Copper Oxide on Exchanger Coils--New Boiler?


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Old 11-07-10, 08:15 AM
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Copper Oxide on Exchanger Coils--New Boiler?

About a week ago my pilot light was out. Given it was the first time I was firing the boiler up in a long time I didn't think about it - relit the pilot and all was well for a week.

A week later, the boiler will not fire. The plumber that came out inspected the boiler, which wouldn't fire because the backdraft safety had disabled the unit. After inspection, he determined that there was proper venting, but that the copper heat exchanger coils were covered in copper oxide, which is most likely causing the problem. He tried to clean them with a flimsy brush with the unit all in place, but couldn't do it.

In addition, a number of times during the inspection the relay clicked wildly. It didn't do this originally...just a few times while he was inspecting the boiler.

At this point, he gave up and indicated I needed a new boiler.

I would like to verify this with the experts here. Is he for real or should I seek another professional opinion? Can the heat exchanger coils be cleaned or replaced? The relay can be replaced, right?

Boiler: Teledyne/Laars JVT50NDI
 
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Old 11-07-10, 10:49 AM
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Good Lord I hope he didn't charge you anything for NOT FIXING your boiler!

Give me some time to dig up a manual for your boiler and take a look-see at possibilities...

And, while I am at that, set up a free account at Image hosting, free photo sharing & video sharing at Photobucket and upload pics (clear, large enough to see, well lighted, etc) of your ENTIRE system... everything that is connected to the boiler... come back here and drop a link to the album so we can view.
 
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Old 11-07-10, 12:10 PM
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Wow, I wasn't expecting such great help. Thanks for taking time to help out.

Boiler pictures by nollmp - Photobucket

Of course he charged me $280! Saturday service at 9PM. I was just hoping you guys could tell me if I should try to get someone else to look at it. I don't want to spend another $200 just to need a new boiler anyway.
 
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Old 11-07-10, 12:50 PM
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Well, why not? We try to give everyone great help!

I'm trying to visualize where exactly it is that you are seeing that corrosion...

Is that taken from some kinda weird angle with the camera stuffed inside the boiler? Are those the burner tubes that see as if they are standing vertically, but are actually horizontal?
 
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Old 11-07-10, 12:58 PM
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It's really hard to tell from where I'm sittin', but I'm inclined to say that it looks bad... if the pic is from the angle I think it is...

Do you have the manual for your boiler? If not, you can download it here:

http://www.laars.com/LinkClick.aspx?...=1607&mid=4009

I need to ask you why there are two boilers? Are you a renter in a multi-family? If so, that heating system is NOT your responsibility. Can you explain why you are in charge of it?

The flue pipe on the other unit's boiler looks real bad... like it's ready to fall apart from corrosion... and if it DOES ...

Please tell me that there are functioning CO, and SMOKE alarms in your home.
 
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Old 11-07-10, 01:02 PM
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Lastly, the 'chattering' relay is most likely due to a loose and/or corroded wiring connection and is the least of your worries.

Is it time to replace the boiler?... uhhhh... from what I can see, I would say... "probably..." but that's a very inconclusive statement, based solely on what I can see in the pics.

You do know that the top cover comes off that boiler fairly easily and would allow full access to the heat exchanger, right?

If it is not 'owned' by you, do nothing further. Call the landlord.
 
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Old 11-07-10, 01:03 PM
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Yes, you are correct. The camera is on the ground looking up and toward the back of the boiler. Those are the burner tubes in the foreground.

The corrosion, from my limited knowledge, is on the copper heat exchanger and is from the condensation that develops on a cold start.

This gives a little info... Heating Help and made me think it could be cleaned without replacing the boiler. However, like I said, I don't want to spend another $200 if the final answer is "replace the boiler".

Not sure if is makes any difference, but the other two boilers next to mine (for the other units in my building) all look the same in terms of corrosion of the copper fins, age, etc and they are running without issue.
 
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Old 11-07-10, 01:07 PM
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It is owned by me, so I am free to do whatever. I can try taking the top off and getting in to clean the coils. I'm just not an expert and don't want to burn the house down.

Followup:

If I try to clean the coils and make sure all the connections are secure, then turn the boiler on, am I risking anything? The backdraft security would just kick the unit off again if the problem happened again, right?
 
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Old 11-07-10, 01:11 PM
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Yes, smoke detectors and CO detectors. That corrosion if from rain getting in, which has been remedied. The flues are not hot so it is still functioning well. I have mentioned the corrosion to the trustees of our association.

I own the unit in a condo complex, so it is my property and I can experiment to some extent.
 
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Old 11-07-10, 06:58 PM
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condensation that develops on a cold start.
BUT... this condensation can CONTINUE throughout each cycle if the boiler RETURN water does not get up to roughly 135 QUICKLY. (notice that Laars is saying 120 in their manual... not sure why so low?) That is the 'dewpoint' of the flue gases on a gas fired system. The condensation problem is especially troublesome with the copper fin tube systems because of the higher thermal conductivity of the copper and the low mass involved.

In a cast iron boiler, the same problems exist, but the temperature gradient between the water side and the fire side of the cast iron is greater so the fire side can be considerably hotter than the water side.

Another point of consideration with copper fin-tube boilers is that of 'temperature rise' or 'delta T' between the supply and the return. Laars is adamant about the fact that this delta T must not be more than 30F and the I&O manual is very specific about why and when to pipe the boiler with a bypass. Check out Section 5.

Bottom line is that there must be adequate flow through the boiler so that the delta T is never more than 30 AND the return water temp must be above 120 ASAP after the boiler is fired up.

I don't see anything on your installation that indicates there is a bypass, but perhaps it is out of the camera's eye... compare your installation to the examples in the Laars manual.

I don't believe the 'rain getting in' story about the corroded flue pipe ... is that the oficial 'story' that you got from someone? I would much sooner believe that what you are seeing is a product of the dreaded flue gas condensation in the flue and chimney.

Not only that, it looks like the flue pipes are made from light gauge air conditioning duct, and there are far too many bends...
 
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Old 11-07-10, 07:09 PM
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I can try taking the top off and getting in to clean the coils. I'm just not an expert and don't want to burn the house down.
Or poison someone with Carbon Monoxide. So, if you do attempt to clean, when you are finished, be sure to reinstall the 'hood' for the flue gases properly.

The backdraft security would just kick the unit off again if the problem happened again, right?
IF that is what caused the problem in the first place. It's very possible that the reason the thing took a dump is because of the bad electrical connection in the first place.

'Backdraft security' ... I think that is your tech's words for 'rollout switch', and 'blocked vent' switch. (see fig 9D of the Laars manual) the bottom line of that diagram shows these two safety switches in series with the gas valve. They are designed to cut power to the gas valve in the event of a problem.
 
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Old 11-07-10, 07:24 PM
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make sure all the connections are secure
I would examine each and every electrical connection in the control box. Pull each of those push-on connectors, one at a time and examine and clean the tab, and look down inside the connector for any signs of corrosion. There can also be corrosion between the wire and the connector at the point of the 'crimp' connection. Remove each of those 'wire nuts' and examine. The 'molex' connectors... the white ones that go to the vent damper, and the one with the jumper (which should be pushed into that empty square opening in the box) should be checked too... in short, everything.

How are you at reading schematics? and do you own and know how to use a multimeter in the event that further troubleshooting becomes necessary?
 
 

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