I have a Weil McLain boiler and for the last two days after the thermostat turned on the boiler did not until I reset the power in the boiler. Why is this happening ?

Two months ago I replaced the thermo cutoff fuse (thermo rollout) because it went bad. I replaced the same part last heating season. I think the rollout switch maybe going bad again. What can be causing this?

 

You are resetting by turning the power off & back on? If so, I doubt the rollout is your problem. Most rollout switches are either manual reset or have a fuseable link like yours. What is the make & model of the ignition control? Is the ignition system spark to pilot then main burner, standing pilot, hot surface, or direct (spark to main burner)?

 

I have a Weil McLain EG-50 gas-fired boiler. I'm not sure about the spark.

 

Yes I am resetting by turning the power on and off.

 

On that unit is a vent damper. You will notice that it has a manual/automatic switch on it. The vent damper is on the flue pipe that come out of the boiler and has an electrical connection to it.

FIRST check to make sure that all the connections are good and tight and that the 'interlocks' are secure. I would try to put it in manual mode with the butterfly open (damper) and see if this makes a difference.

What you are describing sounds like a safety circuit problem (roll out sensors, blocked flue sensor, high limit sensor, etc...) BUT resetting the power would NOT cure this condition.

Or it MAY be a damper micro switch problem. It MAY be something else like the 'brain'.

Like grady stated, it most likely is NOT a roll-out sensor because turning on/off the power does NOT reset a roll-out sensor nor a high limit sensor, nor a blocked flue sensor.

Re-setting the power however DOES reset the 'brain' and resets the flue damper on some units.

I'm NOT saying that this is definitely the problem but you need to rule out what it isn't so that you can find out what it is. Are you with me on this? Sorry if I sound simplistic, but this is the way I work in the field when I am not sure what it is.

You need to rule this out by opening the damper and leaving it in manual mode to see if there is a difference.

If the problem persists, let's go back one step and verify that the safety circuit is NOT at fault.

You may want to try (if you are good with electrical circuits) is to locate the two wires (in and out) from the safety circuit and next time this happens, shut off the power, pull the two wires from the terminals, and check for continuity. There should be a dead short. If not, there IS a problem with the safety circuit or high limit sensor.

IF everything checks ok here, then we will have to check the ignition system and flame sensors. Since you were not sure of the ignition type, and this unit comes with either standing pilot or spark ignition, and assuming you are not up at 5AM, I gave whatever info I could here not requiring an immediate response.

LATER, maybe Grady or someone else can assist you with the ignition and flame sensor part of the course!

Keeping it simple.

Keep us POSTED.

Charlie

 

I have a spark ignition.

The vent dampener is electronic and I did try with a pair of pliers to move it the open position but I did not want to force it and break it. When the boiler first kicks on I do hear it open and it sounds normal to me. Should I force it open?

 

Did you move the little switch to 'manual'?

You need to determine whether or not the vent damper is operating correctly and sending the 'open' signal to the system or not.

If it is operating correctly and you can eliminate it as the problem, then you can start ruling out other things like flame sensors, faulty ignitors, etc...

I would leave it in manual mode and make sure it is open for now.

***This should eliminate it as a possible source of trouble for now. You can see if things operate differently then and may make it easier to locate the problem.***

Make sure that once it is in manual mode you move it to open position. DO NOT FORCE IT! Notice which direction you need to turn it.

Charlie

 

I don't see a manual switch. I'll turn up the temperature and it will kick on. With a flashlight and mirror I'll be able to see if the dampener opens.

Also when the boiler does kick on after I flip the power switch I smell a little gas.

 

I have yet to see a vent damper without one. It should be on the vent damper motor itself. Maybe there is a cover that needs to be removed first? Usually the switch is accessable without removing anything, but it should be there.

I will try to check the site later if you still cannot find it.

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The smelling gas part I do NOT like. Spark ignition is like a spark plug or ignitor on your stove. It sparks once or twice and the pilot lights up (or should). Then the pilot light sensor confirms that there is a pilot present (for safety reasons) BEFORE opening the MAIN gas valve upon call for heat.

Either the main burners are not catching right away (thus the smell of gas) and the unit is shutting down on safety, or there may be some venting problem or pilot light problem with the unit (which may also cause a gas smell).

If you turn the gas valve to 'pilot only' setting (if there is one, some only have on/off) can you see if there is a FULL pilot? *IF you do not have a 'pilot only' setting on the gas valve you will have to look at it with it 'on', but be careful, do NOT get tooooooo close! You are looking at the pilot and the sequence that follows at the heat call.

The thermostat will call for heat, the ignitor will spark once or twice, then the pilot should light and stay lit. When the pilot sensor confirms that there is a pilot present, then there should be a 'click' of the valve which opens the main burner gas flow. There should be a second 'main burner sensor' to confirm that the main burners are lit, but some units do not have them.

