HTP UFT-199 boiler (LP)

83Bella

Hello all. I had a HTP UFT-199 boiler (LP fueled) installed in 2017. Every winter season (I live in CT) the boiler would occasionally lockout with an Error 11 code (repetitive misfires) on very cold days. At first I thought it was the PVC pipes (fresh and exhaust) that are positioned on the Northside of the house (North winds causing a problem?). So I had a tech come out and the pipes were adjusted to slightly different angles. Didn't solve the problem. Contacting HTP for several years now has led to "trials and errors". Recently, I learned of a bulletin that the rubber hose that connects to the PVC fresh air intake when it enters the boiler cabinet has been modified to have a 3/4" hole directly facing the rear of the cabinet (only a few inches away), and cut directly across from what I will describe as a small plastic tubing which I believe supplies some air to the mixing valve? Anyway, tech explained it as drawing a little warm air from within the boiler cabinet so that the extreme cold air won't crystalize at the mixer. I was instructed on how and where to make the hole on the rubber hose. All has been good from early December until this week. Temps are now at 10 degrees and under. Boiler locks out (same Error 11) mostly during the middle of the night and early am (coldest parts of the day). I have to manually push an on/off button on the boiler to get it to start again. Anyway, HTP has now revised my boiler as follows:

1) burner plate (ceramic fiber) is now upgraded to a "double perforated burner"
2) LP orifice original size 0.63 is now 0.635

I have both parts and I've been told to replace the originals. In early December I had the boiler cleaned. Tech commented the burner plate was clogged a bit, he vacuumed it to open up some of the holes. A combustion analysis was conducted at the end of the cleaning. All was according to mfg specs..no adjustments.

Questions (help!):
1) Do any of the recommended "corrective" steps make sense?
2) The PVC fresh air intake and exhaust pipes I believe are 3" diameter. I know that cold air is denser that warm air. One tech told me to consider using 4" diameter on the PVC section that exits to the exterior (use a coupler). How would this help with pressure or warming the fresh air, if at all?

Sorry for being so wordy. After many years still at a loss of what is causing the misfires/lockouts on the coldest days of the year.

mattmia2

What is the pressure of the LP when it is locking out? My first thought is either the vent on the regulator is icing over or the draw on the tank is too much for its size in that ambient temp.

83Bella

Layman here. Not sure what the pressure of the LP is when locking out as it happens sporadically. For instance, happened last night at 3 am then again at 9:30 am. Hard resets in between and a few cycles without lockouts. When last cleaned (early December) tech said that the pressure was fine. The house regulator has been looked at and I was told it is fine. In 2022, I actually wrapped a heating pad around the main regulator but that did not help. As for the tank, I have a 1000 gl propane tank below ground.

pecmsg

The size of the exhaust and fresh air piping is listed in the IOM. (Available on line) Remember the number of bends affects the total length allowed.

EdTheHeaterMan

Since the manufacturer is aware of this problem, and they believe the intake air temperature is contributing the the lockouts, I would stick with that as the primary cause of the problem. With that in mind, the air in the boiler room is much warmer than the outside air, As a test, I would disconnect the air intake pipe from the outside air intake and draw air from the boiler room. Leave the outdoor air intake open the the boiler room so there is enough combustion air in that space. The cold outside air will mix with the warmer boiler room air and your problem should be gone.

It is important to have a working CO detector in your home during this experiment. This is not a permanent fix but will prove the problem IS the air intake temperature. Once you have 2 days at extreme low temperature with no problems, then we can address how to solve the intake air temperature by preheating the intake air with the exhaust air.

83Bella

Thank you. The IOM calls for either 2" or 3" piping. I have 3" and will check the bends and math not to exceed 100'. Each bend as I understand it and type of bend is a feet multiple.

83Bella

Ed - I tried this very experiment in December right before I learned of the redesigned rubber hose that comes with a predrilled 3/4" hole to draw warm cabinet air. Here's what I did. The PVC fresh air intake enters the boiler cabinet from the top. Inside the cabinet the PVC transitions to a rubber hose (clamped on one end to the PVC pipe and clamped on the other end to the boiler fan (?)) Anyway, I loosened the clamp at the fan end and pulled the rubber hose away approximately 1/8 - 1/4". Set up a CO alarm next to boiler. It ran flawlessly. I left the cabinet cover off. Now it wasn't as cold then as temps today but it was still locking out. I then learned of the "hole trick", removed the hose, made the hole in the recommended spot, reconnected to the PVC pipe and fan and it ran without issue for 5 solid weeks..until this week.

83Bella

Ed - Forgot to mention. The 3/4 hole is approximately 2" away from where the rubber hose connects to PVC pipe. The hole is directly across from a skinny tube that pierces the rubber hose and the other end connects to the mixer valve. Thereafter, downstream is where I disconnected the rubber house from the fan assembly and pushed it away 1/4". With the boiler running/fan running it appeared to be drawing basement room air along with fresh air as the fan suction is rather strong. Creating a mix?

