20 Most Recent Desa International RH125AT Utility Heater - Page 4 Questions & Answers

You need to check the fuel nozzle for a blockage and check the fuel filter. Remove the top of the heater and you should be able to remove the nozzle adapter and the nozzle by turn it until the tabs on the nozzle adapter line up with the holes. One hole is bigger than the other so it will only come out and go in one way. If you remove the nozzle from the adapter and hold the nozzle up to light you should be able to see light through it. Use a piece of small wire or something to clear any blockage.
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Make sure the pilot light flame is bathing the thermocouple; not too close, not out of the flame. If it seems in the right part of the pilot light flame, then the thermocouple may be failing; they only produce a few thousandths of a volt and it may be defective now. The thermocouple will look like a tube with a closed end and a thin tubing attached to it going to the regulator.

The safety feature for your fireplace is probably a millivolt pilot generator. It serves 2 functions. It holds open the pilot safety magnet AND operates the solenoid on the millivolt gas valve. The pilot generator is weak. It will hold open the safety but not work the operator selenoid on the gas valve. Replace it. And party on! If you need further help, reach me via phone at https://www.6ya.com/expert/dan_73bbd84fe1d95b61

Here is a guess. I say guess cause the heater is on your bench.

If the adj screw is run all the way in (maxxed out) the pressure should spike to 9-11psi. If it doesn't then you either vhave a worn out rotor & vane assy, or there is a leak around the cork gasket, or a crack in the plastic end cover. Use soapy water to find the leak.

More troubleshooting tips.

That insert must have a milli-volt gas valve. The safety feature used on them type valves is a Thermophile/generator. When these generators get weak they will hold the pilot but when called upon to operate the gas valve solenoid they simply die. Replace the pilot generator.

MILLI-VOLT OPERATION If you need further help, reach me via phone at https://www.6ya.com/expert/dan_73bbd84fe1d95b61

Check manual, get LP conversion part number than order. If no manual look online under the model number and look up.

Dave you can use all three types that you have listed.

The pump is typically set for Number 2/ Diesel Fuel and if you run Kerosene the unit will run a little bit hotter but with a 3E359B you will typically run diesel due to the amount it will use and the increased cost of kerosene over diesel fuel.


Number 1 is similar to kerosene and is the fraction that boils off right after gasoline.
Number 2 is the diesel fuel that trucks and some cars run on, leading to the name "road diesel". It is the same thing as heating oil.

most likely the fuel pressure is wrong. you need a fairly accurate gauge to reset it. there are two screws in the back of the heater, one is a cover for the gauge port the other is a regulator to adjust the pressure, the pressure is set between about 3 and 6 psi depending on how many btu s your heater is. bigger heater bigger psi. for example a 60k btu heater is set at 3.4 psi. these gauges cost 30-40 bucks online, but if you have a welding supply store or a northern tools nearby you can usually find an inexpensive acetylene gauge that will measure that fine and at at that low a pressure. all you need to do is make up a little adaptor to fit, parts also available at same store. mine cost about 7 dollars all in. the pressure setting is critical on these heaters, you cant swag it, you really have to have a gauge and set it.

Make sure you seal the hole where the thermocouple goes into the firebox with high temperature silicon.

Most parts in gas fireplaces are universal, the valve/thermopile and thermocouple are generic parts and should be found at your local gas fitting supply stores.

If you describe what you tried to fix the fireplace thus far I could give you better advice to which part you need to replace in order to get it running.

could you be more specific on the model number and is this a gas or oil fired unit. I have a manual for portable heater units in front of me but I can't find this listing

check to make sure that the end of the thermocouple is in the flame. This is the hot junction of the thermocouple and it the difference in temp that create the millivolts to operate the gas valve. If it is in the flame, replace it and if a new thermocouple doesnt fix it, you need a new gas valve

Check to see if the pilot lite is going past the pin- (flame sensor) if not then your flame is too low , Clean the pilot oriffice or use air and blow out the system for dust.

Assuming this is a wall furnace, take a AA battery and attach one wire to each end, tape or use holder from toy at 99 cent store!!
look at the pilot assembly, 2 wires(may look like one) go to the gas valve. at the gas valve it will be 2 wires attached to the gas valve.

this powers the whole thing! simply atach the 2 wires from batt, to where the pilotwires go (not the thermostat wires, the pilot generator)
tryt now ! does it work? if not , bad valve or try connecting the two stat wies together at the furnace instead of stat doing it to test if stats bad or wires bad. dot keep using it with battery if your sleeping or leaving etc, as ,if the pilot blows out, the gas can flow as if a plt flame existed!!!
flooding gas out into a flameless environment.

SCREW YOUR COMPANY AND **** YOUR JUNK. I REFUSE TO PAY $20.00 FOR ASSISTANCE ON A PIECE OF **** I HAVE USED 1 YEAR. I WILL TELL ALL MY FRIENDS AND FAMILY TO NEVER BUT FROM DESA.

SCREW YOU,
LORI