THERMO 2000 GTH 6, GTH 8, GTH 10, GTH 12, GTH 18 Use & Care Manual

GTH Electric Boilers

Models ranging from 6 kW to 36 kW :

240 Volts ( 1 phase ) & 600 Volts ( 3 phases ).

USE & CARE MANUAL

WITH INSTALLATION INSTRUCTIONS FOR THE CONTRACTOR

Your GTH Electric Boiler has been carefully assembled and factory tested to provide years
of trouble-free service. The following information and safety measures are provided to
enable proper installation, operation, and maintenance of this product.

It is imperative that all persons who are expected to install, operate or adjust this boiler
should read these instructions carefully.

Any questions regarding the operation, maintenance, service or warranty of this electric
boiler should be directed to the supplier.

When all installation steps have been completed, insert this installation manual in its original
envelope, and keep in a safe place (close to the boiler) for future reference.

THERMO 2000 INCORPORATED revision : November 2005

Printed in Canada

Section 1: Dimensions & Specifications

Table 1: Electric Ratings for 240 VAC (1 phase) Electric Boilers:

Current

Model

GTH 6 6 25.0 34.0 2 X 3KW 2 2 2 1 8 50
GTH 8 8 33.3 42.3

GTH 10 10 41.6 50.6 2 X 5KW 2 2 2 1 6 70
GTH 12 12 50.0 59.0 4 X 3KW 4 4 4 1 4 100

GTH 15 15 62.5 71.5
GTH 18 18 75.0 84.0 4 X 4.5KW 4 4 4 1 3 110

GTH 20 20 83.4 92.4 4 X 5KW 4 4 4 1 2 125
GTH 24 24 100.0 109.0 4 X 6KW 4 4 4 1 1 150
GTH 27 27 112.5 121.5 6 X 4.5KW 6 6 6 2 1/0 175
GTH 30 30 125.0 134.0 6 X 5KW 6 6 6 2 2/0 200

GTH 33 33 138.0 147.0

* Current for circulator (9 Amp max)

P

KW

Heating

Elements

Table 2: Electric Ratings for 600 VAC (3 phases) Electric Boilers:

P

Model

GTH 9 9 8.7 3 X 3KW 1 1 1 2 14 15
GTH 13 13.5 13.1 3 X 4.5KW 1 1 1 2 12 20
GTH 18 18 17.5 6 X 3KW 2 2 2 3 10 30

GTH 22 22.5 22.0
GTH 27 27 26.0 6 X 4.5KW 2 2 2 3 8 40

GTH 30 30 29.1 6 X 5KW 2 2 2 3 8 40
GTH 36 36 35.0 6 X 6KW 2 2 2 3 8 50

KW

Current

Amp

Amp

Total

with

Circulator

Elements

1X 3KW

1 X 5KW

2 X 3KW

2 X 4.5KW

3 X 5KW
3 X 6KW

Elements Stage Aquastats Lights Contactors

3 X 3KW

3 X 4.5KW

2 2 2 3 10 30

Wires

Stages

2 2 2 1 6 70

4 4 4 1 3 110

6 6 6 2 2/0 200

Lights

Aquastats

CU

Contactors

Fuse

Wires

CU

A

Fuse

A

Table 3: Connections sizes & Boiler overall dimensions

Connections sizes Boiler overall dimensions

Boiler return 1 “ NPT M Height 12 3/16 inches

Boiler feed 1 “ NPT M Width 16 7/16 inches

Waterworks 1/2 “ NPT F Depth 28 ½ inches

Safety valve 3/4 “ NPT F Shipping weight 99 lbs.

Drain valve 1/2 “ NPT F

Drain valve (GTH

33,36)

Operating temperature : from 50°F to 190°F.; Maximum operating pressure: 30 p.s.i.

3/4 “ NPT M

DTH Electric Boilers USE & CARE MANUAL (Revision November/05), Page 2.

