Furnace Selection

[mazdarod]

I have a 40'X28' shop with 12' ceilings and am looking for a furnace / heater to heat the place. The shop is 2x4 stick framed with two 12x10' doors and is currently not insulated.

My options for furnaces are a Bryant 88,000BTU input 80% efficient or a York 115,000BTU input 80% efficient. They are both comparable in cost.

What furnace would the HVAC guys recommend? Gas source would be NG. I would leave the shop at 40-45deg while I am not out there and then turn it up while working.

 

[theoldwizard1]

Your wasting a lot of money without insulation. You will also nee a bigger furnace.

 

[mazdarod]

Your wasting a lot of money without insulation. You will also nee a bigger furnace.

I will be insulating the shop in the future but not ready for it at this time. How big of furnace would you recommend?

 

[nehog]

Without insulation the bigger the better. You may have to run it warmer when not there or the warmup time may be excessive. Maybe 50-55 degrees?

 

[mazdarod]

Bigger is better so how about (2) 115K BTU units? Hang one on one end of my shop and one on the other side. This would be 230K BTU input 184K BTU output heating capacity.

I could use them both to bring the shop up to temp while I am out there and then use one furnace to maintain temperature while working.

 

[brihvac]

Number one you do not want to use any 80% heater. You need a closed combustion chamber, so that leaves you with a 90% heater. Reason being is that an 80% uses the surrounding area for combustion air. If your using any flammable solvents it could be a bad mixture. It is better to pull combustion air from outside. If it were me...I would get a closed chamber Reznor unit heater and be done with it. You really should not use a household heater in a shop/garage

 

[mazdarod]

The furnace will be mounted either in the trusses or just hanging bellow. Gas fumes are heavier then air so intake of gas fumes should not be an issue.

 

[geologist]

My step-dad has installed furnaces in hundreds of houses over the past 3 decades. I learned a pretty valuable lesson when picking up a new furnace from the distributors. There are maybe two or three major manufacturers of furnaces. Sure, some units are slightly better, but I swear to you that others were nothing more than a switch in name plate.

Goodman is made by the very same manufacturer as Bryant. The difference was literally deciding which name plate you wanted at the distributor, because the serial number for the name plates differed slightly.

Don't overpay.

 

[jvitez]

Until it's insulated, buy a big portable heater, kerosene or propane. Once insulated, do a proper heat loss calc and buy the furnace accordingly. You're wasting a lot of time, effort, and money IMO by trying to heat an uninsulated space. Whatever furnace you'd buy and install will be way oversized and run very poorly, both in efficiency and comfort, once the garage is insulated.

I'm thinking of something like these for temporary heat:

http://www.mrheater.com/product.aspx?catid=47&id=35

http://www.mrheater.com/product.aspx?catid=45&id=26

 

[Mmfh]

I can't tell you a whole lot about what size you need for a furnace, you can probably Google that and dig it up.
I did run a 80 percent furnace in the attic of my old shop for many years. It was a York 80, over about 8 years I had to replace the board in it twice. I bought it used and sorry I can't tell you the size.

That Bryant furnace I think is of better quality though. Until I went high Efficiently at the house here I had a Bryant and it ran with no issues for over 20 years.

So, if I were choosing which furnace, I'd keep in mind brand name as well as size of unit.

Just sayin

Mm

 

[brihvac]

The furnace will be mounted either in the trusses or just hanging bellow. Gas fumes are heavier then air so intake of gas fumes should not be an issue.

I have personally seen a ceiling mount heater with flames licking out of the chamber from paint fumes. The owner jumped the roll out switch because he was tired of resetting it. Its your garage and you most likely will not have problems. But, for the couple hundred dollars more you get a more efficent, close chambered, no doubt its safe heater. I have been doing this for a long time and I have seen what "could" happen. Good luck

Goodman is made by the very same manufacturer as Bryant. The difference was literally deciding which name plate you wanted at the distributor, because the serial number for the name plates differed slightly.

Don't overpay.

Bryant, Carrier, and Payne are the same company and have absolutely nothing to do with Goodman. Goodman comes in a lot of variations such as Ammana, Janitrol, Kenmore,etc. But not Bryant.

