Boiler size?

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Old 05-02-14, 11:00 PM
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Boiler size?

Does a 75,000 btu boiler for a Massachusetts based 2 story 880 sq ft. condo sound right to you? This home was built in 1960 with very little insulation. The windows were upgraded when we moved in. I had a plumber come in to take a look at a leaking boiler and he recommended that we upgrade our current 40,000 btu boiler to a 75,000 one but based on the btu calculations I've seen so far, this seems a bit excessive. Anyone have thoughts on this?
 
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Old 05-02-14, 11:17 PM
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Welcome to the forums.

I'm not a heating pro, they'll be by later, but how did the 40K perform heating the building ?
 
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Old 05-03-14, 05:35 AM
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If the 40k boiler heated the house, why on earth would you double the size?
 
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Old 05-03-14, 08:10 AM
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Oh no... that's just ridiculous.

Chances are that the 40K boiler was already too large!

I've got appx a 75K boiler heating a 2000 sq ft home just fine.

As a 'sanity check' for you, why not download the Slant-Fin Heat Loss program and do the estimate yourself? Might take you a couple hours to input the data.

http://www.doityourself.com/forum/bo...lculators.html
 
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Old 05-03-14, 12:49 PM
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John, just to give you an idea, I live in central MA. I installed a new boiler (modcon) three years ago. The house is about 1200 square feet and it came out to about 34k on the heat loss calculators.
 
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Old 05-03-14, 02:59 PM
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You're payback will be in improving the insulation and minimizing heat loss!

The only consideration for the minimum boiler size would be for recovery time for the domestic hot water!!! If the boiler is heating your domestic HW, then it might affect sizing. Considering the very small square footage of your dwelling, I'd size the boiler to the heat loss. Then I'd look at alternative means to meet your DHW requirements.
 
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Old 05-03-14, 03:46 PM
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The only consideration for the minimum boiler size would be for recovery time for the domestic hot water!!! If the boiler is heating your domestic HW, then it might affect sizing.
To note the superstor contender 35 only need 53K btu recommended...


http://www.htproducts.com/literature/lp-65.pdf
 
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Old 05-03-14, 06:32 PM
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Welcome to the forums.

I'm not a heating pro, they'll be by later, but how did the 40K perform heating the building?
The 40k performed fine over the years which was why I was questioning this upgrade recommendation. I've also been told that the 40k boiler might have been "overworked" because it was not enough for this two story 880sq ft condo. I'm not sure how much truth there is to this claim.

Thanks for the responses everyone.
 
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Old 05-03-14, 06:37 PM
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I've also been told that the 40k boiler might have been "overworked" because it was not enough for this two story 880sq ft condo. I'm not sure how much truth there is to this claim.

LOL... Let me ask you.. did your boiler heat your home fine with this cold cold winter? If the answer is yes then enough said...
 
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Old 05-03-14, 06:49 PM
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I've also been told that the 40k boiler might have been "overworked"
What a line of bull doo-doo.

You've been told by several un-biased pros that the 75K boiler is too big.

Your guy probably has a line on a 75K boiler that he can get real cheap and mark up the he77 out of it and make a tidy profit for himself... and he doesn't have to pay your heating bills.

Don't go for it. In fact, find another guy, he doesn't know what he's talking about.
 
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Old 05-04-14, 05:05 PM
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Is the 880 sq ft per floor or a total for both floors. If it is a total for both floors your heat loss is probably closer to 25k. Look at the us boiler series 2 which goes small enough and heat water another way.
 
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Old 05-05-14, 05:35 PM
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Is the 880 sq ft per floor or a total for both floors. If it is a total for both floors your heat loss is probably closer to 25k. Look at the us boiler series 2 which goes small enough and heat water another way.
It is a total. I did the measurements and I'm currently running the Slant fin heat loss program in NJ Trooper's link and I'm getting nowhere near 75k.
 

Last edited by John.Y; 05-05-14 at 06:05 PM.
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Old 05-05-14, 06:11 PM
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You should get near 25k btu... If that condo is surrounding by other condos then you may get less. Meaning there is a condo attached to yours...

The issue is finding a small boiler..

US boiler Burnham series 2 and the slant fin sentry are good choices.

Let us know what you get as a heat loss...
 
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Old 05-05-14, 06:30 PM
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Yes it is attached to other condos on two sides. I'm seeing around 17k btu in the slant fin heat program. Thanks for the help and advice everyone.
 

Last edited by John.Y; 05-05-14 at 07:25 PM.
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Old 05-05-14, 07:30 PM
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Yes that is probably accurate @ 17k.

The smallest boiler I know ( atmosperic vent) is the s34 sentry slant fin. DOE or 29 K. Has thermal type controls that work off the t stat...

Sentry

You staying atmospheric?

Possibly a mod con boiler but you will pay the price...But will run lower BTU..

I like the peerless purefire pf 50.. Mods down to 16K btu...

Peerless® PUREFIRE®


Just a thought and just my opinion...
 
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