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How NOT to Use Your Heat Pump Thermostat

How Not To Set Your Heat Pump Thermostat

Recently I’ve learned of two people running their heat pump in a way that costs them a lot of extra money. With heat pumps, there’s an extra setting on the thermostat.* In addition to heat, cool, and off, there’s a setting for emergency heat. But what is that setting for? What does it do?

A heat pump, as I wrote before, pulls heat from the outside air (unless you have a ground source heat pump, which pulls heat from the ground or a body of water). As it gets colder outside, your heat pump is able to pull less heat inside. Eventually it can’t meet the heating load of the house. That’s where supplemental heat—which is NOT the same things as emergency heat—kicks in.

What happens when your heat pump can’t keep up?

For most heat pumps, the supplemental heat source is electric resistance (strip) heat. When the heat pump can no longer pull enough heat from outside to meet the heating load of the house, the electric resistance heat comes on and supplements the heat pump. If you have an all-electric home, your supplemental heat source is almost certainly electric resistance heat.

thermostat hvac heat pump mode emergency coolIf your home has natural gas, propane, or fuel oil, the supplemental heat may be supplied by a furnace. This is called a dual-fuel system. Most of these are connected in a way that when it gets too cold outside for the heat pump to supply all of the heat, the heat pump shuts off and the furnace supplies all of the heat.

If your supplemental heat is supplied by electric resistance, it’s 100% efficient. That may sound good, but it’s not. The heat pump, by that same measure, is 200 to 300 percent efficient, so when the heat pump by itself can’t supply all the heat your home needs, you at least want it to supply as much as it can. That gets you more of the 200-300% efficient heat and less of the 100% efficient heat.

Unfortunately, some people have a misunderstanding about how this works, and sometimes that misunderstanding comes from a surprising source.

What’s your emergency?

For some reason, a lot of people overlook that the thermostat says “emergency” (EM HEAT on the Honeywell thermostat shown* here)  not “supplemental,” and think that when it gets cold outside they have to switch over to emergency heat. Now, here’s the kicker. Evidently they have good reason to think that, because in both of the cases I’ve heard about recently, their HVAC company told them to switch over when the outdoor temperature is “in the thirties” in one case and “below freezing” in the other.

thermostat hvac heat pump emergency supplemental high bills arrow

How are people supposed to learn the correct way to use their thermostat for a heat pump when they’re getting such bad advice from the person who’s supposed to know!? If you switch to emergency heat, you’re going to pay a lot more, perhaps hundreds of dollars more, to heat your house.

Another interesting thing about one of these cases is that the owner had just had his electric furnace, which is all strip heat, replaced with a heat pump. He spent thousands of dollars to get a more efficient heating system, and the HVAC installer told him to bypass that extra efficiency and just run it the way his old electric furnace ran.

By the way, electric furnaces have now been banned here with the adoption of our new Georgia energy code. Hooray! Now we just have to teach owners – and installers – on the proper use of heat pump thermostats.*

Do it like this!

thermostat hvac heat pump best mode heating arrow

In short, if you have a heat pump with electric resistance heat as the supplemental heat source, keep the thermostat* in the “Heat” setting. Do NOT use the “Emergency Heat” setting unless it’s really an emergency; for example, when the heat pump doesn’t work. You probably won’t notice a difference in how well it heats your home, but you will notice a difference in your electricity bills.


Allison A. Bailes III, PhD is a speaker, writer, building science consultant, and the founder of Energy Vanguard in Decatur, Georgia. He has a doctorate in physics and writes the Energy Vanguard Blog. He is also writing a book on building science. You can follow him on Twitter at @EnergyVanguard.


Related Articles

A Surprisingly Common Cause for High Energy Bills

Does a Heat Pump or Air Conditioner Condenser Need to Go Outdoors?

3 Ways to Tell if That Contraption Is a Heat Pump or an AC

Finding Balance – Heat Pump Heating Load vs. Capacity

The Mad Hatter, Isaac Newton, and That Old Thermostat


* This is an Amazon Associate link. You pay the same price you would pay normally, but Energy Vanguard may make a small commission if you buy after using the link.

This Post Has 58 Comments

  1. They do know “The HVAC
    They do know “The HVAC tech”But this assures them another visit and another charge the next month to tell the owner something else. It is a game a money Game. Same as the car Mechanic. Sad Truth!There are some HVAC techs who have Higher standards but from where I am very few.

