Intermittent Flame Failure Beckett Burner

RayWohlfarth

Howdy,
I am hoping you can give me some guidance here. I am working on a Beckett Fuel Oil burner model CF375 which had not been serviced for years. It is piped as a two pipe. I am by no means a fuel oil expert. Upon arrival, we found the fuel oil pump was not working. We replaced the pump and the oil filter in the supply and nozzle. They were plugged solid. We replaced the cad cell. We cleaned the electrodes and readjusted. The fuel oil pump was set according to the literature and the fuel to air ratio tested and adjusted. The unit is having a flame failure every 3-4 days. The primary control flashes and we have to do a hard reset. I did hear a pulsation in the flame once while there. I have cycled this thing more than Lance Armstrong's bike. Any suggestions other than an exorcist?
Ray

ScottSecor

It's been years since I've touched an oil burner, but I have spent a lot of time on them years ago.

A few things to look at, could it be contaminated fuel and the filters (and occasionally) the oil lines are clogged again? Could the ignition transformer be weak? Could one of the electrodes be cracked? Could one of the ignition wires be cracked? Could there be a pinhole leak in the oil suction line? Suction line leaks were very difficult to find, I used to install a vacuum gauge on the suction side of the pump and watch for the gauge to "jump." If it jumped often, it was almost caused by air entering the suction line.

Many of the conditions I mentioned would cause at least a puff of smoke when the burner was reset and the leftover fuel from the last cycle ignited.

I'm sure others that service oil burners regularly will have better suggestions.

HVACNUT

Could be any number of things, but from what you said of the filter and nozzle conditions, sounds like it might be an oil line restriction. That is a light commercial burner. Is there an in line vacuum gauge? What is the running vacuum?
Water/sludge in the oil tank.
Weak igniter.

Ironman

Assuming your adjustments are correct, I second checking the vacuum.

Sid Harvey carries Mifco oil gauges/manifold. Everyone that does oil should have them.

If nothing else shows up wrong, replace the CleanCut pump with one that doesn't have a solenoid. We've had an unusually high percentage of those acting up intermittently. Even brand new.

Steamhead

You don't say what primary control is on that burner, but the latest ones (Honeywell, Carlin etc) have diagnostics built in. Installing one could help you pinpoint the problem.

Robert O'Brien

Since it's a CF375, it's a pretty safe bet it has a HW 7184 or Genisys. If it's a 7184, you are going to have to go by process of elimination, if it's a Genisys, a contractor tool will point you in the right direction. The 2 pipe system has no reason to exist, nothing good can come from the return line. The hydrogen can be out gassed at vacuum readings as low as 6". This appears to be a "suction leak" but is in fact hydrogen bubbles which play havoc with oil combustion.

Charlie from wmass

Have you confirm draft numbers both at start up and when warm?

Harvey Ramer

I had one that plagued me in this fashion once. What I ended up doing was turning the thermostat up as far as it would go and made it run till something happened. It took about an hour and a half before it tripped. What I discovered was lack of lubrication in the fuel pump. After a such a long run, things heat up and if anything is awry in the bearing department, it will show up. Motor bearings will sometimes act the same way.
I call it the extended run test.

newagedawn

could be the oil lines are plugged , blow them back and purge the lines, check the filters again ,when systems are that bad sometimes even after changing them they get plugged again

rick in Alaska

If it is a cleancut pump, change the solenoid.
But, my guess is a bad fuel pump coupler that is slipping. Look at the ends carefully and make sure the flats are not rounded down. And, also take the ends off and make sure the splines are not stripped.
Rick

RayWohlfarth

Thanks everyone I stopped by Sid Harvey and picked up the gauge manifold. What a cool thing. Thanks Ironman. I checked the unit and everything was going well. I tightened all the fittings on the tubing and the draft was what the company asked. If it happens again, I will try Harvey's solution.

Ironman

RayWohlfarth said:

Thanks everyone I stopped by Sid Harvey and picked up the gauge manifold. What a cool thing. Thanks Ironman. I checked the unit and everything was going well. I tightened all the fittings on the tubing and the draft was what the company asked. If it happens again, I will try Harvey's solution.

I think you're gonna find it's the solenoid on the clean cut pump.

RayWohlfarth

Thanks Ironman will let you know

Harvey Ramer

I don't know what the coil tolerances are on those selenoids, but enough of a voltage drop could make the coil drop out momentarily. A voltage drop such as might occur when a large inductive load, such as a large motor, starts and the primary service transformer is undersized.

I don't know if this is the problem, but it might be worth looking into.

Robert O'Brien

You can test oil valve coil by checking resistance. It should be between 400-500 ohms. A bad coil will usually be quite hot to the touch after just a few minutes operation

Robert O'Brien

Genisys will save the high, low and average voltages for each of the last 15 cycles

RayWohlfarth

They have the Honeywell R7184B control. Wishing I had the Genisys on this one