2

8

1

/

2

"

C

A

F

B

E

D

I

M

16"

G

H

K

L

16 7/16"

12 3/16"

N

Legeng/Légende:
A) Boiler Water Supply Connection / Alimentation du chauffage (1" npt M)
B) Boiler Water Return/ Retour du chauffage (1" npt M)
C) Safety relief valve/ Soupape de sûreté (3/4" npt F.)
D) Temperature and pressur e G age/ Indicateur de Tempéra tur e et pr ession (1/2'' npt. F)
E) Drain Valve/ Valve de drainage (3/4'' npt M)
F) Fill Water Connection/ Entrée d'eau aqueduc (1/2" npt F)
G) Power supply wi r ing/Alimentation électrique
H) Pilot Ligh ts/ Lampe témoin
I) Electrical Compartments/ Co mpartiment électrique
J) Wall Brackets/ Supports mural
K) Circulator wiring/ Alimentation pompe
L) Thermostat wiring/ Connection thermostat
M) ON/OFF switch/ Interrupteur ON/OFF
N) Elements Co mpartments/ Compartiment d es éléments

J

THERMO 2000 inc.

SIZE

DWG. NO.

A

REV.

DESSIN D'ATELIER GTH/
GENERAL DIMENSIONS GTH

TH2-ATELIER

0

Figure 1

Page 3

General Safety Precautions

!

Be sure to read and understand the entire Use & Care Manual before attempting to install or to
operate this electric boiler. Pay particular attention to the following General Safety Precautions.
Failure to follow these warnings could cause property damage, bodily injury or death. Should
you have any problems understanding the instructions in this manual, STOP, and get help from
a qualified installer or technician.

Section 2: Introduction

WARNING

!

The important safeguards and instructions
appearing in this manual are not meant to
cover all possible conditions and situations
that may occur. It should be understood that
common sense, caution and care are factors
which cannot be built into every product.
They are the responsibility of the person(s)
caring for and operating the unit.

2.1 LOCAL INSTALLATION
REGULATIONS

This electric boiler must be installed in
accordance with these instructions and in
conformity with local codes, or in the absence of
local codes, with the National Plumbing Code
and the National Electric Code current edition.
In any case where instructions in this manual
differ from local or national codes, the local or
national codes take precedence.

2.2 CORROSIVE ATMOSPHERE

The electric boiler should not be located near an
air vent containing a corrosive atmosphere or
high humidity. The limited warranty is void when
the failure of the electric boiler is due to a
corrosive atmosphere.

2.3 INSPECT SHIPMENT

Inspect the electric boiler for possible shipping
damage. The manufacturer’s responsibility
ceases upon delivery of goods to the carrier in
good condition. Consignee must file any claims
for damage, shortage in shipments, or non­delivery immediately against carrier.

2.4 CHECK LIST

Please check the identification tag on the unit to
make sure you have the right model.

List of components shipped with the unit :

• Pressure relief valve set at 30 PSI.

• Drain valve.

• Tridicator (temperature & pressure

gage).

CAUTION

!

The electric boiler should not be located in
an area where leakage of the tank or water
connections will result in damage to the
adjacent area or to lower floors of the
structure. When such areas cannot be
avoided, a suitable drain pan or non­flammable catch pan, adequately drained,
must be installed under the boiler.
The pan must be connected to a drain.
NOTE: Auxiliary catch pan MUST conform to
local codes.

DTH Electric Boilers USE & CARE MANUAL (Revision November/05), Page 4.

Section 3: Installation

WARNING

!

The manufacturer’s warranty does not cover
any damage or defect caused by installation,
or attachment, or use of any special
attachment other than those authorized by
the manufacturer into, onto, or in
conjunction with the boiler. The use of such
unauthorized devices may shorten the life of
the boiler may endanger life and property.
The manufacturer disclaims any
responsibility for such loss or injury
resulting from the use of such unauthorized
devices

3.1 SECURITY CONSIDERATIONS

Domestic and commercial installations have a
maximum design operating pressure limited to
30 psi (207 kPa) by a safety relief valve.

Boiler maximum operating temperature is 190°F
by design. This boiler is designed to be used

only in a hot water heating system.

The heat transfer medium must be water or
other non-toxic fluid having a toxicity rating
or class of 1, as listed in clinical Toxicology
of Commercial products, 5

3.2 LOCATION

The electric boiler should be installed in a clean,
dry location. Long hot water lines should be
insulated to conserve water and energy. The
electric boiler and water lines should be
protected from exposure to freezing
temperatures.

