Triangle Tube Prestige heat exchanger corrosion
I've got a Triangle Tube Prestige boiler. It's a 110 I believe. It's now about 12 years old. It is used for domestic hot water, baseboard heat, and in-floor radiant heat. There's lots of pex involved in the system.
It's got a sort of horn sound for 10-15 seconds when it fires up. I figured it was something easy based on what I've read here and in other forums, but the plumber showed me evidence of rust in the condensate, and says the heat exchanger is almost surely corroded. A few months ago, this same company had to replace the blower, which they say is really rare and evidence that the exchanger is corroded--the blower is having to work too hard. (Incidentally, if you pull the front panel off the boiler, the horn noise stops.)
To prove that the heat exchanger is corroded, you'd have to pull it out, from what I gather, and that's a major undertaking. So they're already talking about replacing it, and doing much else too that's all adding up to a ton of money no matter which option I go with.
He says the pex we have largely does not have oxygen barriers in it. (You can see a lot of the pex when you're in the crawlspace.) He says oxygen is getting into the system that way, and that the iron Grundfos pumps are also contributing to the issue. So he's recommending stainless steel circulators and a stainless steel expansion tank--an "O2 conversion," they called it. That's essentially getting all the ferrous stuff out completely, since replacing the pex would be a nightmare.
The exact text in their description of work is below in case I've misstated anything. It mentions two solutions: replacing the boiler and doing the O2 conversion, or replacing the heat exchanger.
So besides getting a second opinion on this, which they encouraged and which I'll surely do . . . What do you think? Do I have a choice? I suppose I could just do the heat exchanger (assuming that really is the problem), which is the cheaper option. But then the issue comes back, albeit in 10 years or so.
Are there other questions I should be asking? I've learned a lot about these systems over the years but this one is way over my head.
I largely trust this company. The system was originally installed by a general contractor who definitely was no master plumber, and we've had to clean up a bit after him over the years. But this pex thing really takes the cake.
Thanks for reading.
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We found the system had rust in the condensate trap, indicating compromised heat exchanger. Also found the tubing within the home is non oxygen barrier, which allows air molecules to permeate into the hydronic system. This is a hybrid system that has baseboard and radiant heat in the home. We found that all 3 circulators and expansion tank all cast iron, that is causing the rusting into the system. Found the 3in exhaust piping is not pitched in the right direction, which should be back to the boiler causing other compromising issues with the heat exchanger. Spoke with triangle tube in regards to warranty. Warranty has expired, boiler was sold in 2011, boiler is almost 3 years out of heat exchanger warranty. We are providing homeowner options for replacing the heat exchanger which is a month out, or replacing boiler with o2 conversion.
Comments
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Possibly separate issues that may all be related.
horn sound, assuming this started after some time and has not existed since install. On those boilers if the exhaust is being sucked back in to the intake it will deteriorate the venturi material. touch the inside of the venturi, the part you can see while installed, if it is rough even a little bit then Take the venturi off the unit and inspect the back of it, it's probably perforated. if it is, your venting will need to be addressed
Heat exchanger. Someone needs to actually take a look inside the heat exchanger, it sounds like an assumption is being made about a leak, I tend to agree with the assumption but It will be pretty easy to confirm whether or not it is leaking. The heat exchanger is out of warranty, and will probably be expensive. If you are recirculating flue gas as indicated by the foghorn sound there are other components that will be ready to fail
Non-barrier tubing. In my opinion the only way to protect your boiler fully from that stuff is to install a separate heat exchanger in the system so the boiler never comes into contact with that open side, on the open non barrier side you will need all stainless items non-ferrous components. The heat exchanger that separates the system will become a new failure point however, short of replacing all the tubing which is probably not possible, this is the best compromise in my opinion
I would figure out why the foghorn sound is there, confirm the heat exchanger is leaking. After that I would get a quote for a new boiler, separated from the open system with a heat exchanger. If the venting is allowing flue gas recirculation I would fix that, it will cause numerous issues down the line.1 -
Thank you for your thoughtful response. Very much appreciated.
Included here are pictures of the intake/exhaust pipes. Exhaust is on the right. The boiler is in the crawlspace under that hatch. And yes, this noise is a recent development. Should these pipes (just PVC) be modified in some way to ensure the flue gas isn't being drawn back in? We live in a windy place, but these pipes are out of the wind 90% of the time, as the house blocks it.
When I get my second opinion, I'll ask the plumber to look at the venturi and inside the heat exchanger if possible.
