replacing old boiler

dale_10

i need to replace my 20 year old boiler as it is to small and i would like to get something more effecient. i have 2 zones finned base board which i am going to make into 3 zones. would one of the small boilers such as Munchkin or Ultra or Knight work ok with the base board or should i go with a 85% the old boiler is only 40K but calculations show a total of about 125 to 130K is needed.
thanks

BigJoe

I would double check things.
You need 125k but have 40k now? Must not have any impact if temps drop below 50. OR your calcs are off or old boiler is bigger than that (my guess).

dale_10

i double checked and the tag is marked 35,000 output. we do have a lot of south facing windows which help.i have used several calc programs and they come up with about 60k for the main floor and 60k for the basement which is a walkout with south facing windows.

Steamhead (in transit)

When you did your calcs

what indoor temperature and outdoor design temperature did you use? Most programs I've seen default to 70 inside and 0 outside. Depending on where you live, the outdoor design temp to use might be higher.

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dale_10

i am in southern Mi about 70 miles SW of Detroit and i used +5 for the outside temp as this is what they seem to show for Detroit and 70 for the inside.

dale_10

i was looking at the wrong papers when i came up with the 125k what i need is about 60k sorry for the confusion. i think the biggest problem is the amount of base board. at present i have about 39 feet and the program i am using shows that i need about 66 feet. so now i have to see if their is any way to add more length to the exsisting units.
dale

Dave DeFord_3

70 mi SW of Detroit...

That puts you in Jackson, Lenawee or Hillsdale County. I'm not at all sure that +5 is a good design temp for you. I distinctly recall a -22 day there (Ann Arbor) about 15 years ago. If you use +5 for a design temp I'm afraid you will be pretty chilly when we get one of those days that never gets above 0. You should check this out with other folks here but I live about 20 miles away in Jackson and I think I would use -15 or -20 as my design temp. Your call.