  2. On the other side of the coin
    On the other side of the coin, during the cooling season, I see homeowners that will turn there T-stat fan to the “ON” position during the cooling season. I live in the south and this causes some real humidity problems especially when the system is in the cooling mode and the fan continues to run after the T-stat is satisfied and the condenser [outside unit]cycles off. If the fan continues to run it does not allow the evaporator coil [inside] to drain into the condensate pan and re-evaporates the water back into the home and the humidity goes up. I have noticed that this also causes mold growth inside the coil cabinet, around the grills and inside the bootboxes, that have insulation inside them. When the fan shuts down this allows the evaporator coil to drain completely before the next cycle. I have run data loggers in these homes and found that it reduces the humidity level by 10-15% [more in some cases] by keeping the T-stat fan in the “AUTO” position during the cooling season. Most of these homeowners were told by there A/C serviceman it will help keep the house more comfortable to run the fan in the “ON” position. I think the common thread here is that many A/C contractors really don’t understand how heating and cooling systems should be operated. 
    Now that the government has mandated the new “high efficency” units alot of the tactics that the contractors used to get away with will come back to bite them.

  3. I can’t count the number of
    I can’t count the number of times the the system is not set up to use emergency heat from the thermostat. When the switch is in emergency heat I should get over 100 degrees. Often I get 80-90. However, in auxiliary heat mode, I end up with 120 or more. 
    The heat strip banks are wired wrong!

  4. Allison, understanding how
    Allison, understanding how manage a heat pump thermostat is indeed an important part of realizing the benefits. And yes, there’s a lot of misinformation out there. The emergency switch should only be used if the heat pump actually fails — for example, if the reversing valve get stuck in cooling mode. Of course, the average homeowner may not know how to determine if there’s a failure. So the best advice is to instruct homeowners to call their HVAC installer if they find it necessary to use emergency mode to maintain the setpoint. 
    Unless something is wrong, flipping the switch will remove whatever contribution the heat pump is making.  
    Mid-efficiency heat pumps can have a COP approaching 4 (4 times more efficient than strips) at 47F, and around 2.5 at 17F. So there’s no reason to turn off the heat pump as long as it’s working (assuming electric supplemental heat).

  5. Mike, yes, keeping the fan in
    Mike, yes, keeping the fan in the ‘on’ position is another big problem with how people run their heating and cooling systems. Thanks for sharing your data.  
    And, yes, the sad truth is that many HVAC pros just don’t understand proper operation of the systems they sell, install, and service. There are certainly some very good ones out there, but overall, there’s a lot of work to be done in educating the HVAC industry, especially the guys on the front lines.

  6. Sam, I’ve heard some horror
    Sam, I’ve heard some horror stories about miswired heat strips that run in the summer when the air conditioner’s on. The homeowners were shocked and appalled to learn that they were paying to heat the same air they were trying to cool.

  7. David, thanks for clarifying
    David, thanks for clarifying what I’d meant to put in the article but on looking back, realize that I didn’t. Yes, emergency heat is only meant for when the heat pump can’t keep up.  
    One of the two owners I mentioned in the article told me that the HVAC guy must be right because the system was running a lot longer than the old electric furnace he had. When I asked him if the house was staying at the setpoint, he didn’t know. He thought that longer run times meant that something must be wrong.

  8. Daniel, that’s a nice article
    Daniel, that’s a nice article showing how to separate the energy savings you achieve from other factors. Thanks for sharing.

  9. I do turn my heat pump over
    I do turn my heat pump over to Emergency from time to time. The reason for this is if I do not, and the outside temperature is in the 20’s or teens, my heat pump will run and run and run. If it does by some chance get the room temperature up to what is on the thermostat it will remain off for maybe 1 minute then kick back on. So I figure using the emergency heat couldn’t use any more electricity that it already is when it runs non-stop.

  10. Vicky, letting your heat pump
    Vicky, letting your heat pump run continuously will ALWAYS save energy because whatever heat it produces is guaranteed to be more efficient than using the emergency heat. When it’s cold outside a heat pump produces less heat, but it also consumes less energy. 
    Keep in mind that when you leave the t’stat in the normal heat mode, the strip heat will only be energized to supplement the heat pump, making up the difference between what the heat pump produces and the home’s heat loss. By definition, strip heat has a coefficient of performance (COP) of 1.0, while a heat pump efficiency at the temps you mentioned is probably 2.0 or higher, depending on its age (newer heat pumps generally have a higher efficiency rating). For example, my mid-efficiency heat pump has a COP of 2.5 at 17F, meaning it’s 2.5 times more efficient than strip heat. 
    Finally, you should know that even when the heat pump is running continuously, it may still be offsetting a high percentage of your home’s heat loss. The output doesn’t fall off a cliff but declines gradually with temperature. For example, at 17F, a heat pump’s rated output is typically about 60% of its nameplate capacity. 
    So stop using the emergency mode! BTW, you might consider getting a new t’stat. Better heat pump stats will cycle the strips off just prior to reaching the set point, thus allowing the heat pump to continue running. Cycling it off, and then back on again over years of use is not good for the compressor.  

