High efficiency propane furnace????s

[toyotadriver]

I have a newly constructed 30x40 shop building. Well insulated. Where I live we can get temps around 0* F but not for very long. I'm planning on the heat source for the shop building.

I was thinking of installing a 45k btu Mr. Heater vented propane heater. However, I've also been thinking about installing a 92%+ furnace and running ductwork throughout the shop. My concern is, I only plan to heat the shop to about 40-45 degrees all the time and then raise the temp to about 62 or so when I want to work out there. Depending on the amount of propane consumed, I may leave the furnace turned off from time to time. I doubt that the temp inside the shop will drop below freezing due to the ambient temps around here as well as the level of insulation and air sealing of the shop.

I read somewhere that a high efficiency furnace should not operate at temps as low as 40-45 degrees. However, I'm not sure if that's true or not.

So, can I install the high efficiency furnace as I want or should I look at the Mr. Heater instead?

I want this shop (and later the house when I build it) to be as energy efficient as possible. However, I'm willing to install the Mr. Heater if it is the better choice.

And, propane is the proper fuel for me for this location. I will not be heating the shop with electricity or natural gas.

 

[rickairmedic]

The only catch with a 90% or higher efficiency furnace is you canot let the area it is installed in go below freezing at any time after it has been installed and run the first time . These furnaces produce moisture as they run some of which can be left in the secondary heat exchanger which could freeze and break the heat exchanger . I would say as long as you intend to keep the area at a minimum of 40-45 * there wouldnt be a problem . I would set the minimum temp at 45* myself .



Rick

 

[Dragster Racer]

Rick hit the nail on the head. I switched to a hanging tube style heater (mine is a U) and have been pleased with it so far. I suspect my propane usage is down a bit compared to my older Reznor. I will say if you need to heat up the place in a hurry, the tube I have takes a couple minutes before it is really putting out heat. I heat my 40x40x15 with the 50,000 btu tube.

 

[toyotadriver]

Thanks a lot for the info. I think I'll go with the Mr. Heater to avoid any possible problems.