Lochinvar Knight Boiler Flame Fail Ignition Errors - ready to pull my hair out

frustratedguy

So I have been having issues with this boiler (WHB110) since I’ve installed it less than 3 years ago - and it’s always the same issue, flame fail ignition. It will fail and then I’ll fix it, runs fine for a while and then fails again.

This time around, I started getting the error intermittently so I replaced the igniter and flame sensor, worked fine for a few days, then same error. Opened her up, cleaned the HX, burner, condensate drain and put it back together, verified there were no blockages in the intake/exhaust pipes - still intermittent failures. It fails in the morning and then would turn on later in the afternoon when it warmed up.

Gave up and called a tech (actually one of the recommended vendors on this site) - tech came out and said it’s the wiring and to use and extension chord that so the unit wasn’t plugged into a GFCI outlet. Tried that, same issues persisted.

Tech recommended rewiring the unit completely and remove the GFCI and hard wire the pumps (radiant floor heat and hot water) directly to the unit. Got that done and same problem.

Then tech said the inducer (blower) is failing - I was not confident in his assessment but he’s the professional - ordered the inducer, installed it and same issue.

So I’m trying to troubleshoot this thing bc I’m fed up with the tech and I find a weird solution. If I pull the plastic tube that is connected to the intake pipe, blow into it and hit reset, it fires up and runs perfectly.

Today, I called Lochinvar to see if they had any thoughts, after explaining all this to them, he said the combustion may need adjusting and that me blowing into the hose is adding CO2 which is why it is firing up that way - does that make sense to anyone? I mean it makes sense to me but I’m just learning about all this bc I’m fed up with the techs just guessing at things and throwing money in the trash.

I’ve had combustion tests done twice, the last one a year and a half ago, they were supposedly dialed in - and I don’t have a combustion analyzer to verify myself. Do you think it is worth it to buy one to verify and adjust it?

I was thinking of just upping the CO2 like myself without the tool a 1/4 turn on the high fire and see if that fixes the issue - and if not then to buy the tool and do the measurements, it’s not a cheap tool :(

is that crazy - anyone have any experience like this or thoughts?

GGross

Start at the beginning.

make sure you are set to the correct fuel type, and if any conversion was done that it was done correctly

What is your incoming gas pressure?

proper way to measure is in a few steps

1: static pressure, when the unit is off record this number

2: keep manometer on the unit, record pressure at ignition

3: run unit to high fire record the lowest pressure value

4: if possible, with all gas appliances running, repeat the steps

your pressure should be within range at all points, and should never show a drop more than 0.5" wc from highest to lowest recorded values. this is incoming gas pressure, measured at the inlet of the gas valve

Check your venting against the boilers vent manual, be extra critical of your own installation to avoid bias. Even well trained installers mess all of this stuff up occasionally

go through your boilers wiring, confirm your connections are correctly wired, and check each plug to make sure it is secure pay attention to any grounds

Once you are absolutely positive your gas pressure is acceptable, venting is good, wiring is good, you can move on to a combustion analysis, and gas valve adjustment, this needs to done per the manual and requires a combustion analyzer and some level of training to use it. If you had an analyzer you could at least record the values

All of these steps need to be done at installation, so you should have records of this from your install 3 years ago

Jamie Hall

"So I’m trying to troubleshoot this thing bc I’m fed up with the tech and I find a weird solution. If I pull the plastic tube that is connected to the intake pipe, blow into it and hit reset, it fires up and runs perfectly."

Well that's interesting — but it's not the carbon dioxide in your breath. There isn't enough of it, and anyway I presume you stop blowing when you hit reset.

However, your blowing is pushing a lot more air through that tube than would normally be going through, and that puff of air is resetting or moving something in there. What? I don't have either a manual or a diagram for that boiler, and you will need that and some free thinking to figure it out.