  11. I am a new home owner and new
    I am a new home owner and new to heat pumps. There was no manual or anything that came along with the thermostat and I feel very uncomfortable with this not knowing business. I have a call in to have maintenance done but they can’t come out until January!! 
    I live in Pa and its generally cold at this time. I know our house needs new windows but we just have to live with it for now until we can get it switched out. I got thermal curtains to help with the possible drafts. Temps this week range from highs of 45 to lows of 25. I have our t-stat programmed as such wake 5:30 67* Leave 730 65* return 530 67* sleep 65* Does this seem reasonable I don’t feel that i’m asking for too much heat although it does seem very chilly at night. I feel like our outside unit is ALWAYS RUNNING though. Is it okay to program it this way or should i leave it at 67 and just be done with it? Again i’m new to this so i have no idea if i’m operating it properly or what my outputs at the registers are or anything. Ijust don’t want to have a 500.00 electric bill because of my bad prgramming.

  12. oh boy, i had a new heat pump
    oh boy, i had a new heat pump system installed in my home. i live in new york. what a mistake it has been. first we started out the end of winter season being cold. the installer kept giving “options/ idea” to help. all it was is nonsense bs. try fan “on” insted of auto, they slowed the fan speeds down, balanced the distribution, then came back and added more flow to the bedrooms. well at this point we ran out of cold season. so here comes summer. “i promise you will love the ac” well, that should have been my first hint of trouble. the ac running raised the humidity in the home upwards of 58%. run times are short 7-10min. after numerous visits and adjustments, including visits by the manufacture, they may have improved the ac operation. but we wont know until next summer, since it took until the end of this past cooling season to find a possible solution. so here we are back to heating season and it sucks! home is cool at 72 as you move from room to room the temps change, if you make it comfortible in one room the a another may become cool or so hot you have feel it when breathing. still no solutions other than “lets try…” i would think after 1+ yar of this crap there would be an acceptible answer. 
    i learned you should leave the t-stat at one set point, not program various points for different times of the day. it takes these systems a long time to recover from these changes.

  13. gjs, I’ve sold a lot of heat
    gjs, I’ve sold a lot of heat pumps (Rochester, NY). It distresses me to hear your story.  
    Right now Energy Audits in NY are Free (or nearly free if your income is above 130k or so).  
    Granted, some of the problems you have are due to bad/outdated dogma about how to manage temperatures in your home. (We’ve put a man on the moon, but assume changes to hvac technology don’t mandate reconsideration of operational behaviors?) 
    Some of the problem you describe sound like problems other than the heat pump. Get an energy audit.  
    Here’s a tool to figure out your savings opportunity:

  14. In principle, a geothermal
    In principle, a geothermal heat pump functions like a predictable heat pump, by using high-pressure refrigerant to detain and move temperature between indoors and out.

  15. I have a heat pump and have
    I have a heat pump and have turned it to “emergency”.. activating the heat strips. At -11F the heat pump ran for a continuous 36 hours to keep the house at 64 degrees. turning the thermostat up to 68 degrees, the strips hit and was at temperature in 37 minutes. Timing my electric meter, the heat strips use 6 times the electricity but takes 1/72 the time and was 5 degrees warmer (heat pump alone never got above 63.5 degrees). I can’t imagine the heat pump working that long can save money???? 1700 square foot ranch and a $212.00 electric bill to keep the house 64 degrees? Will be burning wood very soon to heat the house, heat pump is worthless in my opinion.

  16. @ Galen, with all due respect
    @ Galen, with all due respect, your logic (“takes 1/72 the time”) is flawed. That comparison doesn’t tell you anything. The 37 minutes is just the pickup load, which is a condition you imposed. What matters is what happens after it reaches setpoint. 
    Obviously a HP can’t hold setpoint at -11F. However, the heat it does provide (apparently enough to offset a 75F delta-t in your case) costs much less than strips. Guaranteed. A mid-efficiency heat pump is roughly 50% more efficient at -11F and 100% more efficient at zero F. 
    But hey, it’s your money.

  17. I have the dual fuel type of
    I have the dual fuel type of heat pump and want to know how I can disable the emergency heat mode on the Honeywell thermostat.

  18. @David P: The term &quot
    @David P: The term “emergency heat” is by definition a manual setting on the t’stat, so there’s no reason to disable. Presumably you want to disable automatic switch-over to furnace?  
    Honeywell makes dozens of models so I can’t be sure without looking at the installation guide. But most dual fuel compatible thermostats (those that don’t require a dual fuel kit) cannot be programmed to lock out the furnace. However, you can disable the furnace by changing the System Type in the installer menu to one without Aux heat. Be sure the compressor lock-out function is disabled. The other method is to disconnect the Aux control wire. Contact me off-list if you need assistance.

