Condensate reservoir blown to bits due to delayed ignition
First, the discussion history:
- Original post, many topics discussed with root issue being the "gunshot sound" of delayed ignition
- More recent post, with specific static and ignition W.C. readings being taken during firing. Large pressure drop observed during firing. Had an LP tech come out and adjust both regulators (at the LP tank and at the house).
After the LP tech adjusted both regulators (these regulators are old; he suggested replacing both of them, which I have now scheduled), I tried firing the unit.
The first three firing attempts failed with large pressure drops.
The fourth attempt resulted in a deafening explosion that blew the condensate tank into a bunch of plastic shards.
I'll admit, I'm kind of at the end of my rope with this one folks. I'm not ready to completely give up, but what next?
Decimated condensate tank:
Shards of condensate tank found within the space:
Comments
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Kaboom isn't enough to get you to give up and have a tech. type who really knows what he's doing to come and give that thing a complete check? Gas pressures under all conditions? Air settings? Ignitor condition and settings? Draughts?
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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@Jamie Hall That's the other problem I'm having. I've had no less than four techs from unique establishments throughout our area come to look at this specific issue. None of them seemed to have the in-depth knowledge to identify, address, and correct the issues. All of them were aware that delayed ignition was occurring. And here we are.
That's why I am posting on this board. You guys have the knowledge that our area lacks.
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Some questions:
- Why are the large pressure drops on ignition continuing to occur after both regulators were adjusted? Are they just old and must be replaced (I am having them replaced)? The consensus here was that the pressure drop was due to bad regulators. Is it potentially due to something else like a bad gas valve?
- It seems to me that the condensate tank exploded due to buildup of LP inside the tank, which then suggests that a lack of fluid in the tank was the root cause. Is this what you'd expect to see if there was no fluid in the condensate tank at time of ignition?
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Sadly, this situation is now pervasive in just about every area. To find an individual that is fully competent on combustion, venting, gas pressure, ignition, modulation and the intricacies of a specific boiler model is nearly impossible for the average homeowner.
If you think about it, what possible qualifications do YOU have to question any of them on your issue to determine what they specifically know about it? You ask them to stop over………..they show up, make a few observations, are generally clueless, and come up with the wrong answer. Your last episode shows the incompetence in dealing with propane………..a highly dangerous fuel if not handled correctly.
But, sadly, when you fail at your worthwhile endeavor, there are plenty of people who are ready to chastise……………no good deed goes unpunished!
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@LRCCBJ thanks for that comment, it's exactly the situation I find myself in and it's worthy of a whole separate thread IMO.
I've had four techs out as mentioned. I have suggested checking this, that and the other thing based on feedback from this forum and based on simple logic. As an engineer myself (different industry than HVAC) you generally follow the most logical path when you encounter any type of fault.
One of the techs listened and did not really act on the information based on the report I requested at the end of his time. Two other techs seemed to listen to my suggestions, but did not provide any readings or data (in terms of reading static pressures vs. demand pressures, for example). I actually never saw any of the techs even break out a manometer, much less a combustion analyzer. The fourth tech was simply here to look at the regulators, and I've called him back to replace them outright.
All of that said, I appreciate this forum! There's a solution to this problem and I'm dedicated to getting it figured out. Cold weather is coming and we have no hot water or heat, so help is always appreciated. :)
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So the LP Gas found its way to the condensate tank thru the condensate line from the exhaust side of the secondary hear exchanger. that is lots of gas! has anyone adjusted the trial for ignition timing? If that is even possible on that system.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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has anyone adjusted the trial for ignition timing?
I can answer that…………and I am not even down there!!
NO.
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@LRCCBJ @EdTheHeaterMan I do have video of the explosion (and the three attempts prior to the explosion) that clearly indicate the sound of spark vs. the sound of the gas valve opening. Is that what you're referring to by ignition timing? I'll post that video here in a bit.
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Now we are getting somewhere.
Whey you refer to "both regulators"………….please explain.
If you have an instant pressure drop when the gas valve opens, that issue needs to be resolved BEFORE you do anything else. Gas is flowing at a rate that is not sufficient for ignition. Who adjusted the valves and how did they do it?
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Wow! 😯
I haven't worked on that particular boiler,but any modulating condensing boiler should have the condensate trap filled prior to operation. Even still, that should never happen. Is this boiler equipped with spark ignition? What kind of condition is the electrodes in? I imagine that if you have combustion that is not set correctly and it's burning LP the electrodes are probably taking a beating.
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@LRCCBJ There's a regulator at our propane tank which sits ~300ft from the house. The line from that tank runs to a regulator right outside the house. So, two in-line regulators before the gas hits the gas valve on the boiler.
Even after the guy came this morning, the gas pressure drop was still significant on ignition, i.e. see this post with the tech's data and the pressure drop data as well (this was data from today).
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The line from that tank runs to a regulator right outside the house. So, two in-line regulators before the gas hits the gas valve on the boiler.
This is the regulator that needs to be tested at the moment there is a trial for ignition. It must hold steady…………typically 10.5" water. You can check this right at the boiler.
