Oil Furnace only stops when it's raining - WTF

I have a Beckett Model "A""AF" forced hot air oil furnace. The furnace has a Tjernlund power venter, model HST-1.
Since the middle of December 2010 my furnace occasionally stops working. When I hit the reset button it always starts and runs smoothly..sometimes it will not start the next time the thermostat calls for heat, but normally it does continue to operate for an extended period(days). The problem seemed to start soon after I did a bathroom remodel where there was a lot of drywall dust.(possible cause?)

I called a service company who came out and serviced the furnance, they said they didn't find anything wrong, but they performed a standard cleaning. A few days later furnace stoped again, I called the service company again and the tech came out ...he couldn't find anything wrong. On a whim I decided to change the Honeywell ignitor myself..that didn't solve the problem.
For the past two months I've been keeping track of when this occurs. I have a programmble thermostat which is set to raise the heat to 68 degrees at 4PM, sometimes when I get home from work the house has not been warmed to 68 and the ignitor reset light is lit. Everytime this has occured in the past 2 months it's been either raining or snowing outside(high humidity)????? Could it be a problem with the power venter?

Oil tanks are in the basement, caps are tight on fill tubes.

Any advice would be appreciated....I've spent too much on random service calls w/ no results.

thanks

What's your baro set at? how are your electrodes gapped? How are the electrodes set in relation to the nozzle? Many service techs forget to look down the blast tube, on beckett's losing the burner head is common, is the head burnt off? do you have a filter IMMEDIATELY before the burner (not more than 12" of line between the burner pump and filter) if not copper flakes could be clogging your pump screen and/or nozzle. What's the angle on the nozzle? brand? firing rate? have you checked the electric eye? are the transformer contacts clean? Is the transformer giving a strong, stable spark? How old's the motor? does it have dead spots? I would reccomend checking all these items yourself, and if the tech didn't figure out a problem after two visits, get a new tech.

Welcome to the Coal Forums!

It is the power vent trying to tell you to stop feeding the Dubai Nation. It probably really is the PV, try reading up on it, or calling tech support.

PS: You could try burning coal; the Japanese can think of about 3 billion reasons to have a coal fired power grid right about now.

I wonder how many Prius cars it would take on a 'hybrid treadmill' attached to a dynamo to replicate the 6 reactors? Several million?

Don't think it would be the humidity, but possibly the low barametric pressure accompanying a rainy or snowy day.
I'm not too familiar with a power vents, but seems like it should come on and establish a draft before the burner lights. Can you tell if it is starting properly? Does your furnace room have adequate make -up air so there's not negative pressure in the room?
Also, even though the service guy said he cleaned and checked everything, maybe he wasn't thorough (or competent?)
The photo eye that verifies the flame presence could be dirty, or defective. Also, the electrodes could be dirty, or not gapped correctly. The ignition transformer could possibly be suspect, although they generally fail completely . Loose wiring connections have also been known to cause intermittent problems.

Only firing problems I've ever had were due to improperly adjusted electrodes - by "technicians".

Definitely not humidity. My boiler has been firing in this dungeon for 16 years .....

Thanks for all the quik responses..wow ....I posted on a couple of other boards and nobody responded for weeks.
You guys have given me a road map that will hopefully solve my issues.

My gut tells me it is something w/ the power venter. I've read about faulty pressure switches, so there maybe something to the low barametric pressure.

I knew I was in trouble when my oil tech told me "he needed to talk to the old man about this one"

I'll keep you informed...

I wasn't kidding about the cause might very well be the PV circuitry, because if it loses continuity, the blower will cease to run, and the burner will shut down as it should in those conditions. It does not sound like a transformer or electrode issue, and the photo eye should not be affected by moisture in the air. That burner has the pre and post purge, and I'm not familiar with the sequence when using a power venter, but it sure looks like that is the issue. ........
Only on rainy days makes troubleshooting tough. I thought about a loose wire on the TT, so I'd check it over one step at a time and eliminate one source at a time. Do you have an electrical tester handy? Note book? Was the PV cleaned recently, or is it time for a look-see?

Why would you blame the PV when he says the reset of the OB heals it all -- till the next time?

The PV only has a proof of draft - if draft fails it stops boiler operation until the drama is fixed - it also sets a red light on the PV board - very noticeable

if you don't see that red signal and the PV is not running when the OB is not attempting to fire -- ( save the purge cycles )

its ( the HST1 ) not the problem

That's where I was coming from sting, It's not likely to be the power vent; Those burners will fire positive just fine and not shut down. Go over the things I mentioned. The reason I mentioned checking the baro (be sure it moves freely and is set low, -.02 or less on the baro if plumb and level) is because I've seen power venters strip the flame from the retention head because of faulty baro or baro settings causing the burner to trip; typically this problem is made worse by electrodes/nozzle position being incorrect.

I guess I was giving the tech too much credit. I agree with your assumptions, but after two visits, I was fairly sure he or she must have triple checked the burner. I keep thinking of dollar signs every time the tech shows up....plus parts.

if the oil burner has been thoroughly checked, some power venters including turdlunds use a draft proving tube that closes a diaphram operated switch when sufficient draft has been proven. then the FF terminal for the cad cell is closed and burner keeps running. I have found this tube blocks up with carbon.

my 2 cents and a quick check

had same problem from a bad delivery of oil...

use a can and run your bypass on oil pump and see what

the oil looks like.... mine had 2 gallons of water....

had a becket gun .... worked fine since... these

were new inside tanks.... soo a bad load of oil.

good luck