In the new House edition article on heat pump systems…maintenance cost is a big factor not highlighted in that article.
Back in 2001 I had a well known firm install a Carrier heat pump air system in an old brick house built in 1900. All new vent work included. At the moment there is no insulation in the stud cavity walls. Only R-13 bat insulation under the roof. The walls will get insulated soon with poured foam. This is in Omaha.
That means the heat pump will operate many more hours than if the house had been a super insulated house. Heat pumps because they do double duty, (heat & cool), will wear out sooner than, say, a standard air conditioner pump. I am on my third heat pump and the bills run over a $1000 each time even with the pump warranty covered. That should tell you that a heat pump air system in this house was not a good decision. In the mean time I now set the gas furnace to kick in at 40 degrees and below to save on heat pump running time. After all. there is certainly no savings in heavily using the heat pump if there is a $1000 bill with every heat pump replacement. I think one of the considerations when looking for a heating and cooling system should be maintenance cost over the life time of the system, but good luck figuring that out. I am of the opinion that heat pump air systems need to be very carefully considered in terms of life cycle cost inaddition to gas and electricity cost. There are some serious negatives here. The math is variable with change in gas and electric rates….and heat pump replacement associated cost events.
I would have been much better served with a standard heat / air conditioner system. That would have been the least expensive. Now on reflection, and considering that with poured foam installed, this house would still not be very efficient. A case could be made to have zoned hot water heat so that only rooms in use get the heat. Same for chilled air.
The only way to greatly improve the energy efficiency of this house would be to remove all exterior wall plaster and install high density foam board under new dry wall. I am 68 years old…and that ain’t gona happen on my watch now.
I thought I would pass along this experience so anyone looking at heating systems would have more to reflect on before shelling out big bucks because of a sales pitch.
I can not emphasize enough that you should take the time to ask a lot of questions about total life cycle cost of any system you are considering. It is a big investment and once the new system is in…..well, you own it. Not much chance of reworking the decision unless your a heating contractor.
Replies
That's why we in the commercial sector often factor in other aspects of 'owning and operating' systems beyond simply the snapshot of the energy picture. Your points are all well taken and pretty much right on.
Keep in mind a ground source heat pump (GSHP) ... highlighted in an article in the same issue should be considerably lower in terms of long term maintenance/replacement costs since the heat pump is not subjected to the weather extremes that have a tendency to 'beat up' a conventional system. GSHP equipment should last considerably longer (assuming a proper design and operation).
If you've been through 3 heat pumps in nine years I'd suspect there's something wrong with the installation.
Heat Pumps and wear....
On the face of it the replacement issue looks like something was not right. But the first heat pump failed almost one year to the day of the installation. I did not have to cough up any money the fist time. The second and third replacement failed the same way. One day I would notice the pump was getting loud. Then it seized up. The third pump one day got loud and I quickly shut it off, but it had seized up anyway when the repairman tried to switch it on. So, all three pumps died the same way. On the second and third pump replacements I had to pay for the dryer cartridge, pump down of the refrigerant and all that. The furnace people really nicked me hard for the extra stuff since the pump warranty is 10 years. And, since the repairman did not have any comments about the failure of the pump I assumed they had seen a lot of pump failures. It is what I call job security. Why would they complain. But I did not get an answer from any repairman when I asked them if this repair was common. Therefore, I assume it is all too common.
I'll admit that in a house with little insulation the heat pump will work many more hours. And it has to work going both ways. Chilled air and heating. Still, my 85 year old neighbor has an old GE central air conditioner that has not had a pump replaced in forty some years since the day it was new. He always reminds me of that when he sees my heat pump being replaced. That does weigh on my mind. Is this a quality control issue? I think it is. Maybe I am stuck with this pump design if Carrier has moved on to new models. But I can not help thinking that this model pump should get some beefing up if for no other reason than Carrier's reputation. I do not think any manufacturer would want to see this on blogs.
I'm guessing that the evaporator coil is missized or the expansion valve or shuttle valve is bad. Could be a simple leak, too, though one would think the repair guys would have checked for that.
My air source heat pump is 16 years old. The external unit has NEVER been serviced...never even cleaned never charged. NEVER
It don't bother me and I don't bother it. A lot of people like to constantly "maintain" things. By that I mean clean them and generally muck around with them in the belief they are doing good. I follow a strict policy of benign neglect. I don't go stick a hose at it. I don't monkey with things. Just let sleeping dogs lie. and my climate is similar to yours.
