Questions about Heat Pump (Update-Found Prob)

kenimpzoom

Rear Admiral
Joined
Jul 13, 2002
Messages
4,807
In my new (to me) house it has a heat pump.<br /><br />Inside unit is Trane, outside unit is Heritage. We just had it serviced by the guy who installed the unit.<br /><br />Is it normal for it to run continuously. It was 40F last night, and the thing never shut off.<br /><br />Also, what is AUX heat, and what is EMERGENCY heat?<br /><br />I also see it has a backup electric furnace, is this the EMERGENCY heat, or the AUX heat?<br /><br />Thanks, Ken
 

llfish

Senior Chief Petty Officer
Joined
May 2, 2003
Messages
695
Re: Questions about Heat Pump (Update-Found Prob)

The last thing you want to use is the emergency heat because it will break you. Electrical usage is unreal. The unit will run longer the colder it gets outside. Running all the time does not sound normal.
 

salty87

Commander
Joined
Aug 12, 2003
Messages
2,327
Re: Questions about Heat Pump (Update-Found Prob)

i just had one installed but only understand it a little. from what i understand, emergency heat is the electric back-up only. aux heat is the heat pump and the elec back-up at the same time.<br /><br />the unit will only heat air to a certain temp, no matter how high you set the thermostat. if you set the temp however many degrees higher than the current temp in the house (this number probably changes and is probably adjustable)...both will kick on to deliver more air flow but the air isn't any hotter.<br /><br />mine runs a bunch too. i just figure i need more insulation. they draw a fraction of the current though.
 

BoatBuoy

Rear Admiral
Joined
May 29, 2004
Messages
4,856
Re: Questions about Heat Pump (Update-Found Prob)

In my neighborhood, the heat pump balance-point is around 35-40 degrees with an indoor temp of about 68 degrees. This means that the heat pump will supply about as much heat as the house loses at that temp. <br /><br />As the outside temp falls toward the balance-point, the heat pump will have to run longer and longer to achieve internal temp. At the balance point and below, the unit will run just about full time. That's the way it's designed.<br /><br />Since internal temp cannot be maintained by the heat-pump function below the balance point, auxiliary electric resistance heat is usually employed. This resistance heat also functions as emergency heat if the heat-pump function fails. <br /><br />The resistance heat is usually in segments or stages. For example, there may be three 5KW segments. If you turn the thermostat up very high, all 3 segments may come on at once. That's why it's better to heat the inside of the house a couple of degrees at at time, allowing the heat-pump to perform it's function, rather than bring on the aux/emerg/supplemental/backup and expensive resistance heat.<br /><br />More modern models may control these functions more acutely.
 

Ron G

Commander
Joined
Apr 28, 2005
Messages
2,905
Re: Questions about Heat Pump (Update-Found Prob)

Just like BB said,the emergency heat are actually heat coils or strips on most and also the air coming out of the vents dosnt seem hot,we have alot of tenants here from up north that are use to furnaces and they always call in about cool air blowing out,The strips do use alot of electricity.I set my thermosat at 70 and try to leave it there all the time.
 

dhammann

Petty Officer 1st Class
Joined
Mar 25, 2002
Messages
299
Re: Questions about Heat Pump (Update-Found Prob)

A heat pump is best suited for MAINTAINING a setpoint temperature…..they are lousy at recovery. If you lower your thermostat during the day and wait till night to raise your thermostat you will not save anything. It is best to recover during the warmest part of day so you can use as much “free heat” from outdoors as possible. In a well insulated house the temperature lag may be 5 to 8 hours so once you warm the house in the afternoon the unit will only cycle occasionally through the night to maintain setpoint.
 

craze1cars

Lieutenant Commander
Joined
Dec 26, 2004
Messages
1,822
Re: Questions about Heat Pump (Update-Found Prob)

