins)

“. ,:..r.

FIG. 15.

22 mm OPEN VENT

15 mm COLD FEED

28 mm ‘T’ (EQUAL) WITH ALL
BRANCHES REDUCED TO 22mm

.-.

7: . . ..

LOW VELOCITY POINT
FORMED IN STRAIGHTL
PIPE.

COLD FEED AND OPEN VENT CONNECTIONS

OPEN VENT

COLD FEED

SYSTEM P IPEWORK

WRONG

WRONG

OPEN VENT

:.- . . . . . *

.a.-....

.

v

..:. - .-*.::

;.:.z.z.- . . .

. . . . .-.’

.

.:..=:.~.y

‘.:::~~~~‘~

.a.-

SYSTEM PIPEWORK

FIG. 19.

RADIATORS

WITH LOCK-

4.5 BY PASSES

It is recommended that an adjustable by pass is
fitted with Chaffoteaux boilersand this is illustrated

in Fig. 19. This is also a British Gas requirement
with all low water content boilers.
The purpose of the by pass is to ensure that there

is under all conditions a sufficient volume of
water circulating through the boiler to enable it
to function. This is particularly important in a
system utilising thermostatic valves or where hot
water control is via a mechanical valve which
closes progressively.
The method of adjusting the by pass is set out in
the installation instructions for all our appliances
and is reproduced below.
“To set the system by-pass, close the by-pass valve
and turn off the required number of radiators to
suit the customer’s minimum needs then open the
by-pass until the boiler lights.”

4.6.1 EXPANSION TANKS

In an open system the feed and expansion tank
performs two functions. It allows the system to fill

and automatically replenishes water lost through

.,.
.;

evaporation and minor undetectable leaks. It also.
accepts the expansion of the system watercontent.
Water, when heated, expands in volume approxi­mately

l/2oth

of its cold volume.
The following notes are a guide to installation
requirements.

1. Cistern water volume should not. be less than
4 gallons.

?

2. Cistern must accept expansion vofrlme :of
system -

(‘/zoth

of water content of system)
between the water level cold and -a point not
closer than 25. mm (1 in) below-the-overflow,
connection.

3. Overflow should be 62.5 mm (2%. in) below
entry of cold mains.

‘.,.

4. Stop cock should be fitted adjacent tocistern
on mains and should be of BS 1010 pattern.

5. The tank should be supported over whole ara­of base.

,.

6. Tank should be provided with lid.

. .,‘1

7. Tank, if in unheated area, should be insulated
over sides and top - not bottom.

:

IA ‘.‘3 ’

.:-

8. Pipes should be insulated.

_‘.

9. Ball valve should be ‘high temperature’;:

,’ ‘i.

FIG. 20.

EXPANSION TANKS

MAINS WATER

OVERFLOW

___.~. --~

-

-

MIN 22 mm

.-.

_-

NOT LESS THAN 25 mm.

-.- - -

WHEN SYSTEM HAS

E

. .

4.6.2 EXPANSION VESSELS
SEALED SYSTEMS

On the Continent sealed systems are the accepted
method of installation. The restriction in the UK is
that it is not possible, at the present time, to make
a permanent connection to the Water Authority
main for filling and refilling.

The basic concept of a sealed system is that a
sealed vessel with a flexible membrane replaces

the expansion tank. The vessel must be capable of
accepting the expansion volume when the water
temperature rises. The vessel is divided into two
compartments separated by a membrane. On one
side is the system water, the other is charged with
either nitrogen or air.

The position for the vessel must be on the low
pressure side of the pump.

The advantages of a sealed system are:-

1. Reduction in labour and material costs.

2. The elevation of the boiling point of the water,

thereby eliminating boiler noise (kettling).

3. Air does not enter the system, thereby minimis­ing the problems of corrosion.

4. No cold feed, open vent or expansion tank.

5. Where static head is limited, i.e. flats.

Chaffoteaux boilers are designed, and British Gas
approved, for sealed systems and are supplied, and
fitted with a high temperature safety device as

standard.

Before selecting a vessel it is necessary to decide

the charge pressure this is usually the pressure to
support the static head of the system above the
vessel. If the boiler is the highest point on the
system the charge pressure should be adequate to
support the static head to the top of the.boiler

plus whatever is the minimum static head required,

by the manufacturer, at the boiler. In this connec­tion we recommend that the static head plus .I0 ft.

is adopted for all our domestic appliances.

. .

Vessels are generally available with charge pressures
of 0.5 bar to 1.5 bar.

0.5 bar = 7 psi = 5 metres of head = 17-ft:head

1 .O bar = 15 psi = 10 metres of head = 34ft. head

1.5 bar = 22 psi = 15 metres of head = 50 ft. head

The correct size of vessel is important, the-size is

relative to:-

1. System water content.

2. Initial charge pressure. Final operating pressure.

3. The boiler flow temperature.
The system water content can be obtained by

reference to Table 17.
Chart for vessel sizing is given in Table 18.

TABLE 17

For the purpose of the calculation, the volume of
the system shall be determined as accurately as
possible using manufacturers’ data as appropriate.
Alternatively the volumes given below may be used
to give a conservative estimate of the system volume:

Conventional cast iron
boiler

10 litres (2.2 gallons)

Low water capacity

boiler

3.5 litres (0.8 gallons)

0.3 litres (0.07 gallons)

Small bore

per 0.292 kW (1,000 -

pipework

btdh) of systems
output

Microbore pipework

7 litres (1.5 gallons)

2.3 litres (0.5 gallons)

Steel panel

per 0.292 kW (1,000

radiators

btu/h) of system

output

0.5 litres (0.1 gallons)

Low water 0.292 kW (1,000

capacity radia:ors

btu/h) of system
output

Hot water cylinder

a system is extended an expansion vessel of in­Lreased volume may be required unless previous
provision has been made for the extension.

(B.G.C. Materials Installation Spec. 3rd Edit.)

calorifier

2 litres (0.44 gallons)

TABLE18

Sizing procedure for expansion vessels - vessel

rolume in litres - flow temp. 82°C.

Safety valve

(bar)
Vessel charge
pressure -bar

Initial system

pressure-bar 0.5

Total water

content of

system

litres 1 gals.

0.5

1.0 1.5

25 5.5 1.68 2.80 5.20
50

11.0

3.36 5.60

10.32

I

I

I I

75 1 16.5 1

5.04 1 8.40 1 15.52

100

22.0 6.64

11.20

20.72 44.08 8.72

15.20 32.96 12.48-f 26.48

125 27.5

8.32

14.00

25.92

55.12 10.88

18.96 41.20 15.60' 33.04..

I

I

150 33.0

1 o.uo 16.80 31.04

175 38.5

11.68 19.60 36.24

200 44.0

13.36 22.40 41.44

I

3.0

I

I

!

1.0

!

1.5'.

