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Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 6022
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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I have a Weil Mclain (CP5470602) boiler which heats our domestic

Customer Question

I have a Weil Mclain (CP5470602) boiler which heats our domestic hot water through an indirect fired water heater. In the past 2 weeks, has shut down, though the circulating pump is running. I called in a repairman, who replaced the oil pump on the first occasion, and the boiler worked for two days, and defaulted to the same condition. The second visit he replaced the the burner motor. The boiler worked Mon - Sat until it again defaulted to same condition. Any ideas?
Submitted: 2 years ago.
Category: HVAC
Expert:  Phil replied 2 years ago.
Hello. It sounds like the man is not an oil burner specialist and that he is guessing...tell me a lot about your technical skill sets so that I can coach you on a diagnosis or recommend a qualified oil burner man to you. In that case tell me which direction you are from the center of the nearest town or city and I will see who is in the area with high customer rating scores. We can go from there.
Customer: replied 2 years ago.
On my old boiler I used to change tips, filter, pump screen etc. The new burner is about 5 years old and have been intimidated by it. I was just curious if this symptom is something that is common or at least a condition that someone was familiar with
Expert:  Phil replied 2 years ago.
So far it sounds like there is an air leak in fuel line that is allowing air into the pump, and that the tech is using the air bleed on each trip and has failed to find the loose or cracked or leaking fitting.
Look for a drop of fuel oil hanging under any part of the burner especially where the fuel line connects to the burner, if you find a drop of oil, you found the problem..its sucking air then vapor locking.
That is my best guess so far.
If you can get me the brand and model number from the oil burner I will see if I can locate a service manual for it.
If I miss you tonight I will respond first thing in the morning.
Customer: replied 2 years ago.
Phil, the tech did say he could not turn the oil pump by hand, prompting the replacing. I'm guessing an air leak could seize the pump? I will check for leaks in morning
Expert:  Phil replied 2 years ago.
Hello again,
The pattern of events with this technician point to gross incompetence... I can't be 100% sure of that from here, but I am 99% sure.
An experienced tech would remove the rotor access plate on the pump before condemning it and clean out any debris that might be in there.
An air lock will not cause the pump to seize... it will simply not allow the pump to move oil when it rotates.
If you had worked on oil burners before you should not have any problem with this one. No need to be intimidated. Get me the brand and model number of the oil burner and I will see if I can get you a service manual for it.
We can go from there.
Customer: replied 2 years ago.
I have the basic manual they gave me when the unit was installed. Its a Weil McLain model WGO 3
Expert:  Phil replied 2 years ago.
Hello again, they use a range of different manufacturers for the oil burner assembly itself, the brand and model number of the burner will be on the burner itself. Beckett most likely, but there are several other brands they may have used. .
Expert:  Phil replied 2 years ago.
You may have to remove the outer cover that fits over the oil burner before you can get to and read its brand and model number name plate.
Customer: replied 2 years ago.
The burner is a Beckett model AFG
Expert:  Phil replied 2 years ago. will be referring to this manual... is this the manual you already have?The boiler should have a combustion analysis and smoke test done every year or so, If the fuel nozzle becomes partially clogged, or the infra red flame sensing eye has accumulated soot due to the resulting incomplete combustion, it will fail to sense flame and shut down the burner. If the fuel mix is too rich or not being atomized properly due to a partially clogged nozzle, the burner will fail the smoke test and in very short order the heat exchanger inside the boiler will clog with soot, or worse, rock hard carbon deposits. If you are reasonably handy you can unbolt the burner assembly from the boiler and inspect the heat exchanger for such carbon deposits. as those build up, air flow past the burner head is reduced and the mixture gets richer and richer... causing serious carbon deposit build ups. Had the technician inspected for that visually? or done the necessry combustion efficiency tests? If not... that is the problem. The primary focus needs to be on who did the the work, if you trust and incompetent technician who has not performed the basic tests needed, then there will be ongoing problems. Look it over, let me know what you think.
Customer: replied 2 years ago.
No, the manuals and addendems are for the boiler itself
Expert:  Phil replied 2 years ago.
We need to discuss in great detail when the last combustion analysis and smoke test was done, and when the last inspection and cleaning of the boiler heat exchanger was done.
Unless those have been attended to there will be problems with boiler.
Tell me about that please, we can go from there.