Bell & Gossett HFT User Manual

HFT Expansion Tanks for

Hydronic Heating Systems

INSTALLER: PLEASE LEAVE THIS MANUAL FOR THE OWNER’S USE.

INSTRUCTION MANUAL

V1000002B

WARNING: California proposition 65
warning! This product contains chemicals
known to the state of California to cause
cancer and birth defects or other reproduc­tive harm.

Safety Instruction

This safety alert symbol will be used in this
manual to draw attention to safety related

instructions. When used, the safety alert
symbol means ATTENTION! BECOME ALERT! YOUR
SAFETY IS INVOLVED! FAILURE TO FOLLOW THE
INSTRUCTIONS MAY RESULT IN A SAFETY HAZARD.

WARNING: Explosion or Rupture Hazard.

A relief valve must be installed to prevent

pressure in excess of local code requirement

or maximum working pressure

designated in the Product Manual, whichever is less.
Do not expose Product to freezing temperatures or
temperatures in excess of 240°F. Do not adjust the
pre-charge or re-charge this Product except for any
adjustments at the time of the initial installation,
especially if Product is corroded, damaged or with
diminished integrity. Adjustments to pre-charge must
be done at ambient temperature only. Failure to
properly size the Product or follow these instructions
may result in excessive strain on the system and may
lead to Product failure, serious or fatal personal injury,
leakage, and/or property damage.

WARNING: Read carefully the product
installation, operating and maintenance
instructions. Failure to follow the instruc-

tions and warnings in the manual may result
in serious or fatal injury and/or property damage, and
will void the product warranty. This product must be
installed by a qualified professional. Follow all
applicable local and state codes and regulations, in the
absence of such codes, follow the current editions of
the National Plumbing Code and National Electric
Code, as applicable.

DESCRIPTION

When water is heated, it expands. Provision must be
made for this expansion in a closed hot water heating
system. The Bell & Gossett Series HFT pre-charged
diaphragm tank stores the expanded hot water and
returns air-free water to the system when the
temperature drops.

OPERATIONAL LIMITS

Maximum Operating Pressure: 100 PSI.
Maximum Operating Temperature: 240ºF.

WARNING: This product, like most products

under pressure, may over time corrode,

weaken and burst or explode, causing

serious or fatal personal injury, leaking or
flooding and/or property damage. To minimize risk, a

licensed professional must install and periodically
inspect and service the Product. A drip pan connected
to an adequate drain must be installed if leaking or
flooding could cause property damage. Do not locate in
an area where leaking could cause property damage.

INSTALLATION INSTRUCTIONS

A. PRE-INSTALLATION

1. Visually inspect expansion tank and check for damage
prior to installation.

WARNING: If the expansion tank is
damaged, it must be replaced. Failure to
follow this instruction may result in serious
personal injury or death and property
damage.

4. If an HFT tank is used with a volume smaller than
required to accommodate expanded water from a cold
start to maximum operating temperature, some
preliminary expanded water must be drawn from system
to bring operating pressure down to normal level. Drain
water from boiler until pressure reads at maximum range
(25 PSIG).

Generally, a smaller tank will cause a higher system
pressure than desired when system reaches operating
temperatures. This condition is normally referred to as a
Summer/Winter installation (boiler is always at
temperature). Tank should be tagged to denote this.

2. Bell & Gossett Series HFT diaphragm tanks are factory
pre-charged to 12 PSI. Adjust pre-charge to equal system
fill pressure.

3. Replace and tighten cap on air fitting.

WARNING: System fluid under pressure and/
or at high temperatures can be very
hazardous. Before servicing, reduce system

pressure to zero or isolate the vessel from
the system. Allow system to cool below 100°F and
above 35°F. Failure to follow this instruction may result
in serious personal injury and/or property damage.

B. INSTALLATION

The Bell & Gossett Series HFT pre-charged diaphragm
tank may be installed into a tee or any other suitable
tapping anywhere in the hot water heating system.

WARNING: A residential tank must be

installed vertically or horizontally. Do not

install on a dead end pipe or in an overhead

joist space.

An ideal HFT tank installation is to screw it into the
bottom of a Bell & Gossett air separator (IAS, EAS or
EASB-JR) located on the supply line. This combination
offers both control of expanded water and continuous
automatic air removal from the system.

After installing Bell & Gossett HFT tanks on the system:

1. Fill system.

2. Vent air from system.

3. Bring system up to maximum operating temperature.

WARNING: This expansion tank, as all
expansion tanks, will eventually leak. Do not
install without adequate drainage provisions
where water flow will cause damage.

WARNING: RUPTURE OR EXPLOSION
HAZARD Like most pressurized tanks, this
tank can over time corrode, weaken, and

burst or explode. Failure to follow this
instruction may result in serious personal injury or death
and property damage.

WARNING: CHLORINE & AGGRESSIVE

WATER HAZARD The water quality can

significantly influence the life of your

product. You should test for corrosive

elements, acidity, total solids, and other relevant
contaminants, including chlorine and treat your water
appropriately to insure satisfactory performance and
prevent premature failure. Failure to follow this
instruction may result in serious personal injury or
death and property damage.

SYSTEM VENTING AND PURGING

After initial venting and purging of air from the system,
more air will be released from the water as it is heated.
Therefore, it is recommended that a Bell & Gossett air
separator be installed on the main.

If the system has multiple loops or zones, the supply
water for all loops and zones must pass through the air
separator for complete and continuous air removal. In
case the piping arrangement does not permit the
installation of a single air separator on the main, air
separators should be installed on each loop or zone. In
this event, only one expansion tank is required for the

system.