micro boiler size

[Tim123]

My first post and question! I live in central MN and finishing my new 720' detached garage (R13 walls R40 ceiling 2" pink under.) I can get a great deal on a 12kw boiler. Too big?
Am I right to think since its a modulating boiler I should be ok and it just won't run as much? I already have my off peak meter for .054kw. Thoughts?
Thanks in advance!

 

[rburke65]

Ok....ill be the first....did you do a heat loss calculation?

 

[EEErik]

Am I right to think since its a modulating boiler I should be ok and it just won't run as much?

Modulation on a boiler is only good if the turn down ratio is low enough. The boiler needs to be properly size for the space. Disregard whether its a good deal or not, the wrong boiler will always be a bad deal. Like it was said earlier, you need a load calc and then you have to determine the BTUs of the radiators you are installing.

 

[tjm129]

Agreed with the heat loss calculation. If you are doing radiant in floor heating checkout a program called loopcad to plug in your info and help with your calculation. A few months ago i installed a 7KW unit from Menards. I am also 720 soft and the same insulation and using it with my infloor system. So far it seems to be working as I designed it. When I did my heat load calc 7kw was more than enough for me. My slab and foundation is also insulated. I have been keeping the garage at 55 deg and with the few cold days we have had so far I have not had any issues.

TJ

 

[Jackfre]

Minot or Miami? It matters.

 

[Radix2]

For an electric boiler, there is no efficiency or operating problem with oversizing (if it is).

Electric resistance heating is basically 100% efficient, and the thermostat will cycle it properly to get whatever temp you want, so if it is a good deal, go for it.