Decommissioning a Tankless Coil

Kafox15

Hello,

I have some questions about decommissioning the tankless coil in my Peerless WBV-03 steam boiler (2014 install). I had noticed some rust spots around the outside of the coil where it attaches to the boiler and I confirmed that it is leaking by doing an overfill test and letting it sit for a while. Seems the gasket is in really bad shape. Is this typical for a 7 year old boiler/tankless coil? Seems a bit premature to me.

Regardless, I am going to take this opportunity to switch to a heat pump water heater instead of installing a new coil. I know that I will need to carefully remove bolts and the tankless coil, clean up the mating surface (hopefully the leak has not done much damage to the cast iron) and install a new gasket/blank cover plate.

Should I expect the cover plate to have to be replaced every 7 or so years like the coil or is there something about the coil that makes it wear out more quickly? Expansion/contraction of the coil/plumbing maybe?

Anything else I need to be aware of? Thanks!

Some pics below.






View from inside the top of the boiler. Gasket has broken into pieces.

STEVEusaPA

But before you do all of that, I'd also remove the jacket and make sure you don't have water leaking between the sections too. The leak on the upper left side of the coil looks like it's coming from somewhere above the coil.

Could be water quality, could be initial quality of the boiler, could've also been the bolts were tight, or the coil gasket wasn't installed properly. Could also be electrolysis.
I think if you do as you say, drain system, spray bolts with kroil or similar...alot...and get the bolts off. Then clean the surface and replace with blank and new gasket, you should be fine.

leonz

YUCK!!!!!!!!!!!!!!!!!!!!!!!!!

Whoever did that installation was not doing the homeowner any favors.

The cover plate is actually part of the domestic coil and it all comes out in one piece.

Your domestic coil is either of the trombone type with multiple race track runs of copper pipe from
the cold water inlet to the hot water outlet or a spiral copper tube the length of the steam jacket.

You need to go to the find a plumber section of the web site HERE to find a steam plumber in your area.

Are there any bronze unions sweated on the copper potable water lines outside the picture?????????
Is there a hot water rated bladder tank in this tankless hot water delivery line somewhere out of the picture feeding a boiler mate?

Does this steam boiler have an automatic water feeder, if not how often do you blow down the boiler to clear sludge and add water back? Has this steam boiler ever been drained and the sludge blown out of the boiler drains?

As SteveUSA said the boiler jacket has to come of first and the boiler checked for any other leaks.

The water lines have to be separated from the coil in the boiler; hopefully there are unions on this pair of copper pipes otherwise they need to be added to make any future repairs easier.

Do you also have a separate hot water used to make hot water in the off season or is the coil piped directly into the cold water inlet of the water heater for year round water heating?

If you do not feel confident in repairing it you need a steam licensed plumber to fix the mess the other plumber made IF AND ONLY IF after taking off the boiler skin the steam boiler is examined for any leaks and is still in good condition. The air vents may need to be cleaned or replaced as well.

Do any of your radiators have steam radiator thermostatic control valves??

If you do not have a drop header on the boiler to make dry steam now would be a good time to add one as this steam boiler has been neglected if it is in safe condition.

Having a drop header or a double drop header will let you heat the home faster and satisfy the radiators need for heat at a much faster rate and also reduce the cycling of the boiler as the radiators will remain hotter for a longer period.

KEEP IN MIND that your insurer may or may not void your homeowners insurance if a repair is made by you and something bad happens, AND THEY WILL ASK YOU.

You need a Licensed Steam Plumber to look at this long before the snow falls.


Being a novice I hope I have not forgotten anything.

EBEBRATT-Ed

@Kafox15

Once you get it off and cleaned up make sure you use "antiseize " on the bolts stainless bolts would be better and studs with nuts are better yet....you get two chances to get it apart the next time.

I have seen a lot worse, take your time use some penetrating oil (Kroil Oil) is best, Work the bolts back and forth...tighten -loosen-tighten -loosen

Tankless gaskets are problematic this is a common issue

Kafox15

STEVEusaPA said:

But before you do all of that, I'd also remove the jacket and make sure you don't have water leaking between the sections too. The leak on the upper left side of the coil looks like it's coming from somewhere above the coil.