Yes, it's normal for them to have long run times. AUX and Emergency heat are essentially the same thing. <br /><br />If your outside unit fails, you will need to switch to Emergency heat so you don't freeze to death, and so you can watch your electric meter spin like a frisbee while you're waiting for it to be fixed or replaced.<br /><br />In normal use, your Aux heat may kick in on occasion using same heat coils inside the furnace as the emergency heat. This happens, for instance, when the temp drops so cold in the house that the heatpump can't keep up (you'll witness this when it gets colder.) The coils temporarily kick in and your "Aux" light on the thermostat will come on while this happens...that light is again just to let you know that your meter is temporarily spinning like a frisbee.<br /><br />It is also normal for a heatpump's outside unit to occasionally kick into reverse. This is an unnecessarily noisy and clunky sequence where the fan on the outside unit shuts down while the compressor violently shifts into reverse at full throttle and then continues to groan like an angry elephant for a while, then you'll see the unit start to steam as it melts any accumulated frost off the coils. During this cycle your Aux heat may also come on because if it doesn't, you're effectively running air conditioning in your house in the middle of winter and you're sucking all the heat right back out of the house that the heatpump worked so hard for the last 8 hours to raise by 0.8 degrees. Once the outside coils are dry and frost free, the unit coughs loudly as the compressor reverts back into normal operation and then lets out a massive sneeze of steam in one last hurrah, as the fan kicks on and it's back in normal heating mode.<br /><br />They're exciting and busy little monsters. Quite efficient at creating luke-warm drafty air, and barely maintaining enough heat in the house to keep you from slipping into hyperthermia. But they're cheap to run, MUCH cheaper than natural gas or propane, and that's all many people care about.<br /><br />As has been mentioned here...one of the worst things you can do to a heatpump is actually adjust the temperature on the thermostat. It doesn't take well to change...<br /><br />They also don't have very long lives. The inside air handler can be quite long-living, but in my experience the outside unit is doing real good if it reaches 10 to 12 years without going kablooey. Then again I suppose I wouldn't live very long either if I was forced to work outside 365 days a year in temps ranging from zero to 110 degrees.<br /><br />I had heatpumps for years. I finally got fed up with all their excitement and bit a very large bullet to install a geothermal system in my house (also another version of a heatpump, but not an air-to-air exchanger, which is the noisy irritating piece). Heavenly. Comfortable heat and A/C, almost completely silent, and notably cheaper to run than even the air-to-air heatpump. It even heats my hot water just 'cuz it's a nice guy. Was well worth the high install cost.
 

tomatolord

Chief Petty Officer
Joined
Oct 1, 2004
Messages
548
Re: Questions about Heat Pump (Update-Found Prob)

crazy how much was it for the geothermal unit?<br /><br />emergency heat - when you shift the temp guage more than 5 degrees<br /><br />aux heat - when the outside unit cannot produce enough heat to heat your house it adds this booster in.<br /><br />In your case it sounds like both are electric coils for the extra heat...<br /><br />Believe me you do not want the electric coils to come on - your meter will spin so fast you could cut concrete with it...<br /><br />I have a duel heat system when the temp goes below 35 it kicks into gas heat mode.<br /><br />good luck!
 

craze1cars

Lieutenant Commander
Joined
Dec 26, 2004
Messages
1,822
Re: Questions about Heat Pump (Update-Found Prob)

Originally posted by tomatolord:<br /> crazy how much was it for the geothermal unit?<br /><br />
Just under $10K including all the excavation work. Minus $700 since I found someone on Ebay willing to buy my old heat-pump and air handler for that much!
 

crab bait

Captain
Joined
Feb 5, 2002
Messages
3,831
Re: Questions about Heat Pump (Update-Found Prob)

this has nothing to do with heat pumps.. <br /><br />but a good buddy has a 'big old going outta town end of mainstreet house'.. has a BIG ole oilburner furnace.. in common winter nite,, says it runs an hour to raise the temp one degree..<br /><br />oil more then morgage..<br /><br /> <br /><br />another friend who has a newly 'manufactured two halves on a truck' homes.. with all electric baseboard heaters.. average electric bill in winter,, 110 bucs..
 