I

2.0 j 1.0 1 1.5 1 2.0 / l.5-;-jjo /

I 1

I 1

10.96 2.16

3.76 8.24 3.12:. 6.64 -

22.00 4.32

7.60 16.48 6.24- 13.20. 3

66.08 13.04 22.80

49.44 18.72 '1 39.68

77.12 15.28 26.56

57.68 21&I-. 46.32

88.16

17.44

30.40

65.92 24.96 52.96

Volume of expansion vessel should not be less than that given above.
Consult manufacturers literature and use next size up.

For flow temperatures over 93°C multiply by 1.25.

over

88°C muitiply by 1.1

(Tables based on Table 3. BS 5449: Pt 1: 1977)

DIAGRAMS SHOWING SYSTEM LAYOUT

PUMP ON THE FLOW

1. EXPANSION VESSEL

2. PRESSURE GAUGE

3. FILLING POINT

PUMP ON THE RETURN

FIG. 21.

4. DRAIN COCK

5. AIR RELEASE POINT

6. SAFETY VALVE

7. TOP-UP BOlTLE
(B.G.C. Materials & Installation Spec. 3rd Edit.)

EXAMPLE

System has a connected heating load in panel

radiators of 26,000 btu/h.

Radiator Volume from 26,000 x o 5

Table 17

1000 .

= 13.00

Pipework Volume from 26,000 x o o7
Table 17

1000 *

= 1.82

Boiler Volume Chaffoteaux 45 -

‘-om data sheet

=- 0.58

Cylinder Volume from Table 17

=- 0.44

System water content

= 15.84

Charge pressure 1 bar
Safety valve

2.5 bar

Vessel size

3.6 litres

It is necessary to fit a safety valve adjusted to the
final system pressure plus 4 psi. The safety valve
should discharge outside the building into a drain
or safe place.
All high points should be vented, in addition it is
recommended that an air purger and automatic air
vent are fitted into the flow pipe adjacent to the
boiler.
An altitude/temperature gauge should be fitted.

gig. 21 shows system layouts.

SEALED SYSTEMS

i‘

ACCEPTED METHODS OF FILLING

: HVCA/IHVE GUIDE TO GOOD PRACTICE.

“r. CONNECTION MADE FROM TAP USED

; FOR OTHER PURPOSE

.-: STOP TEMPORARY HOSE
.v COCK

FIG. 22.

TEST COCK

2. MAKE UP VESSEL ABOVE HIGHEST POINT OF SYSTEh

/

HEATING MAIN’

NON RETURN VALVE

FIG. 23.

3. MAKE UP USING ‘BREAK TANK’ & PRESSURE PUMP
LOW PRESSURE SWITCH TO STAR

STOP MAKE UP PUMP - INTERLD(
WITH BOILER

PRESSURE REDUCING

PUMP

NON RETURN

VALVE .,_

4.7 PRODUCTION OF HOT WATER

if the storage solution is chosen the hot water
cylinder selected must be an indirect, high recovery,
coil type cylinder. The cylinder should be to

BS 1566 which ensures a minimum heating surface
and should be of a grade suitable for the building
static head - generally 30 ft. Grade 3.
Self priming cylinders are not suitabte because the

higher pump duties necessary for low water content

boilers, can -break the air seal. this leads to the
exchange of water in the system and introduces
air and hardness salts. The former can promote

boiler noise and the latter lead to the premature
scaling of the heat exchanger.

Gravity cylinders with an annular heating surface
are not suitable since the higher velocities, with a

pumped system, will cause noisewhich will concern

the consumer.

The cylinder should be sized to meet the demands

of the household. For instance, a family of four
with one bathroom will require a minimum water
storage of 25 gallons, the same with two bathrooms
35 gallons.

It is recommended that the cylinder should be
capable of recovering in one hour, which, if a 25
gallon cylinder is utilised, means that the cylinder
should initially be capable of absorbing 25,000

btu/h.
The high point on the circulating pipework should

be vented preferably using an automatic vent of

the bottle type.
To obtain the required flow and keep resistance to

a minimum 22 mm pipes will normally be reqc

,d
for the primary circuit. A lockshield valve should
be used in the circuit to balance the flow.

It is becoming increasingly popular to pump
cylinders contraflow i.e. with the flow zentering
the bottom of the cylinder and the return taken

from the higher tapping: The rate of heat exchange

in the cylinder is relative to the. temperature
difference between the circulating and the stored
water. If the ‘cylinder is pumped contraflow the
hottest circulating water is in contact .with the­coolest stored water and therefore the rate of heat
exchange is improved. It also helps the venting Tf

the coil.

’

..-.z‘.,:L :$ ,r:‘,2; :

The allowance made for water heating ;in ‘the:

boiler sizing is a function of the. recoven/ time
selected and the method of control,. usually 8 -

10,000 btu/h.

. .

/ +.

,: .

‘>+‘.

There are now available immersion elements whip+

fit a standard 2% in. BSP boss to enable a dir

,
cylinder to be converted to indirect. As this type
of element has a high resistance, a cylinder by pass
may be necessary to maintain the flow rate needed
to operate the boiler.
The heating of stored water is perhaps the most
wasteful use to which a gas fired boiler is utilised.

We not only heat up and continually maintain at

temperature 30 gallons of water in case we might
need it, we also lose heat from both the primary
and secondary pipework and from the.surface of
even an insulated cylinder.

._

,_ :.;.

CONVENTIONALLY CONVENTIONALLY

PUMPED CYLINDER PUMPED CYLINDER

BS 1010 STOPCOCK BS 1010 STOPCOCK

22 mm OPEN VENT

FIG. 25

i

ANK

7

/’

AIR VENT

22mm DOWN SERVICE 22mm DOWN SERVICE

L

ISOLATING ISOLATING

-’ ” -’ ”

GATE VALVE GATE VALVE

15mm COLD FEED

c

MAX 15Omm

(6 ins)

\

DRAIN COCK

75 mm (3 in) INSULATION

LOCKSHIELD-BALANCING VALVE

I

! CYLINDER PUMPED CONTRA-FLOW

22 mn

OPEN VENl

Max 15Omn

(6 ins)

AUTO

1

15 mm COLD FEED

PIPE GRADED TO VENT

BALANCE VALVE

FIG. 26.

USE OF CONVERTION ELEMENTS

IR VENT

r

\

15 mm BY PASS WITH /

.,;

LOCK SHIELD VALVE

-

ALTERNATIVE ARRANGEMENT
SHOWING T/S VALVE

BY PASS

FIG. 27.”

Certain applications requiring small quantities, at
the kitchen sink, for showering and for the small
family are more efficiently accomplished by using
an instantaneous water heater.
Chaffoteaux manufacture a range of singlepoint

and multipoint water heaters and also the first

purpose made gas shower heater, the singlepoint
heaters are flueless or open flued, the multipoints
and shower heaters are balanced flue.

With the exception of the shower heater they are

available for either mains connection (high pressure)

or for connection to a cold water tank supply (low
pressure).

Detaiis of the performance of the water heaters

are in the data sheet included in this booklet.
The multipoint water heater is also suitable ,for
connection to a shower using a mixer valve to

balance hot and cold water pressure. They are also
suitable for connection to most modern washing

machines provided that the machine is capable of
accepting one gallon per minute of hot water.

