HTP UFTC-140W Recurring Error Code 11 Issue
I've been running into this Error Code 11 issue for the last few months (boiler is ~6 years old). Started happening sporadically once a week or so, but is now happening multiple times per day. Powering off and on the unit will eventually resolve the issue but there are times when cycling the power still results in 5 ignition attempts and then Error Code screen. I put a link to a video showing the issue. This was my 3rd attempt to reboot the unit. Finally on the 15th ignition attempt the flame lit.
https://youtu.be/aXwJBJPRJ-k
Once the issue started to happen more frequently I contacted my heating company. They serviced the unit (still happening), changed the ignitor (still happening), and on their last visit they changed the flame sensor (still happening).
Looking around this forum I see folks recommending checking for damage to the flapper and checking the fuel mixture is not too lean. I think they did check combustion (based on little receipts pictured below). I doubt the flapper has been checked.
Does anyone have any ideas on what to check next? I'm thinking the flapper. Heating company thinks last step would be to replace the circuit board ($$), but based on the video this doesn't seem to be a circuit board issue to me. I'm approaching the point of cutting my losses on this thing as service charges are adding up.
Comments
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does it light and fail to prove flame or does it fail to light?
if it fails to light the problem is with ignition or mixture/airflow. does it spark at the electrodes when it fails to light? i think you can see that through the sight glass.
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do you smell gas at the exhaust when it doesn't light? is it lpg or natural gas?
that pressure gauge is the pressure of the water in the system.
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When was the last time the heat exchanger was thoroughly cleaned on the fire side using chemicals?
Has the condensate trap and drain been cleaned?
What type of heat emitters (radiators) do you have?
Your combustion numbers are actually on the rich side.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.0 -
they are actually quite rich, that is probably your problem:
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It’s extremely unlikely that the control board is the issue. Incompetent “technicians” always want to blame that when they can’t diagnose the problem.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.
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It's natural gas. The heat emitters are hydro units (2 zone) with air pushed by HVAC. I'll have to debug more next time the problem occurs (probably later today). One thing I have noticed is a noticeable gas smell outside the house during typical operation (my patio is right near the exhaust). Its transient, but definitely present, even others have commented on it.
Regarding what was done as part of recent service:
- Flushed both sides of boiler
- Inspected high & low volts wire, all thermostats and blower motor
- Inspected the Dx & Condenser coils, all zones and air flow
- Inspected flame sensors and ignitor (and subsequently replaced both)
- Inspected the operation of the circulator pump
- Inspected, cleaned & tested the drain line
- Cleaned the water filter serving the inlet
- Purged all zones
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- “Flushed both sides of boiler”
This sounds somewhat suspicious. You don’t flush the water side of the system unless there’s an issue that would require it. Doing so causes fresh oxygen and minerals to be introduced into the system.
To properly clean the fire side of the heater exchanger requires chemicals; water won’t touch it. It also requires removing the top of the heat exchanger to gain access.
The fire tubes in that heat exchanger have aluminum fins pressed into them to increase heat transfer. The downside to that design is that the heat exchanger clogs more easily and is more difficult to clean. The more the boiler condenses when running at lower water temperatures, the quicker the heat exchanger fouls up. Once that happens, combustion issues and ignition failures begin.
I’ve got two of these boilers with the same issue right now that I’m heading to on my schedule.
If there’s a white paint mark where the combustion blower bolts to the burner, then you have an upgraded flapper and it’s probably not broken.
Bob Boan
You can choose to do what you want, but you cannot choose the consequences.
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That’s a lot of unrelated perceived value you received. Flushed both sides being? Fire and Watersides of the heat exchanger or supply and return. No mention of condensate trap. 6 years of nat. Gas burning : poorly tuned could be a dirty heat exchanger.
I have found genuinely bad HTP boards. All else should be proven good. Assuming a bad board is different than witnessing / identifying evidence of a board fault. Assuming is flailing. It’s doing something because you don’t know what else to do. 15 tries to ignite and then it does and has a fairly close to good mixture burn would have me looking at the gas valve. Does it receive proper voltage and current during the cycle. Does it actually open with gas flowing when it doesn’t ignite? Looking inside at the burner around year 6 isn’t a bad idea. Cleaning the fire side heat exchanger before it clogs is good. Look for good insulation and a clean normal burner. Maybe there’s a small leak that fouls things and 15 tries dries it out enough to ignite. Is there actually a spark happening where it should? A good tech will be able to conclusively answer these questions.
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it is sparking and there is fuel, it seems very likely the mixture is too far off to light reliably, either because it was never set right when it was installed or it is clogged now (although being clogged shouldn't change the mixture but it may make the flow too low when it is trying to light).
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Assuming the testo 320 that was used is accurate and a 50% ignition firing rate, I don’t see a big mixture problem but assuming the testo……..
I have always found HTP products like to run ignite rich but the Korean stuff may vary.
if mattmia2 is right about possible restricted air flow causing conditions that make ignition binary, I’d think other symptoms would be apparent. Fluttering, fog horn , flame drop. That’s just my intuition. Always allow for the possibility of a combination of problems. It could have a slightly restricted HX and a bad spark generator or spark wire or wet chamber, bad gas valve or board.
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I was able to see the ignitor sparking through the sight glass (not easy but do able once you know where to look). Small white/blue sparks probably no more than 1/4 cm in size (or less). Finally lit up after 7th or 8th attempt. On the attempt that did light I don't think the spark was any larger than previous.
