Why?? Is it not keeping your house warm?
( kjpro @ starband . net ) remove spaces to e-mail
Want it done yesterday? Or done right today, to save money tomorrow!!
Mainly, you do not want to have a steam-boiler, for hopefully obvious
Pros: transfers heat more rapidly to building because of higher temp
differential- higher recovery rate results.
Cons: reduced efficiency because of higher stack temp, result of
higher temp of "load" in boiler.
Ideally, for efficiency, temp would be set such that with lowest
outdoor temps of year system can just hold t-stat set-point while
pump(s) run constantly, _and_ burner firing rate is set low enough
that burner runs constantly. This makes recovery difficult, though.
So you set the "aquastat" temp a bit higher than the optimum for
efficiency, besides firing rate.
Other factors apply, certainly. Increased duty-cycle of pump(s) will
reduce longevity. Reduced temp cycling of firesides and lower boiler
temps will increase longevity there. Fuel's not free this year. You
could put together a serious spreadsheet of guesstimates.
Of course, you have sealed and insulated the whole place well?
Thanks for such an in-depth answer. It was just what I was looking for.
I believe you're saying you want the boiler to be set as low as possible and
still keep the house comfy. I guess 180 is a good setting for me.
I have a 12 year old mid efficiency Viessman boiler in my 165 year old
partially insulated stone house and I have had it running at between 100-120
degrees F. since it was installed, I even ran the old ineffiecent boiler at
that temperature for over 15 years with no problem. My house is usually
reasonably comfortable but I would be interested in knowing if I should run
it hotter or leave it where it is.
I have had so many conflicting answers by so many so called boiler experts
that I really don't know who to believe anymore.
I have been told exactly that so do you think I should leave things where
there are or consider buying a smaller boiler that runs hotter but possibly
more efficiently? Are there any safe ways to convert an oversized boiler to
make it operate like a smaller boiler?
Any advise will be appreciated
Oversized Air Conditioners are not good because they run too short a time to
properly dehumidify the air. An oversized boiler will just heat the water,
then shut off, then start when needed.
If you have the old big cast iron type or radiator, then a low temperature
that is steady works just fine. No need for them to heat up to 180 degrees.
You probably have a more even heat in the room with less fluctuation that
Mark, if your answering Zacks question, I am interested in how you determine
boiler is oversized because it is operating at a lower temperature?
The lower temperature boiler has nothing to do with it being oversized, the
temp requirement is because the radiation (baseboards or cast iron heaters ) in
space are sized to put out the required BTU's of the room with a lower
An oversized boiler may be indicated if the boiler short cycled on high limit in
short time while the home is comfortable. This would indicate that you have more
output from the boiler than what the radiation is capable of delivering in the
of time or the circulator is undersized if the water temp difference of the
and returning is greater than 20 degree's.
Maybe I'm missing something of Zacks post...........
To Zack, the norm of boiler is to not have it lower than 140 or you can have
forming in the combustion chamber. This condensation can and will cause
But, 140 may not be obtainable without a bypass if your cast iron radiators are
The boiler should be set to the lowest temperature that is high enough to keep
your house warm.
An often overlooked, but significant, drawback to high boiler temps is the
risk of scalding, particularly for children that haven't yet learned to walk.
If you, or any frequent visitors to your home, have a crawling infant, keep
that water temp as low as you can.
Doug Miller (alphageek-at-milmac-dot-com)
I also have a thermostat that is set low during the day when there isn't
anyone home. Is it better to set it low like 55 or more like 62? What
would save more energy? The boiler woul dhave to work harder at 55 to get
the house up to temp when it finally turns on to the comfy temp of 69.
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