Need advice installing a propane barn furnace

[ponytug]

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.

The newer sealed combustion versions allow horizontal venting, usually at a downward slope to let the combustion water drain easily.

All the best,

Peter

 

[CH4Ohio]

If you decide to go with a DIRECT VENT unit that takes all its combustion air from outiside, you'll see that they are much more expensive to purchase. If you're going to go that far, you might want to just look at mounting a horizontal high-efficiency furnace (Category IV) up high on a platform or suspended from the ceiling. I believe you can buy a 90+ forced-air furnace as cheap as a Category III Direct Vent hanging heater. With the furnace you'll get better efficiency (90%+ vs ~82%) and also be able to vent it through the sidewall with much cheaper PVC.

If your building is really tight, this makes more sense. If you have quite a bit of air infiltration around garage doors, etc., a standard Category III horizontally vented heater is what most people would install.

Might be worth pricing it out. I need to go through a similar exercise prior to next winter.

 

[pmsmechanic]

If you are going to buy something different look at a radiant tube system. They heat objects rather than air and are supposedly more efficient.

By far the majority of large open area buildings are heated with radiant heaters in this area. If you goggle "radiant tube heater" you'll get an idea of what they are.

 

[sixdogs]

If you decide to go with a DIRECT VENT unit that takes all its combustion air from outiside, you'll see that they are much more expensive to purchase. If you're going to go that far, you might want to just look at mounting a horizontal high-efficiency furnace (Category IV) up high on a platform or suspended from the ceiling. I believe you can buy a 90+ forced-air furnace as cheap as a Category III Direct Vent hanging heater. With the furnace you'll get better efficiency (90%+ vs ~82%) and also be able to vent it through the sidewall with much cheaper PVC.

If your building is really tight, this makes more sense. If you have quite a bit of air infiltration around garage doors, etc., a standard Category III horizontally vented heater is what most people would install.

Might be worth pricing it out. I need to go through a similar exercise prior to next winter.

I'm older so not spending the longest dollar possible. The most widely used for the mass market is likely my best bet. I just want to have something to do in the winter, do some maintenance and maybe build something.

I just want something that heats, won't set my diesel fuel on fire and vents from the side of the building. I know I need to spend something but whatever the majority uses sound good enough for me.

Also, the building is insulated really well. They did a great job bt even do I have sliding 18 ft wide doors that will let air in. I'll seal one permanently for the winter and the other should leak enough.

 

[CH4Ohio]

If you are going to buy something different look at a radiant tube system. They heat objects rather than air and are supposedly more efficient.

By far the majority of large open area buildings are heated with radiant heaters in this area. If you goggle "radiant tube heater" you'll get an idea of what they are.

Good point. I got a quote for a couple options for low intensity radiant unit(s). This was just for the heaters and hardware to hang them and equipment ranged from $2500 - $3400. (This did not include venting (which is not cheap), gas pipe, wiring, thermostats, etc. And certainly not any labor!) This price was for a highly efficient unit with well engineered reflectors. Not bad price for the heaters really, but quite a bit more than one or two low-end hanging heaters.

I really like the idea of radiant -- heat the concrete and objects instead of trying to get hot air to stay near the floor.

Main concern for me was the clearances from combustibles and painted surfaces, etc. The radiant heat intensity is such that I was worried that a trailer or taller equipment might be damaged. There seems to be specific warnings about stacking vehicles under or near these tube heaters. (I don't stack vehicles, but it's not hard to have a roof or canopy at almost 10'. I can also see where I might have wagons of hay in one end of the building for a short time -- that would preclude this type of heat in that area.) So even with heaters hanging 12' high it seemed like I'd have some areas where it could be concerning.

If you look at radiant heaters, be sure they're using "low intensity" technology. The sales people or the brochures can explain why. (Doesn't mean the heat is low intensity -- refers to wavelengths of radiation produced.)

Good luck.

 

[CH4Ohio]

I'm older so not spending the longest dollar possible. The most widely used for the mass market is likely my best bet. I just want to have something to do in the winter, do some maintenance and maybe build something.

I just want something that heats, won't set my diesel fuel on fire and vents from the side of the building. I know I need to spend something but whatever the majority uses sound good enough for me.

Also, the building is insulated really well. They did a great job bt even do I have sliding 18 ft wide doors that will let air in. I'll seal one permanently for the winter and the other should leak enough.

Yeah -- I would think a sliding door would leak some.

Diesel or kerosene stored properly isn't a concern. It doesn't vaporize like gasoline. Code requires that a gas burner in a garage or shop be at least 18" off the floor. The thinking is that even gasoline vapors lay on the floor. So a ceiling mounted forced air propane heater is not a safety concern if installed properly.

