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Old 10-25-2008, 12:09 PM   #1 (permalink)
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Heat Pump Temp Lockout Settings to Gas Backup

As fall is settling in, there have been a few cold evenings where heat was requested. I tested the heat output of the Heat Pump and the Natural Gas Burner and both are ready for Winter.

Here's my Question...

(Background): I finally located a copy of the technical instructions for operation of the system through a programmable thermostat. Advanced settings allow multiple fan speeds, etc. There are 2 settings and a statement in the manual that have me wondering what is setting is best:
  • Heat Pump "Balance Point Setting" Temp
  • Heat Pump Lockout Temp
The Heat Pump will attempt to operate at the balance point setting, i.e. 35F. If the pump does not achieve results in 15-minutes, the gas burner is activated. The Lockout Temp is the lowest temperature permissible to operate the pump unit.

From the manual:
1. Capacity Balance Temperature:
This is the point where the heat pump cannot provide sufficient
capacity to keep up with the indoor temperature demand because
of declining outdoor temperature. At or below this point, the
furnace is needed to maintain proper indoor temperature.
2. Economic Balance Temperature:
Above this point, the heat pump is the most cost efficient to
operate, and below this point, the furnace is the most cost efficient
to operate. This can be somewhat complicated to determine and it
involves knowing the cost of gas and electricity, as well as the
efficiency of the furnace and heat pump. For the most economical
operation, the heat pump should operate above this temperature
(assuming it has sufficient capacity), and the furnace should
operate below this temperature.
As it states, it's complicated to determine. Has anyone had any experience with these settings? Cost is an issue, but so are emissions. The Grid is inherently more efficient/clean, but there's a point where the balance tips to favor Natural Gas -- in addition, the burner heats up the house very quickly compared to the Heat Pump.

So here I am

I have the Balance Point at 35F with the lockout at 30F. Perhaps I should conduct some tests at different temperatures and time the electricity usage compared to the gas and try to figure the amount consumed of each ???


“If we knew what we were doing, it wouldn't be called research” ― Albert Einstein

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