Oil fired hot water heater continues to trip

Rodney10

I replaced the Aquastat but it didn’t solve the problem. When I reset it fires and does not trip. After using hot water it trips periodically. What could be the problem? Possibly dirty nozzle?

HVACNUT

What is the ohm reading on the cad cell while running?
Let's start there.
 

Rodney10

You think the eye isn’t good. I watched a vid and will check it out 

HVACNUT

Rodney10 said:

You think the eye isn’t good. I watched a vid and will check it out 

Ok. Don't hurt yourself. 

MaxMercy

Rodney10 said:

You think the eye isn’t good. I watched a vid and will check it out 

The cad cell resistance doesn't tell you if the cell is good or not - it's a starting point to diagnose what's going on with the shutdown. An abnormally high reading could be a bad cell certainly or it's just as likely or more so to be a combustion issue.

Big Ed_4

Fuel supply ? How many units running off the oil tank ?

EdTheHeaterMan

We can all agree that an aquastat is not causing the problem.
If the burner is operating for more than 45 seconds then the primary control is probably fine. BUT There was an article about the old R8184G with the metal cover that was susceptible to a spike in electricity during operation that made the safety circuit partially engage the safety timer heating element. Then it would send a very small amount of electricity to that heating timer. Over time this would build up enough heat to trip the reset contacts. Those controls are so old that you probably don't have one of those, but if you have the removable metal cover R8184G primary control, you should replace it anyway.

If it is not the Primary control and it is not the aquastat, could it be the motor? Is there a dead spot on the motor that fails to start when the motor is warm, but it works fine when it is cooled down? I have had that experience before.

Could the fuel line or other part of the fuel system be compromised? After running for a longer time a clogged filter may slow the fuel down to the point that the flame goes out. We can fix that with a new fuel pump first and if it keeps happening then maybe check the fuel filter.

I have also replaced ignition transformers that worked fine when they were cold but failed to light the spark when they were hot from operation. If the burner cycles off by the limit, then within a few minutes tries to ignite again, that transformer would fail to make a spark.

How about the actual cad cell eye and the wiring harness that connects the eye to the primary control. That could be defective where heat can cause the wires or connections to expand and contract when the burner is warm from operation and when it cools down the poor connection is resolved.

After we spend lots of money on the primary control, a new motor, an ignition transformer, and several other expensive fixes, what should we check next? Those Cad Cell Eyes
are pretty inexpensive. Maybe you should try one of those, but wait until you change out some more expensive parts.

Too bad that there are no good oil burner technicians around anymore. You could sure use one right about now.

EBEBRATT-Ed

Single pipe oil line or two pipe? inside or outside tank? A boiler or furnace running n the same oil line?

Steamhead

EdTheHeaterMan said:

......Too bad that there are no good oil burner technicians around anymore. You could sure use one right about now.

The good ones are right here on the Wall!

Rodney10

I fixed it!!! Simple problem with a clogged up fuel pump filter. I replaced the filter and the nozzle. Yippee 

HVACNUT

Rodney10 said:

I fixed it!!! Simple problem with a clogged up fuel pump filter. I replaced the filter and the nozzle. Yippee 

What's the smoke reading and combustion numbers with the new nozzle? I know the answer. I just want to hear you say it. No pump strainer or is it a Webster pump... or is that what you mean by fuel pump filter?