The electric boiler must be installed horizontally,
directly on the wall. Use the wall mounting
brackets to make the unit level. The wall
mounting brackets are held by four 5/16’’ lag
screws. The openings are located at 16’’
intervals (i.e. standard stud spacing). When the
first bracket is installed you can hang the boiler
on the wall (see figure 1). The lag screws must
be suitably anchored to safely support the
weight of the boiler including water content,
piping and wiring.

CAUTION

!

th

edition

The electric boiler must be located or protected
so as not to be subject to physical damage, for
example, by moving vehicles, area flooding, etc.
All models can be installed on combustible floors
and in alcoves. Ambient temperature must not
exceed 80°F or 27°C.

3.3 CLEARANCE

Minimum clearances for adequate inspection
and servicing are listed in the following table:

Table 4: Boiler clearance

Left side 16 inches

Right side 6 inches

Top & Bottom of the boiler 6 inches

Front side of the boiler 24 inches

Back side of the boiler 0 inch

3.4 PIPING

The recommended piping arrangement is shown
in figures 2, 3, 4 and 5, including the pump,
expansion tank, drain valve, pressure relief
valve, air vent, flow check valve and pressure­temperature gauge. Details about each item
follow.

3.4.1 Boiler connections

This electric boiler may be connected
individually or in parallel with other boilers. If two
or more boilers are connected, the “reverse­return piping” method (whereby the boiler with
the first return inlet also has the last supply
outlet and so forth until the last return inlet
corresponds to the first supply outlet) should be
used to connect the boilers in parallel, to ensure
an equal water flow rate through each boiler.

The BOILER WATER SUPPLY, located on the
top side, and the BOILER WATER RETURN,
located on the bottom side of the boiler are steel
pipes (male NPT threaded connection) where
supply and return line connections are to be
made.

Installing a union is recommended on the boiler
water supply and return lines to facilitate boiler
disconnection for servicing.

Dielectric unions are required for protection of
the boiler and piping if dissimilar pipe material
such as galvanized steel and copper are
present.

DTH Electric Boilers USE & CARE MANUAL (Revision November/05), Page 5.

Use only clean pipe for boiler water lines. Local
codes or regulations shall govern the exact type
of material to be used.

Insulate all pipes containing hot water,
especially in unheated areas.

Install shutoff (ball) valves for servicing
convenience. Thermometer(s) should be
installed on the boiler water supply and return
lines.

Cap or plug unused connections on the boiler.
Do not cap the pressure relief valve on the
boiler since it will damage and shorten the life of
the boiler and may endanger life and property.

3.4.2 Flow check valve

If the heating system is pipe to use only a single
pump, then to minimize flow by gravity & heat
loss during non-draw periods, a flow check

must

be installed.

3.4.3 Pressure relief valve

An automatic pressure relief valve must be
installed during boiler setup. The pressure
rating of the relief valve must not exceed 30 psi.
The safety relief valve must meet the
requirements of the ASME Boiler and Pressure
Vessel Code and limit the maximum operating
boiler pressure. It is a safety device, not an
operating control.

The BTU per hour rating of the relief valve must
equal or exceed the BTU per hour input of the
boiler(s) or heat source(s) as marked on the
boiler(s) rating plate.

Connect the outlet of the relief valve to a
discharge line with its lower tip at most 6” above
a floor drain, well clear of any live electrical
parts. The discharge line must pitch downward
from the valve to allow complete draining by
gravity of the relief valve and discharge line, and
be of a diameter no smaller than that of the
valve outlet. The tip of the discharge line should
not be threaded or concealed and should be
protected from freezing. No valve of any type,
restriction or reducer coupling should be
installed on the discharge line. Local codes
shall govern the installation of relief valves.

3.4.4 Piping system pressurization:
expansion tank

Pressure control devices within the system
ensure that each component operates within
minimum and maximum allowable pressures
and maintain minimum pressure for all normal
operating temperatures. They also allow air
bleeding, prevent cavitation at the pump inlet
and prevent water from boiling within the
system; all this is accomplished with minimal
addition of new water.

