Need advice installing a propane barn furnace

[ning]

How do modern propane furnaces function?

The flame goes into a heat exchanger; you can imagine there's a metal box that gets really hot because of the fire inside, and air is blown around the outside of that metal box and gets hot.

You get the hot air, but the exhaust that comes out of the hot box goes through an exhaust pipe to the outdoors, either through the roof or the side wall.

The more efficient the unit is, the more heat is transferred essentially through a series of hot boxes to the air that's passing by, so the resultant flue gasses are relatively cool.

Exhausting the flue gasses allows you to warm the inside of the place without filling it with CO & CO2; you'll still need a source of air but likely there's enough gaps in such a big building to allow entry of enough air for combustion.

 

[sixdogs]

I did find an installation for the model I have but my specific model variation appears to be superceded. Mine shows a vertical exhaust while the newer versions show a horizontal exhust.

 

[sixdogs]

The flame goes into a heat exchanger; you can imagine there's a metal box that gets really hot because of the fire inside, and air is blown around the outside of that metal box and gets hot.

You get the hot air, but the exhaust that comes out of the hot box goes out the pipe.
The more efficient the unit is, the more heat is transfered essentially through a series of hot boxes to the air that's passing by, so the resultant flue gasses are relatively cool.

Exhausting the flue gasses allows you to warm the inside of the place without filling it with CO & CO2; you'll still need a source of air but likely there's enough gaps in such a big building to allow entry of enough air for combustion.

Is that what sealed combustion is? The version I have is not sealed?

 

[kenmac]

I have hung them with all thread, unistrut. metal straps, etc,
it's going to be a challenge to heat that non insulated pole barn to 55 deg. in the winter.. Attempting to do so is going to eat a lot of propane.

Before I ever installed this heater, I would carefully inspect the HE for rusted out or cracked
Those round tubed HE's were very prone to crack, split at the tubing seems, and rust out on the bottom where condensate collects.

As far as height, you can install it as high as you like, code should be 18'' off the floor where flammables will be stored. But I'm sure you would want to hang it much higher to be out of your way. About 3-5 ft off the ceiling depending on ceiling height ... just remember, heat rises.

 

[MapleLeafFarmer]

you have an older version but these are some spec's for their newest that can give you some guideline re flue size etc..

 

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Is that what sealed combustion is? The version I have is not sealed?

Sealed combustion means that the air for the combustion is pulled directly from outside rather than from the room where the furnace is.
You'd want a sealed combustion unit if there was danger of fuel vapors or if the building was really well sealed.

 

[sixdogs]

I have hung them with all thread, unistrut. metal straps, etc,
it's going to be a challenge to heat that non insulated pole barn to 55 deg. in the winter.. Attempting to do so is going to eat a lot of propane.

Before I ever installed this heater, I would carefully inspect the HE for rusted out or cracked
Those round tubed HE's were very prone to crack, split at the tubing seems, and rust out on the bottom where condensate collects.

As far as height, you can install it as high as you like, code should be 18'' off the floor where flammables will be stored. But I'm sure you would want to hang it much higher to be out of your way. About 3-5 ft off the ceiling depending on ceiling height ... just remember, heat rises.

Barn is fully insulated.

 

[sixdogs]

So if I got a different or newer furnace with sealed combustion chamber I'm OK with my 125 gal of diesel fuel 50 ft away?

There is no way I'm cutting a hole in the roof for a vent. Sidewall is OK but not roof. That's just asking for trouble.

 

[kenmac]

Barn is fully insulated.

I was just going by the pic you posted. I didn't see the walls insulated is the reason for that comment

 

[kenmac]

So if I got a different or newer furnace with sealed combustion chamber I'm OK with my 125 gal of diesel fuel 50 ft away?

There is no way I'm cutting a hole in the roof for a vent. Sidewall is OK but not roof. That's just asking for trouble.

that heater will never ignite that diesel hanging from the ceiling. Most fuel vapors like gasoline being more flammable that diesel, are much heavier than air and gather closer to the floor. It would take a lot of gasoline vapors to be ignited by that unit heater up in the air