Gas and Oil Home Heating Furnaces - Heat Pump Operation
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Dnicejr
10-24-03, 07:22 AM
I have recently bought a hiuse with a heat pump and am curious as to the proper operation of this unit. My previous houses have had gas heat and I am used to the warm air that they generate during operation. With the heatpump the air that comes out of the vents isn't real warm? Is this normal for this type of heat?
dougm
10-24-03, 08:55 AM
I've lived with heat pumps in 2 houses and the air coming out of the vents was cool with both of them unless the strip heaters were running (sup. heat). I've been told the newer ones are better, but I doubt any can compare to the gas furnace we have now.
My experience, contrary to the advice of the "pros" (don't hurt me...) was that my electric bill didn't suffer significantly and my comfort was much greater (less noise, more warmth) if I simply switched to "sup. heat" (there should be a switch on the thermostat...) any time the temps got down below freezing. I may have been lucky in both houses to have had more than adequate capacity to heat with the strip heaters alone. You'll probably have to experiment to see if you do too.
Other advice: Make sure to routinely take a look at the outside unit during heating season and get used to the sounds it makes (defrost cycle kicking in every hour or so). Both of mine had problems with their defrost cycle that would have turned into expensive repairs if I hadn't noticed that they weren't making their usual sounds and looked like big snow balls in the side yard. Also, a heat pump dries the air more than any other type of system (IMHO) so it's probably wise to make sure you have a humidifier ready to run.
Hope this helps.
Doug M.
My experience, contrary to the advice of the "pros" (don't hurt me...) was that my electric bill didn't suffer significantly and my comfort was much greater (less noise, more warmth) if I simply switched to "sup. heat" (there should be a switch on the thermostat...) any time the temps got down below freezing. I may have been lucky in both houses to have had more than adequate capacity to heat with the strip heaters alone. You'll probably have to experiment to see if you do too.
Other advice: Make sure to routinely take a look at the outside unit during heating season and get used to the sounds it makes (defrost cycle kicking in every hour or so). Both of mine had problems with their defrost cycle that would have turned into expensive repairs if I hadn't noticed that they weren't making their usual sounds and looked like big snow balls in the side yard. Also, a heat pump dries the air more than any other type of system (IMHO) so it's probably wise to make sure you have a humidifier ready to run.
Hope this helps.
Doug M.
Ed Imeduc
10-24-03, 10:59 AM
One of the first things we tell people with a heat pump is we can give you the warm home you want But dont stand by or in front of a register. You want 68o ok you want 76o ok. But when you are by the register and the air is blowing over you its the aspiration rate over your body that makes it feel cool.
When units are put in they have to have enough strip heaters in them so it dont blow cold air on the defrost cycle and for back up heat if need be.
Heat pumps have whats called a COP of about 3. That means like for a $1.00 of electric in the heatpump you get 3 times more heat as you would if it was put in the strip heater.
One other thing have had people call up that the unit outside was on fire.----------If all thing are right with the weather and it goes into defrost it will put off steam and just look like smoke
As far as a humidifier Its all in the home.How much moisture is in the home how cold it is where you are. Like how much the furnace runs. "Not the heatpump". Also some of the older furnace have a flue and that means they take hot air you paid for out of the home on you.;)
Go to www.warmair.net and compare fuel cost for where you are
When units are put in they have to have enough strip heaters in them so it dont blow cold air on the defrost cycle and for back up heat if need be.
Heat pumps have whats called a COP of about 3. That means like for a $1.00 of electric in the heatpump you get 3 times more heat as you would if it was put in the strip heater.
One other thing have had people call up that the unit outside was on fire.----------If all thing are right with the weather and it goes into defrost it will put off steam and just look like smoke
As far as a humidifier Its all in the home.How much moisture is in the home how cold it is where you are. Like how much the furnace runs. "Not the heatpump". Also some of the older furnace have a flue and that means they take hot air you paid for out of the home on you.;)
Go to www.warmair.net and compare fuel cost for where you are
dougm
10-24-03, 02:39 PM
True, humidity depends a great deal on the construction of the house, the climate and several other factors besides the type of heating system, but a heat pump becomes a dehumidifier every time it goes into defrost mode. We noticed a big difference in the humidity between running with the heat pump and running with just the strip heaters.
As for savings, the heat pumps were drafty no matter where in the houses we were. In our last house I had a fan control installed so I could lower the fan speed without moving wires around on the furnace. It helped, but once it got much below freezing outside, I had to turn the temp. up several degrees to achieve the same comfort as I had with the sup. heat. I'm sure that negated much of the savings because I never noticed a significant difference on the electric bill. If there was one, it was worth every penny for the comfort.
However, we're off on a tangent...
Dnicejr, Use the heat pump the same way you use any heating system, but watch the outside unit, listen to make sure you hear it defrost from time to time, and don't worry about the steam that will pour off during the defrost cycle (can be really dramatic if weather conditions are damp and cold). If the house is uncomfortable, flip the switch over to sup. heat. Be ready to add humidity if needed.
One other thing: Benefits to the use of a setback thermostat are debatable with a heat pump. When the system exits the setback mode, it has to use the sup. heat to get the house up to temp. During warmer parts of the winter, I found a little savings by NOT using any set back. Only exparimentation will tell what's really best for you.
Doug M.
As for savings, the heat pumps were drafty no matter where in the houses we were. In our last house I had a fan control installed so I could lower the fan speed without moving wires around on the furnace. It helped, but once it got much below freezing outside, I had to turn the temp. up several degrees to achieve the same comfort as I had with the sup. heat. I'm sure that negated much of the savings because I never noticed a significant difference on the electric bill. If there was one, it was worth every penny for the comfort.
However, we're off on a tangent...
Dnicejr, Use the heat pump the same way you use any heating system, but watch the outside unit, listen to make sure you hear it defrost from time to time, and don't worry about the steam that will pour off during the defrost cycle (can be really dramatic if weather conditions are damp and cold). If the house is uncomfortable, flip the switch over to sup. heat. Be ready to add humidity if needed.
One other thing: Benefits to the use of a setback thermostat are debatable with a heat pump. When the system exits the setback mode, it has to use the sup. heat to get the house up to temp. During warmer parts of the winter, I found a little savings by NOT using any set back. Only exparimentation will tell what's really best for you.
Doug M.
hvac4u
10-24-03, 04:39 PM
the unit dehumidifies in defrost mode because it is switched to cooling mode and that is a natural byproduct, there is no avoiding it. i agree with the opinion that setback tstats are not real energy savers on heat pumps, but only in heat mode. they are effective in cooling mode however. a heat pump should not make a house "drafty", aiflow wise they operate just like a gas system, just cooler output temps. i would get it serviced to be sure it is running at top capacity and efficiency.