Loud gunshot sound when HTP-EL150N fires (delayed ignition on propane?)
This morning I was sitting in my office with the window open. The exhaust from the boiler is a couple of feet below the window. Almost jumped out of my chair when the boiler fired - it was as if someone had fired a rifle right outside the window.
Went down to check the boiler and it was running, no error codes, etc. I believe the same thing had happened a couple days prior but I was not in the same area of the house so could not confirm it was the boiler, but it was a very loud sound as if someone had dropped something hard on the wood floor.
I let the boiler finish its cycle, then hit the power switch and turned off the gas line. I am going to be calling our local heating/cooling company this morning, but want to get some advice on what they should be checking or looking for.
Of note, I cleaned the heat exchanger six months ago. It was dirty. While I was in there, I also replaced the spark electrode and flame rectification probe with brand new ones. A couple of months back I noticed that there was water leaking out the back of the machine, especially when it would run longer than a usual cycle, e.g. when someone was taking a shower. A couple of days ago, I opened up the top panel and observed that the temperature switch ("eco flue switch") that threads into the exhaust adapter had corroded away and was no longer threaded in, resulting in an open port - this is where all of the water was coming from. I have a replacement switch arriving tomorrow. Could this opening in the exhaust cause the delayed ignition, or is it more likely something else that's amiss?
Appreciate your input.
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Can't be sure that it is the only thing causing your issue but they are certainly related! And I would postpone troubleshooting until that switch is back in place. Additionally you should really get the combustion readings checked with an analyzer, and check the gas pressure at the unit. check while unit is off (static pressure) note the drop at ignition, run to high fire and shut unit off, record the pressure after the gas valve shuts off. Just to be sure there isn't some other issue.
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Thanks, I will delay any troubleshooting until that switch is back in place. I'm also going to have a pro take a look first. I'm definitely not comfortable turning that thing back on right now!
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You are wise to leave it off until someone can diagnose the cause. Make sure that the exhaust is still properly connected to the boiler when they restart it. The pipe can get dislodged with a powerful event like that.
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein2 -
From your description, it is obvious that the combustion chamber fills with gas before ignition takes place.
Does the spark electrode have the right gap? If too close the electrode doesn't produce enough heat energy to ignite the gas. If 20K is required and you only produce 12K before sparking because the gap is so small, ignition may not take place. Not all sparks are of the same intensity. If too large a gap, delayed ignition is a possibility.
Make sure all the connections in the ignition circuit are sound and that is the grounding part of the circuit, too.
Just something to look at.
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Thanks @HomerJSmith , @Zman , and @GGross … while I'm waiting for the tech to call me back, I went in and checked the gap on the spark electrode. It's a bit small! The manual says 5.0mm +- 1.0mm and this one was showing ~3.5mm.
It's been this way for, oh, 6 months or so. The fact that I'm getting delayed ignition now though, does it relate to this? Can a small-gapped electrode cause things to worsen over time?
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Part of the service is doing a combustion analysis just like was done when it was installed. You need a combustion analyzer and to know how to use it to do the maintenance on this boiler. The mixture is likely wrong and that is why you're getting delayed ignition. In addition to components drifting with wear, leaks in the sealed combustion system will change the mixture so if it was correct when it was installed and is way off now you should be looking for leaks as well as partially clogged intake and exhaust. I think at some points the fuel/air mixture is under positive pressure so leaks can be especially dangerous.
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Burner gets dirty, loose on the burner flange to heat x mounting plate causing leakage of gas around the flange. Combustion off, these units like to run on a bit richer than most other condensing boilers. If bit too lean, they will delay ignite causing exactly what you hear. I had one of our very 1st munchkins doing this back around 2002 and they really hadn't vetted out the iom back then and at 50ppm CO they would delay and the neighbor a block and a half away was complaining about someone shooting off a shot gun. Nope, was the Munchkin. That's when we got more in tune with tuning these boilers to 90-100ppm back then.
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I set the gap on the spark igniter by placing two quarter together and making the gap to the coins thickness so they will slide into the gap. Be careful when you adjust the gap that you don't crack the ceramic. Probably best to move the electrode that is connected to the screw plate.
From your pic, I can tell the gap is too small. The spark jumps the gap before the coil develops enough energy to ignite the fuel.
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Thanks for the tip on adjusting the gap @HomerJSmith ! I am assuming that, even with the properly adjusted gap, a thorough inspection by a pro is the most prudent path forward before I try to fire this thing back up, correct?
I'd be comfortable tearing the unit apart right now to inspect for blockages/dirt etc. but I also don't want to alter its current state in case an observable condition (by someone with the proper equipment) could point to an obvious remedy.