  19. The proper way to use a heat
    The proper way to use a heat pump is to never use a set back of more that 3 degrees, or none at all. Most heat pump thermostats bring on the back up heat when the temperature difference between the room and that thermostat setting is 3 degrees or more. This applies to a heat pump with electric back up heat. 
    The reason for this is that a heat pump does a very good job of maintaining temperature, but is very poor at recovering temperature. 
    Realize is that when you set back your thermostat to say 60 degrees when you leave the house, by the time you get home, everything in your house is 60 degrees (your sofa, stove, dishes, cabinets, the floor, your kitchen table, … everything. That all needs to be brought back up to temperature before you are comfortable. 
    If you are not getting the comfort and efficiency out of your heat pump that you think you should, there may be something that is not right. It could be ductwork, the equipment itself or the actual sizing of the system. Or you could have a major heat loss that you are not aware of. Heat pumps do not do well in leaky houses. 
    If you have not lived with a heat pump prior to the one you now have, there will be a learning curve. I have run across many customers who are used to oil or gas as a heat source who had to be re-educated on how to use their heat pump. Get as much eduction as you can and reap the savings that are available to you. 
    You can find out more at:

  20. Joe wrote: “Most heat
    Joe wrote: “Most heat pump thermostats bring on the back up heat when the temperature difference between the room and that thermostat setting is 3 degrees or more.” 
    That was true for electromechanical thermostats and early digital stats that merely replicated the functionality of their predecessors. But virtually all modern heat pump and multi-stage thermostats can maintain the temperature within one degree by tracking the trajectory and rate of temperature change in fractional degrees. They use this same logic to reduce up-staging during setback, although it’s always best to install an outdoor thermostat or manual override (required in some states) to lock out strip heat when it’s not needed. 
    “a heat pump does a very good job of maintaining temperature, but is very poor at recovering temperature.” 
    That depends on outdoor temp, no? When it’s 45 or 50, a properly sized HP can recover much faster than when it’s closer to freezing. In that case, up to 5 degrees of setback is no problem. But when it’s well below the thermal balance point, even a 3 degree setback may not save any energy. 
    I think it’s important to spend a little time educating clients about these concepts (at least those who are interested) so they can better understand and manage their system.

  21. I have a heat pump and this
    I have a heat pump and this winter has been the worst. I know the temps have been 10-15degrees lower but my bill is now 5x what it has been. We replaced the thermostat this fall and I believe that is the culprit. We had an old mercury one, but I never used the “aux/em” heat. Now the new thermostat kicks it on automatically every time it believes it needs it. My electric strips use 72 amps…I have gone from a $270 bill in Nov. to $958 in Feb. I need help NOW. I need a thermostat that I can prevent the aux heat from coming on until it is a true emergency. What do you recommend. What model is the honeywell pictured above?

  22. Barb, 

    The above thermostat looks like a Honeywell 8000 series. The 8000 series has several different variations. If you look on the back of the thermostat that you have, it should give the model number (it may be in a different location depending on the manufacturer.) 
    Now as far as your issue, it could be not wired right or if it is similar to the above, it may not be programmed correctly. There are many settings in some thermostats that can alter the performance. 
    Not sure if I can help much over the Net because it would require a bunch of back and forth to get the issue resolved. But if you click the link on my name below it will take to to my website and you can call me and I will talk you through the set up. 
    I would be happy to help you get this resolved. I have seen thermostats set up improperly way too many times to count and costing to customer way too much or not getting proper comfort.

  23. David, 

    In regards to your earlier post, I do agree that at 40 or 50 degrees that the heat pump can recover from the set back. However, I felt that the best way to deal with this issue was to make a more “blanket rule” to cover most of of bases that would give my clients the best comfort for the least cost. That is why I said it that way. I wanted to minimize the complexity that would occur when it was warmer. 
    As far as the 3° before the backup electric heat comes on, This is the logarithm that is most prevalent in my area in Central Pennsylvania up in the mountains. Most people have single stage heat pumps with an early version digital thermostat. So I was communicating my thoughts to those types of consumers. But using an outdoor thermostat (thermistor) is ideal to lock out the electric back up above a certain temperature. Unfortunately, (at least in my area) most clients do not want to spend the extra money on a thermostat that gives them that flexibility. 
    Additionally, I find it very difficult for most people as well as clients to really get the concept of some of the newer technology put into their thermostats. My solution is to simplify the explanation as much as possible so that most people can understand it and think with it.

  24. @Joe, an outdoor lock-out (e
    @Joe, an outdoor lock-out (e.g. Source-1 3024-6881/D or similar) doesn’t require a special stat. It has a turn-pot to set the cut-out temperature and simply interrupts the Aux control wire between stat and air handler. If you’re lucky, the cable between air handler and heat pump has an unused pair that can be used.  
    As for staging control, anyone with a legacy thermostat controlling a heat pump with electric strips would be crazy not to invest $40 in a modern stat. It would likely pay for itself before the credit card bill is due 😉

  25. When the temperature drops
    When the temperature drops into the low teens an below, my HP cannot keep up. My inside temp would only warm up to the mid to upper 50’s. I have 2 units, one has a t-stat with an emergency heat selection and one doesn’t but has an auto aux heat (it’s about 6 month old). I had a tech come out and he said both systems were working properly. He recommended that I put the system in emergency heat and replace the t-stat with one that has an emergency heat selection. 
    Do I need a t-stat that has an emergency heat selection? 
    How would I know if the heat strips were wired correctly? 
    What temp would my system blow out in in HP vs HP + aux heat?

