Heating BTU Info?

[L5wolvesf]

Does anyone her have a link or info on figuring out the appropriate sizing of a natural gas home furnace (without A/C)? I’m looking to establish what BTU rating the house needs and there is conflicting info out there.

The unit in our house is ancient (1979 possibly) and has been modified, probably because a replacement original gas valve was not available. I would imagine it isn’t very efficient either. Also, the house has been added on to since it was built.

We would like to upgrade on our own terms before it becomes a “have to” in the middle of winter situation.

Properly sized and more efficient would be our goal.

Thank you

 

[purediesel]

In for info! There is very conflicting info out there. I'm just trying to size a heater for a 47x49x16 area let alone a house. I got btu requirements from 40k up to 140k so I am completely lost. Pretty sure ill end up around the 80k or 125k mark. I liked the heat loss calculator from builditsolar.com. It seemed to take the most information and make a btu estimate from that.

 

[brewchief]

Ideally you need to have a manual J heat loss calculation done, better contractors will do them and there are some third party companies that will do it as well, energy audit companies would be a good place to try. There are some decent online calculators that you can buy a single use license for and do it yourself as well. The big thing to remember is that it's only as accurate as the info that you input.

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[L5wolvesf]

There is very conflicting info out there.

I liked the heat loss calculator from builditsolar.com. It seemed to take the most information and make a btu estimate from that.

Agreed a lot of conflicting info. Thanks for the link

Ideally you need to have a manual J heat loss calculation done, better contractors will do them and there are some third party companies that will do it as well, energy audit companies would be a good place to try. There are some decent online calculators that you can buy a single use license for and do it yourself as well. The big thing to remember is that it's only as accurate as the info that you input.

I've seen references to the manual J calc but not the calc itself. Since this will be a diy install contractors probably wouldn't be interested. Thank you

 

[justinjoyal]

Heat load calc. Anything else = guessing.

 

[ericm]

This calculator purports to be manual J. It's not that hard to do.

https://www.loadcalc.net/

 

[nadogail]

Your local Gas Utility may be of assistance.

 

[L5wolvesf]

This calculator purports to be manual J. It's not that hard to do.

https://www.loadcalc.net/

It mentions manual S but I'll give it a try. Thank you

Your local Gas Utility may be of assistance.

Hadn't thought of them, thanks

 

[ericm]

If you click on the Manual S button it takes you to the Manual S page. If you enter your state you start Manual J (you're already on it's page). Yes the UI design is confusing.

 

[L5wolvesf]

If you click on the Manual S button it takes you to the Manual S page. If you enter your state you start Manual J (you're already on it's page). Yes the UI design is confusing.

When I looked further I saw that. I need to get some of the specific info it asks for before I come up with a "final number".

Thank you