I don't think I'm going to be able to remove the jacket without cutting into the plumbing, so wouldn't it make sense to do that at the same time I am removing the coil and installing the plate?


@leonz Tried to answer your questions in-line below.

leonz said:

Are there any bronze unions sweated on the copper potable water lines outside the picture?????????
Is there a hot water rated bladder tank in this tankless hot water delivery line somewhere out of the picture feeding a boiler mate?
There are unions on the mixing valve and there is an expansion tank, but no storage tank in this setup. You can see more zoomed out pics of my setup in this thread from last year.
https://forum.heatinghelp.com/discussion/182184/tankless-coil-aquastat-settings


Does this steam boiler have an automatic water feeder, if not how often do you blow down the boiler to clear sludge and add water back? Has this steam boiler ever been drained and the sludge blown out of the boiler drains?
It has a manual feed and I top it off maybe once a month or less, so not losing much water at all. I have a probe type LWCO so no blowdown. I do drain and refill once a year and also skim once a year.

As SteveUSA said the boiler jacket has to come of first and the boiler checked for any other leaks.

The water lines have to be separated from the coil in the boiler; hopefully there are unions on this pair of copper pipes otherwise they need to be added to make any future repairs easier.
I am decommissioning this tankless coil, so all this plumbing would be removed, so not concerned about future repairs.

Do you also have a separate hot water used to make hot water in the off season or is the coil piped directly into the cold water inlet of the water heater for year round water heating?
This is our year round source of hot water. There is no other water heater or storage tank. I am switching to a heat pump water heater.

If you do not feel confident in repairing it you need a steam licensed plumber to fix the mess the other plumber made IF AND ONLY IF after taking off the boiler skin the steam boiler is examined for any leaks and is still in good condition. The air vents may need to be cleaned or replaced as well.
What air vents?

Do any of your radiators have steam radiator thermostatic control valves??
They all have Vent-Rite #1 which are adjustable but not thermostatic

If you do not have a drop header on the boiler to make dry steam now would be a good time to add one as this steam boiler has been neglected if it is in safe condition.
Yes, my near boiler piping is not correct and needs to be redone but that is completely separate from the tankless coil. Can you explain how this has been neglected?

Having a drop header or a double drop header will let you heat the home faster and satisfy the radiators need for heat at a much faster rate and also reduce the cycling of the boiler as the radiators will remain hotter for a longer period.
This is something I am planning on doing, but this thread is regarding the tankless coil which is separate.

KEEP IN MIND that your insurer may or may not void your homeowners insurance if a repair is made by you and something bad happens, AND THEY WILL ASK YOU.
You need a Licensed Steam Plumber to look at this long before the snow falls.
Absolutely, this is not something to be ignored but I think you are being a little alarmist here. The boiler is not going to suddenly explode or flood my basement.

EBEBRATT-Ed said:

@Kafox15

Once you get it off and cleaned up make sure you use "antiseize " on the bolts stainless bolts would be better and studs with nuts are better yet....you get two chances to get it apart the next time.

I have seen a lot worse, take your time use some penetrating oil (Kroil Oil) is best, Work the bolts back and forth...tighten -loosen-tighten -loosen

Tankless gaskets are problematic this is a common issue

Will certainly be taking my time getting it off and stop if I get in over my head. This is the kit they sell for my boiler, so I'm not sure if I have other options.
https://www.supplyhouse.com/Peerless-90141-PP1013-Tankless-Cover-Plate-w-Gasket-Hardware-for-WBV-Boilers

leonz

I am not trying to be an alarmist or instigator or spread gloom and doom over your situation.

Taking the boiler jacket off is something that needs to be done to be sure there are no other leaks.

Its better to have a licensed steam plumber look at this as the boiler needs work and at the same time you could ask for an estimate for a double drop header to make dry steam to heat your home faster with less fuel.

An air vent pushes the atmospheric air in the header pipe out to allow the steam to enter the header and then the radiators in your home. Do you have an air vent at the end of your steam header pipe?

If something happens to the boiler while you are working on it no matter how small and you incur a loss your insurer may very well void your policy as YOU WORKED ON THE BOILER without a steam plumbing license.

The other issue is corrosion as you may very well have unseen corrosion that is not repairable.

