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Help with uh-48 multifuel heater.
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MilSurplus
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Heater Manual
Here is a link to Hunter, which manufactures the heater. By looking at your pictures, it appears that you have an older model. That one is not listed on the Hunter web site, but it looks like a lot of the parts are the same.
http://www.huntermfgco.com/pdfs/TM_9-4520-260-13_UH48E.pdf
Hope this helps.
I just purchased an identical heater as yours on E-bay. I was shocked to see that the current draw is 13 AMPS @ 28V. I am now in the process of building a high current power supply for the heater for use in my tent.
Here is a link to Hunter, which manufactures the heater. By looking at your pictures, it appears that you have an older model. That one is not listed on the Hunter web site, but it looks like a lot of the parts are the same.http://www.huntermfgco.com/pdfs/TM_9-4520-260-13_UH48E.pdf
Hope this helps.
I just purchased an identical heater as yours on E-bay. I was shocked to see that the current draw is 13 AMPS @ 28V. I am now in the process of building a high current power supply for the heater for use in my tent.
ida34
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RE: Heater Manual
I appreciate the link but it has already been posted and I have determined that this is not a UH-48. Its internal workings are different from the UH-48.
I appreciate the link but it has already been posted and I have determined that this is not a UH-48. Its internal workings are different from the UH-48.
MilSurplus
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RE: Heater Manual
Sorry about the link. Didn't see the first posting of the manual link.
Word of warning. If your heater is dated around 1963 and you bought it on Ebay, it may leak fuel when you connect a fuel supply and run it.
I found that the donut shaped gasket in the fuel pump was dry rotted. The cap on the bottom of the fuel pump housing was loose since the rubber gasket usually forms a pressure seal on the cap.
You can easily make a gasket from rubber (I used cork).
Sorry about the link. Didn't see the first posting of the manual link.
Word of warning. If your heater is dated around 1963 and you bought it on Ebay, it may leak fuel when you connect a fuel supply and run it.
I found that the donut shaped gasket in the fuel pump was dry rotted. The cap on the bottom of the fuel pump housing was loose since the rubber gasket usually forms a pressure seal on the cap.
You can easily make a gasket from rubber (I used cork).
ida34
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RE: Heater Manual
The seller just got back to me. They were out of town. She found a UH-48 in the warehouse. She said she did not know any were not UH-48's because they looked so similar. She was willing to pay shipping both ways to exchange and make me happy. I instead worked out a deal to just buy the UH-48 and keep the other one to use the parts for other projects. I asked and she does have other UH-48 heaters. They are the B model. If anyone is interested I will pass on contact info.
The seller just got back to me. They were out of town. She found a UH-48 in the warehouse. She said she did not know any were not UH-48's because they looked so similar. She was willing to pay shipping both ways to exchange and make me happy. I instead worked out a deal to just buy the UH-48 and keep the other one to use the parts for other projects. I asked and she does have other UH-48 heaters. They are the B model. If anyone is interested I will pass on contact info.
readyman
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RE: Heater Manual
MilSurplus,
The amp meter doesn't budge on my power supply when I have the UH-48 on and dry running. I haven't put diesel in it yet tho. Does it really take that many amps?
MilSurplus,
The amp meter doesn't budge on my power supply when I have the UH-48 on and dry running. I haven't put diesel in it yet tho. Does it really take that many amps?
MilSurplus
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RE: Heater Manual
Yes, the heater that I have draws about 15 amps @ 28V. That's 420 watts to create 15,000 BTU's ! It's a real energy hog.
I had problems getting the heater going due to a dry rotted carb diaphragm. The heater started up, then started belching black soot. It was obviously running too rich. The rubber diaphragm was like a stiff piece of plastic, and was allowing fuel to be poured in at full delivery rate.
I found a small snowblower carb diaphragm on E-Bay, and tried that. It was the wrong size, but the heater ran OK. When I stopped the heater though, and let it sit overnight, the carb leaked fuel past the diaphragm into the combustion chamber. There was a good quart of kerosene in the chamber ! I am glad that I checked it before I tried starting it that day.
When the heater starts up, there is a loud backfire through the exhaust pipe, then it runs ok. I am pretty sure that it is not supposed to backfire, I think the carb is the problem again. Fuel leaking past the diaphragm when it is not supposed to.
The heater is pretty loud when it is running, sounds like a vacuum cleaner, but it really is a well built heat source worth trying to fix. I ran it for about three hours inside a 16' x 16' frame tent with liner. It brought the temp up 30 degress. It circulated the air in the tent very well, as the fan is very powerfull.
Needless to say I am still looking for the right size carb diaphragm. The size is 1.5" between the mounting holes. If anyone has any ideas where to get one please let me know.
