I am in the process of choosing a new fboiler for my 1000 foot home,
built 1930. Current boiler is 39 yrs old and consumes a lot of oil.
There are insulation improvements that need to be done too.
After reading up some more, I found that you need to insulate first in
order to size your furnace properly. My problem is that while I
definately plan to do that, I wanted to replace the furnace as soon as
possible because of the amount of oil it is consuming and the
possibility of it having problems getting through the winter. I have a
number of projects including replacing back door, insulating floor
joists in basement and putting on storm windows upstairs. It is
unlikely that I will have the time or money to do all the insulating
and improvements before I put the furnace in.
My question is whether it would be possible to properly size the
furnace before all these are done, especially if my contractor is aware
of the improvements I will be making. Also, not one of the 4
contractors that have given bids have crunched my info through a heat
loss equation (that I'm aware of), although the last one crawled all
through the house and looked at everything. I just want to replace the
stupid thing before it quits and hopefully have oil bills lower than my
What should I do?
Numbers can be run for future improvements , although oversizing was
common for boilers, and you did say boiler as boilers heat water meaning
you have radiator heat. Radiators dont suffer the same issues oversizing
does with forced air AC. AC oversized cools to fast leaving the
humidity, air heat oversized can heat to fast and uneven , although gas
flame output can be adjusted few contractors or homeowners do this.
Boilers are a slower more even heat to start with. A smaller boiler is
cheaper. I think "system 2000" I dont know who makes it , is one of the
most efficient boilers made. You dont have storm windows yet! I suggest
you look into replacement windows, new glass technology, less air
infiltration, and better overall insulating compared to storms make them
if you dont have the bucks right now better to size the boiler for the
home today, then insulate in the future. with boilers slightly
oversize isnt a big problem and will lerave some capacity for a
possible future room addition!
Right Bob, saving money on efficient equipment isnt worth it you say,
its that kind of ignorance that keeps people spending all their money on
utilities forever. You forget a few things, one, house value goes right
up with improvements that can be proven to save , two, and old unit will
need repairing and till be old an inneficient. 3, your house can sell
much quicker if its afordable to run, 4, you can afford to operate it. I
forgot there are Condensing boilers that achieve 95% efficiency. Ive
done these things and in 04 season spent 465 for a years gas on 1800 sq
ft Zone 5. down from 2000$. And you Assume gas prices will remane stable
for 10-20 years, thats a big joke to Assume. He can cut his utilities
50% with the right improvements and proper research and planning, but he
has to do it, few salesmen sells whats best.
I just got a $7K price for a System 2000 EK2, installed. Their web site
says the AFUE efficiency is 87.4%. Around here, a Buderus G215/4 in a box
costs $1610.34, with an 86.2% efficiency. Add a modest amount ($2K?) for
an indirect-fired water heater and installation labor and a $1K/year oil
bill, and the System 2000 might save 0.012x1000 = $12/year, for a simple
payback of (7K-2610)/12 = 366 years :-)
I don't discuss prices on here because different areas have different
charges. Plus all jobs are different depending on the location of the unit
and what all is involved changing them out.
I will say that if it was a standard job (no big headaches involved), we
could install a Weil McLain cast iron boiler that gets 85% for about half
that price. Haven't priced a EK2000 in a while, but as I said before, we
don't install them
Don't get me wrong! I LIKE them. Easy as hell to work on and they are nice
and quiet too.....
you get a loan and do both. insulate now for year round comfort, or
else you lose money every day of heating season.
get a boiler now too. modern boilers will save money and you can later
adjust the new boiler's water temperatures to match your radiatior heat
demands even after you insulate. if it's winter where you live now like
buffalo ny there's a waiting list for insulation installed.
It's not the boiler that's using the oil- it's the burner, in whatever
state of adjustment (spray-tip-size, etc.) and tune it's in.
The boiler likely would benefit from changes in heat-exchanger design
that have occurred in ~40 years, and cleaning on firesides and
water-sides. Not to mention automatic stack damper, reduced aquastat
setting, and installation of separate domestic water-heater.
You don't mention the burner, and what it's up to. I'd get expert
Yes, yes, yes, seal and insulate everything. Especially at lowest and
highest elevations of house. Chimney effect.
Install programmable t-stat, and go for max setback & lowest settings
Automatic stack damper can yield huge reduction of energy waste,
especially if you're in, say, Minnesota. Or are you in Montgomery?
Existing burner and furnace, if in decent health now, can survive much
longer once you take serious conservation measures, and reduce the
run-time. Then you can plan/budget replacement at a better time-
You have some chicken-egg issues here. Unless you know the numbers, it is
not possible to make a good decision.
What is the efficiency of the existing boiler? If it is 83% to 87%, a new
one will not save much. If it is 60% or 70%, change it and save 15%+ or so.
That said, the boiler puts out a given amount of heat to satisfy the room
condition and the set point of the thermostat. Assuming you plan to make
changes to save 30% of your heat loss, and put in a boiler with 30% less
capacity, you will freeze your ass off this winter and every winter until
the improvements are made.
Let's make a couple of assumptions. In a day that is 20 degrees outside,
your boiler burner runs 8 hours and burns 1 gallon an hour or 8 gallons per
day at 85% efficiency. You know in the future you will need less capacity
so you put in a smaller unit that burns .6 gallons per hour. In order to
produce the amount of heat you need today, that burner must run about 13.3
hours to make the same amount of heat and it will burn the same 8 gallons
per day. You need to burn a given amount of oil to keep the heat the same.
You mention insulating the floor joists. Why? Is the boiler in the
basement? If so, any heat it generates will go up and help heat hte
upstairs. I'm not so sure there will be much savings. Storm window? Yes,
very important. At least put up the plastic this years.
When was the boiler service last? Was it in good condition? If so, let it
run for the year (or two or three) and put that money into things what will
prevent heat loss. This is why it is important to know the efficiency. It
may be right on the service report. Mine are hanging right on the boiler and
I can see the ones from the past five years. Better to have the old boiler
running less because you are saving heat from escaping than have a smaller
boiler cranking away trying to keep you comfy.
Oversizing a boiler is not a very big deal (unlike AC) . It will cycle more
often and run shorter times. Overall, it will not burn much oil different
than a smaller one. Worry about that after sealing up the house. That will
save you money to eventually buy the new boiler.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.