CONTROLS’ -

5.

CONTROLS

In these days of rising fuel prices it is increasingly
important to have full and adequate control over
the two functions of the system.

1) Hot water generation

2). Space heating
Hot water can be controlled either electrically or
mechanically. Electrically using a cylinder thermo­stat and motorised valve. It is suggested that the
thermostat is placed r/a up from the bottom of the
cylinder. The setting temperature suggested is
46°C (140°F). There are a number of mechanical
valves available all operated by the expansion of a

heat sensitive medium. The most effective have a
phial that can be entered via a pocket into the

stored water, the least effective is that which is

attached to the primary return pipe.

Space temperature is more usually electrically

controlled by use of a room thermostat placed in a
‘representative’ position, usually the hall. A room
thermostat should:

1) Be sited not more than 5 ft. above the floor
level. (when you sit down you are only 3 ft.

tall).

2) Not be influenced by local heat emmitters,
radiators, television and the like.

3) Not be influenced by excessive draughts.

4) Not be exposed to direct sun light.

An alternative control is achieved by the use of
thermostatic radiator valves, most of these are
directional so care should be exercised in siting
them. (The valve is stamped with an arrow indicat-

ing the direction of water flow.)
If a radiator has been boxed in or is likely to be

behind a curtain then consideration should be
given to fitting a valve with a remote sensor.
Various system layouts are illustrated together

with some wiring diagrams. For further information
you should contact the controls manufacturer.
The electrical controls must conform in all respects
to the I EE Regulations and the local codes.
The installation should be fused with a fuse-of a
suitable value, usually 3 amp. The pump should
have adjacent to it a means of isolation.

ABBREVIATIONS USED IN THE.F&LOtilN6

DlAG RAMS

AAV

BIV

LSV

TRV

L
N
S
D
C.

+.

2 PMV

3 PMV
cs-

RS

TC

Prog.

IV
vo

VC

.- ’

,;: :

Automatic Air Vent
Boiler Isolating Valve

Lock Shield Valve
Thermostatic Radiator Valve
Live
Neutral
Satisfied - (stat. satisfied)
Demand - (stat. calling)
Common

-.

Earth
Two Port Motorised Valve
Three Port Motorised Valve
Cylinder Thermostat

_ _:,
Room Thermostat
Time Clock
Programmer
Isolating Valve
Valve Open
Valve Closed

NB 1.

Neutrals and earths have not been drawn

2.

The drawings are schematic only

3.

For cylinder cupboard layout see page 30, 4

:.

-_.

_

DOMESTlC HOT WATER & CENTRAL HEATING -

MECHANICAL CONTROL

TIME CLOCK CONTROL OVER PUMP

AAV

FIG. 28.

MAX

r

a

BIV

\

c-e,,

,

_________

ALL HEATING RETURNS TO BE COMMONED
BEFORE JOINING COMMON RETURN

_‘.

15mmBYPASS

WITH US VALVE

T/CLOCK

FUSE 3a

L””

PUMP

1 LjNj

Chaffoteaux recommend that the hot water thermos&t valve-’
is a 3-Port valve with built in by pass.

N

I

FIG. 29.

\

d

FIG 30.

7

I

DOMESTIC HOTWATER & CENTRAL HEATING -

I 1

MECHANICAL CONTROL OVER HOT WATER

AAV

ROOM STAT & MOTORISED VALVE ON HEATING

(Spring return pattern with auxiliary switch)

Chaffoteaux recommend that the hot water thermostat valve
is a 3-Port valva with built in by pass.

I --

PPMV yv

N,

N, RtSTAT

PROGRAMMER

FIG. 31.

- h :. -;

FIG. 32.

HOT WATER & CENTRAL HEATING CONTROL BY CYLINDER

THERMOSTAT & ROOM THERMOSTAT

SWITCHING MOTORISED-VALVES.

AAV -.“-

.:. .,~ . .

c ------ ‘““‘,
,

I

. ;

1.

I I I I I I-1.. ;-

.T^ x...

:; y:

,

-.. _

.,

5.

._ ^.

.

-

MOTORISED VALVES WITH SPRING

RETURN WITH AUX. SWITCH

I] PROGRAMMER MV

MOTORISED VALVES - DRIVE .OPEN -

PROGRAMMER

DRIVE CLOSED

t 1

FIG. 34.

FIG; 35.

BIV

AAV

HOT WATER PRIORITY

PROGRAMMER _:._

PUMP

t

.J

):

; C.’

T

_ I

T

I Y

3

I-

3 PMV

, .:-

-. , . .

.-me---------------

A--

i,

MID-POSITION FLOW SHARING VALVE

PROGRAMMER

.+.,:..>.,

d .:<:23;2

3 AMP

.:.;.~.~;~~~~~.~~~~,~

:.:: .i.... . . . . . . .

. . . . . ..~.~.~~.~..~~...~.~....~ .,;

. .

.:‘.?.+.:i’: . . . . . .

,;_

.:. .:.:-.:..: . . ...’ . .

. . . . . . . ..~.. >,.

.::.;:<.;.:-.< .

. . . . ..y ;........

. . . . 1 ,....y.,.: . . . . f

‘.~...~.~...~.~...~~...~~ . . . . . .

‘R

FIG. 36.

“.i$~p..

NO?~%ECOMMENC

d .-

I

It is often convenient to group all controls and the

circulating pump in the cylinder cupboard. Ensure

that all components so positioned are accessible.

Chaffoteaux recommend that the flow and return

TIME CLOCK

3 AMP

N-

‘.. N t ,,

s-m*

FIG. 38.

%ROST THERMOSTAT

FIG 39.

FROSTTHERMOSTAT

AUDIO/VISUAL ALARM

ANCILLARY

FIG 40.

LOW WATER LEVEL
LOW PRESSURE
HIGH TEMPERATURE
OR SIMILAR CONTROL

pipework to the cylinder cupboard are run in 22 mm
pipework. Cylinder cupboard layouts are given in

Fig. 41.

c.

l

22 mm OPEN VENT

15mmCOLD FEED I

. e-d.---.

t-

I‘ I

AAV REQUIRED IF FLOvli

AAV -

TURNS DOWNWARDS

TO‘RAD:

-..

22 mm RETURN

22 mm FLOW

: 22

22

mm V~CN VCN I

15 mm COLD FEED

I

,

-\

*.

--w-s--

/’

;

a’

/

._--

.-

+lCIFROM RADS.-

.

.~

-TO RADS. --

FPO :

mmFL=. Q

-- _

22 mm RETURN

FIG. 41

FLUES AND VENTILATION ta-.

6.

FLUES AND VENTILATION

With all the boilers the installer should ensure that
there is adequate combustion and ventilation air,
the requirements for domestic boilers are set out

in Table 19.

Open- flues are governed both by the Building

Regulations and the British Gas Regulations and

are summarised in Fig. 43.