kenimpzoom

Rear Admiral
Joined
Jul 13, 2002
Messages
4,807
Re: Questions about Heat Pump (Update-Found Prob)

Man these are some great replies, thanks guys.<br /><br />I guess I will get used to the unit running all the time.<br /><br />Craze1, yes I have heard it go into reverse, it is very noisy. I'll have to take a look and see if the Aux light comes on at that time.<br /><br />Ken
 

ED21

Master Chief Petty Officer
Joined
Aug 26, 2003
Messages
829
Re: Questions about Heat Pump (Update-Found Prob)

You might need a new thermostat also or the bulbs inside the thermostat might need adjusting. I can't explain the adjusting part, just that since they don't put out a lot of heat when it gets cold, the heat pump can't quite get the t-stat ovet the "hump" to shut off. A new digital t-stat might help.<br />At 40 degrees though a heat pump should have no problem supplying enough heat. I think something isn't working properly if it can't keep up or it is undersized.
 

levittownnick

Senior Chief Petty Officer
Joined
Jul 2, 2003
Messages
789
Re: Questions about Heat Pump (Update-Found Prob)

I picture a heat pump as a window air conditioner put in the window backwards so that the cooler air blows outside and the warmer air blows in the room. It only works down to a limited outside air temperature, thats why the electric heat part.
 

Ben Konopacky

Petty Officer 1st Class
Joined
Apr 5, 2004
Messages
296
Re: Questions about Heat Pump (Update-Found Prob)

JUST A NOTE : heat pumps are sized to the cooling load,not the heating demand.
 

KRS

Banned
Joined
May 15, 2004
Messages
2,383
Re: Questions about Heat Pump (Update-Found Prob)

You all heat your homes in winter.... hmmm. We open the doors for a breeze.
 

kenimpzoom

Rear Admiral
Joined
Jul 13, 2002
Messages
4,807
Re: Questions about Heat Pump (Update-Found Prob)

One last question.<br /><br />In Aux mode is the heat pump more or less expensive to run than a regular electric furnace?<br /><br />Ken
 

BoatBuoy

Rear Admiral
Joined
May 29, 2004
Messages
4,856
Re: Questions about Heat Pump (Update-Found Prob)

Originally posted by KenImpZoom:<br /> One last question.<br /><br />In Aux mode is the heat pump more or less expensive to run than a regular electric furnace?<br /><br />Ken
Probably about the same, if KW of coils are the same and both use similar ductwork. For some reason, heat-pump installers pay more attention to ductwork taping/insulation. That might make a small difference.
 

craze1cars

Lieutenant Commander
Joined
Dec 26, 2004
Messages
1,822
Re: Questions about Heat Pump (Update-Found Prob)

Originally posted by KenImpZoom:<br /> One last question.<br /><br />In Aux mode is the heat pump more or less expensive to run than a regular electric furnace?<br /><br />Ken
Aux mode IS an electric furnace, so I agree they should run about the same. And it costs MUCH, MUCH, MUCH less to run a heat pump than a regular electric furnace. Electric resistance heat is the most inefficient heat you can purchase. The heat pump take the brunt of the heating load so the coils don't need to come on too often...that's their whole purpose in life.<br /><br />Want to prove it for yourself? You have an electric furnace in your house right now...thanks to the work of the heat pump, it doesn't kick in very often. Just switch over to "emergency heat" for a month and wait to see your new electric bill, compare to the next month with the heat pump running. Get ready to take out a loan during the first half of your experiment...
 

D Grass

Seaman Apprentice
Joined
Mar 17, 2003
Messages
34
Re: Questions about Heat Pump (Update-Found Prob)

I don't want to nit pick craze, but electric resistance heat is actually the most efficient type of heat. It's 100 percent efficient. A 92 percent efficient gas furnace means that for every dollar you spend on gas, 92 cents is used to heat the house, 8 cents goes out the pvc pipe to the outside. with electric heat if you spend a dollar, every cent is used to heat the house. That said, you are right, it is the most expensive type of heat. Be wary of the electric power companies claims of the most efficient heat.
 
Top