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Let's assume this unit stays off for at least a week while the problems are diagnosed and fixed… is there anything I should be doing with my indirect water heater to prevent bacteria growth or other issues?
I also notice that when the temp drops on the lines that carry the hydronic fluid (which contains glycol), leaks appear at certain junctions. I've tried tightening those junctions with the biggest crescent wrenches that I have, but they're as tight as can be. Anything I should do to those junctions while the system is cold and not circulating?
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I am a manufacturer's representative for this unit. I won't disclose what company I work for. All work must be done by a licensed professional. under no circumstances should you do any work on this unit if you are not a licensed tech. Here's what is likely going on..
The delayed ignition is typically caused by a fuel supply issue at the unit. The EL series should have no more than a .5" W.C. pressure drop upon ignition. If the pressure drop is greater, the combustion chamber fills with fuel and does not ignite until a proper mixture of air and gas is achieved. By the time it ignites there is an abundance of fuel in the chamber leading to a delayed ignition (read small explosion) within the heat exchanger.
Have the tech check the pressure drop upon Igniton, and adjust the regulator if necessary.
Secondly, the location of the flue sensor and ECO has likely deteriorated from exhaust condensate. the exhaust elbow assembly including the ECO and Sensor should be replaced. it could also be possible the field connection board located underneath has been compromised as well.
Perform a combustion test analysis and make sure all values are within spec.
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Thank you for that info @daveradar ! To summarize, can you confirm that the below red highlighted items are what you are recommending for replacement?
I still haven't heard back from the tech. I think they are very busy with A/C calls since we are going through a bit of a heat wave. However, I did talk to a tech that knows this system pretty well, and he told me to try something that I thought was interesting.
He asked if I had done anything to the burner when I cleaned the coil. I did not touch the burner at all based on advice I had read here and on other forums. His recommendation was to submerge the burner in water and move it around gently a couple of times to remove any sediment or debris, and then let it dry thoroughly before reinstalling. Does this sound like a good idea? Thoughts?
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I'm having difficulty understanding @daveradar's post. How does the ECO flue switch, a glorified thermodisc, or the ECO sensor create a problem with the air/fuel ratio? Do these sensors delay ignition rather than prevent ignition if they fail?
"The EL series should have no more than a .5" W.C. pressure drop upon ignition." Are we talking about the input pressure to the gas valve? Which maybe should be about 11"w/c or the drop thru the gas valve? Does this HTP model require a conversion disc for LP on the input to the gas valve as other HTP models did?
Boilers do pop when ignition take place, but it shouldn't be hellacious. If it knocked you off your chair, something is definitely wrong.
When you fix it let us know what the problem was and your tech's solution. I still think it is the gap on the spark igniter. Does this gap look wider than your pic?
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Technically, the igniter should spark before the gas valve opens or at least the same time. That tab on the igniter screw plate should have a green ground wire connected to it. Why don't you just widen the gap and prove me wrong, you might just save some money on a tech call. Of course, I would want a combustion analysis done with a recently calibrated CO meter.
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@HomerJSmith So, I did the two quarter test for 5.0mm gap. It's actually right on - i was able to slide the two quarters in between the gap with just slight resistance. My micrometer measurement was probably not exactly in between the two electrodes!
This seems to eliminate the gap question. Sounds like the next priority is a gas pressure test?
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Happy to know my suggestion was not the answer. Very slight resistance. One less thing to consider. I still want to know your solution. It adds to my knowledge base.
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Yes. get items, 2, 3 and 4.
OP is having two separate issues. The flue ECO and Sensor have no relation to the air/gas mixture or ignition cycle. Like you said they are there to interrupt or prevent firing if they are in a fault state. i.e. sensor is above 160* so the ECO opens, unit shuts the gas valve and runs a post purge and throws an error code. These unfortunately are located at the bottom of the vent assembly, so over time as the unit condenses the o rings deteriorate and leak. OP is lucky to catch it without it leaking on the field connection board. I typically get the call once that board has shorted out.
And yes, we are talking about the inlet gas pressure. The pressure drop when the gas valve opens should be no greater than .5" W.C. from static pressure. Have the tech read the pressure at the inlet with a monometer, and run the unit. say you're at 13" when the boiler is not running, the pressure should not drop to any further than 12.5"
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@daveradar , thank you for the clarification. Acidic condensate dripping on the field connection board would certainly raise havoc. That's a suggestion that certainly demands inspection.
Isn't there an LP range in which the boiler operates? Like 8" W/C to 13" W/C. What does a pressure drop greater than .5" W/C indicate? Would that be a mis-adjusted gas valve needing a combustion analysis? On previous HTP products I would put a pressure gauge on the inlet and the outlet of the gas valve and that was a minimum drop. Is that right?
