Bell & Gossett V58911B Expansion Tanks for Hydronic Heating Systems - Manual (Page 3)

OPERATING INSTRUCTIONS
1. The expansion tank is typically installed in the bottom of an air
separator. Its sealed-in air pre-charge prevents water from
entering the tank until the system pressure exceeds the pre-
charge pressure.
2. As the water temperature rises, expanded water enters the
expansion tank’s water reservoir. The pre-charge air chamber
absorbs the pressure increase, keeping system pressures below
the relief valve setting.
3. As water temperature decreases the pressure in the air chamber
forces water back into the system until the expansion tank is
empty.
The selection, application, installation and servicing of this product
should be performed by a qualified professional within all applicable
safety and code requirements.
SERVICE INSTRUCTIONS
1. Check the expansion tank periodically for signs of external
leakage or corrosion. If found, the tank must be replaced.
2. If a HVAC system is shut down for long periods or emptied for
any reason, it is necessary to follow the following procedure:
a) Fill system.
b) Vent air from system (see system venting and purging).
c) Bring system up to maximum operating temperature.
Before filling and starting the operation of a HVAC system, a
properly applied and sized pressure relief valve must be
installed and in good operating order.
During filling and start-up after servicing, the system pressure
should be closely monitored to ensure the pressure does not
exceed the pressure relief valve rating.
Consult the applicable pressure relief valve manufacturers
instructions as necessary.
3. If the system pressure is too high:
a. Check gauge calibration.
b. Check to see if expansion tank has lost its air charge.
NOTE: To check the expansion tank air pressure with a tire
gauge either:
1. Disconnect the expansion tank from the system or,
2. Draw off system water until boiler pressure reads zero or
isolate the expansion tank from the system in domestic
water systems, and bleed pressure from the system. All
drains must be kept open during servicing of the expan-
sion tank. (Expansion tank must be empty of expanded
system water.)
3. Then check tank pressure with tire gauge.
c. Check for faulty fill valve operation. First, close manual shut-
off located before the fill-valve; then, draw system pressure
down to pre-set pressure open shut-off valve and observe
system for pressure build-up several hours later. If pressure
build up beyond set pressure is found, replace fill valve
following manufacturers instruction.
d. Check for service water entering system from any other
source such as a defective tankless heater or indirect fired
water storage tank. Use same procedure as above after
shutting off possible water source. Replace defective device
if found following manufacturers instruction.
4. If pressure relief valve drips water:
a. First, check system pressure. If too high, follow steps 3. a.,
b., c., and d. above.
b. If pressure relief valve continues to drip water, even at
reduced pressure, flush relief valve by quickly raising lever
several times. If drip continues, replace relief valve following
manufacturers instruction.
c. If multiple expansion tanks are installed in the system, check
pressure of each for possible air leaks. Be sure plastic air
valve caps are on tight. Multiple tanks should be in the same
location.
WARNING: Signs of leakage or corrosion are indications the
tank may have failed. Periodically check the expansion tank
for signs of external leakage or corrosion. If found, the tank must be
replaced. Failure to follow these instructions may result in serious
personal injury or death and property damage.
WARNING: Insert proper warning about system under
pressure and applicable hazards.
MODELS
HFT-15 THRU
HFT-90
MODELS
HFT-30V THRU
HFT-160V
AIR
CUSHION
AIR
CUSHION
AIR
CUSHION
AIR
CUSHION
AIR
CUSHION
AIR
CUSHION
WARNING: Improper use of air charging valve during venting
of air pressure from tank will create a hazardous condition due
to the escape of high velocity gas and/or liquid. Depress the center
valve core stem, as with a tire valve to slowly vent off gas pressure.
Do not remove the valve core until pressure in expansion tank has
reached zero. Failure to follow these instructions could result in
serious personal injury or death and property damage.