On the exhaust outside my house, was able to smell gas on each ignition attempt but it was a relatively faint smell (not overpowering) even with my nose 6 inches from the pipe.0 -
Given that feed back. I would get a second opinion on your state of tune. You are trusting the numbers from one device. Also know, that you or the next tech may be able to adjust the mixture to achieve consistent ignitions but have only compensated for a root problem. As a tech it’s hard to know the true state of things unless you have done the maintenance. Tuning for/ to a dirty condition isn’t great, though it can bring temporary function. 6 years is a good time to know that your heat exchanger (fire side) is clean and the burner is properly tuned with a trusted certified device. I have two analyzers so that when I have reason to question the one I’m using or just for a periodic test, I compare them.
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A manometer can show a pressure drop at valve inlet or a rise at outlet when the gas valve opens. I had to deal with a Rinnai tankless with a faulty gas valve intermittently coding out. It would work flawlessly after a restart and 50+ tests but would coded out 24 hours later when I was not there. I finally caught it in the act with a manometer on it.
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You can always get a used dumbell to compare it to, not much to go out of calibration on that unless the plastic shrinks or something.
because of the way the gas valve modulates i think the hx being clogged shouldn't change the mixture unless maybe if it is so clogged it brings the airflow out of the range of the minimum firing rate.
my bigger concern about all of these is the supercharger problem. it is compressing the air fuel mixture so if there is an air leak after the gas valve it will leak air/fuel mixture.
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Used dumbbell? Exhaust analyzers do go out of calibration and well meaning techs can detune quite a few boilers before they figure it out. A back up is an essential for a pro. I’d richen up the tune and retest with another analyzer. I haven’t seen a lot of problems with mixed gas leaks. Bar early Munchkin burner to door gaskets. The “super charger” design has been dominant for a couple decades now.
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the type that uses a measured volume of gas then is shaken in a potassium hydroxide solution that absorbs the CO2 so you can measure the CO2 by measuring the change in volume of the gas. unless the container physically changes size, as long as there is potassium hydroxide still available in solution, not much to go out of calibration. i suppose the gas volume changes a little with temp.
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I’ve done that a couple times …. maybe 30+ years ago. The machines have improved a lot in twenty years. I have an old water tube manometer as a back up but trust my digital for daily.
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i find it strange that a service company would check the condensing unit and evap coils but fail to open the boiler up and at least visually check the heat exchanger if not clean it . Also the zero mention of cleaning the trap or doing exactly what the manual suggests for yearly service .Personally any mod con i have installed i make sure that i make it back after the first season to service and nip any issues that have occured which means remove burner chk and clean heat exchanger ,condensate trap chk condensate treatment ,boiler fluid condition clean any strainer and or magnetic separators ,chk expansion tank pressure and prv setting ,chk inlet and out flue piping perform combustion testing in hi /low and ignition firing . Chk and clean spark and flame sensor .
I do all this and a few other things as a regular yearly service after the first year its up to the customer to call being i m not a fan of forcing people to do yearly maintenance being most feel its of no value until there boiler doesn't work in which case its not maintenance its a service call . I feel that if the installation company after 6 years has not opened up the combustion chamber and cleaned the heat exchanger inspected the burner and ensure the gaskets and seals are in good shape they are the wrong company and w there current excellent service they have provided you that in short time they will suggest that you replace the unit or just keep on replacing parts till you say uncle . As other say it could be the board well if ya replace the board and you still have the issue well you can take the board out of the equation maybe it just needs to be cleaned .You will be replacing parts until that is done or you take there suggestion and install something else till the same happens being they just replace units and perform zero maintenance instead of fixing what they installed .
I know this to be true for a lot of installers sad to say but which may not be your case but ya get what ya pay for and as i say the sweetening of a cheaper price is soon forgotten after the bitterness of poor quality . Until some one does a true service on your unit its just change sparker and flame sensor and press reset till the button wears out .
Do yourself a favor and find a better service co constantly hitting the reset is not the answer .
Peace and good luck clammy
R.A. Calmbacher L.L.C. HVAC
NJ Master HVAC Lic.
Mahwah, NJ
Specializing in steam and hydronic heating1 -
Had a similar problem with a UFT-80, a few years ago.
Error code 11, replaced ignitor, replaced flame sensor. Checked combustion again. No luck. Second trip and a call to HTP
On the UFT, the flame sensor is visual. There are two windows on the heat exchanger, one for the flame sensor and one for visual inspection. First, I switched the flame sensor to the other window which resulted in most ignitions on first try. The glass into the heat exchanger was fogged. Also checked this by shining a light directly into flame sensor.
Hope this helps. The glass is replaceable but I little bit of a job to get to it from the inside
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The HX cleaning is a pretty involved task with these things, and as was stated requires chemicals as well as a several hour soak in many cases. Between the HTP and Laars units with the Kiturami HX, I've come across this quite a few times being the cause of error 11. There was also one that made me scratch my head extensively, replaced everything twice, removed the flapper, and then in a last ditch decided to drill a hole in the rubber intake elbow inside the cabinet. That 1/2" hole seems like nothing, but that was about 5 years ago and I haven't gotten another call about it. I mentioned several times that it should be serviced again, but it seems to still be working as intended. Maybe that's something to try, once you verify the HX was actually cleaned properly.
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I had this same issue and unfortunately nothing I tried worked. I had combustion tests, enriched the mixture, a new 2nd stage regulator, new ignition, cleaned hx, cleaned burner, adjusted just about everything I could but was still getting the lockouts on Error 11. HTP reps told me to try a new control board but I couldn’t bring myself to spend another dollar on the unit. I even tried the old ‘drill a hole in the intake’ trick, to no avail. I ended up scrapping the 8 year old unit for a new Viessmann. This thing would act up in all types of weather.
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