Installed, a new (and updated) heat exchanger will be alot. And that doesn't include the O2 conversion. If, instead, we go all new, the quote on a new boiler is even more of course, and the O2 conversion stuff is another chunk of change on top of that. Ouch. A second heat exchanger was not mentioned but I will bring it up if/when I talk to the first crew again.
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@dleihs
If you could XXXX out your pricing, this site doesn't like to advertise pricing given from contractors for work performed, sharing material cost from publicly available places is fine. I would go with a new boiler, with new warranty, seek out a couple of proposals as this is going to be a large investment.
It does look like the installer was trying to separate those pipes, however from my eye it doesn't look like the separation meets the minimum recommended and that separation distance has changed a bit as manufacturers learned a bit more about how these perform in the real world. I could see it being possible that the exhaust makes its way back into the intake, this can happen over time and deteriorate components in the boiler and cause poor combustion.
for your reference I am attaching some pictures of a fouled venturi from an older Prestige boiler I think it was a SOLO 60, this one was recirculating for around 13 years or so before the foghorn sound started. I keep this to show newer service techs that haven't dealt with this issue before
This picture shows the part you can see while the venturi is installed, you can see it is a bit rough looking, it should be real smooth.
after taking it apart this is what was found
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Is that a crawl space opening next to the vent and intake?Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream0 -
Excellent pictures of a bad venturi GGross! Those vent pipe terminations are in a very bad orientation. Those exhaust gasses are hitting the ground and causing turbulance. If there is any snow cover...all bets are off! The exhaust termination should be a min. of 12" above the intake--90° up and then directed 90° out from the bldg. The intake should outlet should be directed 90° down--toward the ground.1
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Thanks all. To answer a few questions (and ask a few more):
The job was inspected when installed, and where I live, I'd be surprised if the county would let anything go, as they're really strict. However, yes, the pipes are very close to the ground. They really can't come out of the wall any higher than that because, yes, that is a crawl space hatch--the unit is right there when you go down into the crawl space. The angle on the pipes could probably be changed and the pipes extended, though, right? Snow is not an issue there because it's under the soffit and the wind comes from the other side of the house 90% of the time, so even when there's heavy snow, those rocks are bare.
Here are a couple pictures of the venturi. It appears to be in better shape than GGross' example, but I think I see some wear. What do you all think?
I also located the condensate cap that the plumber showed me. Here's a picture of that and some related items. His contention was that this stuff in the cap was rust, indicating a rusted out heat exchanger. I haven't tried running a magnet over it yet (something someone else did in another post on this site). But I'm a little skeptical because, as you can see in all these photos, our water here (Rocky Mountain foothills) is just a sandstone- and mineral-laden mess. The whole-house water filter is solid orange when I replace it. Isn't it just as likely that's what this sediment and discoloration is? Or does that stuff not make it through the boiler?
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Cut the 45° fitting off of the external exhaust pipe. "Snorkle" the exhaust pipe "up" 90° (at least 12" length) and then put another 90° fitting on top of it facing "out" from the bldg. Leave the intake as it is, or turn it facing downward. Venturi looks ok but getting 'crispy' around the opening.1
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And don't forget the bird/rodent screens in the pipe ends.0
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There is almost always discoloration in any boiler water. Black, red, brown, gray are all up for discussion.
I wouldn't say yours is at all abnormal. You can use the color for clues. But rust in itself is not bad in boiler water. It indicates that there are ferrous components AND oxygen in the system. Preferably your boiler water has very little oxygen in it so that there is minimal rust. Boiler water circulates in a pressurized, 'closed' system and should generally be able to DE-oxygenate itself. Leaks are not good--obviously. They allow fresh, oxygenated water to continuously enter the system. Boiler water should circulate as a normally "oxygen-starved" heat- transfer medium.0 -
That condensate trap and pump bottom look completly normal to me.
Is this NG or Propane?Serving Northern Maine HVAC & Controls. I burn wood, it smells good!0 -
@Solid_Fuel_Man Thanks for the feedback. It's natural gas. @psb75 It sounds like you're saying rust is just going to happen, but you want to minimize it. I suppose that's effectively what the plumber who came out said, but he has an extremely expensive solution to make that happen. I'm getting a second opinion on Monday and will try to get them to have a look at the heat exchanger as @GGross suggested, though the first plumber said that would be very expensive labor-wise.0
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I am a little confused about this, It takes about 10 minutes to remove the burner on this boiler and get a good look into the heat exchanger. Has this been serviced before? I'm thinking that the plumber you are talking to doesn't want to deal with this boiler or doesn't know how. Is accessing the top of the unit extremely difficult because of the crawlspace installation perhaps? The heat exchanger should be cleaned every year and the combustion tuned. As others have said your venting is incorrect, but not too difficult to rectify. That venturi isn't great, I would replace it sooner rather than later. Likely is not causing you problems right now, but it will.dleihs said:@Solid_Fuel_Man Thanks for the feedback. It's natural gas. @psb75 It sounds like you're saying rust is just going to happen, but you want to minimize it. I suppose that's effectively what the plumber who came out said, but he has an extremely expensive solution to make that happen. I'm getting a second opinion on Monday and will try to get them to have a look at the heat exchanger as @GGross suggested, though the first plumber said that would be very expensive labor-wise.
