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Dirk-D
02-25-2011, 08:28 AM
For starters I have a forced hot air system w/ a Beckett oil burner, and tjernlund power venter.

Over the past couple months the furnace occasionally will not turn on when the digital programmable thermostat calls for heat. The ignitor reset button needs to be pushed to restart the furnace, the furnace will ignite on the first try and stay runnig w/o any issues for a few days.
The problem usually occurs during the day...when I leave for work (6:30 AM) the programmable thermostat is set to 60 degrees, the furnace is set to kick on at 4:00 PM when the thermostat is set to 68degrees.
A few times a week, when I get home from work the house has not been warmed to the set 68 degrees. The furnance typically doesn't need to run during the day because the temperature in the house does not drop to 60 degrees.

I've had the furnace cleaned and serviced, and the technian could not find any problems. I replaced the Honeywell ignitor w/ a new one. I also cleaned the "air sensor tube" that is located on the power venter with compressed air. Neither of these "repairs" solved the problem.

This problem started about 2 weeks after I did a bathroom remodel where there was a lot of dust..not sure if this could be a contributing factor. I replaced the air filter, after I completed the work.

Thanks for any assistance.

david_griffin
03-08-2011, 02:19 PM
Bathroom remodeling may be irrelevant or a coincidence.
Some things I would check:

1. electrodes this is the main cause of misfire. Maybe they are too far or too close to the nozzle.
2. You should buy pressure gauge and vacuum gauge and you should measure oil pressure during operation. You will find a box for oil serviceman on "the biggest auction service" with all hoses and everything you need.
Serch for
"oil burner pressure"
"oil burner gauges"

3. Check the photo resistor whether it operates properly.

4. maybe air/fuel mixture is not proper. Search auctions for "combustion analyzer" maybe you find something cheap.

5. It can be caused by any factor... you have to eliminate one by one.

Believe me it is not so hard.

In general you have to download PDF manual for your burner and you should read it.

Terry
03-08-2011, 02:25 PM
I also cleaned the "air sensor tube" that is located on the power venter with compressed air.


I looked at a furnace the other day that had the connector for the vacuum hose blocked. I was able to clear the fitting with a small drill bit.

Tom Sawyer
03-08-2011, 05:57 PM
Draft has to be proved before power is sent to the primary control so... It's not the power venter. From there though it could be any one of about 20 different things, however that the problem usually occurs after the unit has cooled down I have to suspect there is a problem with ignition and or the nozzle. Low voltage may be another issue too.

david_griffin
03-09-2011, 02:02 PM
Yes, 80% it is ignition problem. Electrodes, voltage from transformer. Take out this burner and try to observe ignition electrodes without fuel.