Lochinvar Knight Boiler WBN156 issues

Mothra

Hello,

I've been getting a Flame Fail IGN error, locking out my boiler (which also serves as my hot water heater) and i'm not sure how to 'fix' this issue. I've had a service guy out three times, to no avail, I am still getting random lockouts. During the winter heat season, the boiler was also exhibiting a rumbling sound during its heat up, which was also not corrected. Any advise on solving these two issues? The boiler is ~4 years old. Thanks.

HomerJSmith

NG or LP?

pedmec

what model lochinvar?
what error code is showing up?

not the rumbling noise but it could be you just need igniters and flame sensors. but you need to supply info on what your tech performed

rumbling noise during the burning phase indicates that your mostly not having proper combustion. there can be multiple reasons for this. start with the most obvious which your guy might have done.

did he inspect the intake and exhaust piping for obstructions?
did you have a preventive maintenance performed on the boiler?
was a combustion test performed?
gas pressures checked?
was the venturi inspected for deformation?

these are just a few off the top of my head but there are plenty more.

Mothra

This is an LP boiler, model WBN156. The error code is: Flame Fail IGN

I had service done prior to winter to verify combustion levels and conduct a cleaning.
I have inspected the intake and exhaust and did not find any obstructions.
Unfortunately, I can't give you the specific specs from their visits.

HomerJSmith

pedmec suggestions concerning LP input pressure at about 11" water column should be checked. You may need to have the combustion checked again with a recently calibrated (important) CO meter.

When the conversion was made from NG to LP, was it done correctly? Everything worked ok until recently? Is your condensate drain and trap on the bottom of the unit draining properly? If not clean it.

Look in your service manual for the fault code in the troubleshooting section as they give some recommendations. What? You say, you don't have a service manual? Your installer took it with him? There are many sources for the manual download on the internet.

Zman

The flame failure combined with the history of rumbling noise makes me think you have a combustion issue. Did the tech leave a combustion analysis printout on the boiler or invoice? I have seen many cases where the tech does a combustion analysis where the boiler is shown to be way out of spec and they don't make the necessary adjustments. I have also seen techs who think that a combustion analysis is just looking at the flame and deciding it looks good.

Alan (California Radiant) Forbes

Homer suggested checking the condensate drain. Make sure there is an air gap between the hose and the drain and that the neutralizer chips have been replaced. Send us some pictures. 

Mothra

Thank you for your responses! It was changed to LP from the installation and I don't believe it was done incorrectly as issues have only been more recent. i will include pictures of my condensation trap. I'm no expert, but i don't believe it is functioning as intended. Unfortunately, i don't have the combustion reading print outs and for my next service call, i will certainly request them along with a CO reading. I'm not familiar with neutralizer chips.

HomerJSmith

Part of my service procedure, I clean the trap. I notice with LP that there is a brown discharge that discolors the trap and neutralizer. I talked to Lochinvar tech about this but we came to no definitive answer. Does anyone have any idea of why this ocurrs with LP?

The hydronic department of my wholesale dist, several years ago, told me that they went out to check on a Lochinvar firetube boiler that operated on LP that failed. When they took the heat exchanger apart, they found that the firetubes were plugged with I assume was combustion debris. I wished that I had questioned it in greater detail. Anyone have that experience?

If the condensate is flowing freely, then I don't expect that the rectification is interfered with by the high humidity that occurs during combustion.

My experience is that the whole trap is discolored as well as the neutralizer. Your trap is only partially discolored leading me to think that maybe the trap isn't draining properly.

Do as Zman suggests and do a service and combustion analysis and see what happens.

Look in the service manual troubleshooting section for the fault code and look at the suggestion as to the cause.

Alan (California Radiant) Forbes

It looks as though your condensate trap is directly connected to the drain which might be the problem. There should be an air gap between the trap and the drain. Remove and clean the trap and re-work the drain to provide an air gap.

The boiler pictured has an internal trap, so you don't see it. It sits above, inside the boiler.

Mothra

Thank you very much for your suggestions! i will work on them as soon as possible!

Alan (California Radiant) Forbes

I would also do what Homer suggested:

The hydronic department of my wholesale dist, several years ago, told me that they went out to check on a Lochinvar firetube boiler that operated on LP that failed. When they took the heat exchanger apart, they found that the firetubes were plugged with I assume was combustion debris. I wished that I had questioned it in greater detail. Anyone have that experience?

Mothra

I changed out the trap to as suggested, however, foolishly, i should've have checked first as this is what was contained in the operating manual. I'll be changing this back as soon as i can

GGross

@Mothra
What did you change the trap out to? I think the suggestion was just to make sure there was an air gap somewhere after your condensate drain. No double trap, no direct connect possibly pulling vacuum on the drain line stopping drainage. The condensate trap needs to stay, its the drain that needs to be seen in full, please take a picture of the drain line as complete as possible once you have it put back together.

Mothra

Yes, i believe i misinterpreted the comment and removed the trap to produce an air gap to the drain as pictured above. I'll be reinstalling the trap once home tonight.

GGross

@Mothra
Yes re-install that trap. The above picture may have been a bit confusing, in that photo there is a p-trap already inside the boiler, the photo was just to show you that there should be something like that (the gap between drain line and drain) after your condensate drain

HomerJSmith

Mothra, your figure 10-1 shows a small tit protruding up just below the term "compression fitting" . This is a vent. Sometimes the condensate water will squirt out of it. I put a vinyl tube on it and run it several inches up the side of the boiler and tape it in place. That would allow it to vent and keep the condensate water from dripping out of the vent on to the floor.

Mothra

I reattached the trap. I don't believe i need a gap from the trap to the drain as the trap has a vacuum break on the stem

- sorry, i didn't see Homer's statement prior to commenting. My trap differs slightly, as it has a whole diameter opening at the top of the stem, not a small tit as shown in the illustration. If you believe i should still extend off of that, i can.

HomerJSmith

Pics please. That tit piece just snaps into the trap.

Mothra

The entirety of the stem is open, without the tit piece.

HomerJSmith

If it is open, in other words you can stick a finger in it, you're missing the tit part that snaps in. It may have been left off when you got the unit. I would contact Lochinvar.

You're right no air gap is needed. An air gap is mostly with potable water issues. But... a vent is important to prevent a vacuum build up preventing the water from draining properly.

Dave Carpentier

An airgap would also ensure a drain backup/plug would never block the condensate, as it would just end up on the floor.