HTP Error 11

GroundUp

Before you beat me up too bad, I'm pretty new to the service side of things and typically only work the construction side so please bear with me. I installed this UFT-80W this summer for a 2500 sq ft, 2 zone radiant floor in a bank and started it up, checked combustion, etc. All was well. I went back when it first got cold just to check on it, it was performing perfect and combustion was still spot on. Fast forward a month, they call and say the floor is cold. I drive up there and there is an error 11, ignition failed 5 times. Gas pressure is 11", intake and exhaust are clear, ignitor tests good and is clean, 1/8" gap, gas valve is magnetized as it should, everything the manual says checks out but it WILL NOT fire. Unplugged the unit and went to lunch. Came back, same thing. 5 or 6 cycles, no fire. Spark is clear as a bell but no fire. I removed the crossover tube from gas valve to mixer and it was clear, removed the mixer and it was clear, put the mixer back on and started a new cycle, sucking indoor air into the mixer through the gas inlet port. Once I assured the gas valve was opening, I replaced the crossover tube and it fired up immediately. Watched it for a bit then shut it down and waited an hour and started a new cycle from cold. Worked like a charm. Okay, fluke deal. Clear error history and go home. We had a warm week and this is coupled with forced air so they likely didn't notice, but a week later (yesterday) I get another call saying they had another error 11 on the screen. Drove back up there yesterday after work to find the same story. Everything checked out but it would not fire. Removed the crossover tube again just for grins and let it suck indoor air for a few seconds, tightened the nuts back up and away it went. Error history showed just a single er11 since cleared the previous week. I spent 2 hours on hold with tech support while there and nobody ever picked up so I left a message, but I just now called the bank and she says it's working fine today. Again, I'm no service tech and I'm still learning these UFT units so it may be something painfully obvious but my little brain is at a loss. Some sort of airlock in the gas feed tube from valve to mixer? Doesn't make sense that it wouldn't get gas until that nut is loosened. Anyone have some expertise to offer on the subject? Please?

JUGHNE

You stated the gas pressure is 11".....assuming this is LPG?
How close is a regulator to the gas valve?

GroundUp

It's NG, 2# service in the industrial park. Regulator is about 3 feet from the gas valve. Manual states anything between 3.5-14" is suitable, would 11" be an issue?

Ironman

Look for a broken air flap after the fan.

NY_Rob

Had a similar error code on my UFT-80W last winter.
Seems the gas valve had somehow drifted lean from it's original calibration 1.5yrs earlier. I watched the flame (through the site glass window) slowly die out after successful ignition time and time again.
Brendon from HTP support told me Error 10 and 11 are almost always caused by too lean mixture- open the adjustment screw 1/4 turn and give it a try. Once the mixture was enriched via the adjustment screw the boiler fired right up and kept running. I then did a CA on it... it was still lean, but enough to keep the flame going on initial lite off.

I had step modulation enabled, so the boiler starts up on a very low flame setting- and when the gas valve went lean the flame simply petered out. Enriching the mix got it running and the CA proved the gas valve mixture setting was too lean.

If you don't have a CA, enrich the mixture 1/8 to 1/4 turn clockwise to get it running but get back there with a CA ASAP.

When it was failing... did you see any flame a the burner once ignition started? On mine I saw a weak flame that got weaker over 5 seconds or so then just died out completely. Kind of like turning off the gas at the tank on a BBQ.

Alan (California Radiant) Forbes

11" static, but what does it drop to on ignition?

Did you check the pressure on the manifold side of the gas valve. Negative pressure gas valves should read -0.1" wc.

That's a head scratcher. Sometimes it works, other times it doesn't.

Ironman may have the answer.

GroundUp

I will check on that flapper next time I get up there, thank you. I don't recall seeing the white paint and the date on the exchanger says 2017 so it may very well be the old flapper.

As for CA, I had it dialed in to what the manual recommends on initial startup and those numbers were almost identical both low and high fire both times I restarted. 1/8 turn in either direction threw it WAY out of spec, it was almost nuts-on from the factory. I left the printout with the unit, but I want to say it was 9% CO2 high and 8.5% on low fire, roughly 70 PPM and 5% O2 both sides. On ignition failure there was never any hint of a flame through the sight glass- spark only. When it did finally light, it was an immediate, perfect looking flame. Suppose I could fatten it up just a wee bit if the flapper looks good.

