Wood stove heat confusing thermostat?

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Old 01-05-14, 01:38 PM
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Wood stove heat confusing thermostat?

We are into the second season of using a wood stove insert to supplement our heating. Now I am wondering if it may be costing us more money than we are saving.

We have a 4,000 sq. ft. house heated by two electric heat pumps with an electric coil backup. I understand that in a typical operation, when the outside temperature goes low enough, the heat pump cannot produce much heat. So the thermostat is set to switch to auxiliary backup when the house temperature falls some number of degrees below to the temperature set on the thermostat.

If I am also burning wood in my wood stove, the supplemental heat from wood stove raises the home temperature. Under certain conditions, it can potentially eliminating the said temperature shortfall. So the heat pump and not the auxiliary may continue to operate in conditions that it cannot produce any heat. I am assuming that as a result it may be running continuously, thus the extra cost, while not producing any heat. I guess if it is call enough, the wood stove should eventually fail to supplement sufficiently, the temperature should drop further, and the thermostat should kick on the auxiliary. Depending on the outside temperature, BTUs of my wood stove, and the location of the thermostat the wasteful part of this cycle will vary in duration. Still the waste should remain.

Q1: Am I correct that the above is indeed what is happening and is indeed a problem?
Q2: The best solution that I came up with so far is to move the thermostat further away from the stove and also set it to auxiliary heat when the temperature falls below freezing. Does this make sense or are there better ways to manage it?

Thank for your help ahead of time!
 
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Old 01-05-14, 02:03 PM
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Personally I'd find a temp on the thermostat that works. Set it and forget it. If your wood stove is providing enough heat the heat pump and it's aux heat will not come on. If the wood is not enough then the technology automatically comes on to make up the difference.

When the room temp drops below the thermostat's set temp it turns on the heat pump. When the room temp is two degrees below the set temp the heat strips are turned on. So, if your wood stove is able to keep the temperature up the heat pump and it's emergency heat will not turn on. If the wood stove keeps the temp around the thermostat warmer than the rest of the house then you can compensate by simply setting the thermostat higher to prevent the heat pump from turning on.
 
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Old 01-05-14, 02:12 PM
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When the heat pump switches to aux, does the condenser outside stop running, or is the aux heat a supplemental heat?

Most heat pumps will use less energy than they output into the home until outsides temp get to 0 degrees F. If your auxiliary heat is a set of electric elements, then you are ahead of the game using your wood stove until you get around 0 degrees out.

It can be tricky to figure out if you are actually saving energy. Typically you figure out how much energy you have used per degree day to compare usage from season to season like this. It gets tricky for you because the colder it gets, the less efficient your heat pump is.
 
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Old 01-05-14, 02:18 PM
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I usually kick my thermostat back to 60 degrees [in case the fire goes out] and let the wood stove heat my house. [my house is smaller] There are times when I've found it beneficial to turn the HP fan on so it would better circulate the heat throughout the house. Ceiling fans and/or well placed fans can help distribute the heat to other parts of the house. I've also disconnected the elec heat strips but that's mainly because my wife likes to jack up the thermostat if she gets cold.
 
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Old 01-06-14, 05:31 AM
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I was under the impression that when aux switches on, the heat pump shuts off, but I guess I am not sure. I know that at 0 deg Fahrenheit no heat is produced, but aren't the heat pumps typically switched over to aux around 30 or so? If I can just determine the temperature at which there is no point running the heat pump, I would just do manual switching to aux when wood stove is on.
 
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Old 01-06-14, 06:15 AM
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I always thought that the heat strips worked in conjunction with the HP but I don't know for sure. We seldom get down near zero but I guess I can find out tomorrow morning if a HP puts out any heat at below zero.
 
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Old 01-07-14, 05:57 PM
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The heat strips will kick on before 0. Pilot Dane explained it here:

When the room temp drops below the thermostat's set temp it turns on the heat pump. When the room temp is two degrees below the set temp the heat strips are turned on.
 
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