Balanced flue terminal positions and the restrictions

on siting are summarised in Fig. 42

If the :terminal is less than 6 ft. above the ground

level it must be protected with a wire guard.

Some Chaffoteaux appliances of the .room sealed

type are approved for use with both Se duct and U

duct installations.
Se duct isa method of multiple flueing in a multiple
storey dwelling. The appliances on a Se duct

TABLE 19

receive combustion air from, and discharge

their.

products into, the duct. Air for combustion and >
for ventilation of the duct is by means of two­horizontal limbs, one to each side of the building
at the base of the duct. See Fig. 44.

.’ .

I _I

:..
A variation of the Se duct is the U duct where-air
for combustion and ventilation is brought--irt’fror& ,
roof level.

The air intake duct is installed flush with$he

inside’;

face of the duct. The flue duct from appliance

is”’

cut

to length usuaily extending I’/ in beyond the: -

inner face of the- duct. InstructionS,,: for~~.each

appliance should be studied carefully.

%: ;

A duct has a maximum carrying capacity and’advic

on sizing or the suitability of ducts isavailable from
the local gas region.

BOILER COMPARTMENT VENTILATION

POSITION

OF

OPENING

HIGH

LEVEL

LOW

LEVEL

TYPE OF APPLIANCE

OPEN FLUED

BALANCED FLUE

AIR FROM

AIR DIRECT

AIR FROM

AIR DIRECT

ROOM

FROM OUTSIDE

ROOM

FROM OUTSfDE

9 cm2

per kW

’ 2

in2 per 5000

4.5 cm2 per kW

9 cm2 per kW

4.5

cm2 pee kW

1 in2 per 5000

2

in2 per 5000

1 in2

per 5000

btu/h

btu/h

btu/h

btu/h ‘.

a18cm2 perkW

9 cm2 per kW 9 cm2 per kW

4.5

cm2 per. kW

4

in2 per 5000

2 in2 per 5000

2

in2

per 5000

1 in2 per.5000

btu/h

btu/h

btu/h

btulh

FLUELESS WATER HEATER (instantaneous) Not exceeding 12 kW - 40,900 btu/h

Minimum

room volume 6 m3 - 212 ft3. Air vent 35‘cm2.

NB Areas specified are FREE Al R and are related to appliance INPUT.

- - - -‘-US ROUTES FOR VENTILATION

VAUIU

ROOF

n

kY III

APPLIANCE ROOM

ttY

ADJACENT ROOM 1

AIR INLETS1 2,3 4,&6

_. -. .-. _-_ L - -’

I

BELOW FLOOR SPACE

--- OIRECT METHODS

-INDIRECT METHODS

._,_.

I

BALANCED FLUES

I

FIG. 42m

_ .-_ .-_

FOR EAVE PROJECTION

--.--k-w-

NOT MORE THAN

n

. . . . . .,..: )..,..$,,,) _:. &;..: ..: :;, ..::,.,:.:,.

if---

;i-i~:~~~~.~~~~.7

3OOmml(l ft)

SPLllTER

I I ’ ’ 3OCtmm
1 I !I

(1 tt1

’ ‘3OOmm

1 I 300mm

(1 ftl

(1 ft)

4 +I &mm 600 mm

NB 1.

TERMINALS MUST NOT BE FITTED

I1

ftl IN SHADED AREAS

(2 ft) ,. .I,

SPLITTER

NOTTO EXTEND

MO

IRE THAN

DEPTH OF

TERMINAL

-

3.

If 300mm (1 ft) BEU
SOFFIT 600mm (2 ft) ON ElTHt
& EXTENDING TO INCLUDE PLASTIC GUT-

2. ,IF LESS THAN 1,800 mm (6ft) ABOVE GROUND LEVEL
FITTERMINAL GUARD

DW EAVE FIT DEFLECTOR TO

fR SIDE OF TERMINAL

TER

FIG. 43.

OPEN FLUES

600 mm _
(2 ftl

I

NE 1. PREFERRED -CHIMNEY LINED WITH

STAINLESSSTEEL LINER

2. EXISTING CHIMNEY MUST BE SWEPT
BEFORE LINING

3. ALL EXTERNAL FLUES SHOULD BE
INSULATED.

SE DUCT & ‘U’ DUCT

COMBUSTION
PRODUCTS

4PPLIANCE !

APPLIANCE f;

AIR

SE-DUCT

CHAFFOTEAUX
BOILER

TESTING OPEN FLUES

All appliances connected to a conventional open
flue should be checked for ‘spillage’.
The following are suggested methods:-

1) Hold a lighted taper so that the flame is below
the lower edge of the draught diverter (Fig. 46.).

Spillage is indicated by the flame being displaced

outwards.

2) Hold a piece of cold polished metal or mirror
close to the lower edge of the draught diverter.
Spillage is indicated by the polished surface

becoming clouded.

3) Ignite a smoke pellet in the combustion cham-

ber. Spillage is indicated by escape of smoke
from the draught diverter.

If an extractor fan is fitted first carry out test on
flue with the fan off. If this is satisfactory open
door to room in which appliance is fitted, connect­ing to room in which fan is fitted, and close all
other doors. Close all windows in the property.

Switch on fan and repeat test. If spillage is detected

open window until spillage ceases. If the open area
of the window is less than 10 in2 put in additional
ventilation, equivalent to area of opening.

If the area is greater than 10 in2 consult the local
gas region.
This test is very important since the installer has a

statutory duty under the Gas Safety Regulations,
Section 47:

No person shall use or permit a gas appliance
be used if at any time he knows or has any
reason to suspect :-

a) That the removal of the products of

combustion from an appiiance is not
safely being carried out.

FIG. 46.

TES

7 WARM AIR

7.

WARM AIR

Warm air heating is the distribution of heated air,

either directly or indirectly, and with the aid of a
fan. and ducting delivering it to the area in which
it is required.
Chaffoteaux market a range of warm air heaters
of the indirect variety.
Water heated by a boiler is the heating medium.
The heated water passes through a water to air heat
exchanger. The heated air is passed to the rooms.
See Figs. 52 & 53.
With modern building methods, where buildings
are of low mass and highly insulated:-

1) a smaller heating requirement is required to
be met by the system,

2) because the buildings are low mass the structure
does not retain the heat.

The advantages of heating by warm air are:-

1) design temperatures are more quickly met from
a coid start,

2) less wall space is used,

3) less conspicuous,

4) continuous air circulation and filtration.
Chaffoteaux, with their appliances, can add:-

5) flexibility - the boiler providing thezheated
water can also provide hot water or additional

radiators,

6) lower risk of corrosion because the boiler heat
exchanger, the water to air heat exchanger and
the pipes and cylinder are all copper.

There is also another and important function

which

Chaffoteaux can satisfy. Many of -Ithe::

direct fired units installed in the 1960’s are

now-.

due

for replacement, and a higher level of

comfort

is

now

required, like heated bedrooms. .F$ther,
few of the generation of heaters installed-at that
time were able to supply domestic hot water, this
was provided by an instantaneous water heater
or circulator.
Warm air heat exchangers are of two basic types:-

Upflow

Air is passed over the heat
exchanger and discharged at
the top of the unit. (Fig. 47.).

