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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22627
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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Hello, I have a Duo Matic/Olsen (BCL115H) Oil fired furnace,

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Hello, I have a Duo Matic/Olsen (BCL115H) Oil fired furnace, it is randomly shutting down sometimes during start up and sometimes during heat cycle and it may go for several cycles before failing. I have replaced in line filter, replaced burner nozzle and cleaned electrodes, tested and verified photocell operation, checked flue and chimney, verified control thermostat operation, verified blower thermostat operation. What should I check next if anything?

what did your test of the flame eye consist of?

Customer: replied 4 years ago.


Continuity with and without light.

how many ohms did you have while operating?

Customer: replied 4 years ago.


I actually removed I from unit and just checked to see if there was a continuity change with and without light source. I did not check it while operating. The unit is similar to a push and twist light bulb, so it would be difficult to access the contacts while operating, also it is on the bottom of the transformer so that would need to be open to access it.

Actually you test from the lead ends at F anf Terminal at the protector relay.

There are 2 reasons for a trip:

One is flame is not there thus the cad cell faults the control.

Two is that flame is there but the is a mechanical fault with the cad cell or protector relay.

So the bid part is finding if we have a problem with flame being present or flame faulting.

You can do any testing of the cad cell from the protector relay instead of under the transformer.

Cad cell testing manual

Now as far as flame leaving _ this can be bad coupling slipping on pump, bad pump, vacuum leak, etc

The process is eliminating and setting a schedule of fault,

I found one that only faulted in the morning,,,,it was a vacuum leak that after the unit stayed off for 4 hrs or more the fuel migrated back into the tank cauasing an early am shut down,

Customer: replied 4 years ago.


I have 380 to 450 ohms across F F (they are actually wire ties not terminals) when operating. ohms when idle was spiking hi to low, so not sure what that is. The fuel tank is above the burner so I should not have drain back. I did notice on first start up the motor sounded like it was working hard for a couple seconds.

is the fault after being off a while?

Customer: replied 4 years ago.

No it tried firing again shortley after I was testing it and it failed.

Thank you,

what is current pump pressure and has the coupling been checked?

Customer: replied 4 years ago.

Do you have any schematics/instructions for this proccess?

I am afraid I dont as this was curriculum in a course.

Do you know how to attach a pressure gage, where? and then how to adjust?

I am all for homeowners doing what they can, but this is a critical setting in dealing with fuel oil. The air must be set right and the oil pressure set right.

The readings should be taken/ adjusted for draft, breech draft, stack temp, stack c.o., smoke the price of oil these must all be set correctly.

Oil is different han gas or propane as you are burning a liquid...and all these settings are critical.

Customer: replied 4 years ago.

I understand, what should the pressure be?

Pressure needs to be 150psi.

I am sorry not to divulge more but an oil furnace is a wonderful unit that can be tuned to provided a given efficiency. You cannot do that with other furnaces...but it takes testing and settings to arrive at proper operation.

Customer: replied 4 years ago.

No problem, thanks for your help.

I wish you well,

I am available for follow up for 30 days after the answer is make sure you rate and then return follow up as needed.

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