Reddy heater pro 115 runs then shuts off

Hello guys,
I'm stuck and could use some help. I have a reddy heater pro 115, it runs but for 30 seconds the shuts off. I unplug it then run it again and it will run for two minutes. It never stays consistent every time I turn it back on it will run for a different length of time but never past 2 minutes. I have cleaned and replace all the filters made sure I have good air psi with in spec and cleaned the vent hole on the fuel cap. Not sure what I'm missing. I have diesel in it currently. Any help is greatly appreciated. Thank you in advance.

It sounds like the over temp may be cutting it out. Does it have good airflow? I guess that would be my first place to look. Is the fan good?

copied from Reddy heat

HSI Principle:

Here s the principle in a perfect operational Hot Surface Ignitor (HSI) heater:

Plug the unit in.
When power is applied, the ignitor (glowbar) glows. After a delay, the motor starts to turn, the fan blows air through the combustion chamber, the fuel begins to flow, because the air pump (rotor) is directly connected to the motor shaft. Air is delivered to the nozzle adapter by the air pump. At the nozzle adapter, the passing air creates a venturi effect, sucks fuel from the tank and thereby delivers fuel to the nozzle at a precise fuel/air rate for atomization.
The photocell starts looking for a flame in the chamber
When the atomized fuel contacts the glowing ignitor, there is combustion.
Then, after 5-7 seconds the ignitor no longer glows and the flame continues to burn on it s own and it should burn until the fuel supply is gone or power is disconnected.
The photocell takes over and monitors the flame for color. Too rich/lean and the flame color changes, or any momentary flame-out and a signal is sent to the computer control board and there will be a shutdown by the electronics.



Now, these heaters are computerized and the computer wants to find a system that is operating at 100%.



IMPORTANT: At less than 100% the system shuts down for safety and environmental reasons. Simply stated- the computer is looking for a reason to shut the unit down because that is its job.



I am going to list some of the reasons that will cause a shutdown in the order of incidence, in our shop anyway.

Water in the fuel people love to buy parts but this is a free fix, just drain the tank. Shine a flashlight in the tank & look for water droplets & trash.

The pump pressure not set to specs. There is not a fudge factor here. Instructions for setting the pump pressure are at http://reddyparts.com/pressure.htm .

The air pumps on the old style heaters could be adjusted to suit the operator s nose. If the heater smells just adjust the pressure a little until it smells good. Not so with the new heaters- you adjust to suit the computer, not you.
Air leak. If there is a crack in the plastic end cover, air line, fuel line, or nozzle adapter. These conditions create a lean mixture--poor flame color
Defective or worn nozzle. Desa warns about annual replacement in their manuals. Depending on annual "hours used" this may or may not be your problem.
Defective control board and/or photocell. Eliminate all of the above reasons for your heater s failure before blaming the electronics.
Incorrect fuel- burn kerosene or diesel.

We?ve had the same issues, if you cant get it running yourself
unless you know someone who really can fix them it?s
cheaper to get another one. We?ve spend hundreds on a 3 yr
old 165 000 btu ?John Deere? unit only to throw it out because
they all said it worked fine when I picked it up and it must be a
new issue.

The most common cause of problems with these heaters is that that rubber or plastic fuel and air hoses stretch/swell where they push over the hose barbs.

That causes leaks that bleed off air before it gets to the nozzle, or lets air enter the fuel flow, either way making for a dimmer/weaker fire that the flame safety control senses and shuts the unit off.

Also, the "eye" or the "flame control" can get weak or "flaky".

Did you check that the "eye" is clean/free of dust and soot, and aimed correctly into the firebox, directly at the flame?

(quoted from post at 14:50:33 02/27/20) The most common cause of problems with these heaters is that that rubber or plastic fuel and air hoses stretch/swell where they push over the hose barbs.

That causes leaks that bleed off air before it gets to the nozzle, or lets air enter the fuel flow, either way making for a dimmer/weaker fire that the flame safety control senses and shuts the unit off.

Also, the "eye" or the "flame control" can get weak or "flaky".

Did you check that the "eye" is clean/free of dust and soot, and aimed correctly into the firebox, directly at the flame?

Click to expand...

I have taken the unit apart and replaced the fuel line, taken apart the nozzle and cleaned it as well. It has new diesel fuel in it so it could have water but I ran it in a different heater I have with no issues. I did check the photo eye and works the way it should. I really hate to throw parts at it.

Fan looks good, this unit doesn't have a thermostat. Would this be on the circuit board?

"I did check the photo eye and it works the way it should".

By what means did you "check" the photo eye?

The way to check it (IF you feel you can do this safely, and at your own risk) is to temporarily bypass the flame safety control so the burner keeps firing and (using an Ohmmeter connected to the photocell leads with them disconnected from the flame control) monitor the cell's response to the flame.

Typically, you should be seeing a pretty steady 100 to 600 Ohms.

If the "eye" is weak or not "seeing" a BRIGHT flame, the resistance will be higher.

If the resistance is high enough (probably in the 1200 to 1500 Ohm range or more), it is NOT enough to keep the flame control "happy" and that's why it's been shutting down.

Sometimes, the eyes fail in the manner of their resistance rising as they warm up, that is why you need to monitor the cell's resistance over some time, and under actual operating conditions.

DON'T leave the heater unattended with the flame safety bypassed, run the test and then put it back as it's supposed to be.

Had some flakes of rust in the fuel tank on one I owned. Would cover the hose shutting off fuel. When the heater died, rust flakes would fall away and heater could restart.

Might try pulling the pickup hose up a half inch from the bottom of the tank and see what happens.

Fred

You need to do a pressure check. It tells the proper pressure and where to check it in the owners manual. I have two Reddy Heaters and had trouble with both. One of them had the fan get too tight and it showed in the manual how to fix that too. They are good heaters though. I had a Mr. Heater bought from Menards. Never could get that thing to work right and it always had a smell when running.
DWF

The most common reason for this is air leaks. Every hose in the system will degrade over time from exposure to petroleum products. That is a good starting point. Since fuel is drawn up from the tank by vacuum from the venturi effect, it is critical to have all hoses and lines airtight.

The photocell is another potential source of trouble. There are two types of photocells. They have different resistance characteristics, but they look and fit alike. They are NOT interchangeable. I found this out long ago when I got a used heater at an auction. It would run for a few minutes and quit. Nothing I did seemed to help. Some research found that the photocell had been replaced with the wrong one.

The safety circuit is rather simple. The photocell is wired in parallel with a heater type slow acting circuit breaker that powers the pump. As the pump operates, current flows through the circuit breaker and photocell. When the photocell "sees" the flame, its resistance goes lower and effectively bypasses the breaker. If the photocell does NOT see the flame, resistance stays high and more current flows through the breaker. The breaker heats up and opens the circuit shutting off the heater.

One thing to also mention is your choice of fuel. I had one heater that I received with a full tank of diesel fuel. On colder days, it did not run well. The fuel was getting thicker as the temperature fell into the lower teens and was not being drawn up well from the tank. I actually had to use another smaller heater aimed at the fuel tank to warm it up to get it running. I also noticed that there is a lot more fumes/smell when you run it on diesel as compared to kerosene. I much prefer to run mine on kerosene.

I have a book from Portable Heater Parts that shows correct repair and troubleshooting.

You can quickly spend more money on parts than what a brand new unit will cost. I know from experience, and I never was able to make the Reddy-Heater run. It found a new home out in the junk shed.