Weil-Mclain HE II-3 on and off

DNAS2019

Boiler will turn on and off till the service switch is turned off, pressure switch tested and by passed properly, no change, HSI replaced, no change this unit does not have a flame sensor most likely the flame proof is done by the HSI, but any way the HSI goes off immediately gas valve is open, yes we have flame for few seconds then shuts off and repeats the cycle again, the roll out sensor by passed works for about 2 minutes or longer then shuts off and restarts, thinking we have a bad control ignition module, have any one experienced this with a Weil Maclain? hate to replace an expensive part and not fix it.
Thank you

EdTheHeaterMan

sounds like your flame sensor is not getting the signal to the control

You could have a dirty flame sensor
You could have a defective flame sensor
You could have a bad ground circuit from the flame location to the control ground.
Or the actual control may be defective.

The first (cheepest) step is to clean the flame sensor.
second step is, run a dedicated ground wire from the flame sensor area to the control. (Can explain that in detail if needed)
Next is to replace the flame sensor
If all else fails then replace the control.

DNAS2019

Thank you for the comment, this unit as mentioned has no flame sensor, the HSI is most likely what tells the ignition module that there is flame, it runs for more than 3 minutes or so if roll out sensor is bypassed, then repeats its cycles again and again, if not bypassed then is a matter of seconds to shut off and starts again and again but never goes to a lockout.

109A_5

Hello @DNAS2019,
Is the Rollout switch open or maybe it has a loose connection ? Why would it change things if it is OK ?
Does the flame thoroughly contact the HSI ?
With the power off Control Module Connectors disconnected and reconnected.
Other connections verified that they are not lose.
All grounds secure.
Power on indicator is on steady through the whole cycle ?

Have you gone through the troubleshooting charts found here ?
https://www.weil-mclain.com/sites/default/files/field-file/he-ii-hsi-control-supplement_1.pdf

DNAS2019

Hello 109A_5.
I have made sure flame is in contact with the HSI, all connections has been checked , all grounds, now the fact the it never goes into a lockout is what makes me think that ignition module is bad, because it doesn't thinks it has an error, the venting system has been checked and flame does not come back to rollout switch, unless I have a bad rollout switch and a bad control module, with all the sensors by passed it runs for 3 minutes or so and cuts off the 24V to gas valve, we can hear the relay clicking on and off louder then it usually does with a new module, the greenlight is solid all the way, and rollout switch is opening a little too son that is why I bypassed it, I did check it at the beginning of operation, so that I am sure is out of range as it is a thermal fuse with a resistor as fuse, ordered it already and left the boiler off and with notes no to be turned on.

109A_5

Hello @DNAS2019,
To me it seems odd how the symptoms change with the things you have done. I was wondering if there was a power problem. So when it cuts off the control module 'forgets' where it was in the cycle and just starts over, so no lockout. 24 VAC is good ?
It would not surprise me if there was a poor solder connection on the control board. BTW I am under the impression that the HSI is the flame sensor also, using flame rectification for detection so flame quality is important.

DNAS2019

Indeed 109A_5,
Very odd situation, not really an error code is displayed, only restarts, never locks out, I did replace the HSI to make sure is sending the right feedback to module and it didnt change one bit, like i said rollout switch is the only change the occurred staying on for longer, I have a steady 24v at gas valve terminal and it cuts off the power real quick a comes back on, so yes most likely a broken solder connection somewhere in module, could be by the high temp wall, didnt take the module out to check, is the only one that didnt get checked.

109A_5

Hello @DNAS2019,

If you have a multimeter I would ohm check the Rollout switch. Also the Temp limit switch is in series with the Rollout switch, are you bypassing the Rollout switch directly at the Rollout switch ?

Does it meet these timing listing ? I'm surprised it does not lockout. Could it be loosing the call for heat ? Have you bypassed the thermostat ?

