11.2.2 Miscellaneous issues
Miscellaneous issues
Issue Diagnosis Fix
‘Ghost’ call
for heat.
Triac or ‘Power-
robbing’ thermostat
sending current to
hydronic heat pump.
Remove connections from hydronic heat pump to confirm
that stray voltage, or current induced in thermostat wiring,
is source of nuisance signal. If so, replace the Power
Robbing thermostat or isolate the thermostat with a relay.
11.2.3 Cycling issues
Cycling issues
Issue Diagnosis Fix
Rapid
Cycling
Incorrect settings or
defective thermostat.
Check operation. Refer to manufacturer’s instructions.
Check setting with ammeter.
Air in system or marginal
water flow.
Bleed / purge system as required. Confirm adequate pump
size and temp rise in the heat exchanger.
Low water flow due to
improper piping.
Review pressure drop of hydronic heat pump piping.
Low water flow due to
restrictions in water pipe.
Check temperature differential across zone / heat
exchanger.
Low radiation. Check actual amount of radiation per zone and refer to
manufacturer’s rating tables.
Appliance Oversized. Compare heat load calculation to minimum hydronic heat
pump output.
Improperly set or defective
controls.
Check operation with ohmmeter / voltmeter.
11.2.2 Miscellaneous issues
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