Ironman

I’ve got a good bit of experience with these boilers and one thing I can tell you is that the ignition process can be very touchy. If the fuel to air ratio isn’t precisely right, you’ll have an ignition failure.

I’m always leery when a tech says the readings are right but doesn’t give the specifics. Did he leave you the print out from the combustion analysis? What was the gas pressure?

The fire tube passages in the heat exchanger are prone to fouling. We just replaced one last week that was only five years old because it was plugged so bad. Was the heat exchanger taken apart and cleaned or checked?

The parts modification should fix your problem - assuming the other things that I mentioned are correct.

mattmia2

Ironman said:

The fire tube passages in the heat exchanger are prone to fouling. We just replaced one last week that was only five years old because it was plugged so bad. Was the heat exchanger taken apart and cleaned or checked?

I'm curious how you clean the HX for routine maintenance? The manual seems sort of vague about how it should be done.

83Bella

Thank you for your comment. The tech did not leave a printout of the CA results. I will call and request a copy should one be on file. Sorry but I'm not up to speed with the boiler terminology. By fire tube passages might that be the ceramic fiber burner? If so, the tech said it was very dirty/clogged and that it is delicate. I was told only one side can be vacuumed? He proceeded to use a small shop vac to clear out as many of the holes as possible without really pushing hard. He then held the burner up to a light source and indicated that many of the holes had been cleared of blockage. (BTW, another tech that I have recently spoken to told me he would have treated the clogged burner as a frisbee right into the garbage can. Don't attempt to unclog it rather simply replace it). Anyway, the tech replaced the now "cleaned" burner as he didn't have the newly designed, modified "double perforated" burner released by HTP. I have since purchased the modified burner but not yet installed. As for the cleaning process, the tech opened up the boiler and scrubbed and picked away had some hard "calcification/scaling". He softened it using a water/white vinegar mix (1:1 in a disposable water bottle to which he punctured a hole in the cap and used as a squirt bottle). The debris was rinsed out of the boiler bottom with the condensation trap temporarily removed and into a bucket. CA conducted at the very end. I was told everything was according to spec/within range? I thought he mentioned something about 10%?

Surprisingly, HTP has revised the rubber hose to now come predrilled with a 3/4" hole to draw some warm cabinet air, revised the burner to what is now called "double perforated", and changed the LP orifice from 0.63 to 0.635. I was told ny HTP customer service that a new CA is not necessarily needed if I only replace the burner to the newer model, however, if I also change to the new size orifice a CA is must. Also, I'm not clear on what the difference is between a "double perforated" and a presumably single perforated original? Rep didn't have an answer. If they are drastically different I would think a CA would be in order, no?

83Bella

Another observation...
When a zone calls for heat the boiler goes through the following start-up process (as best as I can describe/understand it):
Fan runs to clear the chamber
Ramps down and then begins to ramp up
"Clunk" sound which I believe to be the gas valve opening
A blunt pop sound when it ignites.

The tech who cleaned the boiler wasn't happy with the blunt pop sound. He said when it ignites it should sound more like a "swoosh" similar to firing up a gas grill. He thinks the blunt pop is due to a semi-clogged, failing ceramic fiber burner, hence, the reason to install the newly modified burner.

Thank you to everyone for your time and input! Much appreciated!!!

mattmia2

The fire tubes are the passages through the heat exchange itself in the boiler, they are where the products of combustion are pushed through by the fan to transfer the heat to the water after the burner. If there is a lot of soot on the burner that would tend to indicate it isn't adjusted properly.

83Bella

mattmia2 said:

The fire tubes are the passages through the heat exchange itself in the boiler, they are where the products of combustion are pushed through by the fan to transfer the heat to the water after the burner. If there is a lot of soot on the burner that would tend to indicate it isn't adjusted properly.

Thanks for educating me. I will have a different tech come out to replace the burner, the LP orifice and run a new CA. Hopefully, he will be able to evaluate the fire tubes/condition.

EBEBRATT-Ed

I find it ridiculous that a mfg. would change an orifice from .63 to .635. Is this the space shuttle??

This is just another case of a mfg. (and every single one does this) sends the equipment into the field and problems develop. Then it becomes a lab experiment.

Of course the equipment works flawless in the lab. The lab is not the real world.

I agree with @EdTheHeaterMan run it with heated basement air and the problem will likely fade away.

83Bella

EBEBRATT-Ed said:

I find it ridiculous that a mfg. would change an orifice from .63 to .635. Is this the space shuttle??

This is just another case of a mfg. (and every single one does this) sends the equipment into the field and problems develop. Then it becomes a lab experiment.

Of course the equipment works flawless in the lab. The lab is not the real world.

I agree with @EdTheHeaterMan run it with heated basement air and the problem will likely fade away.

