Anyone know a lot about heat pumps?

[pembquist]

I have a question about heat pump operation residential heating. Generally everyone says to have them operate at a steady temperature. There are a few reasons for this the primary one being that a properly sized heatpump cannot raise temperatures very fast and in general will use an auxiliary heat source which is often a simple resistance heater which uses a lot of electricity in order to accomplish this goal. On another forum I was told that a heat pump will use more energy even without aux heat if it has too large a set back. The idea being that in terms of net running time there will be less with a constant temperature than with recovery.

I don't really understand why this would be but I am thinking in terms of kwh into a building vs kwh out of building over time and with a setback there are less kwh out of a building so there should be less kwh required to go into the building.

Anybody?

[APDrone]

Depends on your location.

Upper midwest ( Nebraska ) they suck.  avoid them.

They might be better down south.

We had one for a few years up here and dumped it when we needed to replace our 20yr old furnace.

[Shuffler]

There are several kinds of heat pumps available. Heat pumps today can be efficient in almost all types of weather here in the US. There are even several types of heat source backups for more extreme or extended colder weather.

Your best bet is to have a professional in your area come to your home or building. They will be able to develope an efficient system for you based on your requirements and location.

Someone down south will be much different than someone farther north.

[Copprhed]

As far as back up heat, I have run a gas furnace as the auxiliary heat for a heat pump system. It always costs less to maintain a constant temp than to recover. There is less to recover, which means shorter and less frequent runs. People always forget that when they set back their heat or a/c, all of the walls and the floors and furniture have to get cooled(or warmed)back up. It's not just air temp, it also manages humidity.

[Bizman]

As far as back up heat, I have run a gas furnace as the auxiliary heat for a heat pump system. It always costs less to maintain a constant temp than to recover. There is less to recover, which means shorter and less frequent runs. People always forget that when they set back their heat or a/c, all of the walls and the floors and furniture have to get cooled(or warmed)back up. It's not just air temp, it also manages humidity.

That was something I didn't know. Guess I'd better leave the pump in the bedroom on all the time even when there's nobody home. Until now I've started it when I get home and shut it down either when going for a leak in the wee hours or in the morning when I wake up.

We've had an air conditioner/heat pump here for over a decade. Many neighbours do as well. They work well and efficiently down to -10 centigrade, after that they start consuming power more than what the heat is worth. We also have electric radiators (still off) and a fireplace in every room. Cooking on a wood stove warms the kitchen nicely!

[ACE]

I work on mainly commercial Refrigeration so I’m no expert on heat pumps. But I’ve worked on several.

Like many have said it depends on your climate. Here in Tennessee they work great. Imo I only get to see the negative sides of equipment. IE I fix it when it breaks. Heat pumps generally have more controls than a standard AC straight cool. They also send the hot gas to the indoor coil which means higher pressures and heat. Now a days you aren’t going to buy a new unit with copper coils. You’re going to get a crap aluminum pressed coil that a guy on a factory line welded together. They tend to leak more than a normal AC with let’s say a Gas furnace.

If I was building a house, even in a suitable heat pump climate I would use either Wood heat or Natural Gas. Gas is just so much better IMO. Faster recovery time. Generally cheaper To run than electric in my area.

At our personal house we use a wood stove with water being pumped around it and then to a coil in-line with our main duct supply. We also use the same stove to heat our water and our swimming pool if we wanted to.

Running our 5-ton and our small 2.5 ton heat pump in the coldest of winter months our electric bill is 4-500$. Running wood it’s 150$. You just gotta cut and split the wood

-typing on mobile forgive and errors.

Edit- more than anything IMO you have to have a very well insulated house. If you don’t you’ll be wasting money the rest of your time living there.

[Copprhed]

In respect to refrigerant leaks, I have not seen an appreciable increase in leaks on the new systems. Most are now using R-410A, which is a compound refrigerant that has increased efficiency. I manage and maintain a 58 unit apartment community, and while we use straight cool and electric heat, in Georgia the bills are great. I keep my apartment at 70-72 in the summer and winter, and pay an average 87-100 bucks a month. I work with the installer on every unit(I don't have a warm air license so I have to have someone who does work with me on installs). To get back on the point, as long as you use a reputable manufacturer, i. e. Trane, American Standard, Payne, Carrier or Lennox or even Goodman, you shouldn't have a problem with leaks. Most have a minimum 5 year all around warranty, with some going as far as 10 years so any system leaks are covered. Heat pumps are great, better in some climates than others, but a good HVAC company should be able to get you something that works well. They're even doing heat pump water heaters now!!!!!