  26. Brent wrote: “When the
    Brent wrote: “When the temperature drops into the low teens an below, my HP cannot keep up.” 
    Of course it can’t. That’s what Aux is for. You should only use the emergency setting if the heat pump fails. The tech gave you bad advice. 
    Virtually all heat pump stats, no matter the age, have both an Emergency switch and an automatic Aux mode (although with older stats, the control logic that activates Aux may be poorly implemented). 
    The outlet temperature with and without Aux heat depends on outdoor temp, wattage of electric heat strips and CFM setting. 
    If you contact me off list, I can assist with further troubleshooting. My best advice is to find another tech.

  27. There has been several times
    There has been several times that I would wake up in the early morning hours and notice that my furnace switch over to Emergency Heat. The reason why I notice this, is because it signals a red light.  
    How can this happen, when we have it set to “heat” only?

  28. @Lisa, if the red light comes
    @Lisa, if the red light comes on automatically then that signifies the thermostat is calling for auxiliary heat. In my experience, most heat pump thermostats use different indicators for EM vs AUX. Yours apparently uses the same LED for both. 
    Functionally, there are three differences between EM and AUX… 1) EM is a manual setting, whereas AUX is automatic 
    2) the heat pump (outdoor unit) remains off in EM mode 
    3) electric strips or other supplemental heat source operates as first stage heat in EM mode, whereas the heat pump operates as first stage in AUX mode

  29. Do you mean the the physical
    Do you mean the the physical switch has moved over to the Emergency Heat setting? This is confusing since someone would have to do that manually. 
    What brand of thermostat do you have? 
    Is it possible that you are actually running in Auxiliary Heat when the red light is on? When this situation occurs, is the outdoor section of the heat pump running?

  30. I have a very similar problem
    I have a very similar problem to Barb… We have a heat pump, with an electric furnace. We have lived in this home for two years without incident (we left the settings the way the where when we moved in), and did not have a problem… until this winter. A few months back we had our furnace serviced and our vents cleaned. The fellow that did the service, told us that he had “adjusted our settings to optimize our electrical usage”… Well, we just received our Hydro bill for two months, and it was a whopping 30% increase compared to last year; $966. Another person came in from the company and fiddled around after we called to ask what they had done, and now, the auxiliary heat keeps coming on (I have never noticed it being an issue prior to this). They left saying that they have no idea what is going on and don’t remember what they did the first time. We currently have things set to auto, auto fan, and 21 degrees (no schedule). How can we make sure the auxiliary heat does not kick in? The heat pump is only a few years old, and everything was just fine before the service. ANY advice would be so appreciated! We are so unbelievably anxious to get our next bill!

  31. I live in Virginia, and
    I live in Virginia, and though it’s been colder than usual this year our bills are much higher. I’m getting 80 degrees measured from INSIDE the first vent when the heat pump runs; it’s almost 120 when AUX kicks in. I beleive that our HP cycle times are longer now due to only producing 80 degrees at the vent, in the past, I recall the air feeling much warmer even with no AUX running. Techs have checked the system and indicated there are no leaks and the pressure is right but not able to explain why I’m only getting 80 degrees out of the vents when it’s below 30 outside. I get up to 85 when it’s warmer. 

  32. @Vanessa, I obviously can’t
    @Vanessa, I obviously can’t diagnose your system at a distance but it sounds like the first tech may have just adjusted the cycle rate. If so, this would only affect operation when outside temps are well above freezing. 
    More to the point: A 30% increase over last year isn’t at all surprising since demand for Auxiliary heat increases geometrically as temperatures drop. Heat pumps are very efficient but they can’t handle the entire load.  
    In cold climates, I specify natural gas Aux heat (dual fuel furnace or hydronic fan coil). Depending on local energy costs, it typically costs just as much to heat with propane as with straight electric heat. So in cold locations without access to natural gas, improving the home’s envelope is the only way to reduce your home’s reliance on supplemental heat. 
    Infiltration is typically the biggest contributor to heat loss so air sealing should always be the first step in reducing the supplemental fraction.  
    I recommend having an energy auditor do a baseline blower door test and thermal scans. Sounds like you’re in Canada, so you’d like to see well below 3 air changes per hour at 50 Pascals (the blower door tech will understand this). And then consider insulation upgrades.