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Neil Young said it better than me: "Rust never sleeps."0
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@dleihs
I would almost guarantee that venturi is toast. in the pic it looks almost like paper, similar to what the bad one I posted above looks like. It will cause the unit to get incorrect air/fuel mixture and in my case the unit was burning pretty toxic.
for reference this is what a brand new one looks like, that venturi is made of a hard plastic, when it gets rough and brittle looking like that it has been sucking in flue gas, I would bet money the back side of your venturi is perforated
If a plumber told you inspecting the heat exchanger would be expensive I would get a new plumber, you have to get into the heat exchanger to do a proper service, no two ways about it.
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@delta T Thanks, I'll see if the guys today will take a look at the heat exchanger. I think it *has* been serviced before, but I certainly have not been good about getting it checked out every year. Top of unit is not flush to the "ceiling" of the crawl space by any means. @GGross I did call the second plumbing company first thing this morning and asked them to put that venturi replacement part on the truck if they have it before they come out. And yeah, the first crew said pulling the heat exchanger would cost a ton (I guess I should not say how much on this forum) but that he'd show it to me and show how corroded he is sure it is if I let them go ahead with replacing it. Will report back about how this afternoon's visit from the second company goes.0
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You can't see the whole heat exchanger but you can see and clean the top and bottom. The covers for the top and bottom are held on by "spring clips". No tools necessary. Like opening a suitcase!0
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@psb75 I don't believe that's the case with my unit (2011 Prestige Solo 110). I don't see any clips on the top or bottom.
The plumber yesterday (Monday) said, yes, the venturi needs to be replaced and is causing the noise. He also said pulling the heat exchanger would be very difficult, but they might be able to put a camera in there to take a look. He's going to give me a quote on cleaning the heat exchanger, which I'm embarrassed to say I don't think I've ever had done. (I guess it can be cleaned without being pulled?)
Finally, he showed me a picture of the igniter, which was pretty discolored, and recommended it be replaced. He thought it would be pretty expensive, but the PSRKIT15 replacement kit is cheap so I think he was mistaken about that. (He was younger and I don't think he has a lot of experience with these units, though the company is listed on Triangle Tube's web site, so I think they've been through the training.) I'm skeptical—probably a wire brush would handle the discoloration—but I might just have them do it while they're in there.
Anyway this is shaping up to be far less catastrophic than I thought it could be. Thanks to @psb75 @GGross and @delta T for the help. Maybe that exchanger is corroded, but if so, maybe I'll just run it until it fails.
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Your tech may have thought the igniter would be expensive for good reason, the next series of that particular boiler had an ignition update that was offered for free for a few years, it included a new control board, igniter, transformer and a few other goodies. Now that they are not offered free, that update kit is a bit pricey (though a whole lot cheaper than the sum of cost on all the parts about half actually)
The igniter almost definitely needs to be replaced, it probably has the reddish brown discoloration I have seen on those boilers when they recirculate.
Cleaning that heat exchanger every few years would generally be important to get the longevity you would expect from this boiler. In your case it looks like you have made it out relatively unscathed despite several jobsite conditions that should have lowered the life of the boiler. Fixing your venting will be important for the long run, you do not want to continue recirculating flue gases through the boiler. It is possible that other components are affected by the flue gas issue, I sometimes see the fan go out, and even control boards. You may want to start planning to have a replacement, at least start stashing away some funds for it, but make sure when you get a new one that the venting has been fixed
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Sorry, I got the wrong thread. I was involved in a Buderus GB 142 thread.
NOT Triangle Tube. My bad. Very different heat exchanger.
The Triangle Tube 110 is touted by the mfg. to be "self-cleaning." They are generally quite maintenance free ex-changers. I have one in my house.
All igniters and ionization rods are considered "consumables" and should be replaced as needed.
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@psb75 Ha, no problem. Glad I'm not crazy! Anyway, I'll go ahead and get the igniter replaced while I'm at it. Thanks, and thanks to @GGross for mentioning that too. Yes, it does have reddish brown on it. I'll be buying some new PVC today to snorkel it up. The fan did go out, by the way—it was replaced a month or two ago.
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