GroundUp

Do NOT make any adjustments without an analyzer! A 1/4 turn could easily bump the CO2 out of place by 2-3% at high fire. You said you have had combustion tests done twice- what are the O2 and CO2 readings? Surely the technicians left you the printouts after they were done. 90% of the time when this happens on these boilers, the burner is dirty and/or the gas line is undersized. I know you said you cleaned the burner, but did you actually get it clean? Was there any sort of green scale in the HX when you opened it up, indicating exhaust gas recirculation? These units are VERY picky with EGR, and if present, it can and will corrode the mixer but I assume you checked and cleaned that too while replacing the inducer?

frustratedguy

GGross, thanks for the step by step. I maybe worded that badly, it was professionally installed when we built the house.

When the tech came out he verified the gas pressure and vents and said they all checked out. I’ve ordered a Manometer to check for myself.

Jaime, that’s a good point, I’ve tried cleaning out the ports the plastic tube connect to, but I wonder if there’s something blocking something….ugh

frustratedguy

thanks GroundUp - there was no green residue, just black/white soot - and I cleaned the HX until it was smooth and used compressed air on the burner. The test results are attached

Oh, and what is the mixer?

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tim smith

what is the error code when it shuts down? That will help guide us. Is this infloor radiant? Slab or underfloor? Helps decipher build up in heat x tubes sometimes. Looks like propane from the analyzer print out, correct?

frustratedguy

yes - it’s propane and the boiler is for radiant in slab and our hot water.

The error is flame fail ign

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GGross

How long have you had this same issue? and did it start right after getting the propane tank filled?

frustratedguy

it’s been about two weeks - and the propane hasn’t been filled for a while. Just looked and the tank (1000 gallon) is at 35%

I don’t know if it’s propane bc once it starts, it will run normally, the flame just doesn’t ignite unless I blow into the tube

tim smith

I would be inclined that the tubes in heat x have some combustion grounds build up in them. 3 yrs it might be. The tubes only have about 3/16th of an inch passage in them and they are dimpled about every 8 or 10” along length of tube vertically. The dimples are pinch points in the length of tubes, the coffee like grounds from products of combustion build up at these punch points. There is no written procedure to clear these, just flushing won’t get them out. Every install varies as to how much of these “ grounds” build up and how long between excess build up before restriction.
Another thought is make sure you got the correct OEM igniter flame rod assembly. There are few different ones and the wrong one may fit but not be correct. Make sure both flue and combustion air pipe are totally clear. We some times disconnect from boiler and use shop vac to pull or push through to verify clear. Won’t always work but usually can clear.
Good luck

tim smith

did the tech replace the blower or did you? If tech did, he should have checked combustion normally. That would at least give you a bit of info now.

GGross

Unless that gas valve is wildly different than similar ones. The air tube you are blowing into pushes air against a little diaphragm in the valve, there is usually an adjustment screw behind a metal cover on the valve that adjusts the diaphragm, thats the really sensitive adjustment screw that you need to wait a minute or more in between each 1/8th turn (or even less) I am telling you this not so you can mess with it but rather to implore you to not blow into that tube as it could damage the diaphragm. It is very likely that blowing in there temporarily changes the combustion levels

Looks like your combustion has been off since install.

Please get someone else to test your gas pressure as well, you have a regulator with a roughly 3' flexible gas connector attached. There isn't enough volume in that little bit of gas line for most condensing boilers. They usually a want a minimum of 10' of appropriate sized piping between a regulator and a condensing boiler.

frustratedguy

thanks for the input - the igniter and flame rod are OEM, and ordered from the parts list in the manual.

Where are the tubes in the HX that you are referencing with the dimples? How would one go about in cleaning them?

Tim - I replaced the blower myself and it was an OEM part.

frustratedguy

thanks GGross - I’m going to order the combustion analyzer and manometer now.

see if I can dial in the combustion and double check the gas pressure.

I will avoid blowing into the tube - I didn’t realize it could damage something. Thanks

tim smith

comb readings definitely off. Adjustments are suppose to be done by qualified individuals. Just letting you know. Can be dangerous if not aware of all that goes into adjusting.

frustratedguy

that’s fair - the process seems easy enough but I don’t want to do something that puts my family in danger.

