I need a boiler sizing calc done

John Ruhnke

Eric,

Slant Fin makes a free and real nice heat loss calc software that you can use to size your boiler.

http://www.slantfin.com/heat-loss-software.html

John Ruhnke

<A HREF="http://www.heatinghelp.com/getListed.cfm?id=96&Step=30">To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"</A>

Eric L._2

I need a boiler sizing calc done

in my house in the Bronx. A replacement is in order and I want to do it right. Anybody here have any experience with anyone who does manual j calcs? Thanks in advance.

Eric L.

tim smith

Regarding calcs

Maybe Mad dog will chime in, he is in floral park I think. He has a plumbing and heating company there. If not you could always buy a software program like Wrightsoft which has a manual J calc program if you want to be more detailed than the one that is on this site at top. It would be a learning curve for you but might be interesting and $$ are not too bad. Tim

Brad White_184

Steam or Hot Water?

If you have hot water heating, yes, go the Manual J route as suggested.

If you have steam, the system has to be sized by the connected radiation capacity regardless of heat loss, although knowing the heat loss is always fun and interesting to have.

That you are in the Bronx, you will find yourself surrounded by knowledgeable steam professionals- I could name five near you in the greater NYC area but will leave that to you. All are excellent.

Eric L._2

Has anyone had experience with the SLANTFIN

program. Is it detailed enough to do a proper sizing? If not what is it missing? Thank you for all your valuable information.

Eric

Mark_46

Hi Eric,

Yes, I am using Slant Fin's application.

For my needs (non-commercial, residential application) it was sufficient. I'm sure some of the other software applications avaiable may have additional features or more detail (like direct sunlight exposure, northern otr southern exposures, etc) but I cant speak from experience. Im sure some of the pros here could.

Slant Fin's free app is fairly detailed. You enter your rooms and their dimensions and then choose from defined constuction types eg 2x4 with insulation, sheathing, shingle siding or...masonry wall, so many inches think, etc. Similarly, double hung window with storm windows or casement, etc. These categories dont always fit exactly with your structure but if you know the values of wall/window etc you can manually enter the loss factors.

As you might expect besause the software is free it can generate a recommneded equipment list using Slant Fin products after the heat loss is complete.

The only trouble Im having with it is I cant transfer the heat loss file (or job as they call it) from one copy to another running on another PC.

Eric L._2

Has anyone had experience with the SLANTFIN

program. Is it detailed enough to do a proper sizing? If not what is it missing? Thank you for all your valuable information.

Eric

Eric L._2

Thanks for the reply

I already ran the the program for the whole house heat loss and the result I got was a 65000 btu requirement! It sounds so small but I inputed all the parameters correctly. The boiler installed now could easily be more than twice that. Does that sound like the norm? Its a converted Pierce Butler coal boiler I think. No tags so I don't know the ratings. Thanks

Eric

Mark_46

Eric,

Things that come to mind:

1. What outdoor temp did you enter in the software? The outdoor temp value (design temp) should be the value for your geographical area according to the Hydronic Institute divison of GAMA

2. Approximately how many square feet is the house? Older homes with upgraded insulation and envelopes might be in the 30 to 40 BTU loss per SF and an uninsulated older home in the 50 to 60 range.

3. Generally speaking - yes - boilers installed decades ago that were oversized is not uncommon. This was probably due to (but not limited to) poorly insulated, leaky homes and low fuel costs. With my own home, at the time it had about 55,000 BTU/hr loss with a 120,000 BTU input boiler installed!

Buzz G.

The software is easy and probably as accurate

as it needs to be because we all have more improvements to the envelope than we think. I used it for 2 story house with basement and attic and came out with a number that was very close to other methods.

Al Corelli_2

The Bronx

If Mad Dog is too busy, we handle The Bronx.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Eric L._2

If my square feet of radiation equals

about 50,000 btu but a heat calc says I need 65,000 btu why would I oversize the boiler when I couldn't possibly get more out of the radiators unless I raised the temp from 180. Let me add to that the house is plenty warm on sub 30 degree days with present radiators. Thanks again for your time.

Eric

Eric L._2

TO answer

The outdoor temp I inputted was 20 deg. The house is 1985sq ft and has about 490sq ft of radiation which I figured out from the EDR tables I found. The boiler is a converted coal boiler which must be at least 50 yrs old.

Buzz G.

Heat loss & radiation

is different for HW and steam. The pros tell us that you really can't use the rad surface with HW. What did you use for the calc with rads?

Eric L._2

I found a few different

EDR tables for column and tube radiators , even "slenderized rads. Took the measurements did the math and "WALLA".

Buzz G.

Not what

I meant by sizing-what factor was used to multiply the rad sq ft by to get total radiation. The pros say you cannot use that like you do for steam.