Downflow

Air is passed over the heat
exchanger and discharged at
the bottom of the unit. ,.

FIG. 47.

DOWN FLOW

UP FLOW

r

-----

1 I

1

FAN

. .

3’

FILTER
HEAT EXCHANGER

4

PLENUM - NOTSUPPLIED

BY CHAFFOTEAUX

5

ALTERNATIVE FAN POSITION

: FIG. 48.

-STUB DUCT

k k

HEATER

l/v

,. -

‘FIG. 49.

RADIAL

R ‘-

Jl

R~HEAT<R

1

R

43

R

R

EXTENDED PLENUM

.

L.

Distribution of the air is then directed, by ducts,
the outlets of which may be:­Stubducts

Registers to rooms directly off

the plenum.

Floor perimeter

Air is passed through round or
square ducts from the plenum
to discharge through the floor,
preferably under windows, to
get the best entrainment.

Ceiling perimeter

As floor perimeter but dis­charging from the ceiling (used
where there is a loft.or large
void above the rooms).

Low side wall TFie registers are placed in the

walk at low level. The dis­charge rate should not exceed

High side wall

300 fpm (ft. per minute).

Registers are placed at high

level on inside walls. Carf 3s
to be taken with the choic.. of
grille so that no discomfort is
caused to the occupants.

The distribution systems are of four types. (See

Figs. 48 to 51).

. ../.

i

. .

Radial The ducts radiate,to. registers

from the centrat .heat source.

Extended Plenum The plenum is extended-.and

the supply to the :jegisters is
taken from the 4arge:duct:Air
flow should not-:exceed 500
CFM and the;ple&m should
not be more than.--20.,ft.,.. iin
length.

Step duct

Where the-- duct-- gradually

reduces in size and the supply
ducts are taken off Yhe,:main

duct.

FIG. 52.

FIG. 53.

AAV

; I

---.---------------.,

I I

8

I :

I

I I

ADD A RAD :

I I

I

a
I I
: :

, e----a
:------------------------a

ADD A RAD

1 GAS SERVICES

‘2,

8.

GAS SERVICE

.

_ -__.

It is equally necessary to correctly size the gas
pipes as to size the pipes carrying water. l n the same

way that pipes offer resistance to water so they do

to the passage of gas. The carrying capacities of gas
pipes are shown in Table 20.. expressed in ft3 for
metres run.

It is therefore a pre-requisite to calculate the volume
of gas required.
This is obtained by the following:-

Boiler input in btu/h

CV of gas

The calorific value of natural gas is normally

‘30 btu/h/ft3.

I convert from ft3 to m3 divide by 35.31.

.,hen commissioning an appliance it is recommen-

ded that first the pressure is checked with a gauge
at the inlet to the appliance when running and all

other gas appliances in the property in operation.

At the inlet to the appliance under the conditions

as above the pressure should not be less than 8
in.w.g.

.._ . .

d

,’

Next the pressure at the burner manifold should be
checked and adjusted after 10 minutes in operation.
When setting/checking the pressure on a balanced

flue boiler ensure that all doors and windowsare

closed to the room in which the boiler is situated.

Having set the burner pressure all other appliances

should be turned off including the pilot lightsand

the consumption checked at the meter to confirm

that the gas consumption is as shown on the data

badge of the appliance.

TABLE 20.

Discharge on straight horizontal copper tube with 1 mbar differential pressure between ends for gas of .,.

relative density 0.6 (Air = 1).

. .

.

LPG 9

9.

LPG

LPG is liquified petroleum gas. The fuel source is
either crude oil or direct from the North Sea. The
gasses available are either Propane or Butane.
The gasses are stored as liquids under pressure.

Propane turns into gas at a lower temperature than
butane and is, therefore, stored at a higher pressure.

When the tap is opened the pressure is released, the

liquid boils and gas is evolved.

TABLE 21

49 160 0.12 4.4 0.90 31 1.85 65 3.8 :;135- :

- 55 180 0.12 4.1 0.80 29 1.75 61 3.6 : 130:

- 61 200 0.11 4.0 0.80 28 1.65 59 3.4 120.

OUTSIDE DIAMETER OF COPPER TUBING

i 27 t 90 1 0.041 1.3 1

1.7 1 0.291 10.1 1

6.8

1 61~ t 200 1 0.02 1 0.9 1 1.1 1 0.191 6.7 1 4.5 0.26 1 9.3

Il.01 135.6
~ 0.79 128.0
~ 0.68 i 24.6

0.601 21.2

0.50 1 17.8

0.47 16.5

+

0.44 15.7

12.7

0.33! 11.8

1.0

I Imo 1 Metric I Imo 1 Metric I Imo.l­‘%iLl 22mm I ’ K in

28

mm “1 iA .’

ft3 /h 1 m3 /h ft3 /h lft’/h m3/h ft3/h ft3/h

62.018.01 283.01 195.0

15.96 5620 444.0,-

.

I

75.01 1 4.33)

4

17.5 2.12 52.0 153.0 120.0

15.0 1.85 65.21 45.0 1 3.91 t 138.0 108.0

14.01 1.72 1 60.91 42.0 3.62 1128.0 100.0

13.0) 1.56 I 55.21 38.0 3.34 1118.0 92.0

I

12.0 1.48 52.3 36.0 3.17 112.0 88.0

11.0 1.40 49.3 34.0 3.03 107.0 84.0

-

All Chaffoteaux appliances will burn either

propane or butane in their LPG form. Remember,

rvever, if you change gas from propane to butane

or vice versa, it will be necessary to reset the pressure

regulator.

For propane the regulator should be set to give a
working pressure of 14.6 in.w.g. at the appliance
and 11 in.w.g. for butane.
Tables 22. & 23. show the properties of the two
gasses.

LPG is heavier than air, and therefore care should
be exercised in storing the gas cylinders. They should
be stored external to the property and above
ground level.
So far as installation is concerned the only factors
of system design which differ from natural gas are
the pressure drop in gas pipes. This is summarised
in Table 21. and the necessity to use the appropriate
isolating valve (usually a diaphragm type) where
the

supply

pipe enters the building and appliance.

-r YCAL PROPERTIES OF BUTANE AND
F,‘3PANE.

TABLE OF PROPERTIES

The following tables shown typical physical

properties for commercial grades of Butane and
Propane. All Metric units relate to Metric Standard

conditions of 15°C and 1013.25 mbar (dry).

Imperial units relate to Normal Temperature

and Pressure Condition of 60°F and 30 ins. Hg

(saturated).

TABLE 22

STORAGE AND HANDLING

Storage tanks should be located in accordance with
Table 24 based upon the capacity of storage con­cerned. The separation distance given in Table 24
must be maintained at all times, and no building
extensions, fixed ignition sources, etc. should ever
be allowed to encroach within it.

