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spikie 01-23-2013 07:13 PM

problem with 50+ yr old oil furnace
Have a 1960 Preston oil furnace which is having problems.. it injects oil and ignites but won't stay lit.. I ran out of oil, so I put in 25l of pump diesel until my delivery showed up.. so it ran fine with pump diesel... Took about a min to start.. once I got the oil delivered is when problems started.. here is a video of what the unit is doing..

I have bled the lines, cleaned out the inline filter and pump filter, I have cleaned the injection tube (not sure what its called) but I replaced the brass leads on it that connect to the transformer as one had a crack half way thru at the 90 bend and replaced the nozzle. I have bled about 1.5gals so far.. I assume that would be enough to get any air out of lines. With the bleeder nut removed to pump starts and runs.. seems to have pressure as it shot 6+ft when I didn't have the plastic bleed tube lined up right.. I also cleaned and tested the CAD sensor and it reads 43 Ohms with led flash light pointed at it and increase as the light is pulled away all the way to infinate when dark as it should..

Any help and or idea would be greatly appreciated.. It will run like shown for about 5 mins until the overload on the motor trips from it getting hot..


beenthere 01-23-2013 09:48 PM

Limit, burner motor or primary control.

hvac5646 01-24-2013 05:11 AM

is that the new pulse technology:jester: oil furnace

gregzoll 01-24-2013 07:49 AM

Fifty years old, time to replace with a newer higher efficient unit.

Mr.HVAC 01-24-2013 11:48 PM


Originally Posted by gregzoll (Post 1100788)
Fifty years old, time to replace with a newer higher efficient unit.

Same advise here.

Why put more money/headache on something this old.

Finding someone who is experience on this unit is either retired or dead.

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