Tell me about it! Very frustrating... I, agree, the warm basement air will likely resolve the issue but many including HTP insist that fresh air come from the outside. Basement air might introduce some dust and other contaminants but then again the outside air is likely to do the same. It's a rather large basement (all open) and I have several other LP fixtures in my house. Again, I was told not cut-off the fresh air entirely rather introduce a little cabinet air (hence the 3/4" hole in the rubber hose). Interested in learning if there are other ways to heat/warmup the outside air as it enters. Thank your for your comment.

EdTheHeaterMan

Here is an idea I once tried in a basement between the rafters of a finished basement. was only able to cut the sheetrock of one joist bay. Of course I picked the wrong joist bay and could not fit two 3" pipes and the necessary 45° elbow in the that space. So I extended the 24" section of pipe to 8 feet to get into the unfinished boiler room where I put the reducing Wye that split the pipes from concentric to separate pipes.


This may help you to preheat the exhaust gasses with 8 feet of exhaust inside the 8 feet of cold fresh air for combustion. I didn't want to offer this option until you completed the test to see if warmer fresh air solved the problem.

I'm greedy that way!

Mr. Ed

83Bella

Mr. Ed - An interesting concept. Thank you for sharing. Not sure if I can replicate such a setup given some constraints. I will show it to the tech I contract with.

Ironman

mattmia2 said:

The fire tube passages in the heat exchanger are prone to fouling. We just replaced one last week that was only five years old because it was plugged so bad. Was the heat exchanger taken apart and cleaned or checked?

I'm curious how you clean the HX for routine maintenance? The manual seems sort of vague about how it should be done.

Here’s a somewhat extensive post on another site where we discussed this:

https://www.facebook.com/groups/819878938473404/permalink/1792105484584073/?mibextid=W9rl1R

83Bella

UPDATE:

Temps in CT have been in the low teens this weekend (a guarantee the boiler would misfire and lockout). I found a new tech and he was willing to come out on Saturday. Here's what transpired (I had all the new parts on hand):

1) Tech replaced existing burner plate with redesigned dual perforated burner;
2) Tech replaced exiting 0.62 LP office with new 0.635 LP orifice (I mistakenly listed the original as 0.63 earlier in this post);
3) Tech replaced fan
4) Original fan was making noise which sounded like bearings. Upon inspection the fan blades each had a little nip on the them as though something was pulled through the assembly. Minor cut in each blade.
5) Tech ran CA on low fire and high fire. He had a hard time getting it balanced. He kept playing with dip switches 6 & 7 while trying to fine tune low and high fires. At times, at low fire the boiler would go out.
6) He finally got low and high balanced (so we both thought). He packed up and went to his next job.
7) Shortly thereafter I noticed the boiler would make fluttering/rumbling sound when in high fire mode.
8) Called tech and he agreed to come back. While awaiting his return I was able to get through to HTP tech support (yes, on a Saturday morning). I mentioned to the customer support tech all the parts we had replaced and the fluttering/rumbling sound at high fire. Tech confirmed LP office had been changed from 0.62 to 0.635 and burner changed to dual perforated. Tech suggested: a) check the gas pressure, b) get the low fire as close to 10 on a CA as possible, and c) get the high fire between 9.5-10.

9)Upon his return he checked for gas pressure at the boiler. He commented that pressure would drop to below 9 when the boiler turns on. He thought it was too low. He increased pressure at the main regulator and retested at the boiler. When boiler fires the pressure now held close to 13. Tested low fire to high fire and no sound of fluttering/rumbling. He was content.
9) It's now been more than 24 hours in low teens temps and windy. Pressing my luck here but so far the boiler has not failed!

Could the fix be a combination of a) a 3/4" hole in the fresh air rubber hose to introduce some warm cabinet air into the fuel mix, b) redesign of the burner and c) slightly larger (+2.5%) LP orifice? Could the orifice have caused the gas pressure to be too low?

Keeping fingers crossed my misfire (Error 11) code during the coldest days of the years (for the past 5+ years) has finally been resolved. If so, I hope this post helps others down the road.

If things change (back to misfires) I will return and post another update.

Many thanks to all the advice and guidance!

Teemok

13" w.c. for LP while running is high. Makes me wonder what he set the static pressure to. 11" is the common static(no appliances on) pressure.
Never should static pressure exceed 14".
Good techs don't like flirting with the limit and would rather solve the underlying problem.
A low dynamic pressure when the static is properly set is either a tank vaporization rate limit problem (often exacerbated by cold temperatures) or the gas piping is too restrictive. Raising the static pressure can overcome a piping restriction problem to some degree. It won't fix a tank vaporization rate problem.

The HTP's fixes look like a better burner and a bit more fuel. Compromising the sealed combustion nature of the appliance is an engineering shame.
If the problem was with gas pressure/volume delivery, these upgrades might just make things a bit worse.
You might have had an existing bad tune, along with a with low dynamic gas pressure volume delivery problem.
Now with the upgrades and the LP regulator adjustment, you have a better tune with a boarder line acceptable gas delivery problem mitigation.
Just because it isn't locking out doesn't mean all is just right and the root causes of the problem were found and properly addressed.
I know, doing it right can be trying.