,

The. whole of the area within a distance of 3 m.

from tanks up to 2250 litres water capacity, or 10 n-r
from larger tanks, should be maintained at ALL
times - free from weeds, long grass or combustible
materials. Tanks should not be sited adjacent to

any pits, drains or other depressions.

’

Tanks should be protected by industrial type

fencing where the risk of trespass or tampering ,is
high. Large tanks should always be protected:.

,.

Where damage to LPG systems from vehicular

traffic is a possibility precautions against: suctt~-

damage should be taken. The degree of protection

required will depend on actual site conditions,
including the density of traffic, the nature of.the
traffic, and the overhang or reach of the vehicles.

Strategically located motorway type crash barriers

or concrete or steel bollards will be suitable for

most installations.
Where an earthing point is provided for the dis­charge of static electricity, this should be clearly
visible and readily accessible at all times.
Metalled vehicular access to the tanks should be
provided.

BUTANE

Calorific Value (Vaporised)

Volume of gas produced per

Mass of Liquid

Volume Occupied per Mass of Liquid

Volume of Air to burn Unit

Volume of Gas

METRIC UNITS

121.5 MJ/in3

49.2 MJ/kg

28.2 MJ/litre

0.41 m3/kg

1743 1 /tonne

30‘

IMPERIAL UNITS “‘.

3200 btu/ft3

21150 btu/lb

121610 btu/gal

6.6 ft3/Ib

390 gal/ton

.i

30

4-

TABLE 23

PROPANE.

Calorific Value (Vaporised)

Volume of Gas Produced

per Mass of Liquid

Volume Occupied per Mass of Liquid

Volume of Air to burn Unit

Volume of Gas

METRIC UNITS

95 MJ/m3

50 MJ/kg

25.5 MJ/Iitre

0.54 m3/kg

1957 1 /tonne

23

IMPERIAL UNITS ‘,’

2500 btu/ft3
21500 btu/lb

110080 btu/gal

8.6 ft3/lb
. _.

437 gal/ton.

23

“.

Location and

spacing for tanks for industrial, commercial and domestic bulk storage.

l-ABLE 24

Maximum water

capacity of any

single

tank

in

Litres (Gallons)

450

(Up to 100)

450-2250

(Over 100-500)

2250-9000

(Over 500-2000)

9000-l 35000

(Over 2000-30 000)

Maximum total

water capacity of

all tanks in

Litres (Gallons)

6750 (1500)

27000 (6000)

Minimum Separation Distance in Metres (Feet)

From building, boundary, prone*

line* or fixed source of ignition

: a. 1.

Between tanks

Below ground

Above Buried Valve assemblyt and Above &low ’

ground portion

and loading/

ground ground

unloading point

: . .

.1

above ground

n :

None**1 3 (10) 1 3 (10)

1 None Il.5 (5)

..,

=3 (10) 3 (10) 3 (10)

~ .‘.I

l(3) !.5(5) ’

3

(10)

I

7.5 (25)

Whether built on or not.
Where tanks up to 450 litres water capacity are sited adjacent to mobile homes, caravans, site huts and
similar buildingsof a non-permanent natureconstructed of combustible materials, additional precautions
should be taken. In such circumstances the minimum distance between the shell of the tank and the
building should be one metre, and the minimum distance between the filler valve on the tank and any
door, openable window, ventilator or other point of gas entry into the building, should be three metres..
The isolation valves, filling valves and pressure relief valves located on the manhole cover of the under­ground tank.

10 SERVICING AND SY§TElUl FAULT-FINDING’

10.

SERVICING AND FAULT FINDING

Annual servicing should be carried out by a com­petent person and a servicing schedule is set out
below. For ease of servicing, Chaffoteaux recom­ment that the boiler isvalved on both sides as shown

in the various system diagrams.

Annual Service

1 Clean the Burner
2 Clean the Heating Body
3 Clean the’ Pilot Assembly, Thermocouple

and Spark Electrode

FAULT FINDING CHAkT -- SYSTEM

I

FAULT CAUSE

Insufficient heat to room

insufficient hot water

4

Clean the Gas Filter

5

Clean the Thermostat Capsule

.

6

Clean the water filter

-. I

Three Yearly Service

1

Clean Burner, Heating Body, Pilot

--‘i

Assembly and Thermocouple

.

2.

Replace the Gas Filter

;.;

3.

Replace the Diaphragm

4 Clean the Gas Valve

I.. 1

n

.

., :. ,,.

.

..,

-.-

__

Insufficient gas flow

Insufficient water flow
Boiler not coming up to full gas

! Short cycling around

y cylinder

s Short cycling around by pass

;

Heat loss incorrect

~,. Radiator too small

Radiator obstructed

- Too large a temperature
difference

Room thermostat

Cylinder not high recovery.
Mechanical valve used with

by pass

Air in coil

+ Cylinder stat. too high

on cylinder

‘.)

REMEDY

Check inlet pressure at gas
cock.

,.

Check manifold pressure and
adjust.

Open all valves and by pass.

. .

Check by consumption at

.:

meter. Refer to Installation

:
and Maintenance Instructions
for remedy. Change pump if
necessary.

Check a balance valve is
fitted and correctly adjusted. _. 1’

Check and adjust - see:

... :

Installation Instructions.

Check system resistance is

”

within pump duty.

.i

Check heat loss - look for

r
excessive ventilation ­unrestricted chimney etc.

Check radiator output and
adjust for temperature
difference of 20°C.

Remove obstruction or

__

relocate radiator.

Balance System.

1. Out of calibration.

2. Neutral not connected.

3. Influenced by local

heat source, TV etc.

Replace.

Check and fit if necessary
and adjust.

Ensure cylinder is vented.
Re-locate ‘/3 from bottom

_

of cylinder.

FAULT

Delay in switch to
heating in DHW
priority system
(as for
insufficient heat)
plus

Boiler noise

Noise from system

Overflowing
expansion tank

Radiators hot
when motorised
valve is closed.

WARM AIR

Insufficient heat

Noise (mechanical)

Noise (system)

Cylinder stat. out of
calibration

Poor contact between
cylinder stat. and
cylinder

Air in system

Insufficient Head

Incorrect cylinder fitted

Scale in heat exchanger

Water velocity
exceeds recommendations

Air in system

Insufficient capacity

Reverse circulation

Incorrect fan speed
incorrect duct sizing

Register not balanced
Filter dirty
Low mean water

temperature
Too large a differential

on room stat.

Fan hunting

Loss of dynamic balance

due to accumulation of dust.
Distortion of rotor or

bearings

Fan speed
Duct sizing
Restricted register

Obstruction in duct

L

CAUSE REMEDY

I

Replace

Clean surface of cylinder
and re-locate using heat
grease.

.:

Check cylinder and air vent
as recommendations in
Section 4.2.

._d

Vent high points. . .‘.;

Is charge pressure correct

on sealed system?

_‘, ::

_._

,

.’ .
Have recommendations been -’
followed regarding pump, cold
feed and vent positions.