The increase in boiler water volume resulting
from higher temperature is stored in the
expansion tank during periods of high operating
temperature and is returned to the system when
the temperature decreases.

The expansion tank must be able to store the
required volume of boiler water during maximum
design operating temperature without exceeding
the maximum allowable operating pressure, and
to maintain the required minimum pressure
when the system is cold. Contact your installing
contractor, plumbing supply house, or local
plumbing inspector for assistance.
The point where the expansion tank is
connected should be carefully selected to avoid
the possibility that normal operation of automatic
check or manual valves will isolate the tank from
a hot boiler or any part of the system. Pre­charged diaphragm expansion tanks are
preferable to air control (see section 3.4.6).

These tanks incorporate a balloon-like bladder
or diaphragm. It is inflated, prior to filling the
system, to a pressure equal to the setting of the
water pressure makeup regulator.

The expansion tank should be located on the
suction or intake side of the pump. The pump
can be located either just upstream or just
downstream from the boiler.

3.4.5 Water pressure makeup regulator

Make-up systems must be employed as
required by codes. An automatic fill valve
must be used with a backflow preventer as
required, to maintain minimum system pressure
by supplying water to make up for leakage.

3.4.6 Air bleeder

Oxygen should be excluded from the system to
prevent corrosion. As hinted at in section 3.4.4,

DTH Electric Boilers USE & CARE MANUAL (Revision November/05), Page 6.

this precludes the use of air in direct contact with
the boiler water as a pressurization means.

Installation of manual or automatic air vent
devices prevents air from accumulating in the
system. Air vents should be installed at all high
points to remove trapped air during initial setup
and to ensure that the system is tight. Regularly
purge the air out of the system while taking care
to avoid personal injuries or property damage
caused by hot boiler water spray.

3.4.7 Circulator zoning recommendations

The preferred location of the circulator pump for
each zone is on the boiler supply side, with the
expansion tank between the boiler and the
pump.

A flow check valve must be installed in each
zone, preferably on the outlet side of each
circulator pump, to prevent water flow to other
zones where no heat is required.

3.4.8 Zone valve zoning
recommandations

The preferred location of the circulator pump is
on the boiler supply side, with the expansion
tank between the boiler and the circulator. Use
zone valves with low pressure drop.

3.4.9 Pump & pipe sizing

3.4.9.1 Boiler water temperature drop (BWTD)
through the heating loop

A simplified design method based on a 20°F
temperature drop (BWTD) between boiler outlet
and inlet is commonly used. Although such a
method is widely used and generates
satisfactory system performance when applied
properly, it does not determine the system
operating point. The pipe size is often
uneconomically large, and the actual system
flow rate is likely to be much higher than
intended. Such design methods seldom
consider temperature drops higher than 20°F,
which results in overdesign.

Another method by which the boiler water
temperature drop (BWTD) could be calculated
is to assume a constant supply boiler water
temperature minus the return boiler water
temperature. For example a boiler might have
a return temperature of 140 °F. Assuming a
constant supply boiler temperature of 180 °F,
the BWTD would be 40 °F ( = 180 °F – 140 °F).

Second example: If the boiler water has a return
temperature of 120 °F and the boiler supply is at
140 °F, then the temperature drop is 20 °F
(=140 °F – 120 °F).

The following table suggests temperature drops
(BWTD) to be used in calculating the pump flow
rate.

Table 5: Temperature rise through the boiler

PROPOSED BOILER WATER

TEMPERATURE RISE THROUGH THE

BOILER (BWTD)

System

type

Baseboards

Cast Iron

Radiators

Radiant

In-Floor

Boiler
water

Supply

tempera-

ture

190°F to

140°F

160°F to

130°F

130°F to

90°F

Boiler
water

Return

tempera-

ture

170°F to

120°F

140°F to

110°F

110°F to

70°F

BWTD

20°F to

40°F

20°F to

40°F

20°F to

40°F

3.4.9.2 Pump flow rate calculation

The boiler output rating must correspond to the
calculated heating load or be within the sizing
guide recommendations. Use the equation
below to calculate the pump flow rate.

