Had a call from a friend and she asks me about my opinion of the payback in changing out a 50’s vintage nat. gas boiler with something new and more efficient. The heat bills, to her, seem high on this ranch house with basebd HW. This is a purchase in NW Ohio. Original Andersen windows, decent crawl and minimal insulation in the attic. Around here this vintage would more than likely have old 3-1/2 fibreglas in the walls. I have not seen this house, can only rely on the phone call.
So with minimal information, would anyone care to help answer her question, my experience is pretty bare.
She’s a sweetheart.
thanks
Remodeling Contractor just outside the Glass City.
Replies
Hard to say Calvin. Depends on how efficient the existing boiler is. A safe bet would be that she could save 10-20% with a non condensing boiler.
You probably already told her to have her weatherize and insulate first, then have a real heatloss calc done. She would then be able to downsize the boiler and really maximize savings. There are probably enough air leaks in the house that if you added them all together it would equal an open window, literally.
So tell her to close the window and then get a better boiler :)
Thanks homer. That was pretty much the picture I painted. I had guessed at the same percentage potential. I'll put her in touch with a couple htg contractors I think I can trust to give her some straight advice. Appreciate your help.Remodeling Contractor just outside the Glass City.
Quittin' Time
That was our experience. We replaced a '60s vintage cast iron boiler with a modern, wall-hung unit and our gas usage is down about 15% compared to last year. Average temperatures are about the same, so we're comparings apples to apples.
Here is what I would suggest:
Insulate, insulate, insulate. If the walls are filled already, seal the attic/ceiling penetrations then blow in some cellulose. Cheap, effective, reduces heat loss. Then go around the perimeter and seal all weatherstripping, etc. to minimize heat loss. Then seal the floor and the walls of the crawlspace.
Once the envelope is reasonably tight, do a heat loss calculation and consider installing a modulating, condensing gas boiler. The marginal cost of going with a Trinity or Munchkin is typically tiny compared to the efficiency gains that some people have reported (40% improvement over a 80% AFUE non-condensing gas boiler). This will be particularly true if the baseboard will be sized to require no more than 140F degree hot water on a design day. If you want hot water, also go for a indirect like the Superstore.
The degree to which a modulating boiler can take advantage of the baseboard emitters in her home depend a bit on the design-day heat loss and the temperatures that the baseboard has to maintain. However, even when the boiler becomes non-condensing on a design day (let's say water temps are 180F out and 160F in) it's efficiency will be in the high 80's and design days only happen 1-3% of the year. The rest of the time, a condensing and modulating boiler will save gobs of energy and hence save $$$ also.
Another big plus of these boilers is that they're designed for sealed combustion and hence keep the intake and exhaust gases out of the house enevlope.
Thanks constantin, I looked at the munchkin thread and will pass that discussion along to her. Hopefully she has online ability now and I can send her the link to The Wall. It will help give her some background information to talk with the htg contractors. My knowledge is minimal eventho we have infloor heat. Appreciate the thoughts of users and those in the tradesRemodeling Contractor just outside the Glass City.
Quittin' Time