Kerosene Heater - I’m stumped (?)

[CobyRupert]

I have a 40,000 btu Reddy kerosene heater made by Desa (similar to picture). I think they were sold under a lot of names. Anyways, it will run for a couple minutes, then suddenly quit. (No sputtering, etc..).
Here’s what I’ve done:
- Checked that air pressure to nozzle was 3 lbs.
- I cleaned the fuel nozzle, then replaced the nozzle and the nozzle adaptor (as one of the hose connections tabs was partially broke off). Retrieved broken piece from hose.
- Replaced fuel filter.
- Checked (meggered) photo eye. I bought a new photo eye, and the old one meggered lower when both placed up an incandescent bulb.
-Cleaned and tightened photo eye connections to circuit board.

Still cuts out after a couple minutes of running.
I noticed that with circuit board panel unscrewed and laying flat (only connected by wires, it would run, but when I tried to screw panel back on, it would cut out within 30 seconds. Coincidence?
I thought: Must be the circuit board. Maybe the relay to the motor drops out, etc.. so I bought a new $50 circuit board.

I pretty much have a new heater at this point
Again, it runs for 5 minutes then turns off!

I’m going to put the new photocell in (maybe old one goes from better than new to bad when it gets warm?)
When it turns off, the nozzle looks like it’s spraying well and igniter is glowing.
I’m really stumped.

Any ideas?

 

[neverfailyou]

I have a 40,000 btu Reddy kerosene heater made by Desa (similar to picture). I think they were sold under a lot of names. Anyways, it will run for a couple minutes, then suddenly quit. (No sputtering, etc..).
Here’s what I’ve done:
- Checked that air pressure to nozzle was 3 lbs.
- I cleaned the fuel nozzle, then replaced the nozzle and the nozzle adaptor (as one of the hose connections tabs was partially broke off). Retrieved broken piece from hose.
- Replaced fuel filter.
- Checked (meggered) photo eye. I bought a new photo eye, and the old one meggered lower when both placed up an incandescent bulb.
-Cleaned and tightened photo eye connections to circuit board.

Still cuts out after a couple minutes of running.
I noticed that with circuit board panel unscrewed and laying flat (only connected by wires, it would run, but when I tried to screw panel back on, it would cut out within 30 seconds. Coincidence?
I thought: Must be the circuit board. Maybe the relay to the motor drops out, etc.. so I bought a new $50 circuit board.

I pretty much have a new heater at this point
Again, it runs for 5 minutes then turns off!

I’m going to put the new photocell in (maybe old one goes from better than new to bad when it gets warm?)
When it turns off, the nozzle looks like it’s spraying well and igniter is glowing.
I’m really stumped.

Any ideas?
View attachment 684995

Similar problems with my 55k BTU. Ended up getting new air pump rotor with 4 new vanes and an air filter kit and cleaned fuel filter. These are wear items and need replacing periodically which I never have done. Used an air pressure gauge to set air pressure.
The heater uses air pressure to suck fuel to an injector with a Venturi effect.
After repair, my unit worked for several hours until the igniter deteriorated and blew the fuse on the circuit board. I have gotten a new igniter and am waiting for the new (special size) fuse to arrive from Amazon.
Good luck.

 

[dodge man]

I have nearly identical heater. Mine had the pump housing cracked. I have fixed that same problem about three times. It is plastic. I just glued it every time. Your problem sounds similar but different. I bought the pressure gauge designed for these heaters. Is that what you used?

 

[LouNY]

Sounds like it could be the vane pump acting up as it warms up.

 

[CobyRupert]

Yes, I have pressure gauge for these heaters. It shows a 3.0 lbs (recommended setting).
I’ll double check air pump, I thought pressure was pretty steady, but will make sure it’s not wobbling.
If it’s the fan (air pump), wouldn’t I see flame or fuel spray “sputter” (I’m not) and have to wait for photo eye to detect it and shutdown; or can shutdown happen pretty instantly?

 

[dodge man]

If you have the correct gauge and are at spec your OK there. When my pump was cracked the pressure was way off.

 

[Industrial Toys]

I spent many hours in frustration on a Reddi Heater. Changed the Nozel and never had any more issues.

Make sure filter is clean too.

 

[Popgadget]

The nozzle works just like a siphon spray gun. You can supply it regulated 3 psi air and watch it suck fuel and see the spray pattern to confirm or condemn it.
It easiest to remove the nozzle and the mount so you can test it outside the heater.
Older units with metal suction tube and a flare nut to attach to the burner head had a filter that was inside the tube at the flare that was often overlooked. I’m guessing that yours is newer and uses plastic and flexible rubber hoses though. The rubber hose versions are easier to test outside the heater.

 

[Industrial Toys]

Like I said, I had similar trouble. Went through all the troublshooting steps. Kind of gave up until I came across a trashed unit and grabbed the nozzel. No more trouble. That's just MY experience with these.

 

[CobyRupert]

Things (I think) I learned.
1) One of the things stumping me was pump motor would shut off, even when I had the photocell pointed directly at an incandescent bulb. (Photo eye previously tested <100 ohms when pointed at bulb.)
My thinking was that motor should continue to run regardless of flame, fuel, air, nozzle, etc... if photocell is still satisfied. Why would control board stop motor if it thinks flame is good? Somehow, this is not true and I’m not sure why. Otherwise you would think you have a faulty photocell, photocell connection or control board that’s triggering motor shutdown.
Does photo eye and control board know the difference between a steady light bulb and a fluttering flame? Seems too sophisticated, but only explanation I can come up with.

2) Measuring 3 lbs air pressure at the sample port on the pump does NOT mean you have 3 lbs at nozzle. Check hose for chaffing & leaks. On mine, there’s a 90 fitting the hose line slides onto at the pump that was not screwed in all the way.
Same when you put the pressure sample port plug back in. Got to be tight.