I see he adjusted it to 13.2"…………near the max desired. Fine. The question that begs is what it does when the gas valve opens.
Don't bother with the regulator on the tank. Very unlikely that this is the issue.
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I would change the reg on the tank also.
300' run is pretty lengthy for a small reg to respond…….JMHO
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@LRCCBJ When the gas valve opens a significant pressure drop occurs (> 2" W.C.). See this post for data prior to the regulator adjustments.
Now, see this video for the exciting moment where the condensate tank exploded. The explosion occurs on the fourth attempt which leads the boiler to enter lockout mode. You can see that although I am tempted to cut power to the boiler during its failed attempt sequence, I let it run to its end state (max of four attempts at ignition) of a blown condensate reservoir. Of note, the manometer is set to show MIN value, and it drops from >13" to 11.2" on the first ignition attempt, and maintains that low end throughout each attempt, including the explosion attempt.
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Check the manual on the boiler. What is the requirement for gas pressure at the boiler? 11.2 might be more than sufficient!
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Clearly, gas pressure absolute is NOT the issue here!!
However, the caveat on that above statement is the drop when the gas valve opens. The gas valve at the boiler needs to respond to the drop to 11.5" and it may not be all that pleased with that. Notice the manual limits the drop to 1" water column. They know something about the regulator at the boiler that we don't!
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Clearly, the gas valve is not maintaining the setpoint and I would change it. Before you spend the money, it would be interesting to see what the inlet pressure to the valve is when there is a load put on it. Jughne is concerned about the 300' run from the tank.
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@LRCCBJ @JUGHNE I am going to have both regulators replaced (the one at the tank and the one at the house) before I try anything else.
The inlet pressure is right around 13.2" at this point… when a load is placed on the unit, we drop to around 11.2" - see the video linked above.
I'm not sure what happened to that gas valve when any of the four techs came to look at the system. One thing that jumped out from the manual is that it is highly discouraged practice to check anything at the gas outlet side. Maybe one or more of the techs did that and now the gas valve is in an unknown state?
DO NOT adjust or attempt to measure gas valve outlet pressure.
The gas valve is factory-set for the correct outlet pressure and
requires no field adjustment. Attempts by the installer to adjust
or measure the gas valve outlet pressure could result in damage
to the valve and cause substantial property damage, severe
personal injury, or death.0 -
Some digital meters are slow to respond for a quick change in anything….pressure…..voltage….etc.
I would try a water column manometer.
First, IMO, I would change both regulators that are outside.
The first stage should give you about 10 psi to the second stage.
LP regs have an expiration date that the gas supplier usually looks at and changes them as needed.
Also are you looking at the LP section of the gas supply requirements…..not the NG ones….could be different.
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Thanks @JUGHNE , good info. I'll have the tech measure the first stage for 10 psi to the second. I am thinking these regulators are so old that the only option is to replace. Why gamble on 30 year old equipment?
I'll build a W.C. meter with my son who is super interested in this stuff. It will be good to get that real-world confirmation alongside the digital manometer.
And yes, I'm taking care to focus only on the LP values in the manual as opposed to the NG ones, appreciate the reminder.
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Why not call the boiler MFG , explain the issue and ask them if they have a tech to recommend or a factory guy who can look at it. Some MFGs don't like to talk to building owners or homeowners but it's worth a try.
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I'm not sure what happened to that gas valve when any of the four techs came to look at the system. One thing that jumped out from the manual is that it is highly discouraged practice to check anything at the gas outlet side. Maybe one or more of the techs did that and now the gas valve is in an unknown state?
DO NOT adjust or attempt to measure gas valve outlet pressure.
The gas valve is factory-set for the correct outlet pressure and
requires no field adjustment. Attempts by the installer to adjust
or measure the gas valve outlet pressure could result in damage
to the valve and cause substantial property damage, severe
personal injury, or death.This is quite interesting. Might be a negative pressure gas valve that the mfr. wants nobody anywhere near it!!
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Looking at purchasing two items:
- 7450P-200 (Condensate Collector Unit, $248 from Jupiter Heating)
- 7450P-025: Dungs Gas Valve (EL-80 and EL-150, $273 from Jupiter Heating)
Disclaimer - I love Jupiter Heating, excellent shop with great service. Question is - is >$500 worth throwing at this problem? Do I just need to be looking at a new boiler at this point?
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@SuperTech Thanks for the response. The electrode was replaced just a couple of months back. Gap was checked and confirmed to be right at 5.0mm per the manual:
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I probably would consider replacing the boiler, at its age it has high miles and may not last much longer. That's old for a condensing boiler. But I don't know your situation and how long you plan on staying in your home. This frustration coupled with the big boom might be the last straw for me, but then again I like the satisfaction from repairing things too.
