Baffaled with 1950's Reznor US-100 F unit heater 100,000 BTU

ncmoko333 · 12-24-2011, 05:02 AM

I have a 1950's Reznor 100,000 BTU unit heater, natural gas, i want to convert it to LP, it is a discontinued model, no kits available. while searching for conversion kit on-line thought i found the right one, cant find anywhere to de-code serial number, (BE4N1356) new kit came with size 55 orifices for LP, while i was investigating this, i see the NG orifice is size 45, new kit came with 6 orficies, waited to take heater apart untill new kit showed up, orifices totally different, wont fit so kept looking on-line to figure this out, googled what size orficies are in a 100,000 BTU heater, i found a useful website, asked how many burner orficies are in my heater, it has 4 burner orficies, website said size 55 for LP and 54 for NG, problem is my 1950's Reznor unit heater has size 99 burner orficies. im baffeled. where do i go from here. why are they so big? i cant find anything. any information would be greatly appreciated. thnks matt!!

harleyrider · 12-24-2011, 10:47 AM

Quote:

Originally Posted by ncmoko333

I have a 1950's Reznor 100,000 BTU unit heater, natural gas, i want to convert it to LP, it is a discontinued model, no kits available. while searching for conversion kit on-line thought i found the right one, cant find anywhere to de-code serial number, (BE4N1356) new kit came with size 55 orifices for LP, while i was investigating this, i see the NG orifice is size 45, new kit came with 6 orficies, waited to take heater apart untill new kit showed up, orifices totally different, wont fit so kept looking on-line to figure this out, googled what size orficies are in a 100,000 BTU heater, i found a useful website, asked how many burner orficies are in my heater, it has 4 burner orficies, website said size 55 for LP and 54 for NG, problem is my 1950's Reznor unit heater has size 99 burner orficies. im baffeled. where do i go from here. why are they so big? i cant find anything. any information would be greatly appreciated. thnks matt!!

Put it at the curb.............let the scrappers have it.

arney907 · 01-18-2013, 07:03 PM

I have a retiring Reznor LUS-100-F Natural Gas heater, serial HE903L818. The valve to the pilot light does not work, and the fan motor is slow starting when the garage is cold, but you can have free of charge any part on it provided you pay shipping. Let me know if you're interested within the next few days before the trash man finds it. Your post is a couple years old, but I hope this helps. Contact me direct at <Email address has been removed by a Moderator>.

hawkblade · 01-31-2013, 04:40 AM

I have that exact same model furnace in my garage and I cant figure where the pilot light is and how to light it.It has not been used for along time but Im sure it still works. Any help would be appreciated thanks.

danpik · 01-31-2013, 09:40 AM

Quote:

Originally Posted by hawkblade

I have that exact same model furnace in my garage and I cant figure where the pilot light is and how to light it.It has not been used for along time but Im sure it still works. Any help would be appreciated thanks.

If it has a pilot light then there will be a small diameter (1/4") tube and a thin brass tube (1/16") coming from the gas valve leading to it. Trace it out and see what you have.

techpappy · 01-31-2013, 01:07 PM

You may have to remove front cover plate OR lower bottom cover plate to locate burners and pilot assembly.

techpappy · 01-31-2013, 01:11 PM

I do not have an orifice conversion chart but, propane has about 1 1/2 more btu's/cfm than NG so, it would make sense that the required orifice size to convert from NG to LP would be a lot lower so, 99 to 55 sounds reasonable. May also require new gas pressure regulator.