Pump flow rate = Boiler output ÷
BWTD ÷ 500

• Pump flow rate is express in U.S. gallons
per minute or GPM.

• The Boiler output ( in net BTU per hour) is
the maximum heat to be transferred through
the heating loop to meet the heating load.

• BWTD is the boiler water temperature drop

For example, a 24KW electric boiler has a rated
output of 81,888 BTU per hour. The system is
designed for a temperature drop (BWTD) of
20°F.

Pump flow rate = 81,888 ÷ 20 ÷ 500 = 8,2 GPM.

DTH Electric Boilers USE & CARE MANUAL (Revision November/05), Page 7.

The following chart propose water temperature
rise vs flow rate in GPM.

Table 6: Temperature rise vs flow rate (GPM)

Model KW

o

10

F 20oF 30oF 40oF

BWTD

GTH 6 6 4,1 2,0 1,4 1,0
GTH 8 8 5,5 2,7 1,8 1,4

GTH 9 9 6,1 3,1 2,0 1,5
GTH 10 10 6,8 3,4 2,3 1,7
GTH 12 12 8,2 4,1 2,7 2,0
GTH 13 13,5 9,2 4,6 3,1 2,3
GTH 15 15 10,2 5,1 3,4 2,6
GTH 18 18 12,3 6,1 4,1 3,1
GTH 20 20 13,7 6,8 4,6 3,4
GTH 22 22,5 15,4 7,7 5,1 3,8
GTH 24 24 16,4 8,2 5,5 4,1
GTH 27 27 18,4 9,2 6,1 4,6
GTH 30 30 20,5 10,2 6,8 5,1
GTH 33 33 22,5 11,3 7,5 5,6
GTH 36 36 24,6 12,3 8,2 6,1

3.4.9.3 Pipe sizing criteria

Proper selection of pipe size is important to
efficient system operation. A large pipe size
results in lower friction losses and may allow the
selection of smaller, more economical pump.
The increased pipe size, however, costs more
initially and must be balanced against the cost
savings realized be smaller pump. Likewise,
small pipe costs less initially but must be
balanced against the increased operating cost of
pumping water through a system with high
friction losses. An economical balance should
be reached between pump size, operating costs,
and pipe diameter.

The ASHRAE fundamentals handbook states
the general range of pipe friction loss used for
the design of hydraulic systems and upper limits
of water velocity in piping.

A variety of upper limits of water velocity and/or
pressure drop in piping and piping systems are
used. One recommendation places a velocity
limit of 4 feet per second for 2 inch pipe and
smaller, and a pressure drop limit of 4 feet of
water per hundred feet for piping over 2 inches.
These limitations are imposed either to control
the levels of pipe and valve noise, erosion and
water hammer pressure or for economic
reasons.

Please note that in the smaller pipe sizes, this
velocity limit permits the use of friction loss rates
higher than 4 feet per 100 feet.

Fluid velocity should be above 1-1/2 to 2 feet per
second in order to carry entrained air along to a
high point in the system where it can be purged.

It is generally accepted that if proper air control
is provided to eliminate air and turbulence in the
system, the maximum flow rate can be
established by a piping friction loss rate of 4 feet
of water per 100 feet. This allows velocities
greater than 4 feet per second in pipe sizes 2
inches and larger.

As piping ages, friction losses increase. It is
recommended that for most commercial design
purposes a safety factor of 10 to 15 % be added
to the values in the tables.

What is a “foot of water”? A column of water at
60°F, 5 feet tall, creates a constant pressure of 5
feet of water at the bottom of the column. If the
water column is 2.31 feet tall, the mass of water
creates a constant pressure (head) of one (1)
psi (pound per square inch). Pressure losses are
expressed either in “feet of water” or in psi.
Pump manufacturers usually prefer feet of water
units.

3.4.9.4 Pump or circulator selection

Performance characteristics of centrifugal
pumps are described by pump curves, which
plot flow versus head or pressure together with
other information such as efficiency and power.
Consult the manufacturer’s pump curves to
select the proper model or ask your pump dealer
or your HVAC wholesaler for a recommendation.

