TP-M11
17
Pump does not run
In areas where hard water is present the
pump may “stick” and fail to run. Often,
closing the isolation valve on the return
leg and opening the drain port so that
water flows through the pump can free
this. For Grundfos pumps, remove the
screw-on cover from the face of the
pump, and rotate the shaft one turn with
a slotted screwdriver. If either method
fails to free the pump, removal for
cleaning or replacement is necessary.
The daily pump exerciser will help
prevent pump sticking.
Pump is noisy at start-up
Air is present in heating loop. If sound
has not diminished within 1 minute,
purge air in accordance with the
Start-Up
procedures. If heat source is a water
heater, check to make sure branch
connections for heating loop are
horizontal to prevent the collecting of air
in the heating loop. See the drawing:
Typical Plumbing Connections at the
front of this manual.
Water heater T&P is weeping
A check valve or back-flow preventer
may have been installed in the system.
Some form of pressure relief may be
required. Options are:
•
Install expansion tank
•
Install pressure relief valve; locate
outlet over laundry tub or floor
drain.
•
Install combination toilet
tank/pressure relief valve
Insufficient or no heat
•
Plugged air filter or coil. Refer to
Maintenance
section for filter care
and coil cleaning.
•
Air in heating loop; purge system.
•
Inlet and outlet connections to air
handler backwards; reverse
connections.
•
Water heater supply tube (dip
tube) is restricted or damaged;
check and/or replace.
•
Supply water temperature set too
low or not calibrated properly;
check water temperature. In the
case of water heater; If the
temperature has been set low
because of homeowner
preference, it may be necessary to
install an anti-scald valve to
control the faucet temperature and
raise the operating temperature of
the water heater.
•
Restrictions in heating loop;
remove restrictions, check valve
stuck, isolation valves too
restrictive, left partially closed after
purging or closed valve.
•
Water heater supply temperature
is unstable. Check water heater
setting and temperature sensors
for good contact on coil headers.
Cold water at hot faucet
When heat source is a water heater, the
most probable cause is reverse flow
through the heating loop from a stuck
check valve; repair or replace valve.
Fan runs for cooling but not heating
Room thermostat may be connected
improperly. Refer to
Electrical
section or
wiring schematic on door of air handler
for proper installation.
Heating during Standby Mode
Probable cause is thermal siphoning.
See check valve description for details;
repair or replace check valve. Check
elevation of air handler above water
heater to see if motorized valve required
for positive shut-off.