Even "sealed" combustion units aren't "sealed" to the point that you could install them in a flammable atmosphere. I wouldn't worry about the diesel.

It's not the high tech NASA solution, but look at the unit I mentioned from Menards -- just to give you a starting point. Hang it, pipe it, vent it out the sidewall. Might even need two but it's cheaper than buying one large 175K BTU or larger unit.

 

[sixdogs]

In doing my research on this, I called a local farm company that sells and installs furnaces like this. My goal was to find out what a new one would cost and to ask some questions about the old one and venting the exhaust.

My biggest question was can the vertical exhaust be converted to horizontal. I got some maybes there but he's doing further checking, talking with an older installer and maybe calling a tech at Lennox. He said he thinks--and is pretty sure the vertical exhaust can he angled to horizontal but not positive.

Here's the pic of the back again showing the vertical vent.


We also spoke about the newer furnaces with enclosed flame and I do like that. The question now is on the vertical to horizontal exhaust and what I can learn. CH4--can this exhaust be vented horizontal in any way?

 

[2manyrocks]

I suggest looking for the installation manual. What I remember about direct vent water heaters is they used a fan and had different sealing than the heaters that were vertically vented.

 

[ning]

In doing my research on this, I called a local farm company that sells and installs furnaces like this. My goal was to find out what a new one would cost and to ask some questions about the old one and venting the exhaust.

My biggest question was can the vertical exhaust be converted to horizontal. I got some maybes there but he's doing further checking, talking with an older installer and maybe calling a tech at Lennox. He said he thinks--and is pretty sure the vertical exhaust can he angled to horizontal but not positive.

Here's the pic of the back again showing the vertical vent.
View attachment 3422004

We also spoke about the newer furnaces with enclosed flame and I do like that. The question now is on the vertical to horizontal exhaust and what I can learn. CH4--can this exhaust be vented horizontal in any way?

The manual will typically provide a graph showing how much horizontal is allowed; typically some is, but whether it is immediately or not varies.

Power Venting indicates that kits are available to convert to side venting; my bet is that they're pricey.

 

[CH4Ohio]

I'm not sure you want to hear this, but here's my opinion . . .

If some engineer at Lennox tells you how to do it, or what to modify in order to do it, you can do it. You'll need to hang onto his written approval just in case you need to assure someone or some insurance company later. Anything can be done if it's specially engineered. I'm pretty sure you won't get an engineer to put anything in writing.

Barring that . . . Note the designation of "Category I" near the top of the rating plate on your unit. That means this unit is non-condensing and uses a "negative pressure" vent. In other words, it does not produce sufficient positive pressure to vent horizontally and it depends on its HOT flue gases to create a chimney effect in a vertical vent. That's the ANSI rating plate and the ANSI standard that this furnace was designed to. Even though it has an "induced draft" fan, this simply establishes air flow through the heat exchanger and is not powerful enough to create positive pressure sufficient to vent horizontally. It is NOT a "power vent".

A Category III unit has a positive pressure vent and can be vented either way. (It could look almost exactly like yours.) However it's still "non-condensing" meaning it has "hot" flue gases and must still use special sealed high-temp vent material -- whether vented up or out. Most of the new units are using metal vent but older units were required to use expensive high-temp plastic materials. This would be the cheapest solution.

A Category IV unit has a positive pressure vent but is condensing (higher efficiency, cooler flue gases, has a secondary heat exchanger). That's why these high-efficiency furnaces have a condensate drain teed into the PVC exhaust vent. These units can be vented up or out horizontally and can use cheap PVC because heat is not an issue.

There are units, especially from the mid-80's, that are listed as BOTH a Category I and III. BUT it's right on their rating plate. They are designed such that they can be vented either way, if instructions are followed. They require the expensive high-temp sealed vent material if vented horizontally. Their design limits are right on the edge and the way that it's ultimately vented determines whether there is positive or negative pressure in the vent system.

Based solely on the rating plate, your heater is a Category I heater and must be vented vertically using natural draft.

Having said all that . . . . You asked if there was any way to vent that unit horizontally . . . You could mount a separate power vent at the outside wall and run standard metal vent to that. You'd penetrate the wall using a special termination kit that comes with the power vent. This would create a negative pressure between the heater and the power vent fan and then it would be sealed from the fan outlet through the wall termination kit. It has to be wired into the gas valve to ensure the unit won't operate unless the fan is operative. (Not difficult to wire in.) This would be an expensive option too. This used to be done a LOT -- No way would I recommend it today.