Ill try another vendor and cross my fingers

EDIT - ok, made an appointment with another vendor, I called several and 4 vendors said they don’t do combustion analysis, I asked do you repair boilers and they said yes, but you don’t do combustion analysis?!?!

GGross

When you get the analyzer make sure you have the fuel type set correctly on it before you start

Your service manual has a section about making the adjustments, read carefully. what Lochinvar calls the the "bias/offset adjustment screw" is the one that controls that diaphragm. It says so in the book but you really need to wait an entire minute between each 1/8th to1/10th turn on that one, and you generally only adjust that for your low fire.

Before you pull out that analyzer though you need to double check your venting against the vent tables, your gas pressures as I stated above (checked at the boilers gas valve, not the regulator), and you should inspect the burner if you are able to get that deep. It sucks when you can't get good techs in your area, just try to get all your ducks in a row before you start out, and give yourself plenty of time for each step. Better a DIY service than a tech without the tools and knowledge imo. refer to your service or install manual as much as necessary, most if not all the info should be in there. I like to read through relevant sections entirely before starting out, and keep the section open to reference as I go if its new to me

frustratedguy

thanks GGross - the new tech is coming today and he has the combustion analyzer - if he/she is also not able to fix it, I will just give it a shot myself. I appreciate all the precautions you listed, I read that in the manual and on several posts so if it comes to that, I’ll be careful.

frustratedguy

well the tech came over and took a look and said they don’t work on radiant floor heating - even though I explained it’s for my hot water as well (and I told them over the phone) ugh - back to square one.

Interestingly, if I disconnect the plastic hose that runs out of the intake pipe - and not even blow in it, just unplug it, the flame lights and it works as it should - I’m at a complete loss and have no idea who to call

GGross

What the heck is going on in that area it seems like it might be a good place for someone to open up an HVAC service shop! doesn't work on radiant floor heating! give me a break, its a combustion issue with a boiler

frustratedguy

seriously, my thoughts exactly - and I’m in Northern Virginia, in the DC area, not in the middle of nowhere

Jamie Hall

Have you tried @Danny Scully or @Steamhead ?

At some risk of the obvious — double check the condition of that plastic hose. What does it connect to at each end? Is it really free and clear?

frustratedguy

Sorry, have I tried what with them? Are they in the DC area?

and thanks, yes I checked the plastic pipe - it’s all intact and no obstructions.

I just called lochinvar to see if they had a company to recommend and they referenced me to their site, where I searched and there isn’t anyone within 100 miles.

Although they did agree that the combustion just needs to be tweaked - now to find someone to do this combustion analysis and tweaking

Alan (California Radiant) Forbes

Try Kensington Plumbing and Heating

6804 PINEWAY, 20782 University Park
Maryland (301)864-1117

I don't know if they are close to you and I don't know if they service Lochinvar boilers as I found them on another manufacturer's website.

frustratedguy

thanks buddy - that’s quite a ways from me, but I appreciate it

frustratedguy

so I can’t seem to find anyone to do this analysis so I ordered the combustion analyzer and will do it myself.

This may be a stupid question but the manual says to remove the plug from the vent connector to insert the probe and the video on lochinvar university says to remove the flue sensor and insert the probe - which is it?

Another YouTube video, the guy (Mikey Pipes) drilled a hole for the sensor - which seemed wrong because I have had the tests done but there are no holes in my vents.

Also, is this the plug they’re saying to remove in the manual?

IMG_8105.jpeg

Jamie Hall

If there are no holes or plugs, the combustion analysis was never done right. It can't be done without sampling the flue gas

frustratedguy

can you do it by removing the flue sensor like it says on lochinvar U?

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GGross

Most condensing boilers have an inspection port near the boiler on both the intake and exhaust built in.

where the flue pipe connects to the boiler check to see if there is a screw on plug of some kind. Most condensing units will have these installed from the factory since many installs will be field converted to LP

SuperTech

I've done it both ways, depending on the boiler. Either way will work. The majority of the boilers have a cap on the flue pipe connector on the top of the cabinet that you can unscrew for combustion analysis. Some older models didn't have this and removing the temperature sensor was the way to take the flue sample.