IF the damper microswitch is working ok then you MAY have a dirty or faulty MAIN BURNER SENSOR or faulty PILOT SENSOR causing the problem. I will assume that you have a HEALTHY pilot!

I am ASSuming that there is no BUZZZZZZZZZZing coming from the 'brain'.

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A process of elimination is required to find the problem, but SAFETY issues MUST be addressed FIRST!

IF you are not comfortable doing all this or if you feel it is beyond your expertise, please call a technician. We cannot guesstimate what your level of proficiency in these matters is, and this type of repair can be VERY risky to someone not thoroughly familiar with the safety system gas fired units have, (not to mention that you stated that you smell gas sometimes).

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IF you see a poor pilot or partial lighting of the pilot bar or burners, SHUT OFF the unit and call a technician! If the flames want to come towards the OUTSIDE front, something is preventing proper venting!

ALSO be aware that a single use roll-out sensor CANNOT be subjected to excessive heat so------so if you are doing this be ready to shut the unit down immediately if the flames apppear to escape the combustion area, or you will most likely spend alot of money and time replacing these.


Charlie

 

There is no buzzing from the brain.

I called a boiler tech he looked around a little but did not really see a problem. He was looking to see if I was hitting a reset button. I explained that all I do is turn the thermostat on and it usually works fine. But twice in the last 2 days I had to hit the power switch on the boiler to get it to start up. He was stumped. The tech called someone and that person was stumped too. I have to call when the problem is happening.

I'll go check the pilot light. I am pretty sure I saw a pilot only setting.

 

It's kind of like the toothache that has been bothering you for the past week but goes away ten minutes before you sit in the dentist's chair!

Charlie

 

update:

I am still having the problem. I have had to replace the thermo roll out twice since I posted here. The funny thing is that stops working on the coldest nights where I set the thermostat to kick on through out the night.

When I was able to catch what the furnace was actually doing I heard it kicking on for a minute or two then kicking off and it would continue to do that until the thermo roll out blew or until I power cycled the boiler.

 

There is not much more I can help you with here because the problem seems to be intermittent and unpredictable. A GOOD technician should be able to find the problem if he is there while you are having it.

He needs to check the safety circuit BEFORE re-booting the system (turning it off then on again) to see if the safety circuit is at fault or not.

He needs to check the control voltage at various points to make sure it is present where it is supposed to be.

He needs to determine if the sensor at the damper might be at fault. This is the only part that I can think of that may move mechanically when you re-boot the system and re-activate the micro switch which MAY enable the burners. WITHOUT activating this micro switch the burners will NOT come on. I seriously suspect this may be the problem if not the brain.

IF EVERYTHING checks good, then he should replace the brain (ignition module).

Wish I could help you better.

 

That thermal roll out blowing is not a good sign. It often indicates a problem with venting. This problem could be caused by a dirty boiler, partially blocked vent (pipe or chimney), a poorly drafting chimney, or sever negative pressure in the house.

 

The roll-out sensor blowing out several times is usually due to a venting problem as Grady points out. A roll-out sensor however CANNOT be reset by a simple rebooting of the system as you described, turning the power on and off. That is why I suspect that the problem MAY be with the vent damper.

Since you had a technician there and the boiler was presumably working then and he made no mention of an obstructed vent, I will assume that the vent was open and clear at the time. A technician can usually spot a poorly venting boiler by the character of the flame, especially if it is blowing out roll out sensors!

If the vent damper was actually closed and the micro switch got stuck or malfunctioned and the 'brain' thought that it was open, you would have the burners come on with a closed flue. Another sensor may actually stop the boiler, such as an automatically resetting stack mounted spill sensor, and then the boiler would fire up again when it cooled off for a few minutes. Then the process would continue again and it would repeat. Perhaps by turning off the power and then back on the damper mechanism resets to 'home position' and hits the micro switch and things go back to 'normal' for a bit. Then a week or two later-same problem.

THIS is why I originally asked you to locate the 'manual/automatic' switch on the vent damper assembly. If you put it in 'manual - open' position you will have a vent damper that is open all the time. This is not the efficient way to run a gas boiler, BUT, it MAY help you find out if the problem is in the vent damper unit, or something else. IF the boiler has no more problems with the switch in 'manual - open' position, I am willing to bet my paycheck that the vent damper is at fault. If the problem persists, then you can be pretty certain that it is something else that is causing the problem.

Sometimes in this business you need to find the problem by a process of elimination. THIS is one of those times. The average technician may not have the time to spend there to find a problem such as yours and will usually start the process of elimination by CHANGING a part at a time until he hits pay dirt!

If you have deep pockets, start changing one thing at a time (or let the technician do it). If you have the time but not the money, start by finding that little switch and putting it in 'manual-open' mode first so that we can determine if the damper is the problem.

Some pictures of the boiler, vent damper, flue pipe from the boiler to the chimney would be helpful.

Good luck.

Charlie