On Sep 17, 4:20*pm, Heathcliff wrote:
Trying to get ahead of the curve here. *Heating season is approaching
and my boiler is old. *I doubt I will replace it until absolutely
necessary, but when it happens, I will need to decide what kind to
get. *House is about 2400 sq ft and climate is fairly severe
(Chicago). *Hot water heat, natural gas fired. *Have separate water
heater for domestic uses. The boiler I have now is a Peerless unit
from the 1980s.

Need some more info to give you a complete answer.

Clearly you have hot water heat, but what kind? The issue is that
condensing boilers maximize their efficiency when their return water
temp is below 130 F. If you have a baseboard system, you will never
see temps that low, and, even with radiators, you probably won't be
able to heat your house in cold weather with water temps like that.
The question is "How much efficiency do you lose at say, 150F for a
water temp?" If it is a percent or two, no big deal, but any more
than that really starts to affect the payback. Given that these
boilers aren't typically expected to last more than 15 years (give or
take), and they cost about twice as much, it is hard to make the
numbers work unless you have radiant floor heat, which operates at
lower temps.

You also have to be careful when sizing and setting the temp for
domestic hot water, since setting the temp sky high will give you
faster recovery, but affects the efficiency also.

JK



I see you can get units that are 95% efficient, with sealed combustion
chambers and stainless steel heat exchangers. *All of those sound like
good ideas, but how are they in practice? *Do your fuel bills drop?
Do they give trouble? *Do they last? *Are they worth the extra $$? *--
H