  33. @Luke, the high (120F) supply
    @Luke, the high (120F) supply temp with Aux running indicates your strips are grossly over-sized. This causes comfort issues by creating a large contrast when strips cycle off. A strip heater kit large enough to create that much temperature rise will necessarily include a staging sequencer to avoid this problem. Sounds like the sequencer may be defective or improperly connected. 
    80F supply does sound a bit low for 30F outside, but not by more than a few degrees. If your air handler and/or return ducts are in located in unconditioned space, you should check the air temperature as it enters the return side of the air handler. Cold air leaks in the return ducts will reduce the temperature of the entering air, thus dropping the supply temp by the same amount. Also keep in mind that direct sunlight on outdoor unit will affect supply temps, so day vs night makes a difference. 
    In any case, your system should be running nearly continuously with 80F supply air, with strips adding a little bit as required to maintain the setpoint. Blasting 120F air isn’t the best way to do that. 
    As for your recent high bills, see my response to Vanessa. I wouldn’t necessarily assume your system is behaving any differently than in past years.

  34. We had a new heat pump
    We had a new heat pump installed in October, with new programmable thermostat & thought we might see some savings. We got the highest electric bill ever for last month- higher then when we had teenagers living at home. We have a 1300 sq ft single family home, with only 2 people – 3 rooms not even used. Increase of 25% over same time last year. We had the HVAC installer come out to check the system & he gave the advise to switch it to emergency heat when the temperature dropped below freezing. I kind of thought this was bad advise. We’re getting an energy audit next week.

  35. Diane, 

    Yes, an energy audit is always a good idea. I believe that the first step in energy efficiency is to “seal the envelope” and make sure you are not loosing energy through leaks. 
    You are correct about using emergency heat below freezing. Many heat pumps can produce enough heat down into the 20’s. Although some people disagree with me, my philosophy on managing heat pumps is to have as little set back as possible and even none at all when it is the coldest. Emergency heat will consume up to 5 times the electric that the heat pump will use. 
    You have to realize that this has been one of the coldest winters in a very long time. So some slight increase in electric use is expected. Also, what type of thermostat do you have and are you sure that it is wired correctly? If you have one of the more advanced thermostats, you need to make sure that it is set up properly for your type of system. 
    If you need further assistance please post back and either I or someone else will be able help you through this.

  36. @ Joe 

    @ Joe 
    Thermostat is a Honeywell Focus Pro 6000 
    We do have leaks. Part of the house is old – was built as a summer cottage. We remodeled & added an addition, new windows & siding in 1987, so there is some outside insulation & some blown fiber insulation in the walls & ceiling of the old part. Newer addition has better insulation. There are definitely leaks around some of the windows – not the windows themselves, but around the framing. We have weather strips at the bottom of the outside doors, but there are leaks along the side framing. And leaks along the baseboards in some rooms. A couple of the inside doors have large gaps, and the door to the old porch (now laundry/utility room – this is a drafty room) has a gap that we stuff with a towel when it is cold – tried one of those strips from TV and it did not work. 
    The heat is uneven. Some rooms too hot while others too cold. 3 rooms are not being used. I shut the vent totally in one room (and it is still plenty warm)& shut it partially in the other two. This makes the Master Bedroom very warm, but does nothing to improve the temperatures in the living room or dining room, which tend to be cooler, Maybe the problem is in the ductwork (which was done in 1987 when we remodeled) 
    I hope that the contractor doing the audit can give us low cost solutions because we have no budget for any major remodeling.

  37. Diane, 

    I will say that a heat pump does not handle a leaking house very well. So, stopping those air leaks should show some major improvement. Finding proper door weatherstripping can sometimes be quite tricky to get the right one to create a proper seal. I am hopeful that the energy audit guy can give you some low cost do it yourself solutions for you. 
    I can not advise you properly from over here on your uneven heat, but it does sound like a duct issue. Possibly leaking or not properly sized or balanced. 
    OK, so you have a Honeywell 6000 series thermostat, but there are several variations for different systems. Do you know if you have a single or 2 stage heat pump? Do you know the variant of the thermostat that you have? Should be something like TH6320U or TH6220D. 
    I have the install manual for the thermostat in a PDF so that you can make sure that it is set up correctly and I will help to walk you through it; (you have no idea how many thermostats are set up and programmed incorrectly.) If you click the link in my response it will take you to my web site where you can send me an email and I will send you the PDF to properly setup your thermostat for your system. If you have any problems with that you can call me if you like, I am on the east coast (PA).

  38. @Diane, yours sounds not
    @Diane, yours sounds not unlike most other older homes — leaky envelope, poorly done duct system and a shiny new, often high efficiency HVAC system that does nothing to solve the fundamental problems.  
    Sorry to be the bearer of bad news but the money you spent on a new heat pump last fall would have been better spent on air sealing, duct system repairs and air balancing.  
    If you have the means to do long-term financing for another round of improvements (home equity lines are dirt cheap now), you may be able to keep out-of-pocket to a minimum when you consider the energy savings.  
    The key is to find an advisor you can trust and get multiple quotes so you can make smart choices.