--_.“-z

Check cylinder is an indire&”
type an’d is not a self priming-

,

type.
Check for system leaks.

De-scale heating body if
necessary.

Check pipe sizes and

enlarge if necessary.

Vent system thoroughly.
Replace.

Ensure heating returns
commoned before joining.
main return.

i !,

,..

Check calculation and adjust:
Increase fan speed (take care Q

with noise).

Rebalance system.
Remove and clean.

‘.

Ctieck pump duty and boiler.
operation.

Ensure anticipator is

connected.
Clean Fan.

Lubricate or replace as

necessary.
Clean filters.

Check size of relief grilles and
return air register and ensure
of adequate size.

Adjust.
Replace in correct size.

Adjust.

.

’

t

Remove.

._, s,..; _-

11 DATA

WATER HEATERS

t

Clearances

mm 178

I

50 152

Bottom

1”s 7 2 6

mm NIL

75

NIL

Sides

IITS

NIL

3 NIL

Gas connectron 15 mm copper 15 mm copper 15 mm copper

Water connectron

I

15 mm copper

Inlet 15 mm copper

15 mm copper

Water

flow

rate

Raised

50°C - (90°F)

Raised

?I+,- ,LeII\

1 /mm

w*

t

lmin

6.5

1.44.

111

outlet spout or 15 mm copper

2.5 Raised 6.3

0.55 2O’C (36“ F) 1.39 i

4

16 Raised 36,

Weiaht

Flue we

,,...... I ._. ___- -.-

, avke-,-rl ‘I 1 w*

2.44

-.

0.92 35°C (63°F) .79 -1

I h,^.. Min normal ^^___I

pressure

lbar - 15psi 0.45 bar 6.5 PSI 0.5 bar 7.5 psi

preSS”re lObar - 150psi 10 bar 150 psi 10 bar 150psi

1.3 m 4.26 ft - -

I

essure

Max low _ pressure

1.5” 4.9 ff
25” 82 ft 24 m 80 ft - -

19 Kg 42 Ibs 6.9 Kg 15.25 Ibs 10.7 Kg 23.5 Its 1
Hetght 205 mm 8 ins Flueless or 125 mm 4.9 ins
Wrdth 305 mm 12 ins 3 ins0 240 mm 3.4 ins

From

Internal

From

External

Htgh

Low

High

Low

cm1 102

tnz 15.8

cm2 102

In: 15.8

cm’ 51

in: 7.9

cm2 51

1”: 79

I

35

5.4

P!us openmg wmdow

LPG - Propane
Burner pressure
Restrlcrors
Manrfold ~nrector
Gas Consumoton

Gds Connecr~on

“‘Ih

ft’/h

10 in.w.g. 10 in.w.g. 10 in.w.g.

None 2.75 mm 41909 3.25 mm 37251

074 14154/19 070 14154/10 072 14154/12

1.17 ,434

.43!

41.3 15.32 15.44

“2 I” RSP

12 mm copper

% I” BSP

N.8. BRITONY LOW PRESSURE

Heat Inr>ut

29.21 kW
Heat Output 21.90 kW
Burner Pressure 13.5 “bar
Mamtold lmector Stze 118
Gas Consumptron

2.70 m’/hr
Water Connectron 22 mm cooper
Water Flow Plate Raiseo 50°C (90°F) 6.311min

99.600 Btu/h
74,700 Btu/h

5.3 ins.w.g.

98.18 ft’/hr

1.38 g.p.m

DOMESTIC BOILERS

Man1 told wxcor

118 1 116 I

113

1 113 1

113 1 113 1

113 I

113 1 118 1 118

lla 1

Min flow rate 450 Ill/h 1.65 qom

450 lit/h 1 65 qom

720 lit/h 2.6 qpm

j head Puma on flow 2.0 m 6.5 ft 2.0 m 6.5 ft 3.5 m 11.5 ft. 3.5 m 11.5 ft 3.0 m 9.75 ft

Max stattc head 30 m 98 ft 30 m 98 ft 30 m 98 ft 30 m 98 ft 30 m 98 ft
Weight 13.6 Kg 30 Ibs 13.6 Kg 30 Ibs 14.3 Kq 31.5 Ibs 14 3 Kg 31.5 Ibs 19 Kg 421bs
Water capacity I0.182~1it0.Ckloals i 0.182 lit 0.04 aals I 0.58 lit 1 02 ots I 0.58 lit 1.02 ots

I -. - -

Flue size Height 1 125mm 4.9ins 1 4in8 lOOmm0 1 205mm 8ins 1 4in0 lOOmm8 1 205mm eins

Width 1 240mm 9.4 ins 1

4

305 mm 12 ins 305mm 12 ins

High crZ*

90 90 150 150 210

From. 14 14 23 23 31

a

cgm Internal cm’ 90 180 150 300 210

.g f $

Low .

in2

14 xl 33 46 31

I

-Gal

u OCE gTL I External From High r cm2 In2 45 45 7 I I 45 90 7 I I 11.5 75 75 11.5 75 75 15.5 105 105 .

~~

Part No I 14154/10 14154/10 1415400 14154/10

I

14354/10

Gas consumotlon ita 14.12 11 07 14.121 1 11.07 23.1 118.14 13.8 23.1 18 14 1 13.8 31.6 26.23 20.40

m’ I 0.4 i 0.3

I

0.4 I 0.3

I

0.64 1 0.51 1 0.38 0.64 1 0.51 1 0.38 i 0.9 I 0.74 t 0.58

FUEL COST ESTIMATING
The following table of fuel consumptions is based

n the energy consumption of houses as published

1 the I.H.V.E. (Ref. B-1817).

in the table the following assumptions are made:-

1) Equal amounts of daytime heat for full house
heating.

2) Temperatures that are controlled and allowed
to fall at night.

3) Properly insulated properties.

4) Consumptions related to the S.E. England

(adjust for other Regions).

TABLE 25.

I

FUEL

CALORIFIC

VALUE

GAS

N. Gas 29.31

kwhltherm

L.P.G. 7.113

(propane)

kwh/litre

OIL

28 set 10.18

kwh/litre

35 kec 10.57

’ kwh/litre

SOLID FUEL

Sunbright E

7.495

kwhlka

L

5) Internal temperatues of 21°C (7O”F), 18°C
(65°F) and 16°C (60°F) (see Table 1.).

6) Domestic hot water allowed on a percentage
basis.

^.

_-

Estimated consumptions allow for appiiance

efficiencies.

Allow for standing charges,:. hire

- _ _

charges, servicing or the repayment of loans when
calculating running costs.
To compare fuel cost multiply the fuel consumption
by the appropriate fuel cost.

936

1355

therms

therms

3856 5582

litres litres

2802 4079

litres

litres

2689 3915

litres

litres

6022 8672

kg

kg

3908 5631

kg

kg

18777 -27444

kwh kwh

1515 2020

therms

therms

6241 8322

litres

litres

4611 6030

litres

litres

4426 5788

litres litres

9635 12767

kg

kg

6303 8404

kg kg

31054 40804

kwh

kwh

25638

kwh

37064

kwh

41888

kwh

55250

kwh

G-LOSSARY 12

‘.