I never did check gas pressure after ignition, I was preoccupied and forgot. Gas/burners is definitely a weak area for me being construction only so my knowledge on negative pressure valves is nonexistent; been trying to get into an HTP factory class for a few months now and there never seems to be one available for the UFT. Nobody around here even carries them, the nearest wholesaler is 8 hours away and they don't offer any information.

NY_Rob

On my UFT-80W I can easily hear the sequence of events leading to successful ignition even with it's cover on.

You hear the blower pre-purge then ramp down and steady at a lower speed, I hear the click..click...click of the spark then a definite "clunk" of the gas valve opening... then lite off.

On failure... do you hear the "clunk" of the gas valve opening? It's quite loud.

Brendon has told me they hardly ever see failed gas valves on the UFT series (I ordered a spare for my system just in case).

GroundUp

NY_Rob said:

On my UFT-80W I can easily hear the sequence of events leading to successful ignition even with it's cover on.

You hear the blower pre-purge then ramp down and steady at a lower speed, I hear the click..click...click of the spark then a definite "clunk" of the gas valve opening... then lite off.

On failure... do you hear the "clunk" of the gas valve opening? It's quite loud.

Brendon has told me they hardly ever see failed gas valves on the UFT series (I ordered a spare for my system just in case).

Yup, it's very audible and the front of the valve becomes magnetized when the valve is powered. Also I gave it the sniffer test with the crossover tube removed, it seems to be operating just fine. The more I think about it, I am fairly certain it's a flapper issue seeing as it clears when the crossover tube is removed and the mixer is allowed to pull a large volume of air versus trying to drag gas through the valve in a vacuum. I feel like that blast of air pushes the flapper open and then it maintains

NY_Rob

^ interesting, hopefully that's all it is.

Are you going to order the flap and replace if needed or just run without it?

GroundUp

I'm going to wait until it acts up again and then pull it apart to check. If it's busted I'll pull it out and probably order one after the fact to replace it at a later date. I hate buying a pile of parts I may not need, seeing as there is no local supplier to stock them. I usually have an 80-120k unit on the shelf I can rob parts from if I need to, but I'm not going to order the flapper until I know it's broken

NY_Rob

Sounds like a plan.... but FWIW- when I ordered a replacement flapper for my UFT-80W it was backordered for three weeks even though it showed as "in stock" on the HTP parts website.

At this point, if mine goes (I have the older style flapper from 2016) I'm undecided if I'll replace it or not. I have the new design flapper in my spares box, but it seems like a part designed for cascaded boilers not single installs like mine. And, who knows if the "new design" flapper will hold up either? If you pick it up in your hand (I'm referring to the "new design" flapper) it's very flimsy- you need to be careful removing it from it's plastic shipping bag without damaging it.

I wonder if other fire tube mod-cons have a flapper in the induction inlet?

nicholas bonham-carter

Ground up-This brings up the point we make to homeowners we make, of letting the installer make the equipment choice he is comfortable with, and which has a strong local wholesale support with readily available parts.
Would there have been another boiler available in your area, with better support?
Maybe your in a rather “dry” rural area, with no wholesalers nearby.—NBC

GroundUp

> @nicholas bonham-carter said:
> Ground up-This brings up the point we make to homeowners we make, of letting the installer make the equipment choice he is comfortable with, and which has a strong local wholesale support with readily available parts.
> Would there have been another boiler available in your area, with better support?
> Maybe your in a rather “dry” rural area, with no wholesalers nearby.—NBC

The only one nearby in a mod/con is Navien, and I will not put my name on those things. I can get Lochinvar about 100 miles away, but unfortunately the price point doesn't jive with my locality. In order to compete with the Navien, I need something like the UFT. I did have a supply house 45 minutes away stocking HTP last year, but I was the only one buying them and they stopped carrying them. They now carry NTI, but they order to suit and keep nothing on the shelf. Really the only thing in stock anywhere is Navien

GroundUp

Welp, it was good all winter and finally acted up again and went out on error 11 yesterday when it warmed up outside. Tore it apart today and the flapper was in perfect condition, took a pressure reading on the gas and found it to be -0.1 while running, combustion still right where I left it and gas inlet pressure still at 11". I removed the flapper anyway just to see what happens, but it sure didn't appear to have been any part of the issue. Everything lines up with spec, so back to the drawing board I guess

NY_Rob

Do you see a flame starting in the sight glass?
If it does start and then peters out... try adjusting the mixture screw 1/8 to 1/4 turn clockwise to richen the mixture. If it does fire up at that point and sustains... re-adjust the mixture screw with a CA setup.