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No matter your next steps to getting a functioning boiler, I would replace the regulators. Often the gas company will do this for you, perhaps letting them know a portion of the boiler blew up would get them to act quickly. As for your boiler, is it fixable? probably… but it appears that it wasn't being maintained as well as you thought. Those coffee grounds that blasted out of the trap imply whoever serviced it had not been flushing out the heat exchanger as they were supposed to. I can tell you for me personally I wouldn't be putting $500 into a gas valve (that we don't know if its bad or not), I would be putting that money towards a new boiler with a new warranty. If I were going to fix the boiler though, my first step would be changing the regulators (do this either way) then checking with the manufacturer to make sure the condensate assembly is sold independently of the heat exchanger, replace the condensate assembly, fully clean the heat exchanger, and start over the steps of dialing in combustion, include tech support in this, and test the gas valve with them before replacing it. If I were told I needed to get a new heat exchanger for the condensate assembly I would likely be back into looking for a new boiler
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@GGross Thanks for the input. This boiler was manufactured and installed in 2014, so it's not as old as maybe you and @SuperTech were thinking. The condensate unit is sold separately from the heat exchanger, so replacement is an option there.
I am definitely going to have both regulators replaced before trying anything additional here… I have started looking at new models, but not sure where to start since this system is pretty unique. It has an indirect hot water heater that is heated with hydronic fluid from the boiler, and the same boiler is also responsible for heating hydronic fluid that is circulated through the radiant floor heating system. In addition to that, the same hydronic fluid is also cooled by two outdoor A/C units while at the same time allowing the boiler to maintain a portion of that hydronic fluid at a proper DHW temperature.
I was thinking of the possibility of getting rid of the indirect tank and having a dedicated tankless hot water heater (condensing style) in addition to having a second boiler that is dedicated to heating the hydronic system during the winter months. However, seems like it'd be simplest to try to find a unit that is a drop-in replacement for what's there now as I'd like to minimize the amount of repiping that would need to be performed.
Any recommendations on units that would be a good replacement for this particular setup?
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Remnants of the condensate tank, for posterity:
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I would stick with using an indirect water heater. Your system is nothing unusual. Any boiler should work for a replacement. Make sure it's size properly and the installation is done according to the manual. And, yes. Absolutely replace those regulators.
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If the tank and house regulators are within limits, I would think they are fine. Your propane company that provides the tank should check the regulators for free and replace them if necessary. If everything is hunky- dory. I would call HTP tech about a free replacement of the control board. They would want to know about this problem. You said that the gap on the igniter is fine. Is the cable from the board to the igniter good and not grounding out and the ground wire, OK? Your problem could very well be in the board, I think.
I have had problems with the Molex connector with HTP boilers and other makes. Sometime just re-pluging them in will solve the problem. If so. replacing the cable would be the solution. What happen is that the jacks in the Molex plug don't make good contact with the pins on the board.
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Thanks @HomerJSmith , while I am going to have both regulators replaced (one less thing to suspect and worry about when diagnosing the real problem), I did check the ground connection between the board and the housing and it is clean (no corrosion, etc.).
When you say "the board" are you talking about the field connection board or the main control module that lives on the access panel (the door that swings open and allows one to service the unit)? The field connection board looked like it had been compromised due to the flue gases that had seeped out due to the rotted out flue sensor. I cleaned the board up and re-soldered a number of Molex connections that appeared to have either shorted out or were showing signs of corrosion. I did not check the connector pins to see if they too had developed corrosion due to their close proximity to the acid. I am including some pics of that process so that you can make a better assessment.
All of that said, I am at the point where I'm shopping for a new boiler. I am going to keep this HTP unit, however, find the problem, and fix it. Once its fixed, I plan to put it into service in my shop, which has in-floor heating that has never been hooked up. So it will not get thrown into the trash. I will probably have more posts about testing that unit, including bench-testing various components of that unit, in the future.
Underside of field connection board (the tech said "the board was fine"):
Field connection board after cleaning… I also re-soldered all of these connections so that they had nice shiny solder when they were reinstalled:
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Update - LP company came out yesterday and replaced both 1st and 2nd stage regulators. Now I am getting very consistent readings at the boiler gas intake valve, right at 12.45" WC without any jumping around. Previously, the reading was jumping up and down even while taking a static reading, even after the valves were "adjusted" the first time.
So, feeling good about the regulators and it seems as though they were definitely a cause of all the issues that arose.
Sadly, I'm moving on from this boiler as the explosive failure really caused me to start doubting the integrity of all the other internal components. I'm in the process of taking this boiler offline and shopping for a new one. Once this boiler is offline and I can examine each component in detail without worrying about pressurized lines, etc. perhaps we'll find all of the issues and be able to bring it back into service.
Will keep you posted on progress!
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I have preached to many rural people that regulators have only a limited life and they do wear out.
They don't think there is anything to wear out as they can see no moving parts.
But there are moving parts inside and that they are moving with every change in the load. The diaphragm is a form of rubber that can be stretched/moved only so many times. The mechanical pivot points/arms/springs will wear out with use.
If I remove a regulator or gas valve I smash it with a hammer before throwing it away to insure no-one will try to reuse it.
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@JUGHNE Smashing with a hammer makes good sense! We get pretty brutal weather here during the winter (intermittent temps that drop to -40F for a couple of days here and there) and it makes sense to me that those rubber diaphragms would eventually give up the ghost after decades of use. These regulators were from the late 90's, so they had seen their fair share of temperature fluctuations.
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