12.

GLOSSARY OF TERMS

Btu/h

Calorific value

Cold feed

Conduction

Contraflow
Convection

Delta
(symbol A)

Expansion

Gas rate

Grille

Index Circuit
K factor

L.P.G.
Microbore.

- Is a measure of heat and stands
for British Thermal Units per

hour. It is the amount of heat

required to raise 1 lb of water
1°F.

- The amount of heat released by
the combustion of a given

quantity of fuel.

- The pipe leading from the feed
and expansion tank to join the
system through which water is
introduced into the system. It
should not be less than 15 mm.
The point at which the cold
feed enters is called the neutral
point.

- The transfer of heat from a hot
to a cold mass with which it is
in contact. (direct means).

- Against the normal direction of
flow.

- The transfer of heat from a hot
to a cold mass by the action of

air, gas or liquid passing over it.

- Difference - A t = temperature

difference

- A p = pressure
difference.

--All liquids gasses and solids
expand in volume on a rise in

temperature.
In a heating system it is neces-

sary to make provision for:

1. Expansion in water volume.

2. Expansion in pipes.

--The amount of gas consumed in
a measured period of time.

- A non adjustable facing used on

the termination of a duct.

- The heating circuit with the
greatest resistance.

- A factor given to building
materials relative to the resis­tance they offer to the conduct­ing of heat -

surface to surface.

- Liquified Petroleum Gas.

- Systems in which connections
to radiators are made in 6 mm,

8 mm or 10 mm tube”usually

from a

central manifold.

Open Vent

- Also called the safety vent pipe
or expansion pipe. AT pipe of

not less than 22:‘mm‘-Q) rising
throughout its entire .length to

vent atmosphere above thewater’

level in the feed and expansion
tank. Its purpose is .to. relieve
pressure in the system. in the:

event of thermostat failure and

to accommodate changes in:
water level due to the:operation­of the pump.

,..*-. n

Neutral point - Point at which cold feed:. is

connected to the system: Called
the neutral point since the
pressure is always thestatic head
pressure and is not influenced
by the operation of the pump.

Plenum - The take off from a warm air

unit to which the distribution
ducts are connected.

!

Pump head - The pressure imposed on a

system by the operationof the
circulating pump. Tfi3 ability of
a pump to overcome a resistance
as to support a column of water.

Radiation - The heat transferred -Trbrn. one

body to another bywave motion.

Small bore

- A system of circulation using
15 mm, 22 mm and .2B -mm
pipes.

.._ *a,, . ‘;-

.‘“;’ ;.;.

Static head - The pressure imposed on a system

by the height of the:.feed and

expansion tank above -any part’

of it.

I. ,

Thermocouple

- A heat sensitive probe made of I
dissimilar metals which,, when
heated create an electrical cur-

rent (measured in millivolts)
due to the A t between the hot
and cold junctions.

‘U’ values

- The amount of heat per hour
passing through a measured area
of a given material of given
thickness per “C or “F.

Venturi

- A restriction in a pipe which
creates a pressure differential.

‘3 CONVERSION TABLES

13. CONVERSION FACTORS AND USEFUL COMPARISONS
MULTIPLICATION FACTORS FOR UNIT CONVERSION

Imperial to SI
LENGTH
Inch to millimetre (mm)

foot to metre (m)

mile to kilometre (km)

AREA

25.4

Millimetre to inch (in)

0.039

0.305

metre to foot (ft)

3.281

1.609

kilometre to mile

0.621

sq. inch to sq. centimetre (cm’)

VOLUME

0.093

sq. metre to sq. foot (ft’)

10.764

cubic foot to cubic metre (m3 1

bit foot to litre (I) or cubic

decimetre* (dm3 1

pint to litre (I)

gallon to litre (I)

MASS

0.028

28.32

0.586

4.546

ounce to gramme (g)

pound to kilogramme (kg)
ton (U.K.) to tonne (t)

HEAT’-

28.35

gramme to ounce (02)

0.454

kilogramme to pound (lb)

1.016

tonne to ton (U.K.)

Btu to-kilojoule (kJ)
therm to megajoule (MJ)

HEAT FLOW (Input and Output)
Btu/hour to watt (WI

1,000 Btu/hour to kilowatt (kW)
1,000 Btu/hour to megajoule/hour

(MJ/h)

FI .OW RATE

1.055

kilojoule to Btu

105.5

megajoule to therm

0.293

0.293

1.055

,ic foot/hour to cubic metre/hour

(m3/h) (gas)
cubic fodt/hour to litre/hour (I/h)
cubic foot/hour to millilitre/second

(ml/s)

-gallon/hour to litre/hour (I/h)
gallon/hour to millilitre/second

(ml/s)

gallon/minute to cubic metre/hour

h3/g)

gallon/minute to litre/second

PR ESSU R E

0.028

28.32

7.866

4.546

1.263

0.273

0.076

inch w.g. to millibar (mbar)
pound force/sq. inch to bar

CALOR I FIC VALUE
Btu/cubic foot to megajoule/cubic metre

2.5

millibar to inch w.g. (in.w.g.1

0.4

0.069

bar to pound forcekq. inch

14.5

(MJ/m3)

0.038

SI

to Imperial

cubic metre to cubic foot (ft3 1

litre or cubic decimetre to cubic

foot (ft3 1
litre to pint
litre to gallon

watt to Btu/hour (Btu/h)

kilowatt to 1,000 Btu/hour
megajoule/hour to 1,000 Btu/hour

(Btu/h)

cubic metre/hour to cubic foot/hour

(ft3/h) (gas)
litre/hour to cubic foot/hour
millilitre/second to cubic foot/hour

(ft’/h)
litre/hour to gallon/hour
millilitre/second to gallon/hour

(Gal/h)

cubic metre/hour to gallon/minute

(gal/m)
litre/second to gallon/minute

megajoule/cubic metre to

btukubic foot (Btu/ft3 )

35.31

0.35

1.76

022

0.035
2205

0.984

0.948.’ ’

0.00948

3.412 ._

3.412

0.948

35.31 .-

0.035

0.127

0.22.:

0.792

3.67

13.198

26.34

-ubic decimetres will be used in the gas industry to express gas volumes and the space occupied by

appliances, etc.

USEFUL.COMPARISONS

1 gallon water = 10 lbs = 0.16 ft3

1 ft3 water = 6.23 gallons = 62.35 ibs.

1 Btu wiil raise 1 lb water 1 o F in 1 hour.

1 K cal will raise 1 Kg (1 litre) water 1°C in 1 hour.

1 m3 water = 1000 Kg = 1000 litres.

OC:to°F= 1.8C+32

“F to “C = s/9 (“F -32)

1 bar=lOmofhead=15psi=34ft.ofhead.

1 psi = 2.31 ft of water = 703.03 mm of water.

ESPOOI