Boiler sizing question.

[JohnDS]

I am getting Natural Gas and I need to size my boiler. I know a lot of different variables come into the equation for this type of question with heat loss, but I am not doing that and am hoping someone can help so i can get this done already since winter is coming.

There is no heating system as it was stolen prior to purchase, but i just finished installing the baseboard.

Single story ranch built in 2000
Located in Long Island
Full unfinished basement where heating equipment will be located.
1240 sqft current heated space
2 baths
51ft of hydronic baseboard
Indirect hot water heater

This will be one zone(well, technically two zones, one for hot water heater). I may possibly consider finishing the basement in the future with another zone but not anytime soon.

I am going with an Alpine Forced Hot Water HE Stainless Steel Condensing Boiler. My choices are:

80,000 input
105,000 input
150,000 input
210,000 input

Please help?

 

[IFIXH20]

You might want to have a HVAC contractor come out to do a heat load calculation. They should give you a bid for free. Then you will have the correct size for your area. Get three bids.

 

[JohnDS]

Ok, im in long island and i did a heatloss calculation and came up with about 46000 btu heatloss(including basement) with inside temp at 70 degrees farenheit and outside temp at 25 degrees Fahrenheit. I also did the calculations with an outside temp of 15 degrees Fahrenheit and got 56,000 btu heatloss(including basement as well).

Obviously i am not sure which outside temperature to go with which is why i gave both senarios.

1) How do i figure out which outside temp to go with in long island? And which insude temp?

2) Assuming the numbers I came up with are correct, would an 80,000 btu input condensing boiler with 96% efficiency be suitable for my home given these numbers?

 

[IFIXH20]

JohnDS, Heat load calculation needs to be done with a Manual-J. There are lots of variable that goes into a load calculations like how many windows, how many windows faces south,the R rating of your insulation, what type of roofing, your area design winter temp, square ft and so on. If you go too small the system works itself to death and will not keep up, If you go too big the system over fires and shortens the life of the system- Both ways are not efficient. You should have some PRO's from your area come out and give you some bids-- IT'S FREE...
We love helping peoples around here but I think this one needs someone to come to your home.

 

[Ron]

I just replaced my 100,000 BTU furnace to 70000 BTU as suggested by the dealer since
he told me my ductwork was too small.
Since my old and new furnace are 80% efficient I will be losing 24,000 BTU. The dealer
told me this should suffice for my house but when the flame and the blower run the
heat coming out of my registers is not hot. It took 50 minutes to raise the temperature
in our house 3 degrees. How can I find out the 24,000 BTU loss in farenheit degrees?

 

[IFIXH20]

BTUs are calculated by how many BTUs it takes to raise 1lb of water 1 degree.
It takes roughly 8.3 BTUs to raise 1lb of water 1 degree. By your numbers it looks like someone oversized the unit or someone undersized the unit. Dropping from 100,000 to 70,000 is a big drop even if you where going to a 90 plus percent efficiency unit. Did someone do a proper heat load calculation ?