Design Help for a New Guy

Re: Design Help for a New Guy

Fishermedic wrote: »

Lee,

Do you have anything for pre-warming the fresh air into the HRV? I noticed the outdoor air temp at -15.7 and a fresh air to HRV temp of -10.9. What's warming the air before the HRV? I've seen mention of a ground loop in the intake duct for this purpose, is that what you're using?

Bryan

Bryan,

Good eye for catching the pre-heating effect. The pre-warming of the fresh air coming into the HRV is mostly due to the rather long ~25' entrance air duct that runs through the conditioned crawl space. Although the air duct is insulated, it still picks up some heat from the conditioned crawl space, especially at the low fan speeds where there is a lot of time for heat exchange. During the daytime and very early evening, it also picks up some heat relative to the average outdoor temperature since the long duct run is to get the entrance air from the south side of the house to take advantage of the solar heating at that end. (The exhaust goes out the east side toward the driveway, the "low-pressure" side of the house with prevailing west winds.) Cooling the crawl space air by pre-heating the fresh air is not as bad as cooling the air on the main floor, but it is not "free" from an overall energy standpoint. The stale air inlets for the HRV are in the crawl space, and this provides the circulation of air from the main floor to the crawl space. It also means the cooled air in the crawl space is more likely to be exhausted from the house.

The idea of earth tubes to preheat the air is always popular, but usually not practical due to the expense for a small gain, and the growth of mold, etc. due to condensation, rain, or leakage in the earth tubes.

Fishermedic wrote: »

My first choice at the moment is a fireplace

Hi, I am near Thunder Bay, so our weather is about the same. We have a 2000 sq ft bungalow with a full basement, everything electric. 5 years ago I put in an RSF Energy fireplace (Onyx 2 model), our electric furnace has not run once since we started burning it. I have an 8 inch in-line blower plumbed into it and circulate air all thru the house with it. Our Ontario Hydro bills are now $150-$180 year round, being that you are from here, I'm sure you know that is not too bad. That unit probably paid for itself in the first 2-3 years. Not sure exactly but I think I burn about 5-6 real cords per year. Sitting in front of the fireplace is a real nice place to have a beer too.