Cad cell

Vrod1250

My beckett burner runs 4-5 minutes then the ohms go real high, then it tries to recycle then goes into hard lockout? New cad, new cad socket, new nozzle and filter. I have a raised system with return line, Tiger loop and check valve. Using 7284 controller and clean burn pump with solenoid?

EBEBRATT-Ed

Why replace all those parts and get the incorrect ohm reading which means the flame is out of wack. Changing the control and cad cell won't fix that.

You need a technician with a combustion test kit that knows how to use it and get the burner and boiler cleaned up and adjusted.

HVACNUT

Vrod1250 said:

My beckett burner runs 4-5 minutes then the ohms go real high, then it tries to recycle then goes into hard lockout? New cad, new cad socket, new nozzle and filter. I have a raised system with return line, Tiger loop and check valve. Using 7284 controller and clean burn pump with solenoid?

What's a "raised system"?
And "return line, Tiger Loop and check valve". There's no return line back to the tank, right?
No check valve should ever be needed.
Where's the restriction?

EdTheHeaterMan

@Vrod1250, you have made some statements that the professionals do not understand.

I have a raised system with return line

I don't know what that means

Tiger loop and check valve

Are you talking about the Firomatic valve that comes in the box with the tiger loop? Or are you talking about a check valve that you purchased separately?

Using 7284 controller and clean burn pump with solenoid?

I think you are talking about the Honeywell R7284A primary control (digital display) or R7284B Primary control (idiot light) with a Beckett CleanCut Pump with built in solenoid valve.

These are good parts to have for diagnosing oil burner and combustion problems, but you are describing an issue that replacing those parts will not solve.

It sounds like you have an oil flow issue. Where is the tank? How long is the fuel line from the tank to the tigerloop? Have you checked the fuel line for blockage?

A new flame sensor will detect a poor flame resulting from a blocked fuel line in the same way as an older flame sensor that is in working order.

I would always ask my technicians that worked for me : "After you replace that part and the same thing happens, where will you check next?" Sometimes the answer is a simple adjustment or replace a fuse or just clear a dirty fuel line. Then i would say..."Do that first and see if it works". The customers do not need to buy unnecessary parts so you can learn on the job. You should do what you know that cost the least. Get it fixed, get paid, and move on the the next job.

It is the process of elimination with the lowest cost repair, then moving to the next until you find the problem. It sounds like you have fired the PARTS CANNON at your problem with little success.

Vrod1250

My burner is 10 feet in the air in a shop (code here) the controler and all parts were working last year. The ohms are steady running fine for 5 minutes or so then the ohm spike over 3500 and it goes into recycle, it fails to ignite and locks out.

Vrod1250

The only parts I changed are the cad cell and socket, with nozzle and filter, basic maintence. The other parts were there.

SuperTech

I assume this is a forced air furnace, I can't imagine a boiler installed 10 feet in the air. If your cad cell resistance is in the normal range (300-600 ohms) after ignition then it's possibly the furnaces blower causing a change in combustion and the ohms are reading higher as a result.  This would indicate a heat exchanger failure.  Best thing to do is get a technician who is familiar with combustion analysis to diagnose it. It shouldn't be too hard for a good tech with the right tools to figure out quickly.  It will be really difficult to figure out without the right tools and experience. 

HVACNUT

You've got a hanging coffin.
Like @SuperTech mentioned, it could be a cracked HX. Does this increase in resistance coincide with the blower coming on?

Where is the oil tank? It's typical to use a lift pump and Day tank with that setup. Or 2 pipe with a B pump, depending.