Yes, the heater that I have draws about 15 amps @ 28V. That's 420 watts to create 15,000 BTU's ! It's a real energy hog.
I had problems getting the heater going due to a dry rotted carb diaphragm. The heater started up, then started belching black soot. It was obviously running too rich. The rubber diaphragm was like a stiff piece of plastic, and was allowing fuel to be poured in at full delivery rate.
I found a small snowblower carb diaphragm on E-Bay, and tried that. It was the wrong size, but the heater ran OK. When I stopped the heater though, and let it sit overnight, the carb leaked fuel past the diaphragm into the combustion chamber. There was a good quart of kerosene in the chamber ! I am glad that I checked it before I tried starting it that day.
When the heater starts up, there is a loud backfire through the exhaust pipe, then it runs ok. I am pretty sure that it is not supposed to backfire, I think the carb is the problem again. Fuel leaking past the diaphragm when it is not supposed to.
The heater is pretty loud when it is running, sounds like a vacuum cleaner, but it really is a well built heat source worth trying to fix. I ran it for about three hours inside a 16' x 16' frame tent with liner. It brought the temp up 30 degress. It circulated the air in the tent very well, as the fan is very powerfull.
Needless to say I am still looking for the right size carb diaphragm. The size is 1.5" between the mounting holes. If anyone has any ideas where to get one please let me know.
MilSurplus
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RE: Heater Manual
I figured out why I was having problems with the heater. The heater is meant to be run at or above the fuel source level. I was feeding the heater with a five gallon can of kerosene on a tripod. This is why the carb flooded out, and the heater filled with fuel. It also explains why the heater backfired when I started it. The fuel was above the level of the heater which was foce feeding the fuel pump.
DUH !
I stuck a clear plastic fuel line in a pop bottle with kerosene in it, and when the heater started, it sucked the fuel through the hose. It worked perfectly.
I turned the heater off, and tried another run at it, and now the preheater is not working ! It's not drawing the high amount of electrical current it was before.
I am going to shelve this thing unitil the weather warms up. Pretty frustrating.
I figured out why I was having problems with the heater. The heater is meant to be run at or above the fuel source level. I was feeding the heater with a five gallon can of kerosene on a tripod. This is why the carb flooded out, and the heater filled with fuel. It also explains why the heater backfired when I started it. The fuel was above the level of the heater which was foce feeding the fuel pump.
DUH !
I stuck a clear plastic fuel line in a pop bottle with kerosene in it, and when the heater started, it sucked the fuel through the hose. It worked perfectly.
I turned the heater off, and tried another run at it, and now the preheater is not working ! It's not drawing the high amount of electrical current it was before.
I am going to shelve this thing unitil the weather warms up. Pretty frustrating.
ida34
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RE: Heater Manual
I have not had time to mess with mine yet. I have been doing body work on the cucv.
I have not had time to mess with mine yet. I have been doing body work on the cucv.
MilSurplus
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RE: Heater Manual
I measured the resistance of the preheater coil. and detemined it was bad. More bad news.
I am trying a last ditch effort to replace the preheater coil. Since the heater is dated 1964, I know that a replacement coil is out of the question. A 40 watt low voltage (24V) soldering iron coil should work if I can fit it in the compartment where the original preheater coil was.
I measured the resistance of the preheater coil. and detemined it was bad. More bad news.
I am trying a last ditch effort to replace the preheater coil. Since the heater is dated 1964, I know that a replacement coil is out of the question. A 40 watt low voltage (24V) soldering iron coil should work if I can fit it in the compartment where the original preheater coil was.
ida34
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Bringing back an old thread. I finally sat down and worked on both heaters. I got the non UH-48 to work on gasoline first then fed it diesel. It smoked bad on gasoline and worse with diesel. I opened the damper and it was shooting a 2 inch cone of flame out the exhaust. This scared me so I went to work on the UH-48. That ended up in a no go partly because of an inop fuel pump. I went back to work on the non-UH-48. It was marked as gasoline with no mention of multifuel. The only way I could get it not to smoke was to increase the opening on the damper. Initially the temp on the combustion chamber was around 1000 degrees with the exhaust running around 300 degrees a few inches down the exhaust pipe. I put on an exhaust pipe and put it out the window of my shop. The exhaust was running around 160 degrees. I turned the fuel down until I got a consistent combustion chamber temp of around 650-700 degrees. I also cranked down the damper a small amount and ran it for some time with no black exhaust. I ran it through a couple of cycles before declaring victory.
Has anyone taken temps while they are running? Mine never cut out even when it was running 1000 degrees although I noticed a couple of red spots developing on the combustion chamber. What temp are they supposed to shut down on?
Has anyone taken temps while they are running? Mine never cut out even when it was running 1000 degrees although I noticed a couple of red spots developing on the combustion chamber. What temp are they supposed to shut down on?