Back in 2001 I had a well known firm install a Carrier heat pump air system in an old brick house built in 1900. All new vent work included. At the moment there is no insulation in the stud cavity walls. Only R-13 bat insulation under the roof. The walls will get insulated soon with poured foam. This is in Omaha.
Wait, what? You say your old drafty, leaky, uninsulated house is killing your heat pumps. How in the heck did you settle on this as your solution in the first place? Was the original plan that you were going to insulate shortly after getting this high efficiency unit installed, and then never got around to it? Fer crying out loud man, you live in OMAHA... it gets to , what -70 there? (I used to live in Iowa) I always though heat pumps were for mild climates... Omaha is not a mild climate.
It sounds to me that you are blaming the technology for its miss-application. It's like being mad at the computer because your cave doesn't have a power outlet. You might want to have another company come out and evaluate your HVAC needs, I think something is seriously wrong here!
Sounds like you had a quite incompetent installer - and incopetent replacement technicians.
Like others have said, have never had to service either of my heat pump either - air-air for over 45F, GSHP for when it is under 45F.
Your post is a good testimonial for learning how to DIY stuff, the more complex the better to be able to do it right. If you had learned how to do hvac 10 years ago (rather than going to a few ball games or whatever was non-productive), you would now have $1000 wortth of tools for life plus $2000 left over, plus the knowledge. And your HP would be humming along nicely.
Heck, you even could have installed your own GSHP, save about $6000, plus have your own backhow left over <G>
BTW, anything under 85 is still young.
>>>At the moment there is no
>>>At the moment there is no insulation in the stud cavity walls. Only R-13 bat insulation under the roof.
With that little insulation, it's no wonder that the HP is working overtime. But like Dan said, three pumps in three years seems odd.
We've been super happy with ours... going strong for heating and cooling after six years.
FWIW, in my area (NW Ohio) we figure on 15 years for central A/C - 10 for a heat pump - with, of course, a lot of variation.
Set points...
I have had different installers tell me different set point stories. Originally, the heat pump would shut down and the gas furnace would take over in temperatures below the low 20s. I asked the repairman on the second heat pump replacement to raise the set point to 32 degrees, but he did not definitely indicate that he would. I asked the last repairman to visit here to be sure the cross-over from heat pump to gas be set to 40 degrees. He would not indicate that he did so. Just to make sure this happens I now program the thermostat so the gas furnace kicks on below 40 degrees. Not at all happy about this turn of events.
I had intended to have the house better insulated and, indeed, I did get some insulation installed, but this house needs more work than I can do now. I am hoping with the energy efficiency credits offered by the government it will now be a good time to finish tightening up the house. There are rivers of air moving up the inside walls during winter and new exterior insulation is just a part of the challenge. In the last few years the house got a new roof and all new bead board around the eves. All new copper pipe has now replaced old steel pipe. And a new service entrance with breaker box....and almost all new wiring. There are still two rooms with knob & Tube wiring left to replace. So I have spent some money along the way. But I admit that in hind sight I wished that I had bought a regular gas furnace / airconditioner. Better yet would have been zoned hot water heat, but that is getting into money. Live and learn.
I guess I'd find the phone number to the Carrier (or whatever brand) and talk w/ a technical rep to find out the designed and intended operating range of the unit. All else is conjecture, really. I've heard some people say some units are designed to operate in the 15-30 degF range, but historically units fall way off under the 35-40 degF range and go for the backup heat.
Your situation sounds like you MAY have some contractors that aren't doing something right or maybe not checking something (heck, they don't care ... they get to sell you a new unit every couple of years). Maybe they are simply missing something. You've got plenty of evidence that it isn't the technology, really, but something wrong w/ your situation. Maybe time to roll up your sleaves and find out what is right for your specific equipment.
Somethings wrong...
I put a heat pump (air to air) system in my poorly insulated home and it works great.
Three systems since 2001?
Something is fundamentally wrong with your installation and the people you have "fixing" it, not the technology.
Of course, the unit should shut itself down and turn on emergency heat when it gets literally too cold for it to operate. But some jackleg could have disabled that function, or mis-installed it.
There is a difference between "too cold to operate" and "cold enough to work hard".
if working hard, AND under a very heavy load (say, a poorly insulated house), you can really shorten compressor lifespans. Or so I gather from GSHP installers who ran higher water temps for a few years.... same kind of deal, I imagine.
I'm definitely making this up, but it would be my suspicion at least that the low outdoor temperature operation coupled with the very heavy load is what wrecked the units.
The controllers should have been set to disable the units when temps were too low.