Multiple boilers for increased efficiency?

jim_112

Pat one of those 200k boilers could heat the whole house. Are the boilers side by side in the basement.If so you may be able to tie both zones into one steamer.I think that would equate to big savings.

Patrick North

Hearing a lot of what to me sounds like nay saying on the merits of setback thermostats. Much of the argument seems to center around radiant setups, but the points of argument are broad enough that I'm starting to wonder about how much I'm saving by setting the ol' boiler back to 55 overnight. We have one pipe steam, in a good sized three story house- about 3000+ sq feet. Around 400EDR, total. We've done plenty of insulating, with more as we can afford it (got the biggies out of the way- blown in in the attic and walls of the third floor).
Here's the rub: we've got two boilers serving the house which conveniently allow us to set the unoccupied (at night) first floor waaay back, while keeping the second and third livable. When we replace these boilers we've thought we'd replace both of them rather than use a single larger boiler, but now I'm getting skiddish over any possible savings. On first blush, without crunching numbers, do you guys think we'll ever recoup the extra costs of buying and installing a second (albeit smaller) boiler through lower gas bills realized by setting back the first floor at night and the 2nd and third floors (to a lesser degree)? This is our first year in the place, and I doubt we've got much time before we'll need to act. Even if we didn't, I don't think I'd be inclined to test this out by leaving the thermostats set at 68 all winter…
Any and all opinions appreciated.
Thanks,
Patrick

jp_2

do your own testing

everyones got their 'option' on this, so far I have not seen any good data on the 'wall'.

track heating degree days, if you have nat gas, clock the meter in the morning and at night.

use set back for 2 weeks, then go off set back for 3 days then track heating degree days and gas meter again for 2 weeks.

then plot the resolutes, heating degree days VS gas usage.

if you have oil it'll be more tricky

jim_111

twin boilers

Need info /each boiler's size - are they piped independently one piped to heat the main floor and other the two top floors.

Patrick North

JP- a two week commitment I can handle- I'll try that. Though I guess I've got a few situations to check- no setback, same setback for both boilers, and independant setbacks (different setbacks for the two boilers).
And Jim, yes, they are piped independantly- one only serves rads on the first floor, the other handles the second and third. Both are oversized by 75%-100% at about 200K BTUs apiece. Replacement boiler(s) would, of course, be properly sized.
Thanks,
Patrick

Patrick North

Yes, they are side by side, and I don't imagine it would be much of an issue to tie the two together if we went with one boiler. I'm wondering about maintaining the two zones (with much smaller, properly sized boilers, of course) over tying them together and firing a single boiler (of about the size of the individual boiler we have now).