I am doing a 11,000 sf 3 level house which is being completely renovated and will have new HVAC and be very tight with new windows and closed cell insulation. The house is essentially two wings each of which has mechanical space at the lower and attic level, and everything is open currently so running mechanicals is as easy as it ever is.
I am considering different heating solutions and looking for thoughts.
Because no natural gas is available but an excellent electric service with whole house generator backup is already in place, my first thought was geothermal, which I have done before with good success (expensive install, but reliable and with good operating costs). I also like that with geothermal there are no outside condensors and associated noise, but on this house I think I can hide them well so that may not be a major consideration.
However, another (experienced, quality) builder is urging me to look at cold weather air source heat pumps split systems, which he has been using, but which I never have.
Because wall head units would not be acceptable to my customer, I would likely do a number of ducted head units with very short duct runs to adjacent rooms (e.g.: 1 unit might serve 4 kids bedrooms). This would allow me to put in a few smaller systems in strategic locations and save some costs on all new ductwork (the old ducts were moldy and I have removed them).
I anticipate this will save me money on equipment and drilling (not sure how much yet, but remember there is a 30% geothermal tax credit reducing my costs on both the field and the equipment, so I have to compare net costs).
I am Southeastern PA which is zone 4 bordering on zone 5, so January is avg temperature of 40/22in January and 86/62 in July with high summer humidity (but remember it will be a tight house).
A little lookiing tells me there are several manufacturers whose air source systems seem well suited to this climate (he uses Carrier but I see a lot of net discussions about Mitsubishi and Fujitsu).
so … any builders or HVAC stars who have gone through this want to chime on on what they would be thinking on ground versus air source heat pumps, and whose you are favoring for reliability and performance?
Replies
There is a lot of variability re how practical geothermal is based on the nature of the soil (and whatever's beneath it) and the amount of land available for this use. Also, in some parts of the country the health department or another code body may get involved due to the risk of groundwater contamination (especially if a groundwater system is used). You should do a "sanity test" on geothermal for your location before you invest a lot of time in pursuing it.
split air source heat pump
I'm as certain the geo will work as you can be before you check the geology - as I said I have done it before and our area is very good for it as the drilling is easy and you normally get schist and some water, good conductors. All systems are closed loop that I have ever seen in this area, and there are no issues with the county approving them - a fair amount of geo is getting done here now, and there are a number of highly experienced installers to choose from several of which I have worked with before.
It is the air source heat pump I am less sure about - I have yet to see this done - the norm in our area is forced air with gas, or sometimes a boiler to air handlers, more rarely geothermal (though increasingly common). I'm interested in hearing if anyone has been successfully doing it in a similar climate for a high end clientele, and how they are specing it?
i am doing a ground source system on the current house i am on now, considered the mini splits but they could not compete with the 30% rebate.
I have never used them but walked through a large high end home a few mnths back that had a mini split, ground source, and radiant floor heating. The mini splits were mostly servicing a large room for the kids homeschooling, a 8 car garage, and indoor pool area. everything else was on the radiant heat with the ground source heat pump.
If you go with the minis please come back and let us know what you thought.
Mini splits
will do - what zone are you in Mark?