White Rogers Cycle Pilot

Larry (from OSHA)

Any ideas about erratic operation on the cycle pilot spark type system. The system will operate normally for a while, then I can hear it click from I think the gas valve and the flame drops out. It goes right into restart cycle with a 30 second pre-purge and then pilot lights up. Main burner fires after the pilot has proven and it runs for a while again. Sometimes it will run normally for extended periods of time and other times it will act up frequently like several cycles in a 5 to 10 minute period. The mercury flame sensor is good. The draft switch is good. The pre purge timer is good. The main system relay is good. The grounds appear to be good. I would think that if the solenoid on the gas valve was failing, it would just fail and not intermittently. The spark control sparks just fine, but beyond that, I just don't know.
Has anyone seen this type of failure, and know what needs replacing?
As always, your help is appreciated.

pperkins

YES I HAVE.IF ITS A WHITE ROGERS GAS VALVE, THERE'S A RESISTER FOR THE PRESS SWITCH INSIDE GAS VALVE..
IS THIS A WEILMCLAIN BOILER?














/

Unknown

Mercury Pilots

have to be cleaned. The mercury has to stay at boiling temp during the entire period the pilot is lit. The flame may look good but pull the pilot and clean it anyway. Nine times out of ten that is all it takes. The tip of the mecury sensor should glow cherry red, if it does not open the pilot adjustment screw to allow a little more gas to get the element to glow cherry red. The flame should be hitting the upper 1/2 to 3/8 of the sensor.

Larry (from OSHA)

weil mclain

Yes it is a weil mclain HE series 2 about 20 years old. The valve is about 10 years old.

Unknown

pperkins I have not heard

about a resistor inside the gas valve. Is that something new White Rodgers has come up with? There was a resistor that was externally used on some older White Rodgers valves with pressure switch problems. It was called an EQSO resistor and was plugged into the mercury sensor SPDT plug on the valve. That problem with pressure switches was as best I knew solved with a "beefed up" pressure switch.

Glenn Harrison_2

If I read your post correctly,

the main burner AND pilot goes out? If this is so,and based on the fact that you say it goes into the 30 second pre purge, and the fact that the drop out is very erratic, I would bet your dropping out the pressure switch. Have you noticed or thought about if this happens more frequently on windy days? Have you put a differential manometer on the two ports on the pressure switch? Look on the pressure switch and see if the rating is stamped on there. If not most of the HE II units I have worked on have either a .85" or .95" differential. I would bet that either the flue pipe is full of debris, or the diaphram has a pin hole causing it's sensitivity to be reduced. I have had to replace a few bad switches on units that ran just like yours. One last possibility is the inducer is not running at full RPM. I've had this happen once, and it was a real pain to finally determine.

Larry (from OSHA)

I think you lost the bet Glenn

Flue pipe is clear and no pin hole in the pressure switch.
My thoughts were also headed towards the pressure switch too. After checking with my multi-meter, it seems to work ok, but, might not as the micro switch will click but not make the contacts close with a little bit of vacuum applied and with a very little bit more, will close the contacts. However, I'm not sure that is/was the problem. I cleaned and tightened the quick disconnects at the rollout fuse and it seems to work ok for the moment. This whole thing seemed to be somewhat ambient temp dependent based on how long of a burn it was. So, we'll see.

Thanks to all for the input.

Larry

Dan Foley

HE Plugged?

Have you pulled the collector box to make sure the heat exchanged is not sooted up or plugged? -DF

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Glenn Harrison_2

I never said I was a winning gambler >

But I frequently bet on the answer based on past experience. If it turns out to be the fuse link, then another lesson learned.

One thing, if you have a manometer, attach it to a tee fitting, then one hose from the tee to the switch, and then another hose you can suck on. Gently suck about 1" out of the switch, and tighly pinch the tubing you were sucking on, and watch the manometer. If the pressure holds, the switch is good, if not the switch diaphram has a leak.

I just had one other thought, if this occurs due to length of run time, maybe the timer gets hot and drops out.

This sounds like one of those calls that keeps me awake at night. Pleas let us know what the outcome is.

Larry (from OSHA)

Yes Dan

I've done that too. The pressure switch seems to have more than enough across it to work. (I don't have a manometer) Quite frankly, I think this is an electical glitch. Have you ever seen a thermal rollout fuse or any other part in there become erratic and not quite fail completely? Thanks for your input.

Larry

Steve Miller

don't have a manometer?

I don't see how you can do a service call without a manometer. You really need a Magnahelic gauge with a +- 1.0 W.C reading, teed off the pressure switch tube along with a volt/olm meter on the contacts of the pressure switch to know if it's cycling on the switch. The pressure switch may be good and doing it's job. I've seen where the venting is maxed out on it's equivalent lenght and fittings, work for awhile when the induced motor is new and later, the pressure switch would open and cycle the burners because the induced blower doesn't have enought oomph to close the contacts. In that case, you'd have to address the venting. Have you checked the filter? It may be cycling on the limit from a clogged filter or undersized ducting.

I couldn't tell if you're a homeowner working on your own furnace or a new service guy just out in the field. If you're in the field, buy the tools you need even if your employer doesn't supply them because then, they're always yours. Also, get all the training you can. Most supply houses have occasional classes that you can get a lot from. If you're a homeowner, I'd get a professional out to diagnosis the situation.