[Shuffler]

I have to negate the trane. They used to be great units. My brother had their top of the line unit put in their custom ranch home. The first time they went out there it did not work. Condenser had weld buckshot all over it and leaked. They went round and round with trane. Since then he moved to Amana and I moved to Daikin. We are both happy with our heat pump systems.

Daikin actually makes Amana and Goodman.

[ACE]

I have to negate the trane. They used to be great units. My brother had their top of the line unit put in their custom ranch home. The first time they went out there it did not work. Condenser had weld buckshot all over it and leaked. They went round and round with trane. Since then he moved to Amana and I moved to Daikin. We are both happy with our heat pump systems.

Daikin actually makes Amana and Goodman.

I just worked on a Daiken heat pump yesterday. Changed a faulty control board $28 my cost. And 2 defrost sensors $8 my cost. You can’t beat that. If it was a trane it would have been 150 for the board.
I will say this about trane. Their commercial units are solid if maintained. I have a 15 ton straight AC split system at a hospital that’s running for 6 years now. Maintenance free!  Just clean the coils every year twice a year.

[Shuffler]

I just worked on a Daiken heat pump yesterday. Changed a faulty control board $28 my cost. And 2 defrost sensors $8 my cost. You can’t beat that. If it was a trane it would have been 150 for the board.
I will say this about trane. Their commercial units are solid if maintained. I have a 15 ton straight AC split system at a hospital that’s running for 6 years now. Maintenance free!  Just clean the coils every year twice a year.

We have 4 trane 20 ton units on our fabrication shop that have been fine since 2008.

Will never suggest anyone get their home products after his experience at the ranch and mine at my home.

My Daikin has been running trouble free since 2016. My electric dropped from 350 plus a month to around 125 when we moved to the Daikin heat pump. That is in a 2200 sq ft home, August here in southeast Texas.

[ACE]

We have 4 trane 20 ton units on our fabrication shop that have been fine since 2008.

Will never suggest anyone get their home products after his experience at the ranch and mine at my home.

My Daikin has been running trouble free since 2016. My electric dropped from 350 plus a month to around 125 when we moved to the Daikin heat pump. That is in a 2200 sq ft home, August here in southeast Texas.

Nice. Yeah Trane commercial is awesome. Home line products. Nahh.

[Copprhed]

The thing is that everything now has planned obsolescence. In 2000 I worked on a 25 year old(yes, from 1975) Lennox heat pump system that was still top of the line for 2000 systems. All I did was a seasonal cleaning and a top off of 22 and it was perfect. On property I still have Rheem units running from 1998.
Today you can plan on 7 years, maybe ten with good regular maintenance. If I could give advice it would be to change filters regularly, and get your outside unit cleaned before any season it will be used, and to have the evaporator coil check every 5 years and cleaned if needed. If filters are changed properly, it should not really need doing.

[mikeWe9a]

It should cost less to allow the temperature to fluctuate when you are gone.  The amount of heat transfer will be highest when the house is at its set point, as that will be when the temperature difference between inside and outside is highest (heat transfer is a function of temperature difference - the higher the difference, the faster the transfer).  The amount of heat lost over a given amount of time will therefore be higher when the house is maintaining that constant temperature.  While the pump will run longer to recover from (for instance) 10 degrees below its set point than it will to recover from the 1 or 2 degrees needed to activate the thermostat, the total amount of time over the several cycles it used to maintain that temperature during the same period will be longer than it takes to recover the temperature.  The only way that more energy could possibly be required to recover vs hold is if aux heat is used to raise the temperature more quickly.  In every other case, since less heat was lost/gained due to natural heat flow, less heat has to be moved by the heat pump.

Mike

[Vulcan]

Heat pumps are very popular in NZ. Everyone has them as we have a moderate climate. Nobody leaves them on all the time, they warm up rooms reasonably quickly. You do need to size them correctly. Brands like Daiken, Mitsubishi and Fujitsu are popular here.

[save]

The new heat air-to-air pumps are very good, most have them in Sweden. I've had mine for 15 years, with fill up of refrigerant (R410) once after 7 years, they tend to lose at number of percent every year.
The newest have much better performance below freeze point than the older, and are more quiet.