  39. Diane, 

    If I were you, I would look into what your state has to offer regarding rebates or incentives for weatherproofing your home. Some states have free services others may cover part of the costs and some may have rebates either through the state or the power company. 
    What state are you in? 
    I hope this helps.

  40. @David 

    The new heat pump replaced a 24 year old system that was leaking refrigerant. We had hoped to see some savings.  
    We are in Maryland. I will discuss these things (leaks & duct work) with the energy audit person.

  41. @Diane, I didn’t mean to
    @Diane, I didn’t mean to suggest you had a choice… just trying to drive home a point. In all likelihood you would have seen savings had this winter been more typical. Looks like it’s still not letting up for you guys. Here in SE AZ, we’ve had the warmest winter in recent memory.

  42. we own a vacation condo
    we own a vacation condo/townhouse of about 1100 sq. ft. and are there a few times a month. i leave heat on in the winter to prevent freezing,45 degrees, when we come in on weekends turn it up to 68. it has been an unusually cold winter here in west tennessee and our electric bills have been extremely high. should i install a digital thermostat? thanks, bob

  43. I just moved into a totally
    I just moved into a totally refurbished apartment (due to fire) after a year if waiting in a temporary apartment in same complex. The complex was 30years old and the heating system ( electric furnace) was never replaced . My winter electric bills ran around $200 a month during a normal winter for a 860 sq ft apartment. The new building/apartments that got stripped and redone were equipped with heat pumps with no instruction on how to efficiently use it. They installed the Lennox Merit Series heat pump and air handler (cheapest and not energy star rated) 
    The Lennox comfort sense programmable stat I gave up on, so I have the heat in normal mode and on a hold set point of 68 degrees at day and 65 at night. It looks like it has 3 stages; heat lo, heat hi, then the manual EMG heat.  
    What I don’t understand is why it runs on the “low heat” and auto fan when the room temp hasn’t deviated from the 68 degree setpoint. It would make sense if the room temp dipped to 66 or 67 and it kicks on but that is not what is happening, it remains constant. I’m panicked that not only have I had a huge increase in my rent, but that the high electric bills will remain the same. I honestly don’t trust the maintenance staff to know what the heck they are doing. Especially now that they have two types of heating units to contend with.  
    Is the system working correctly? I don’t even know who to call it get an honest answer . Oh, I live in northern Delaware. 

  44. Hi Janine, your expectation
    Hi Janine, your expectation is based on the way older bi-metal (spring) actuated thermostats worked. Why would anyone want the temperature in their home to droop 2 degrees below desired setting before engaging the heat?! 
    Digital thermostats measure temperature in smaller increments than shown on the display. With a properly sized heat pump, modern t’stats achieve tight temperature control with long, efficient cycles by monitoring the trajectory (direction) of the temperature change as well as the rate of change. So when the heat pump’s output is roughly in balance with the building’s heat loss, it will have long, efficient cycles as it maintains the setpoint.  
    When heat pump capacity and heat loss are roughly in balance, if the thermostat were to cycle off when the display first reads 68 (which actually means 67.5F), then it would cycle back on in a few minutes. Instead, it continues to run until the temp reaches 68.4 (typical).  
    During milder weather, it may overshoot slightly depending on minimum run time or cycle rate settings in the installer menu. 
    BTW, Lennox Merit series is single stage only. If your t’stat shows “Lo” on the display, it may be set up incorrectly. At worse, this would only cause a delay in energizing supplemental heat.

  45. @Bob, a digital stat is more
    @Bob, a digital stat is more accurate and less expensive than the electro-mechanical type. But it won’t necessarily save energy. Potential energy savings claims relate mostly to setback (and advanced staging algorithms for multi-stage systems).  
    One thing you could do is disable the electric strips when the condo is unoccupied. Also, some stats are Internet compatible. You could raise (and monitor) the setpoint from your PC or smart phone in advance of your visits. But if cold enough, you’d still have to rely on the strips once you arrive to finish raising the temperature by that much.

  46. Hello, Could you explain what
    Hello, Could you explain what is meant by 1,2,3 Stage. 
    We have a brand new Lennox elite XP14 what stage would it be. 
    Thank You

  47. @Francis, the majority of
    @Francis, the majority of furnaces, A/C’s and heat pumps operate at a single capacity. They’re either on or off. That’s considered a single stage.  
    So ‘stages’ refer to how many discrete steps in capacity a particular model has.  
    Variable capacity (or modulating in the case of a furnace) means a system can vary its capacity continuously within a certain range. 
    Multi-stage and variable capacity equipment is more expensive, but generally has a higher efficiency rating. 
    The XP14 is a single-stage heat pump. Technically speaking, the supplemental electric heat installed in the air handler provides 2nd stage heating capacity but it would be incorrect to call the XP14 a 2-stage heat pump.