Steve M

Larry (from OSHA)

> I don't see how you can do a service call without

> a manometer. You really need a Magnahelic gauge

> with a +- 1.0 W.C reading, teed off the pressure

> switch tube along with a volt/olm meter on the

> contacts of the pressure switch to know if it's

> cycling on the switch. The pressure switch may

> be good and doing it's job. I've seen where the

> venting is maxed out on it's equivalent lenght

> and fittings, work for awhile when the induced

> motor is new and later, the pressure switch would

> open and cycle the burners because the induced

> blower doesn't have enought oomph to close the

> contacts. In that case, you'd have to address the

> venting. Have you checked the filter? It may be

> cycling on the limit from a clogged filter or

> undersized ducting.

>

> I couldn't tell if you're

> a homeowner working on your own furnace or a new

> service guy just out in the field. If you're in

> the field, buy the tools you need even if your

> employer doesn't supply them because then,

> they're always yours. Also, get all the training

> you can. Most supply houses have occasional

> classes that you can get a lot from. If you're a

> homeowner, I'd get a professional out to

> diagnosis the situation.

>

> Steve M

Larry (from OSHA)

Steve

Thanks for your input. I am a homeowner and this appliance is a boiler.

Larry

Mitch_4

DIDN'T White roger

make an add on resisitor as a service kit for the gas valves that were lacking one? I remember carrying them in my truck at one time.

curiousity kills

Pull the three prong adapter from the mercury flame senser out half way and jumper out the two poles closest together sit and monitor the system this will rule out the fame senser. If the flame doesnt cut out replace the senser.

Larry (from OSHA)

Good tip

Thanks for the suggestion. I think the flame sensor is good, but, I'll try your idea. I hate intermittant problems!!!

Larry

Dale

Gas valve resistor

This WR valve is notorious for having a bad INTERNAL gas pressure switch, it usually looks like a main valve being powered on then off, get the correct resistor package (I think 40 ohms but Timmie will know), put it in parallel with the pressure switch and the problem may go away.

Dale

Top of valve

There's a pin connection at the top of the valve, you unplug it and put in the resistor card with holes in it to align to the pins, this is the easiest way to add the resistor.

Mike Reavis_2

I would also check the metal taps

at the collector hood. Pull the flex hose off gently, and push a wire, or correct size drill bit into the opening of the tap. It is just a precaution--but I have seen them get rust, and other debris in them. Be careful not to send the drill bit too far into the tap, and lose the bit in it. I've never done it yet, but everytime I do clean one with a drill bit I get the same feeling as when I walk over the top of a large storm sewer grate in a parking lot while holding my car keys in my hand!

Larry (from OSHA)

Dale

That sounds exactly what this unit is doing. Thanks alot for the resistor suggestion. Do you happen to know why this fixes the issue?

I really appreciate all the feedback.

Larry

Larry (from OSHA)

this looks like it

from the WR catalog

http://www.white-rodgers.com/pdfs/catalog/cat_page_074.pdf

Larry

Cheeze-Tech

A couple more thoughts

How old is that mercury pilot assembly? There should be a four digit date code on it (week/year). If it is 8-10 years old it is probably bad. My experiece with them is that when they get old they will drop in and out just like you describe. I think if it is over 5 years old I'd probably replace it.

A second thought though less likely, I have run into a couple of gas valves that had and internal pressure or sail (flow) switch that could be going bad. If you can read a wiring diagram you would notice another switch in line with the coil for the gas valve. From the looks of your pictures I don't think yours has it. I would check the merc. pilot first.

Good luck!

Cheeze-Tech

A couple more thoughts

How old is that mercury pilot assembly? There should be a four digit date code on it (week/year). If it is 8-10 years old it is probably bad. My experiece with them is that when they get old they will drop in and out just like you describe. I think if it is over 5 years old I'd probably replace it.

A second thought, though less likely, I have run into a couple of gas valves that had and internal pressure or sail (flow) switch that could be going bad. If you can read a wiring diagram you would notice another switch in line with the coil for the gas valve. From the looks of your pictures I don't think yours has it. I would check the merc. pilot first.

Good luck!

Cheeze-Tech

A couple more thoughts

How old is that mercury pilot assembly? There should be a four digit date code on it (week/year). If it is 8-10 years old it is probably bad. My experiece with them is that when they get old they will drop in and out just like you describe. I think if it is over 5 years old I'd probably replace it.

A second thought, though less likely, I have run into a couple of gas valves that had and internal pressure or sail (flow) switch that could be going bad. If you can read a wiring diagram you would notice another switch in line with the coil for the gas valve. If that was the case you would need to replace the whole gas valve. From the looks of your pictures I don't think yours has it. I would check the merc. pilot first.

Good luck!

Larry (from OSHA)

Mike

At least if you lose a drill bit in the collector box, you got a good chance of retrieving it. (A little bit of extra work, but...). As for me, I'll be walking AROUND those large sewer grates!

Larry

helpingothershelpthemselves_2

Am I correct by saying "hydraulic safety switch " instead of "Mercury Flame Sensor " Since the industry is trying to get away from admitting that mercury is a viable and still used compound. Politically correct ?

Larry (from OSHA)

Update - Attention Glenn Harrison

Just so you know, crow tastes like chicken.

Did I say you lost the bet? I meant to say I did not check that pressure switch closely enough. You said you wanted to know what the deal actually was so here you go...It seems that the pressure switch after 20 years got a little less flexible (just like some of us!) and with a new pressure switch life is good.

I want to thank everyone again who posted, as all the suggestions were both relevent and worth looking at.

Larry

Glenn Harrison_2

Just glad to hear you got it figured out,

and thanks for letting us know.

Hmmm, maybe I should play the lottery tonight

By the way, crow tastes better with mayo, trust me, I know. Been there, done that, hated the after taste.

Have a good weekend, Larry.

Glenn