Ironman

Removing the flap may effect your fuel to air mixture. I'd check it with a combustion analyzer like Rob suggested.

GroundUp

It's spot on, same as before. Fires right up after I reset it, can not get it to act up in front of me. Like I said, it was fine since November and went out on error Tuesday. Wednesday upon my arrival, it took right off and is still working fine today as it had for the previous 4 months. I'm going to be an unhappy camper if I need to drive up there several times a year to restart the stupid thing

NY_Rob

You shouldn't need to do that. It could be a simple case of it running too close to a lean condition and a transient lower than normal gas supply pressure caused the non-start condition.

If you have a combustion analyzer... tune the gas valve to the rich end of the spec to to be safe.

GroundUp

NY_Rob said:

You shouldn't need to do that. It could be a simple case of it running too close to a lean condition and a transient lower than normal gas supply pressure caused the non-start condition.

If you have a combustion analyzer... tune the gas valve to the rich end of the spec to to be safe.

I know I shouldn't need to. But seeing as there is apparently no cure for the issue, I don't have much choice in the matter. Combustion is dialed in to the dead center of spec, and gas supply pressure is 11" being in industrial park- not your average low pressure home supply. It'll try 9 times to fire before locking out, so I'm very doubtful that any surge in pressure has any bearing on this unit. Considering there are 2 FA furnaces and a gas WH in the building off the same meter and 7 other boilers just like this one in the same industrial park, 4 of them by me and none with this issue

NY_Rob

To be honest... I've found the gas valve on the UFT to be less than precise over time when measured under similar conditions/loads using the same calibrated/certified CA.

For 5 weekends in a row I took combustion readings on my UFT after having a flame-out situation one morning due to running too lean.
What I found was even with the DIP switches set to low fire as recommended by the manual I was never able to get identical readings from the week before (or the week after). I eventually gave up trying to "dial in" the gas valve and finally set it to the rich end of the spec and haven't had an outage in 2yrs now.

GroundUp

Hmmm... It's definitely something to try out if this happens again! I'm fairly new to CA so I don't have a ton of experience in that area but I was under the impression it was best to aim for as close to the middle as possible to give it slack to wobble both ways. Little fat can't hurt I guess, if it comes to that. Thanks for the info

mlarco

Having this exact issue error 11 and not sure how to adjust the mixture screw. Where exactly would it be located. I'm on a htp uft-199w. Seems it's not getting enough gas to keep lighting. After a few on off attempts and letting the unit sit for a bit it seems to fire up but only after a while.

Need help asap if anyone can direct me to which is the mixture screw.

Thank you 

mlarco

I figure from the diagram from the manual where the screws are. However, I am wondering which one is needed to be adjusted to turn up the gas mixture. The inlet screw or the outlet. Inlet obviously makes sense but when adjusting the inlet screw does the outlet screw get adjusted the same also?

Thanks

dko

Are you planning on just turning them randomly by feel and then firing up the boiler to see if it worked?
For you

mlarco

The last time this was happening was on a previous unit of mine which was replaced under warranty for being defective however for this error the tech had stated it was running too lean causing the same error 11. I know a CA needs to be done also and I'm going  to arrange the normal guy I use for this to come by and do it but for the mean time the unit doesn't seem to get enough gas. It will fire up after so many attempts and stay on till there's no need for heat or hot water and the next time the system has a demand it will give the same error until I wait a bit and reset it let it run through its phases.

I can see the unit firing up and the flame slowly fading away till it turns off.

Ironman

This is NOT something a DIY should be attempting to do! You’re running the risk of an explosion or CO poisoning.

Only a properly trained technician with a combustion analyzer should attempt this.

Erin Holohan Haskell

@mlarco, this site is here to help people, but not if they are going to put themselves and their families in harm's way. Please listen to what these experienced pros are telling you and hire a properly trained technician and do not touch it in the meantime.