Cost of Mod Con Boiler?


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Old 08-19-08, 08:15 PM
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Cost of Mod Con Boiler?

I am converting to propane. A local supplier sells munckin and weil-mclain (approx 150k BTU/hr input) boilers in the range of $3500-4000. Is this the going rate? I am trying to justify the premium price of these units relative to a conventional boiler. I estimate my payback will take at least 5years - however not sure of the best way to estimate. Any advice would be appreciated
 
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Old 08-19-08, 09:17 PM
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Make a spreadsheet with all your heating options listed down the side, and your one-time and repeating yearly fuel and maintenance costs going across for each one. Don't forget things like the cost of removing the old oil tank and getting the chimney lined, if they apply.

You may find that a cheaper boiler will pay back sooner. The biggest trick will be predicting fuel costs and consumption. I assumed a 20% price increase each year.
 
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Old 08-19-08, 09:36 PM
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Do a heat loss analysis !

HUGE House ? 150K is a darn big boiler ...

I bet you can get one half that size and save a ton of money, both on the boiler and on the fuel that you won't be wasting.

Go to www.slantfin.com and download the FREE heat loss software. It's easy to use, but does tend to overestimate the heat loss a bit (maybe 20% or so...) Only then should you think about what size boiler you need. NEVER size a new boiler from the old one, fuel was cheap, they didn't care...

If you've got an average size home, I bet you come in well under 100K heat loss.
 
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Old 08-20-08, 07:50 AM
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Trooper you got that right. I talked to a guy the other day he got 3 prices. They ranged from 120k to 180k. He had a heat loss done and the loss was 48k. Well worth the time for the heat loss.
If you don't feel comfortable doing the heat loss yourself there are some sights where they will do it for you for a fee.
 
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Old 08-20-08, 03:19 PM
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The boiler in this joint is 140K. Slant-fin tells me 72K, but actual heat loss based on measured oil use, and degree days tells me it's more like 55K ... so the boiler installed here in 1984 is almost 3X too large.

I bet that 11 out of 10 boilers installed more than say 5 years ago are 2X too large.

I think there's some good reading over at www.comfort-calc.com about this...
 
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Old 08-20-08, 03:24 PM
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I think you are close except for one thing. Instead of the last 5 years it is 11 out of 10 installed today. In all honesty I feel about 80-85% of all boilers installed today are 100% - 150% oversized.
It is an everyday conversation
 
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Old 08-20-08, 05:42 PM
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Why is this boiler oversizing so prevalent? Is it the cya factor to keep customer warm and happy or the sheer lazyness of the installer to do a proper heat loss calc? Maybe the installers just don't know better.
Is it common these days for installers to be trained properly or not?
 
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Old 08-20-08, 07:51 PM
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Mostly cya. A boiler that is too small will be immediately apparent whereas a boiler that is too big will simply be inefficient. Very seldom will someone notice that the boiler fires for two minutes and is then off for one minute as long as the house is warm.
 
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Old 08-20-08, 08:34 PM
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Load Calc

I used the slant-fin program on the first floor before the program crashed. It showed that I needed 75K Btu/hr jsut for the first floor. I extrapolated, to arrive at 125k BTU/hr. Then figured I would need I larger boiler capacity based on efficiency. Another rule that I have used is multiply 30 times the home square footage to estiamte capacity. In this case my home his 3600 ft2 and the capacity is 110 BTU/hr.
 
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Old 08-20-08, 10:55 PM
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3600 sq ft ? I'd call that a fairly large home... probably twice as much as this one ... so perhaps 110 isn't really that far off ...
 
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Old 08-21-08, 09:12 AM
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If done properly the heat loss for the second floor will be higher than the first floor as the ceiling for the first floor does not have a heat loss but the second floor ceiling will.
My last house was built in 1919, three story, no side wall insulation, 10" in ceiling and 3" in kneewall on third floor, 1850 sq ft. The heat loss was 68K. If I would do simple math 1850 + 1850 = 3700 sq ft. 68k + 68k = 136k heat loss. So if you home is old and no insulation values you could be close, otherwise not.
 
 

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