Natural gas to Propane change over help

About 20 years ago I was given 2 Reznor heaters for natural gas. They were purchased for in a fire house and when they remodeled they went with a gas furnace. I used one of them for in my 20x24 open 14' peak ceiling shed/garage with great results. The other one has sat in a corner since then. They were only used about 2 years at the firehouse which would be very few hours on them. The one i'm using here at home has been in use for at least 15 years with no issues.
My second garage (which is my dads) is 28x36 with 16' ceilings. I dont work in there that often and I'm currently using a 125,000 BTU kerosene torpedo heater when I'm there to heat with. But it's so noisy and my dad hates the smell and noise. So i thought I could use the 2nd Reznor and convert it to propane. Was wondering if anyone could tell me if the BTU's are good enough to heat that area and also where I could get the conversion done. I dont want to do it myself as I know nothing about it and wouldn't want to risk a fire or explosion.
The model on the Reznor is XL105-5, the sticker on the side says:
normal input 105,000 btu's
Thermal output capacity 81,900 btu's
Serial number is AMJ31G8N64843

I've read that some of the older heaters can not be converted which means I would need to update to a modern heater. If so what recommendations for brand do you have?

Thanks Rod

Save me some time here? I actually went to the Reznor site and they say manuals are only available to dealers, so I cannot download one

Is this a conventional flame burner with multiple burner cells? Spark? Hot surface? what? for ignition? Combustion air intake from where? In the heated space or "sealed?'

The website says "limited parts" available. This means you may NOT be able to buy regulator parts and orifices. "IF I" had this thing I'd probably (when I did this work) be able to come up with a used/ new regulator spring for the gas valve. And if I could not get orifices I might be tempted to drill them. THIS IS NOT ACCURATE. Just like carb jets, drilling gas orifices makes for turbulent gas flow, and the drill size may or may not flow "as you would think."

So far as sizing, you will have to use your head. The torpedo is rated 125K? This puts ALL the heat into the room. Is it "over" rated? Meaning does it easily overheat the room, or is it "just enough?"

Please check the label and make CERTAIN the 85K rating says OUTPUT and not INPUT. If so, you are basically comparing 125K to 85K. If there was some "headroom" with the torpedo, then you should be OK

It gets pretty cold here. My neighbor has a shop somewhere around the same size. We put in an old 70% 125K input, and it does fine.

There are online but requirement calculators. The better the r value of building the easier it is to heat. Open rafters vs drop ceiling?
As for the conversion....i bought a "Big Maxx" propane furnace. I bought the NG conversion kit at the time, right off shelf for an extra $30.
You HAVE TO VENT, when you heat with gas/flammable liquid.

^^One key to the OP is whether he can still get those parts^^

"A story from the old days."

When I worked for a local Lennox dealer, we put equipment in two houses which were "going to have" nat. gas. So they put in LPG temporarily, and we ordered the equipment for LP and and also went out to see about the appliances the OWNER had bought, which were Sears gas range and dryer.

I had one HELL of a time with Sears over the years. I HATED dealing with those a-holes
1....When you call their 800 parts line, you never knew if you were going to have a 1 minute wait or a 1 hour wait. "I'm betting on" a 1 hour wait

2....One time, some woman answered, and told me "I can't help you my computer is down YOU WILL HAVE TO CALL BACK" WTF did you answer your phone then!!!!????

3....In the case above, they wanted my gas license number (then issued locally by then Washington Water Power, later Avista) AND THEY TOLD ME IT was not a legit number!!!!

All in all a gigantic waste of time.

ODDITIES: (At least back then)

When you buy a (then) typical water heater, you order it for nat. gas or LP BUT IT CAN NOT BE CONVERTED

When you buy a gas range IT COMES WITH ALL THE PARTS to convert, typically the burner orifices are screwed into a little "storage" bracket along with the regulator spring. Sometimes, you simply turn the regulator cover plug/ screw/ adjuster "over" and this is longer on one end or t'other causing more/ less spring pressure

Furnaces generally you order a conversion kit, but after a couple of years "no bets" on whether you could still actually obtain one!!!

I converted a old Reznor 90,000 BTU a long time ago for my garage. It was natural gas and all I did was remove the control valve and install a propane regulator. The jets are smaller for propane and I couldn't get the jets any more so I soldered them shut and drilled them smaller. My first attempt the jets were to small and the flame was really short so I drilled them larger till the flame was about 1" to 1.5" tall and it worked great.

If you already have NG, I would do as much labor yourself and get a gas tech to make it legit. I bought mine probably 7-8 years ago and only used it 1 winter. Cost me a bundle and shuffling 150 lb'ers of propane around gets old.

It did burn up the propane for sure, but if that's all you got it's better than freezing your a** off

Every governing body will require an engineered kit from the original manufacturer to keep its certification and safety rating. Getting these parts may be difficult if not licensed.

I tell all of our customers when it comes to DIY and there is a problem the insurance companies would love to find anything not certified or not to code so they don't have to pay anything.

brian6pac said:

I converted a old Reznor 90,000 BTU a long time ago for my garage. It was natural gas and all I did was remove the control valve and install a propane regulator. The jets are smaller for propane and I couldn't get the jets any more so I soldered them shut and drilled them smaller. My first attempt the jets were to small and the flame was really short so I drilled them larger till the flame was about 1" to 1.5" tall and it worked great.

Click to expand...

LOL!! Been there done that. The difficulty going TO LP is that you have no way of rating the burner except by eyesight of the flame size, and in a ducted system, if you had taked temp rise readings, you could double check them. With nat. gas you can "clock the meter" to make certain you have the proper gas usage.

Manometer readings at the manifold are useless without knowing that you have the proper orifice sizes.

It sure sounds like I should just have someone qualified to take a look and if they cant get parts just buy a new sized correctly unit. Appreciate everyones input. I was worried it wouldnt work and now I will probably just put it back into storage for when I need a new one in my home garage.
Thanks Rod

Where is your sense of adventure, it's not fun if it's not dangerous, LOL