Repeated broken hot surface ignitors on Lochinvar

[Lugs]

Good evening and thanks for looking at my problem.
I have a older Lochinvar boiler (18ish years) that is putting me through my paces. Its a CBN1255 low pressure hot water boiler. A few months ago the burners and firewall were replaced. I reused the original refractory on the firewall. the problem is the hot surface ignitors are failing at an alarming rate for unknown reasons. Previously installed was an OEM replacement Starlight brand ignitor, and they are all cracking at at the base of the porcelain insulator. when using a OEM ignitor it will fail also, without cracking. The system is running smoothly after replacement and we can not replicate the problem. Sometimes the ignitor will last 4 days sometimes over a month. Water temp is a steady 165. It lights easy every time, Gas pressures are spot on at 9" wc inlet and 3.5" wc manifold. It has a new Ignition module as well. Neither water flow or draft through the tubes are considered to be an issue.
I have a theory but its just that. i suspect that the porcelain of the ignitor is taking too much heat and degrading until the ignitor ultimately fails. I'm not sure how to prove this other than use a spacer or such to keep less of the ignitor in the combustion chamber. (and hopefully more of it in the refractory) Why I mention this is because the last ignitor still in operation was removed for inspection - I found a faint discoloration on the porcelain. Upon applying a very slight pressure it cracked exactly where the others are cracking. This makes me think the Refractory around the ignitor is not protecting it.
I appreciate any ideas you all have, and i know my boss and customer will as well since they are starting to get a bit more than irritated. Thanks in advance and sorry for the lengthy post. just trying to give details.

[StayinCool]

Just some curiosity, have you verfied the output voltage to your hot surface ignitor from the new ignition control? I've never had it happen but I've heard that improper voltage to them can wipe them out. Of course never touch the carbon element during installation. Its possible that the refactory is not protecting it but "HSI" and ceramic in general can take a lot of heat.

[yamyam]

Have been trolling these boards for some time now. But if something keeps failing. It's usually not the part that's the culprit but something else that's causing it to fail. Sort of like when you keep "popping" fuses. Would you keep suspecting the fuse?

[danielworkerbee]

Any chance there is a gap around the ignitor that is letting air around or maybe there should be a gap to let air around to cool the ignitor.
Any chance your condensing and it's dripping on the ignitor?
Did anything change about the system lately , re-pipe, added a zone, added combustion air to room or blocked combustion air ?
luck dan

[Lugs]

Thank you for your responses.

Output voltage from the module is fine, that has been verified... there is no air gap around the ignitor, each comes with a new gasket. No water or condensation leaks are thought to be causing this (that thought did cross my mind) but there is no residual evidence of water hitting the ignitor or wet refractory. Of course with the combustion chamber being so hot it would not stay wet for long anyway. I have monitored the ignitor through the sight glass on the boiler and see nothing but a even burning flame. no sparks or deviance of flame color and shape on the ignitor at all.

Combustion air has not changed since install. The boiler uses two large Belimo activated dampers that open for fresh outside air and a hot water heating coil in the boiler room to keep it tempered. The unit has two air proving switches to protect from low air.

I noticed that the OEM replacement part has a glazed insulator and does not crack, it simply starts loosing flame signal over time. The Starlight brand cracks and also looses signal.

Yamyam-- yes I realize that it is not the part being replaced that is the problem. That said, this boiler is providing heat to a three story commercial building and temps outside are well below freezing for the last several weeks. So break or not, its getting a new ignitor anyway until the killer is found lol.

[allstar08]

PLT 3400?

Twice a year is standard.

[jayhawker]

Have you pulled the burners and cleaned them? The company I work for had a Lochinvar boiler that had half of the burners burnt up and was still lighting, Lighting hard and locking out once in awhile but still would light.

[Lugs]

yes plt3400 but.. burning out in less than a month. if not oem then less than 2 weeks.
and yes all new burners. and new ignition module.

[allstar08]

What is your return water temp?

[doubleduece]

dITTO ON RETURN WATER TEMP., IF IT IS BELOW 130 IT WILL CAUSE THE FIRESIDE TO CONDENSATE, WATER COULD BE DRIPPING ON THE HSI..

[ccut]

I'm courious was this an issue prior to the refractory work, and have you talked to Locinvaar?

[tunaguy]

Good suggestions concerning water leaks, return water temps, and others.

Have you checked your amp draws on igniter, should be approx 3.5-4.0. Does the igniter go through repeated re-lites? Does the burner start with delayed ignition sometimes, which would indicate excessive air pressure. These boilers can be pain sometimes. Poor ground, air leakage, cracked burners, low air pressure, and other issues can cause these boilers to go through excessive trials. Some conditions will allow boiler to start/restart constantly without showing a manual fault.

Lochinvar has good phone support at 1-800-722-2101. Good luck

[Lugs]

I will check the return water temp on Monday.. i honestly dont know what its running at. I don't know if the problem was an issue before the refractory work.. that's just the point where i got involved. Some detective work may be in order. I have not amp'd the ignitor during startup.. but did check voltage from the module and signal strength after ignition during boiler on time. It runs and lights smoothly first time though, no delay of any sort. I did call lochinvar but was on hold and passed around so much I did not really get anything answered (I don't think it was a 800 number though, I got it from a local lochinvar parts dealer). I might need to be a bit more patient on the phone. Thanks for the idea on the return water temp. I will look into that first thing and see if that is could be a problem. Thanks again for the ideas.

[kwhvac1]

I have seen something like this and it seemed to be from short cycling. Try to check differental in honeywell controller. Make sure return water temps is above 130 and boiler room temp is tempered...above 60

[kenny98023]

We replace them twice a year as well.

[CynicX]

I agree, check for condensation or anything for that matter falling onto the ignitor. Although I'm not familiar with thats particular system I had another one eating through ignitors. I resorted to ordering OEM, what do do you know it came with a shield that screwed in so nothing could fall onto the ignitor, havent heard from them since (5 yrs or so)

[retiredhvacdude]

red to yellow cool afellow red to white, heat tonight

[Dilp172]

Sometimes when they get old (for a lochinvar old is 60 days ) the metal shrouds internal to the heater bend, crack, warp to the point they will crack the ignitor.

[blewbyu2]

condensation on the HSI. Does it also serve as flame rectification? I've had the same problem with several Lockinvars and always wondered if I could install something to divert the water away from the ignitors, but up to this time always keep several extras on site.

[al o]

is this a sealed combustion boiler? was the fireside of the heat exchanger cleaned when you had her apart? definetly appears to be overheating and i would check your draft ,make sure the heat x is clean,check breeching, flue,boiler room presure, poor overfire draft could have caused the failure of the burners. 18 years on one of those boilers is a long time! keep us posted.

[north10]

Boy, that sure does sound like condensation dripping on those ignitors. I had a couple of older Lochinvars doing that.

[250]

:CU:Hello,
don’t you just love working on crap?
Could you tell me, how many boilers? Inside or outside? storage tanks? Is there more than one controller and how many stages? Reset? lock out? What are the temps in and out?
Thank you
250

[HVAC rocks]

CHECK the ground. Be positive you have a good ground.