I'm sorry you are having so much trouble finding someone who knows what they are doing. It's ridiculous that no one in your area can perform a combustion analysis and tune your boiler. I can't fathom how these guys can do their job without using one

frustratedguy

Thanks guys - I think the cap is what I took a picture of, it makes sense where it is. I'll try that and let you guys know how it goes on Sunday….fingers crossed

GroundUp

I'm late to the party but as others have mentioned, your combustion is way off and needs to be adjusted. These units actually like to be on the rich side of the spectrum from my experience, with the CO2 slightly higher than the 10.8% high fire and 10.5% low fire indicated in the manual. The gas supply as has been mentioned is also sketchy and may very well be pulling the pressure down too low as the ignition process is happening, resulting in a failure. Lochinvar wants the pressure drop from static to be less than 1" WC. So if you have 11" WC static, it should not drop below 10" WC when the gas valve first opens. There is a port on the gas valve from which to take these readings. The mixer is the device that the intake pipe connects to, where the gas and air are mixed; like a carburetor of sorts- though that is probably okay if there is no sign of EGR. The burner may very well need to be cleaned with soap and water if the combustion has been this far off for 3 years, not just compressed air. First thing though will be to get that gas pressure drop checked, and get somebody out with an analyzer to raise those CO2 numbers and simultaneously dropping the O2. A very common mistake with adjustment on these that I see (and have made the mistake myself early on in my career) is that there are two different adjustment screws. One is for high fire and one is for low fire- you can't adjust the high fire screw in order to dial in the low fire combustion, and vice versa.

mattmia2

How do you adjust the high fire? It seems like in many installations it would be difficult to find someplace to dump the heat to fire on high long enough to wait a minute between adjustments.

Alan (California Radiant) Forbes

https://forum.heatinghelp.com/discussion/comment/1812120#Comment_1812120

Yes, this can be tough to do if you don’t have a DHW indirect to increase the setpoint temperature or the heating system is locked out on WWSD. Creating a demand can be impossible. Look up the weather and make an appointment for a cold morning? Or disconnect the outdoor sensor.

GroundUp

https://forum.heatinghelp.com/discussion/comment/1812120#Comment_1812120

I usually create a false heat call to run the circulator(s) or just wire them to a cord so they can dump the BTUs. Service mode in these boilers will run high fire until the high limit is reached if you let it. 99% of my work is high mass radiant so I don't usually have an issue getting rid of it.

frustratedguy

I got the analyzer and tried to make a few adjustments but stopped to ask a question. For the high fire adjustment, it started at CO2 at 8.25% - I adjusted it by a 1/4 turn counter clockwise and it barely moved the number, I adjusted another 1/4 turn and it went up to CO2 at 8.32 - I waited 2-3 minutes between adjustments with the sensor running.

So I stopped at that point to see if that is normal - based on the comments that i received prior, a 1/4 turn (on the high fire, not the low fire 'bias') could move it a few percentage points, which was not what I was seeing.

I just wanted to ask so I am not over-cranking it.

GroundUp

Is the boiler in service mode at 100% fire while you're making these adjustments? If it's way out of whack like yours was, it can take a couple turns to get back into range but once you're close, it can jump very rapidly. I always like to start with low fire though, and get that dialed in prior to adjusting high fire. The unit NEEDS to be running either 10% (low fire) or 100% (high fire) when making the appropriate adjustments, which is done using the service mode. Do you have the analyzer set up for the correct fuel type for sure?

frustratedguy

Thanks for the confirmation - I figured it needed a few turns but wanted to be sure.

Yes, the adjustments are done in Service Mode, and I have not done the low fire yet, but those numbers weren't too far off but I will double check them.

Also, yes, I did select the right fuel type for sure (I double checked it a few times) and I start the unit out in the fresh air so it can calibrate correctly - It's a Tesco brand

frustratedguy

so no matter what I did, i could not get the CO2 past 8.52 - so I'm guessing there's something else wrong and not going to mess with it anymore….looking for another contractor

mattmia2

Check the pressure with it firing first. If there isn't enough fuel supply you will never be able to make it rich enough.