Furnace size

n0c7 · 03-12-2013, 01:12 PM

What size natural gas garage furnace would I need to heat a 20x22 insulated garage with 2x4 walls, closed off insulated ceiling, 9ft walls to 22C(72F)? on a really cold day say -40?

yuri · 03-12-2013, 03:55 PM

depends on what U plan 2 B doing in there (wood working/dust, paint or fumes from solvents)and how often U plan 2 open the garage door. A 240 volt 4800 watt construction heater from HDepot would do just fine. The smallest gas furnace is 45,000 BTU which is way oversized and there are unit heaters that hang from the ceiling but they are fairly large capacity also. If you need a faster recovery rate then a gas unit heater would B better and U should talk to some of your local HVAC contractors about them. Lennox makes a couple nice well built garage unit heaters. If you are going to any work in there which can be combustible then the T class Lennox unit is airtight and safer for those environments. If you just need basic heat then a construction htr is the cheapest bet. Unless gas is dirt cheap in Alberta vs electricity. Was not when I wuz in Calgary but we got cheap elec/Hydro in Mb. vs your coal/oil/gas fired plants.

http://www.lennox.com/products/garage-heaters/

**beenthere** · 03-12-2013, 05:31 PM

Modine Hot Dawg heaters start out at 30,000 BTUs, and go all the way up to 125,000 BTUs. Can use outside air for combustion also.

av-geek · 03-12-2013, 09:59 PM

You may want something like this instead for a garage:

http://www.superiorradiant.com/Produ...edHeaters.aspx

Something that heats with radiant heat versus heating the air. The radiant heater will give you more direct heat and you won't have as much issue with loosing the heat when the door goes up.

n0c7 · 03-12-2013, 10:11 PM

Quote:

Originally Posted by av-geek

You may want something like this instead for a garage:

http://www.superiorradiant.com/Produ...edHeaters.aspx

Something that heats with radiant heat versus heating the air. The radiant heater will give you more direct heat and you won't have as much issue with loosing the heat when the door goes up.

I've worked in shops with those. They are very good for tanning your scalp. I find them very uncomfortable to work in even in shops with 20ft ceilings.

n0c7 · 03-12-2013, 10:13 PM

Quote:

Originally Posted by yuri

depends on what U plan 2 B doing in there (wod working/dust, paint or fumes from sovents)and how often U plan 2 open the garage door. A 240 volt 4800 watt construction heater from HDepot would do just fine. The smallest gas furnace is 45,000 BTU which is way oversized and there are unit heaters that hang from the ceiling but they are fairly large capacity also. If you need a faster recovery rate then a gas unit heater would B better and U should talk to some of your local HVAC contractors about them. Lennox makes a couple nice well built garage unit heaters. If you are going to any work in there which can be combustible then the T class Lennox unit is airtight and safer for those environments. If you just need basic heat then a construction htr is the cheapest bet. Unless gas is dirt cheap in Alberta vs electricity. Was not when I wuz in Calgary but we got cheap elec/Hydro in Mb. vs your coal/oil/gas fired plants.

http://www.lennox.com/products/garage-heaters/

Natural gas is affordable here, thats why I ran the line to the pad. I ran a 1500W space heater in a basement suite and it was costing $100 a month in power before. My gas bill for my house is about that

n0c7 · 03-12-2013, 10:14 PM

Quote:

Originally Posted by beenthere

Modine Hot Dawg heaters start out at 30,000 BTUs, and go all the way up to 125,000 BTUs. Can use outside air for combustion also.

Do the ones that pull outside air tend to cost more?

**beenthere** · 03-12-2013, 10:45 PM

Quote:

Originally Posted by n0c7

Do the ones that pull outside air tend to cost more?

Yes they do. Stainless steel heat exchanger is a bit more money. Plus the separation they do for the combustion air adds some money to it.

Haven't sold one for a while, but its not much more for what your getting.