Doesn't the HPT boiler come with NG configuration and need a conversion kit for LP? Thanks again daveradar.
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It sounds like the appliance regulator has trouble doing its job if the line pressure drops over a certain amount on a demand even though this is why there is an individual regulator at each appliance. i suppose this is why adding a large diameter piece of pipe as a reservoir sometimes fixes this problem.
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@HomerJSmith Yes, this unit was converted to LP back in 2013. @daveradar , does this have any bearing on the great data you are providing? See pics below for details…
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Large pressure drops indicate either an undersized gas line, or a line that doesn't have enough volume (too short, still an undersized line) or a regulator that is reacting too slow. Older equipment was more forgiving on this, and often burned poorly because of it, so many who have a ton of experience with traditional equipment overlook a 1" drop as not a big deal. Often it can be with newer condensing equipment. The flue sensor, which I imagine is more of a probe that shuts the unit off when the flue temp is too high, being rotted out creates an open flue passage back into the boiler cabinet, which can affect combustion for sure as the unit may attempt to purge excess fuel from the exhaust before ignition, which ends back up in the cabinet and sucked in to the intake air instead of just clean air.
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For the pressure drop test you only need to test at the inlet of the valve. As the other poster said, a large pressure drop is indicative of a gas supply issue, not the gas valve itself. Since this is an issue on a boiler that has been installed for some time, OP should have the utility company check the regulator. The gas valve is likely fine.
For the EL series the gas pressure range is 3.5" to 14". The EL manual doesn't discern between LP and NG, but on other units it says between 3.5-9" for NG and 11-14" for LP.
a combustion test must be done once the pressure drop issue is resolved (if that is the issue). that's where you would see some fine tuning of the valve to get the proper CO and CO2 readings.
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Hi folks, got the tech in today and he basically tore the entire unit apart. Some highlights:
- Gas pressure tests with a manometer are "good" (I did not get specific data recorded from his readings, but that may be due to the fact that he found other issues…)
- The exhaust elbow was totally caked up with debris that was preventing the flaps from moving freely. @daveradar you had mentioned just buying a new one, I think I'll do that even though the tech was able to clean it up enough so that they are moving freely now, but who knows how long that will last
- Biggest issue (according to the tech) was the mangled gasket at the rear of the boiler module that connects a pretty cheap-feeling piece of ABS to the exhaust portion at the top of the unit
The recommendation from the tech was to get a new gasket (the one at the back of the boiler module.
However, when I looked in the parts schematics for this unit, it appears that there is no option to purchase the gasket (it's not even shown in the diagram), or to purchase the cheap plastic ABS manifold piece. According to the parts schematic you would need to purchase the entire boiler module in order to get those two parts. I'm hoping this is not the case!
Does anyone have a recommendation on getting these two specific parts without having to replace the entire boiler module?
Here are some pics and short descriptions of the activity today:
- This is the gunk that was clogging up the exhaust elbow, preventing it from moving even with pretty forceful hand pressure
- Here's the exhaust elbow after it had been cleaned. I could flip it over and gravity would do the job of moving the two flaps. It still looks pretty dirty though. Thinking it best to just get a new one as they're pretty cheap.
- Here's the problem part - the ABS manifold and the gasket that came of the back of the boiler module.
- Closeup of the damage to the gasket
And here's the parts schematic - as you can see, buying the ABS piece and the gasket don't seem to be an option
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I think that flap is just to prevent backdrafting in common vent applications and can be removed on a single vent application but I am not positive of that.
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Ya, some parts a impossible to get, Lochinvar's flue sensor grommet, Caleffi's 172 pump gaskets, any boiler heat exchanger, etc. Try an get a Therman wire. Go to your boiler's tech and beg them for a gasket. Sometimes your crying and tears will soften their heart and they will send you one for free like Caleffi did for me which is why I am a big, big promoter of Caleffi products.
When patience turns to desperation ( it seem like I have been desperate more than I like), I have used Hi-Temp silicone and put those kind of parts together.
P.S., big concern!
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If they won't sell the flue adapter (The black plastic piece) then they should be able to honor the heat exchanger under warranty if it still is. Some manufacturers sell this piece and others do not. Generally they rot out due to site conditions, boiler not draining condensate correctly, or pitched improperly, flue issues etc. Quite possibly that boiler really needed a cleaning several years ago and may not have been draining correctly, with the gasket in that poor of shape I would check extra carefully at the metal of the heat exchanger where it connects to that flue adapter before making a decision on what to do, I usually see that starting to rot out as well with condensate drainage issues
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Just got off the phone with HTP in Rhode Island - the guy was super helpful and did confirm that the ABS plastic piece and gasket are not an option to purchase separately, and that the only way to get a replacement would be to purchase the entire boiler module.