However, Goodman makes one hell of a unit and they are cheap. I put a lot of them in. Goodman also makes closed chambered 90% heaters as do all manufacters.

 

[mazdarod]

Until it's insulated, buy a big portable heater, kerosene or propane. Once insulated, do a proper heat loss calc and buy the furnace accordingly. You're wasting a lot of time, effort, and money IMO by trying to heat an uninsulated space. Whatever furnace you'd buy and install will be way oversized and run very poorly, both in efficiency and comfort, once the garage is insulated.

I'm thinking of something like these for temporary heat:

http://www.mrheater.com/product.aspx?catid=47&id=35

http://www.mrheater.com/product.aspx?catid=45&id=26

JVITEZ, thank you for the suggestion. An option like this was what I was originally going to use to get by however for the cost of these units I have been able to find a new natural gas furnace for the same price.

I'm of the opinion that with the proper ducting you should be able to get the furnace to run at peak efficiency regardless of shop size. I have not done any math yet but the fluid mechanics and thermal dynamics make sense to me.

 

[mazdarod]

I've decided on a 80% Efficient NG York Furnace, 130K BTU input 104K BTU output. Furnace is brand new in box and I got it for $150. Now on to the mounting configuration and ducting.

 

[joey d]

WAY to big, I made that mistake years ago on a free furnace for my garage. Gas bills went from $150 to $400 because the oversized furnace cycled every few minutes. Spent more time heating up the flue than the garage. Now i have a 45000 hanging from the ceiling and the cycles are longer, it feels comfortable, and less on the gas bill. And I still think I could have gone smaller. Leave it in the box and turn around and sell that thing for 400, and spend the difference on the insulation.

 

[mazdarod]

WAY to big, I made that mistake years ago on a free furnace for my garage. Gas bills went from $150 to $400 because the oversized furnace cycled every few minutes. Spent more time heating up the flue than the garage. Now i have a 45000 hanging from the ceiling and the cycles are longer, it feels comfortable, and less on the gas bill. And I still think I could have gone smaller. Leave it in the box and turn around and sell that thing for 400, and spend the difference on the insulation.

What size is your shop and what does your duct work look like? Do you have any pictures?

 

[joey d]

my shop is 30x24 with 9' ceilings. I know its a little smaller than yours, but I hate to see a guy waste money. My old furnace sat about 18" off the ground and the duct work ran through the attic. duct work cost me about $200, and another $100 for the plenum. So between the high gas bills and the abandoned duct work if I would ve just bought the beacon morris I got now, id be hundreds ahead.

 

[D KRAGER]

WAY to big, I made that mistake years ago on a free furnace for my garage. Gas bills went from $150 to $400 because the oversized furnace cycled every few minutes. Spent more time heating up the flue than the garage. Now i have a 45000 hanging from the ceiling and the cycles are longer, it feels comfortable, and less on the gas bill. And I still think I could have gone smaller. Leave it in the box and turn around and sell that thing for 400, and spend the difference on the insulation.

After it's insulated very well, it might be a bit overkill. But for now it will work just fine. I have a 100k unit in a 30x32.

If you plan on keeping it cooler, then kicking up the temp only when you are out there working, go with a larger unit, which is what the OP is wanting...

 

[mazdarod]

Joey thanks for the info, do you have any pictures of your plenum / duct work? I have been searching the site for different ideas on mounting configuration and duct layout. The furnace I got is a downflow unit and I believe can be mounted on it's side. Ideally I would mount it horizontally in the attic space that way I can run the supply and return duct work horizontally across ceiling.

If anyone has pictures or threads for similar installs please share.

 

[mazdarod]

So the model number on the York furnace I got is: PS8D20N130DN11A. Does anyone know how I can lookup a manual or technical specs on this thing? I cant seem to find anything on google or when searching on Yorks site. 130BTU, 20CFM, 80%.

 

[Motofixxer]

At full insulation, you should be using about a 70-80k Btu max. Spend the money insulating the ceiling at a minimum. Then you will retain at least some of the heat. If that is completely out of the question staple up some 6 mil plastic, you will likely need it up there anyway for any finishing. I have some pics of my shop and what I did below in my Sig.

 

[stevefasano]

removed due to