I don't see too many discussions on Green Building Talk for questions/recommendations (etc...) on Non Geo Thermal heat pumps

I've found one called  http://ths.gardenweb.com/forums/hvac/

Does anyone know of any others?

I'm looking for a heat pump only heat source for a home I'm building on the Northern Calif Coast.

I posted a thread in the Geo Thermal forum on this board, but it digressed and the conversations there seem to like to stick to Geo Thermal..

My take on it is that moving large amounts of heated air just isn't that green. There has been discussion here of highly efficient air to water heat pumps and quite a bit more for ductless minisplits.

The Northern California coast is not what I think of as a rigorous heating challenge. Just off the cuff, highly efficient radiant seems appropriate as would ductless minis.

This website offers a huge amount of greenbuilding information. http://www.greenbuildingadvisor.com/ There are several threads discussing minisplits and tight, EE housing. The consensus there, and based on my own observations, is that minisplits make a lot of sense over radiant, especially if you need AC as well. Often, the cost of radiant exceeds a minisplit, without the value add of AC. However, the minisplit works best in an open floor plan. If you have access to natural gas, and don't need AC, even with the COP advantage of +3 vs .95 the minisplit may not have a ROI advantage over the radiant. All this assumes a tight house, low BTU load. Are you really on the coast with design temps in the 30's? Need AC? Have gas? I'm above Sacramento, need AC and design temp is 28*, no gas. ; so minisplit works great for me. Radiant costs more, and requires an additional system for cooling, so is not green at all.

PS; i think as i reread ICF's post ; he and I are saying much the same thing. Ductless minisplit is usually considered a separate system from a ducted heat pump requiring large fans. Minisplit don't have to MOVE much air from heat source to the room; that's why they are efficient. But if you have a complex floor plan, and need a duct system, a heat pump still has advantages as noted in my first post because of its COP. With outside temps on the coast rarely below 40, the heat pump is very efficient.

Really, I'm looking for a forum that discusses choices among stand alone heat pumps for heating, not alternative types of heating solutions. Radiant isn't a cost effective option. To do it correctly (warm board or pouring an inch of concrete in the floor, isn't cost effective and you'll never realize An ROI. Radiant is a little more green but enough to offset the increase in hardware costs. And I'd still need to install a duct system to move around air, according to many on this very forum.

So radiant is out. Period (I simply can't afford it).

My heating needs are not tremendous as it is a mild zone. Average low temps in Dec, Jan, Feb ar typically mid to upper 30s. It can get below freezing though.

I will have many west facing windows, choosing HSHG glass to assist with heating during the daytime. Windows will be Alpen 725 series - excellent uf and R factor.

The home will be tight. I will air seal all outer walls, the attic floor and under the crawl space sub floor. I will probably spray foam all outer walls and under sub floor too.

I will air seal all the ducts too

I am installing the ducting system myself

So I'm trying to compare heat pump (all electric) brands (3 ton, 30BTU, 2 stage comp, variable speed fan AH) based on price to quality ratio, reliability, SEER, EER & COP specs. And if I end up using a local contractor to provide the HP/Air Handler then I will need to consider what brands they sell. Again, a good friend of mine has offered to supply me an American Std/Trane 3 ton unit & AH at cost, as well as coach me on most of the installation needs. Then I would just need to contract locally to have the refrigerant installed.

Carrier, Trane, Amer Std, Rheem, Lennox are all main stream brands. Looking for opinions on why certain brands should or should not be considered.


And, I do not want ductless either.  I'd have to have 6 or 7 units, and still would need a duct system for the ERV/HRV. Not particularly interested in the esthetics of units mounted to the walls (inner and outer) all over the place.

To do it correctly (warm board or pouring an inch of concrete in the floor, isn't cost effective and you'll never realize An ROI.

That's not really how to do it correctly. Radiant makes a lot of sense if you are already doing concrete floors. Common examples are single level homes on a slab and ICF in which your upper floors are also formed concrete like Insuldeck or similar. Then, you polish the concrete floors, getting a high quality finish and an extremely efficient radiator. That kind of a system is extremely affordable. If you absolutely must have air conditioning, you will want to consider the ductless minis before you go to a system in which you have to have ducting. Ductless minis begin to fall short in climates which have extreme lows and there is no good source of backup heat.

Traditional air source heat pumps are less desirable because they have to attain temperatures of 110F or higher to heat the air, which is substantially higher than you should have to get the radiant heating fluid in a good system. They lose efficiency the higher they have to push the temperatures. I run a radiant system which only has to get to 85-90F. Then, there is the issue of the energy required to move the air.

HRVs move far smaller amounts of air through much smaller ducts. Installation cost and operating costs are not comparable to traditional ducting.

I will have many west facing windows, choosing HSHG glass to assist with heating during the daytime

Up here, in WA, that's a mistake. The west windows only see sun later in the day or towards summer when you really don't need the heat load. You want to open up the South windows with the high heat gain glass, making sure you have enough overhang to shield them from high summer sun.

A mini split is a "state of the art" heat pump. BUT It lacks the ability to "duct" it's output to remote parts of the house. The indoor portion is also ugly. I plan on using a mini split but putting the indoor unit in a closet with (5) Panasonic whispergreen fans to move all the conditioned output to the perimeter of the house through individual ducts in the floor with return air flow through the ceiling service cavity. The fans will be set to deliver slightly more air than the minisplit's rated CFM and controlled by a current sensing relay sensing the mini split's operation. The Whispegreen fans are "smart" fans and move the selected amount of air independent of duct loading, within limits.

with (5) Panasonic whispergreen fans to move all the conditioned output to the perimeter of the house through individual ducts in the floor

Have you calculated how much heat can be moved by a single fan at the initial maximum output temperature of the indoor unit and compared it to the heating needs at that duct outlet?

Posted By ICFHybrid on 07 Jul 2014 09:37 PM

with (5) Panasonic whispergreen fans to move all the conditioned output to the perimeter of the house through individual ducts in the floor

Have you calculated how much heat can be moved by a single fan at the initial maximum output temperature of the indoor unit and compared it to the heating needs at that duct outlet?

YES!   The share of the minisplit's output handled by each fan is somewhat adjustable.  Each fan can be set to deliver 70 or 90 or 110 or 130 CFM.  The 15,000 BTU/hr minisplit processes 530 CFM max.  With the total fan delivery set to 540CFM there could be 4@110+1@90 or 3@110 +1@130+1@70 or 2@110+1 @130 +2@90etc.  Meaning individual fans could deliver between 1944 BTU/hr and 3611 BTU/hr.

I think you are going to find a substantial difference between theoretical output at the minisplit head and the actual delivered output at the end of the ducts.

Posted By ICFHybrid on 08 Jul 2014 02:47 PM
I think you are going to find a substantial difference between theoretical output at the minisplit head and the actual delivered output at the end of the ducts.

I agree.  There will, no doubt, be losses of heat through the ducts, even if they are well sealed and insulated, to the basement.  Regardless I expect better heat distribution than a centrally located mini split, at least as good as a typical forced air heat pump system but with far lower energy use, especially in cold weather.

I hope you let us know how it works out.

Did you do your mini-split in a closet with ducts?  How did it work?