  48. Thanks for the info! I just
    Thanks for the info! I just moved across country due to a foreclosure & rented a room in someones house. The elec. bill came & it was DOUBLE what my old house used & Im only renting a SINGLE room. Sure enough I looked at the stat & the emerg. heat was on. I been here 60 days & feel like room mate ripped me off with her stupidity!

  49. I’ve been having pretty good
    I’ve been having pretty good luck with my HP as far as performance goes. My question is: at night I turn the unit completely off just before I go to bed, 10:00 pm. Then turn the unit back on in the morning around 7:00 am. Does it save on electricity to do it this way or is it more efficient to leave it on all night?

  50. @Dave H: assuming your system
    @Dave H: assuming your system has electric supplemental heat, it’s a bad idea to turn it OFF at night. Your thermostat will undoubtedly rely on supplemental heat to recover in the AM, more than offsetting any savings.  
    It’s OK to setback your thermostat a few degrees at night during milder weather (e.g., overnight lows in 40’s), but you’ll need some way to keep your strips off during the recovery period. The best way to accomplish that is with an outdoor thermostat. Some hp thermostats support an outdoor temperature sensor for this purpose. Otherwise, special outdoor thermostats are available for this purpose (see 3024-6881/D). During colder weather you’re better off reducing or eliminating setback.

  51. We have a constant dispute in
    We have a constant dispute in our house about the cooling function of our HP. The house heats up during the day and when the outside temp cools down at night my father believes we should shut the HP off. In his opinion the system cannot cool the air outside if it’s below 20C outside.  
    The issue is that the exterior and the upper floor has been heating up all day and unless the cool air is actually blowing, the second floor is extremely uncomfortable.  
    There are 8 floor vents on the first floor and only 4 ceiling vents on the second floor though the square footage is the same so I have blocked 4 of them downstairs. I think that should even out the air flow better and make the cooling much more effective upstairs.  
    The question I have for you is what is the lowest outdoor temperature that an air-air heat pump can tolerate while in the cooling function?

  52. @Sara, an A/C (or a heat pump
    @Sara, an A/C (or a heat pump in cooling mode) can operate well below 20C, and in fact, capacity and efficiency increase as outdoor temp drops. That said, if it’s too cold, low refrigerant pressure can cause problems. 
    Different manufacturers specify different low limits. For example, York specifies a minimum of 10C in cooling mode. I’m not aware of any AC or HP that won’t operate safely down to at least 13C. 
    Sounds like your duct system is poorly designed. Having a single system serve upstairs and downstairs without zone control doesn’t work well because the load balance between up and down is very different in summer vs. winter, requiring different amounts of air. Unfortunately, this is common practice. Some states are now requiring zoned equipment or air distribution in multi-story homes. 
    However, indiscriminately closing off vents is a bad idea. It not only redirects airflow, but also reduces system airflow due to the additional back pressure, which can lead to problems (e.g., coil ice), especially if duct system and/or filter is undersized. I suggest you call a mechanical contractor with NATE or National Comfort Institute certification to balance your duct system and install a damper that can be used to adjust upstairs / downstairs flow rates between seasons. That’s the only way you can ensure system airflow remains within an acceptable range.

  53. I have just bought a home
    I have just bought a home that is equiped with a heat pump, it was installed in May of this year. The former owner said if the fins on the outside of the heat pump become frosted more then about two thirds then I need to switch the heat over to emergency. She has also went threw two units in the past 12 years with this being the third. My question after reading your info and knowing not to use the emergency heat unless its an emergency is do I need to be concerned with frost and if so what do I need to watch for,how do I need to fix it?

  54. Kelly, 

    I understand your concerns. Many people who have never had a heat pump before get confused on the most efficient way to use it. You can go to my web site at and click on the “Heat Pump” link to learn more about how the heat pump works and how to get the most efficiency from it. 
    I hope that helps you and if you have any other questions, please post back here so that others can benefit from the information. 
    Also, I would like to understand what you mean when you say that the previous owner went through 2 heat pumps in the last 12 years. Normally, 12 – 15 years is the life expectancy of a heat pump (just my experience). In order to properly diagnose the issue we will need more information.

  55. @Kelly, frost is normal and
    @Kelly, frost is normal and unless it turns into a solid coat of ice, has on minor impact on performance. Heat pumps are designed to go into a defrost cycle to melt the frost. Early heat pumps didn’t do this very well, which is one reason they got such a bad rap. Today’s heat pumps have intelligent defrost control, so that if there’s little or no frost present, the defrost cycle will terminate quickly, typically in less than a minute. That said, it’s important that the defrost settings be adjusted for your particular climate.  
    Sadly, it sounds like the former owner spent a LOT more money on heat than was necessary. The fact that she was on her 3rd heat pump within 12 years suggests there may be problems that still need to be resolved. I recommend that you try to talk with the tech that did the last replacement to see if you can find out the cause for the failure.

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