The unit was manufactured in 2013 and HTP offers a 12 year warranty, so he suggested I just try to get something back with the warranty and put it towards a new unit. However, after getting a bit down that road, he asked if I had the original purchase receipt. I did not as we moved in here 6 years ago and the unit was installed in 2013.
Well, that is a no-go, apparently. He explained that unless you are the same person who purchased the unit, the warranty has no chance of being covered. I found this to be pretty amazing, and he acknowledged that it is strange. Has anyone ever heard of this kind of thing? Apparently me purchasing the house (which included this boiler) voided the warranty on this unit?
The last resort is building a custom gasket. I'm willing to go down that road rather than buying a brand new unit. Any suggestions on where to start?
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The warranty is there to sell the product, it was never meant to be used, it seems. The unit came from a wholesaler they would have a record of the purchase if you provide the serial number. Ask the wholesaler to help you. Go to your local TV consumer's help line and tell your story and ask for their help. File a complaint with the state consumer's agency. You may have State or Federal protection. The FTC’s Bureau of Consumer Protection may help you if you make a safety report about a product's safety issue.
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Thanks @HomerJSmith , I talked with the company in town who installed the unit, they confirmed that these types of warranties are "non-transferrable" and it says as much in the manual.
Talked to the tech's supervisor as well and he did not recommend trying to fashion a custom gasket for this particular part as it's critical to the unit operation and, if done incorrectly, could be dangerous. Any opinions on that?
So now I'm thinking about a new boiler (sigh). Which brands are tried and true? I want to have something that will last, has good part availability, is easy to service, etc.
It just seems pretty tragic that a simple rubber/foam gasket could bring down an otherwise operational (and very expensive) boiler like this one.
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Seal it up with high temp silicone and save money for a new boiler.
This is the way things are now and it's not just boilers. Go shopping for car parts, dishwasher parts, etc etc etc. You look it up on line and after 8 -10 years or so you will find some parts unavailable.
I have tossed many appliances because parts are not available.
And if your looking for something better in a mod con you will not find it.
After 10 years or so they have changed designs, and no one (apparently) is making them supply parts for older units.
Theat is why some will only install cast iron boilers
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The problem isn't that they stopped providing that part, the problem is that for some reason it isn't a service part.
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I'm not sure what kind of gasket that is. Is it solid rubber or squishable foam gasket? If it is solid rubber as your pic seem to be, is it square or round profile? You may be able to get a gasket that will fit from O-rings America. You would need to measure the inside dia and the outside dia and thickness. The material would be Nitrile, I would think, although it could be EPDM or Silicone. Measuring accuracy is important.
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@HomerJSmith that gasket is a combination of solid rubber with a foam backing on one side, so it seems pretty custom. @GGross I will try to get some detailed pics of the location where this gasket seals against the rear of the boiler module today.
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Did you manage to get that flue adapter off the unit without removing the entire heat exchanger? That's fairly impressive! Usually there isn't enough room in those cabinets to remove them, at least on the brands I deal with and they actually sell them as a repair part lol .
If you are going to attempt repair just keep in mind the purpose of that black plastic piece. It adapts your flue system to the boilers heat exchanger, so exhaust gas will run through it, it needs to seal tight. Anything used to repair needs to be able to handle the flue gas, and the heat. Additionally acidic condensate from the flue system will drain back to the boiler through that fitting, so you don't want to block that off, or stop the condensate as it will slowly degrade the material used to patch. Check that the boiler is level, if it is not the condensate will pool up and cause this over time (possibly the original cause of failure?) and if you attempt repair put a CO detector near the unit to be safe. I don't really advise this as a DIY, but if you are going to do it you should just be aware of what that part does, and how critical it is that the repaired fitting does not leak.
If it comes down to it, a new unit will come with a new warranty but I understand that is a large expense
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Here are some pics of the rear of the boiler…
This is looking down at the top of the boiler module with the flue removed. You can see the corrosion on the left side that built up due to the flue eco sensor port that had been sitting open for quite a while.
View from the very rear, looking towards the front of the boiler. On the right is the corrosion from the open flue eco sensor port. The area that the gasket is responsible for sealing seems to be pretty clean, i.e. no heavy corrosion.
A couple of more pics…
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@GGross Wow, that gasket does look promising… I am going to contact Jupiter Heating to see if they can confirm its measurement. Interestingly, I combed through the parts diagrams in the manual and this part number is not in the manual anywhere. Maybe it's something they provided more recently? Fingers crossed!
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You can go another route and search for Giannoni/Sermeta parts.
Didn't go further than finding the above link, but can start from there. Could be pointless, personally didn't want to go down that rabbit hole.
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