DNAS2019

Hi 109A_5,
I do have many multimeters, using the fieldpiece for that continuity check, the temp limit switch seems to be working fine, the rollout switch is literally jumped with a wire jumper, the pressure switch is jumped after the blower starts to make sure it reads the switch in open state, I have ordered the module will update if that fix it, the only thing is really weird is the fact that with the rollout switch jumped it runs longer, not even close to satisfy the temp adjusted to 190.

109A_5

Hello @DNAS2019,
I'm generally not a big fan of continuity checks. Since it varies widely (in my opinion) between meters. I have seen some multimeters say 100 Ohms is good continuity. I much prefer an Ohm reading. I would think the rollout switch would be no more than a few ohms and a bypass jumper should make no difference if rollout switch was good.
I'm just wondering if a higher than normal rollout switch resistance is influencing a faulty electronic control on the Boilers thermostat connections.

DNAS2019

Hi 1095_5, Its possible as I am not sure what is the resistance in that rollout switch should be, but the OEM one is also ordered along with ignition control module, hoping this will fix it, there arent many components to fail in this setup.

Shane_2

I would try a different HSI (glow plug) before replacing the ignition module. I have had brand new ones not provide enough juice to light the gas valve even though they appeared to be working correctly. Make sure the little hood is in place on the glow plug.

Also double check the chimney even thought the fan and pressure switch may be working fine.

Make sure all burner doors are in place for testing as well.

Remember working on quite a few of that model over the years with the same problem.

DNAS2019

Hello Shane_2
I hear you, thanks for your input, I have swapped the HSI, Although it makes sense what you are saying the flame comes on but but then goes out few seconds after it came on, like the control powered the gas valve but then some type of amp draw shuts the 24v to the gas valve, checking the voltage at gas valve is on and off in few seconds then eventually HSI feed back tp control is lower then it should be, its a trick situation where many things could be happening, by passing all safety the control still shuts the gas valve off.

109A_5

Hello @DNAS2019,
I have read that flame detection with a HSI may be not as robust as one would think or compared to a dedicated flame sensor rod type setup. I wonder if not all HSI units are made the same. If when they are used for situations requiring Flame Rectification for flame verification maybe they are different, like a different material or alloy. Kind of like sensors for modern cars OEM sensors versus problematic aftermarket sensors. Also Flame Quality may have a huge influence if the technology is a bit marginal anyways. So I can see where the air flow through the system could be an issue and not so obvious.

And then I always wonder where there is no apparent dedicated Ground bonding path (inside the equipment jacket) for the purpose of the Flame Rectification system there could be marginal issues too. I think I looked earlier in the thread at the wiring diagram for your unit and only saw an equipment ground to the building electrical system but not a dedicated Ground (or return path wire) for the purpose of Flame Rectification.

And also as stated before the jumper on the Rollout sensor changing the run time of the burner seems to be an odd symptom.

DNAS2019

109A_5, I agree with you, very strange situation where when jumped it runs for longer but still shuts off and then again and again. I will be replacing the ignition module tomorrow and not change anything else as for location of the HSI. I have replaced 2 Trane furnaces HSI in the past 2 weeks and the furnace had similar symptoms, except that it wouldnt power up the gas valve, now this one does power up the gas valve but it cut the power off within seconds, like all has been proofed but then control doesnt hold up.

DNAS2019

just an update, the ignition module did the trick, working right on first attempt, called the customer and confirmed it after a day of replacement.
Thank you all for all the tips.

109A_5

Hello @DNAS2019,
Glad to hear it is up and running. I wonder if the control board could have been repaired with a soldering iron in a few minutes. Poor solder joints are very common and cause all sorts of weird problems.

DNAS2019

Hello

109A_5 said:

Hello @DNAS2019,
Glad to hear it is up and running. I wonder if the control board could have been repaired with a soldering iron in a few minutes. Poor solder joints are very common and cause all sorts of weird problems.

Not this one, upon checking the bottom of the board there were no joints issues on this one, more likely relay gas valve problems, or a bad resistor or diode or maybe a triac, I know it was not worth keep fighting with it.

Shane_2

Glad you were able to get it running and thanks for following up.