Two words: reversing + valve.

wrote in message
.. .
In article , Bob wrote:
The supply temperature of an air to air heat pump will feel cold because
it's lower than your body temperature. He has no back up heat, so the
air
never feels warm. In a typical tract home where the builder hired the
low
bid HVAC contractor, the duct work may be too small, so the velocity of
air
coming out feels even colder because of a wind chill effect on the body.



OP here.

Thanks.

However, in this case, it will blow as cold as when in AC mode for
very extended periods ( much longer than defrost cycles ).

So cold for so long that the whole house gets gradually colder instead
of gradually warmer.

I'm really curious if the defrost circuit is bad or if the
thermostat is insane.

When the heat pump desides to start blowing cold, the voltage
at the reversing valve lead at the thermostat goes from
26.6V to 0.0V.

Is this voltage change due to a "command" from the defrost control
circuit?

Can the defrost control circuit even drive that voltage level?

If not, It would seem that the cold is due to the thermostat
loosing its mind.


Again, thanks for any help.