Greetings, have a heater with new lines, filters, nozzle, fuel, pressure set, new ignitor...Problem... have poor start up, most times will not fire. will get better average of start up when cover is off. I can see element heat up and fuel delivery but no fire . Seems fuel spray not making good contact with element... Help, thanks, Eric A.

Make sure that the ignitor is in the mist of atomized fuel. Or better yet do you have signs of fuel atomization? Check fuel filter usually an in line transparent type filter, if it is clear check the nozzle they have a screen inside as a filter as well no fuel there lines to the tank are next in line if you have fuel up to the nozzle it may be time to replace the nozzle sorry but you can not clean them any slight bend or widening of the holes changes the rate of the nozzle. Pay attention to the GPH rating and spray angle when replacing the nozzle.

I have a 125t and the igniter works,it is getting fuel and still won't lite. Can you help?

If...the air pump pressure is right, the ignitor glows, the fuel is hitting the ignitor, then the unit will have combustion......unless.....

1. there is an air leak on the pressure line
2. there is a vacuum leak on the fuel line
3. there is a leak at the nozzle adapter
4. there is a restriction either in the nozzle or the fuel filter
5. the nozzle is worn and is spraying fuel rather than fogging fuel

FOUND THAT THE FUEL HOSE AND AIR PUMP HOSE HAD BEEN REVERSED AT THE NOZZLE-PUMP HOSE NEEDS TO BE CLOSEST TO THE BLOWER HOUSING-I USED A VAC GAUGE TO TEST THE FUEL LINE-WHILE THE AIR PUMP WAS RUNNING-NO VAC-REVERSED LINES AND STARTED UNIT-ADJUSTED AIR PRESSURE-ALL IS WELL

it's the ignitor itself, if everythingelse is working or new then your just not getting enough spark. Also check your air lines as they do tend to get brittle and if your not getting enough air it won't light either.

ground wire on the circuit board needs to be checked and these units need to have a GOOD three wire cord with a proper grounded outlet

This is going to be a tough one. You have been thorough, done it right, and it damn sure ought to fire off every time!

There is something that is causing you a problem and don't think that because you put in new parts that you didn't get a bad part. It happens. Not often, but it does happen. I have rec'd nozzles from the factory that had the orifice installed sideways, so, I know it happens.

If the ignitor glows- (it only stays on for 5 seconds, then quits)
If the fuel fogs (not sprays)
If the fuel hits the glowing ignitor
Then it should fire off-- every time.

Now, if the photocell doesn't like what it sees, then the photocell will shut the heater down within 5 seconds, but it at least should have ignited. Right? Unless the photocell or the board are bad. Maybe.

Lift the top, and watch. What's happening. Are you having a fuel problem or an electronics problem? For instance- is the ignitor glowing every time at start up or only sometimes.

Let me know what you find.

John- the ignitor does not stay on for the duration of the running time. It only stays on for the first 5 seconds. This is long enough for the flame to ignite and perpetuate itself, assuming the fuel delivery system is up-to-par. The photocell monitors the flame color and if the flame becomes off-color then the photocell tells the control board to shut the unit down. Naturally, too rich or too lean affects flame color.

Now, I'm confused by your description "the heater cycles 3 times". Tell me more.

I'm glad to see that you checked the pump pressure. Have you used soapy water to check for air leaks all the way to the nozzle? A leak in the airline, fuel line, or a crack in the nozzle adapter will cause no fuel delivery, or reduced fuel delivery as well as reduced atomization of the fuel - all of which can cause a lack of combustion. A restricted fuel filter will cause starvation.

Eliminate all possibilities of a fuel delivery problem before you start blaming electronics because there is not much way to test the board or the photocell successfully without DESA's diagnostic tool. Unfortunately, replacement of the componants is cheaper than the tool.

What did you set the air pump pressure at? This is critical on heaters with Hot Surface Technology. Setting the pump pressure is always the FIRST place to start troubleshooting on these heaters.

Here are some things that can prevent ignition even though there is fuel & glow:

1. wrong air pump pressure
2. the nozzle is restricted & distorted not allowing fuel to contact the glowing ignitor
3. the nozzle is worn. It should produce a cone of fog, not a spray.
4. there is water in the tank below the fuel.

Silvercliff- since you use the word “plug” I am assuming that you have a spark plug type heater, not the new technology HSI type (hot surface ignitor) that uses a glowbar and an onboard computer.

Reddy heaters are simple to troubleshoot, but you must understand how the system operates.

Since you state that the heater produces a fog at startup indicates that you are getting “some” fuel.

Obviously, the fuel is not igniting.

Now, you must determine if there is any spark. Is a good spark arcing across the electrodes on the plug? If not, is spark being produced by the Ignition Control unit (aka spark box, transformer) ? If not, is the Safety control (reset) sending electricity to the Ignition Control unit?

If there is a good strong spark at the plug, then you are having a fuel delivery problem, even though there is “some fuel”. Understand that the amount of fuel being delivered to the nozzle is DIRECTLY related to the air pump pressure. If the air pump pressure is not correct, then the fuel delivery is not correct. Setting the pump pressure is not difficult. Pump pressure is CRITICAL. Instructions for setting the air pump pressure can be found at www.reddyparts.com .

If the air pump pressure is correct, then check the following:

1. Cracked air line preventing correct pressure at the nozzle.
2. Cracked nozzle adapter preventing the fuel from being SUCKED from the tank.
3. Clogged fuel filter.
4. Restricted or worn nozzle. The fact that your heater is a spark plug type heater indicates that it has some age on it. DESA recommends annual replacement of the nozzle. Are you using the original nozzle? Worn nozzles produce a SPRAY. New nozzles produce a FOG. The nozzle produces a cone shaped fog. If the cone is missing (not hitting) the spark, for some reason, then there will be no ignition.
5. Finally, and don’t laugh, is your fuel 100% kerosene or diesel? Water sinks to the bottom of the tank. The heater draws fuel from the bottom. If there is an inch of water on the bottom…….., well, water will not ignite.

I hope this helps.