efficiency issues

glanz p.h.c.

I'm looking at replacing a boiler that is approx. 50 years of age. My question is how to go about determining it's afue rating. Can anyone set me in the right direction. Also, there is no rating plate.

John_19

efficiency of old boiler

A 50-yr old boiler is likely to be 55%-70% efficient. No AFUE ratings existed 50 years ago. One general rule of thumb is, if a recent combustion efficiency test rating is available, multiply that test rating by 0.85 (85%). So if a combustion efficiency test gives a value of 80%, then the approx. AFUE-equivalent is 80% x 0.85 = 68%. This is very much a broad approximation. Also, remember that if you're replacing an old boiler with a new one, the old one was probably oversized and you could heat your home with a smaller capacity boiler, which will save you even more. See http://www.aceee.org/consumerguide/reheat.htm

steve_26

why

you don't need it.
A new boiler is what you want to figure out.
Do want 85% or condensing technology?
Don't waste your time with the old one.

steve

R. Kalia

no good way

There is no good way to determine the AFUE now. Assume 70%; it may be worse, but that way you will not be disappointed if you savings are not as high as you hoped. Boiler manufacturers and contractors will mention numbers like 30% to 50% savings, but they can't and won't put it in writing.

glanz p.h.c.

size & zoning questions

Thanks for the info. This house is a solid concrete house with a bedford stone exterior. All ceiling radiant 3/8" tubing. Presently it is zoned by 3-b&G pumps, I plan on 86ing that and using only zone valves. Do you think that taco pump supplied with the Burham series 2 will suffice or should I look at another B&G. We clocked the meter at approx:200,000 btu's, I did a load calculation and determined that I only need 110,000 to heat the area. My only problem is that who's to say there is enough radiation.

Larry_4

Choosing your boiler.

you said you had radiant tubing. Why would you not go with a condensing full modulating burner with outdoor reset to keep low hot water temp feeding the tubing. It sounds like it would be a perfect match keeping your boiler in the 90% range and with full modulation you will match the zone load so the boiler really never shuts down ( as long as low fire on the boiler matches the btus required for that zone. Viessmann makes a greaT burner for that application. You would want to due heat loss calcs

glanz p.h.c.

I would love to install a mod. boiler but my application will not permit such. The present boiler is running at 110 degrees due you think that if I use outdoor rst that I might have a condensation problem at lower water temps. IF so what about primary-secondary piping to solve the problem

glanz p.h.c.

need severe help

I want to thank everyone who has replied to my threads. Please continue to help me with this particular job JASON