3.5 ELECTRIC POWER SUPPLY

Wiring must conform to the National Electrical
Code and to state or local code requirements.

The electric boiler must be electrically grounded
in accordance with local codes, or, in the
absence of local codes, with the National
Electrical Code.

3.5.1 240Vac models

Wiring must be from a 120/240 Volt (single
phase, 60 Hz) circuit protected by a properly
sized breaker. Wire gage (3 wires, ground)
must be properly sized. Consult the boiler rating
plate to select the proper breaker and wire gage

DTH Electric Boilers USE & CARE MANUAL (Revision November/05), Page 8.

3.5.2 600Vac models

Line wiring must be from a 600 Volt ( 3 phase,
60 Hz) circuit protected by a properly sized
breaker. Wire gage (3 wires, ground) must be
properly sized. Consult the boiler rating plate to
select the proper breaker and wire gage.

3.6 PUMP POWER SUPPLY

3.6.1 240Vac models

Connect only a 120 Vac, 9 amp. (maximum)
pump to terminals C and C on the electric
pannel. Do not use a 600 Vac pump or one
drawing more than 9 amps. The logic circuit is
designed to activate the circulator based only on
demand by the thermostat after a time delay.

3.6.2 600Vac models

Use a relay (Honeywell #RA-889, RA-89A) or
the secondary contact of a zone valve (if the
heating system is zoned using 4-wire zone
valves). When a thermostat calls for heat: the
relay will power either the boiler pump or the
zone valve (the zone valve will power the boiler
pump upon opening fully). See figure 6 for more
details.

If the heating system is designed to use only a
single pump, then to minimize flow by gravity
and heat loss during non-draw periods, a flow

check must

be installed.

3.7 CONNECTING THE THERMOSTAT

3.7.1 For 240Vac model

3.7.1.1 Single heating zone
Connect a low voltage thermostat to terminals T
and T on the electric panel (DO NOT apply any
power to these terminals!).

3.7.1.2 Multiple heating zones
Connect the zone valve end switch to terminals
T and T on the electric pannel (DO NOT apply

any power to these terminals!). See figure 6.

3.7.2 For 600Vac model

3.7.2.1 Single heating zone
Connect the low voltage thermostat to a relay
(Honeywell #RA-889, RA-89A). See figure 6.

3.7.2.2 Multiple heating zones

Zone valve zoning
Connect the low voltage thermostat to the zone
valve. Components must be wired to ensure that
only the zone valve corresponding to the zone
calling for heat is actuated and that the circulator
is powered on a demand from any zone.The
transformer used to power the zone valves must
be sized for the load represented by all zone
valves in the heating system. See figure 6.

Circulator zoning
Connect the low voltage thermostat to the relay
(Honeywell #RA-889, RA-89A). Components
must be wired to ensure that only the circulator
corresponding to the zone calling for heat is
actuated. See figure 6.

DTH Electric Boilers USE & CARE MANUAL (Revision November/05), Page 9.

3.8 CBE-EM DUAL ENERGY
INSTALLATION

In order to obtain a special rate from your
electric utility for residential use, your GTH boiler
can be hooked-up to an existing oil heater.
Contact your electric utility to find out if your
property is eligible for such rates and how to
register for them. For installations instructions,
refer to figure 12, 13 and 14.

The CBE-EM dual-energy control (an available
option, three-way, motorized valve (1’’ NPT F
standard) included) is specially designed to
electric utility standards. The CBE-EM control
selects the least expensive energy source based
on outside temperature, user choice or a signal
from your utility.

The CBE-EM dual-energy control will start up
the oil burner upon receiving the appropriate
signal, even if the thermostat in the house is not
calling for heat. It will shut off when the
temperature in the boiler reaches its target on
the Limit Control. It is for this reason that the
piping requires an anti-gravity valve (flow check
valve) or motorized zone valves.

A three-way, motorized valve (1’’ NPT F
standard) will direct the water flow either to the
oil-fired heater or to your DTH electric boiler,
depending on the signal received. This way,
your oil heater will cool down and eliminate any
energy loss, either through the chimney or by
way of conduction in the boiler room.

DTH Electric Boilers USE & CARE MANUAL (Revision November/05), Page 10.