correc size boiler

sidney r. bray

Ryan-
Get me an email address or fax and I'll send you the specs.
Thanks.

sidney r. bray

Sizing a new hot water boiler

I don't know if anyone can provide me with the right sized btu boiler for my home on this web site, but having had 5 different contractors come to my house, only one asked for the sq.ft. of my home, window/door sizes, insulation, lineal feet of piping,etc. and he even thought like the others that my boiler HE 5 WM 133k input was too small. Essentially, they looked at the existing 133K btu's and said because of the size of piping (lots of 2" & 11/2" galv steel) and radiation (lots of the older column styled standing radiators) that I would need to go up one size to be safe. My house is a single level 1434 sq.ft. with 78% basement area, well insulated walls/ceiling + all newer Low E double paned windows and steel insulated entry doors. I've ordered the Slant Fin free cd rom but haven't received it yet, not sure if it will size a boiler on cast iron radiation or not. Is there someone else out there that should I fax them the specifics, they would perform the sizing of a new boiler for a nominal charge?? My boiler has a hairline crack which we tried to seal with a product called "Sealmaster" which did not hold up. Since this is my only source of heat, I need to move rather quickly but don't want to get caught purchasing an over or under-sized boiler based on someone's hunch and the size of system I have now. I've talked to two different contractors out of the area and because of distance wouldn't bid on the job and be competitve but think that I may in fact be over-sized the way I sit now. I live in Upper Michigan where we've had a mild winter thus far, but who knows about the next six weeks or so. I'm losing about a drop of water a second when boiler is not cycling, and less than that when it is running...any suggestions would be appreciated.

jp_2

house ever cold?

well has the house ever been cold?, wouldn't warm up? one way to know if the boiler is too small. I realize we haven't been below zero in a couple of years north of you, U.P.

Boilerpro_3

Proper sizing

A hot water boiler is sized on the heat loss of the home, NOT the radiation. With a smaller boiler, the radiation simply does not run as hot, but still transfers the btu's to the space. I would suspect that your current boiler is probably a couple sizes too big. With an output of about 105,000 and a square footage of 1434, that's 100 btu's per square foot. That's nearly 6 times what it takes to heat my home in Northern ILLinois! (built 1906 well insulated frame with lots of of weatherstripped windows and doors) I am sure its colder up there, but not that much colder!

The Slant Fin calculator will size the boiler based on heat loss, as it should, for hot water boilers.

I'd check the Find a Pro section at this site, I know there are good professionals in Michigan, just how close, I don't know.

Boilerpro

sidney r. bray

Boiler size

No, the boiler has always kept the heat required in the home, just that it burned cool until I installed a by-pass line a couple of years ago to get the temp up from about 120 deg on a colder day (near zero or below) to about 135 deg. That cooler running boiler is what may have caused the hairline crack...the by-pass should have been put in 15 years earlier.

sidney r. bray

Boilerpro-
I just clicked on that "Find a Pro" site, no professional available within a 100 mile radius. We live in the south-central area of Upper Michigan, close to Iron Mountain (home of Steve Mariucci and Tom Izzo) so it looks like I'd have to fax to someone the spec's out of the area or soley rely on the Slant Fin cd to do the job correctly.

Boilerpro_3

The CD should work well

Just give it good data to work with. You'll be shocked at how small a boiler you need! Just remember to leave some heat for the basement.

Boilerpro

Boilerpro_3

The CD should work well

Just give it good data to work with. You'll be shocked at how small a boiler you need! Just remember to leave some heat for the basement.

Boilerpro

Mark_46

Sizing

Sid,

I just went through this in another thread. It's all about heat loss. I too used the Slant/Finn software, easy to use. just make sure you have the outside design temp available for your area in order to input into the software.

My home is not insulated with original windows and triple track storms, etc. My heated sq ft is apprx 1,570 (1,800 living sq ft) My calculated heat loss is 51,600 BTUH. As I undetrstand from several of the helpful people on this board, your heat loss is essentially the boiler size needed. Of course you have to pick from stock sized boilers so I guess theyre never exactly what you need but you take the closest available. Unless of course you need more capacity for eg domestic hot water, heat in the basement, etc.

Brad White_9

Just like in Med School, Mark!

When I was trained as an EMT, (years ago) our medical director gave us this dictum regarding procedures but it applies to design techniques and life in general I suppose:

"Learn one, do one, teach one (and sometimes they added, "Screw one")

Part of passing on to the next. What I love about The Wall!

ryan

heat loss

I live in the southern lower, too far to come up there though. but I could do a heat loss for you, With my WrightJ program just takes me a few minutes.

Greg_34

heat for the basement

Just Curious, What exactly is meant by "leave some heat for the basement"? Cheers, Greg

Mark_46

LOL

Brad,

Exactly. Sometimes I feel I only take info from this wall as I dont work with HVAC for a living. So if I can, and since I could, I gave back!

Boilerpro_3

If

you figure your load for the upper living space level, remember there is loss for the basement too. I don't remember if the program does loss calcs for basements, but I bet it does. Also, some of this is covered by the 15% "piping and pick up factor" (piping heat lost to the basement) which I always ignore for low temp systems like yours. I would opt for a condensing boiler in your case, it is probably a great match for your type of system.

Boilerpro

Brad White_9

I agree, Boilerpro

Every surface that has a delta-T across it must be considered. Too often the basement or losses to it are ignored. An uninsulated floor over a basement 10, 15 or 20 degrees cooler can be a big number.

And a condensing boiler? Absolutely.

Not to pile on a "me too" but to reinforce the universal points.

Brad

Jason_15

Condensing bad idea?

In your area I would be very careful about using a condensing boiler. I know, they are a great idea. It seems that they are somewhat less than reliable, and you DO NOT want to be left without heat in the U.P. for several days trying to get someone that knows where to get parts and how to work on one of those. I am in Wisconsin, and Mod-con boilers are still like alien technology here. I wouldn't put one in my house.

air/flo

boiler sizing

Condensing boilers are the future, especially with the cost of fuel.thought you measure basebord or radiators to get output?..