heat pumps

[fishman]

Last but not least, do not use a night setback thermostat. The warm-up in the morning will force the heat strips to come on and it will kill the efficiency of the system. Over 30% more power is used overall when a set back is used. Set it and forget it, and it will operate most efficiently.

paul

I purchased a digital thermostat at Home Depot a little over a year ago that is designed for a heat pump. It states that the auxiliary heat won't be activated unless the bump-up temperature is really different. Five or six degrees never activates the auxiliary heat. It should actually be much more efficient than my old manual version, since aux heat would come on pretty easily on it.

So, I think it's working the way I say it is. I've only managed to active aux heat by manually bumping the temp from 62 to over 70 degrees. Downside is that it does take a long time to raise the house temp a few degrees.

 

[techman]

mechanic,

I didn't see any mention regarding water or ground source heat pumps which are much more efficient than air source heat pumps since they derive their heat from the earth or water supply which is at a steady state ~50 year round.

I converted to geo heat pumps a couple of years ago (see: http://www.tractorbynet.com/forums/rural-living/74680-geothermal-heat-pump-project.html ). The ground temp does vary seasonally, mostly due to the heat/cool you are dumping in to it, but still a great improvement over air systems.

I agree it is a great system. My only other comments are regarding DX systems. They look great on paper, but I have seen quite a few problems with DX units. Most soil has a thermal transfer rate of about 1 btu/hr/deg F. You can't get much of an efficiency improvement when the soil is the biggest thermal issue. You will see good efficiencies at first, but the soil will cool down (or heat up) over the season and lower efficiency as time goes on. The thermal transfer of the plastic tubing used in regular ground source heat pumps is 10 times better than the soil. Additionally there can be issues with corrosive soils that can lead to very expensive repairs if the copper tubing corrodes.

There were quite a few DX manufacturers in the early days of geo heat pumps. Most are gone today, with just a couple left. That says something.

paul

 

[techman]

I purchased a digital thermostat at Home Depot a little over a year ago ...

You did the right thing. Very few programmable thermostats have that capability, and most people buy one off the shelf and end up paying big time for the supposed "cost savings" of using night setback.

Buyer beware

Paul

 

[Bird]

Bird, your outdoor unit is a two and half ton thirteen SEER heat pump. Keep in mind, depending on what it's "matched up" per the indoor coil/blower/air handler, ratings may differ per the manufacturer (one example would be if an expansion valve was installed or not).

Surprised that for the time (it was made on the 24th week in 1999) that someone did actually put in and spend the extra money for a 13 SEER unit.

Hmm, I remember hearing something about an expansion valve, but don't remember what it was. Anyway, I thought I had a good picture of the unit in the attic, but I don't. I'll attach the picture I do have and see if the numbers are legible. At any rate, the model number is RBEH 17J14SFAA and the serial number if T M4800 02564. And it has an Aprilaire 2200 air filter system.

And that's about the size I would expect. It only has to heat and cool about 1,295 square feet.

 

[fishman]

Thanks Techman, you had me worried there. I know I did have a problem finding one that was specifically for heat pumps, and it did cost about twice what a "regular" digital thermostat cost.

As an aside, my family can't or won't figure out how to reprogram it. So I've got the temp set really low in my house this winter and am saving some real money. One of my coworker's had an electric bill that was over twice as high as mine, and his house is smaller. Problem is, he has a manual thermostat and the kids figured out how to work it. . .

So maybe not the way the savings are supposed to happen, but I'm saving none-the-less.

 

[Bird]

Problem is, he has a manual thermostat and the kids figured out how to work it. . .

Did you ever notice how many businesses have a lockable cover over their thermostats to keep employees from messing with them? When I was gainfully employed, I've even had to give some of my employees an emphatic direct order to never touch the thermostat for any reason. It never ceased to amaze me how many people think if it's 73 in the room and they want it at 70, they need to turn the thermostat to 60 to get it to cool off quicker.

Our house has a Robertshaw 9620 digital programmable thermostat "7 Day Programmable 2 Heat / 2 Cool". Since I didn't know how to work it and couldn't find a manual in the house when we bought the place, I went on the Internet and found and downloaded a manual. Quite some time later, I found the original manual on top of the water heater. But I guess all that "programmable" stuff is wasted because we have it on manual, set the temperature for the Winter and won't change it until we change to cooling.

 

[cp1969]

just my $0.02, I have a 3200 sq ft (living) home with two heat pumps. I would never go the heat pump route again. Too drafty..............

In Louisiana?!?

I wouldn't need anything more than a T-shirt if I lived that far south. Being covered with an insulating layer of blubber, such as I am, takes a lot of the edge off those drafts.

 

[mjarrels]

Maybe a stupid question... but how do large buildings heat in this cold weather... ie airport terminals, large box stores etc. Was at Dullas and Detroit airports about two weeks ago and they were warm. Huge areas to heat.

ask the chief

mark

 

[BobRip]

Maybe a stupid question... but how do large buildings heat in this cold weather... ie airport terminals, large box stores etc. Was at Dullas and Detroit airports about two weeks ago and they were warm. Huge areas to heat.

ask the chief

mark

Really big buildings don't have to heat. Many air condition year round. The heat generated by lights, equipment, and people is enough to heat the building.

 

[kenmac]

Maybe a stupid question... but how do large buildings heat in this cold weather... ie airport terminals, large box stores etc. Was at Dullas and Detroit airports about two weeks ago and they were warm. Huge areas to heat.

ask the chief

mark

Some use very very large boilers