I am not trying to spend your money, I only want you to see this with your eyes open; the coil is probably still in good condition and does not require replacement as the boiler is not flooded and has been providing you with plenty of hot water.

EdTheHeaterMan

There is one important thing about tankless coils on hot water and steam boilers that is often overlooked. Tightening the tankless coil plate. I have read this in several boiler IO manuals "After 250 hours of operation, check and tighten the coil plate flange bolts to the proper torque." As a rule no one tells the homeowner about this. Some manuf. don't even include this info in their manual. All my new boiler installation included a free 1 year maintenance inspection service. (This got me in the house a year later in order to have an opportunity to provide a service policy.)

Every tankless coil job needed the bolts tightened. I know they were tight when I installed the boiler a year before (because I check), but I find some of the bolts are hand tight just 1 year later. The gasket gets compressed as the metal expands and contracts from steaming to maintaining DHW temperature. It happens on every boiler.

Those boilers I maintained, after 20 years the coil gasket show no signs of leaking at the flange gasket. Just about every other DHW coil boiler I work on (installed by others) has rust within 4 or 5 years. I try to snug up on the bolts but if i think they may break, i leave my hands off.

This story is brought to you in an effort to help you keep this from happening in the future even, if a pro does the work. In about 3 months tighten up on the bolts, then in 3 more months do it again. After that, you will never have a leaking gasket on the cover plate. Dont be a gorilla, just about 20 to 25# torque. (about 1/4 turn past snug) ALSO follow the previous recommendation to put "NEVER SEIZE" compound on the bolts. In 20 years if you need to remove the plate for any reason, the bolts will come out without breaking off.

Yours Truly
Mr. Ed

MikeAmann

You are lucky that your tankless coil bolts ARE stainless. That doesn't mean that they will freely just come out. Corrosion from the tank and plate itself can bind the bolts. Do as the others have said - plenty of penetrating oil and work them back-and-forth slowly. Use anti-seize on the re-install.

heathead

Mr. Ed

Thank you for your points about checking the bolt torque , after some time. Sounds like this is a true solution for a permeant fix. It's like the fine print after getting new tires installed the lug nuts should be check after 250 miles. Makes perfect sense, thanks for the tip.

Jersey2

From my observation, that plate isn't doing you any favors, it only has one bolt on the top and bottom and no bolts on the corners. And the left upper corner looks like heat damage, not rust.

Kafox15

MikeAmann said:

You are lucky that your tankless coil bolts ARE stainless. That doesn't mean that they will freely just come out. Corrosion from the tank and plate itself can bind the bolts. Do as the others have said - plenty of penetrating oil and work them back-and-forth slowly. Use anti-seize on the re-install.

What makes you say the bolts are stainless? I don't believe they are. I was lightly brushing off some surface rust and a few of the bolts heads just fell right off. Seems this tankless coil is more far gone than I thought. I am in the process of installing a heat pump water heater after which I will call a pro to remove this tankless coil and install the plate. I don't feel comfortable drilling the bolts out myself.

EDIT: Any specific contractor recommendations in the Merrimack Valley, MA area? I assume this job doesn't necessarily have to be done by a steam pro. I'll check the contractor lookup as well.

MikeAmann

Your second pic shows the bright and shiny bolt head with no corrosion. The THE on it tells me it is stainless. I have a huge assortment of those. Even so, stainless is not indestructible. You could have an electrolysis condition happening. Your unit is only 7 years old and is eating itself to death.

Kafox15

Updated pic below showing the bolts that have rusted away. Could you explain more about the electrolysis condition and what that means for this boiler? The tankless coil is no longer in use as I have fully switched over to a heat pump water heater.

MikeAmann

Galvanic corrosion is caused by self-induced current created by electrical potential of two dissimilar metals in contact with an electrolyte. It can occur when two dissimilar metals (such as copper tube and steel pipe) are connected in the presence of an electrolyte. Fresh potable water is a weak electrolyte.



You can test for this by using a multimeter on the DC mV scale. Ground one probe (known good earth ground) and you need to find a way of getting the other probe into the boiler water. If you read too much voltage, then you will definitely have electrolysis.

Kafox15

How much voltage is "too much"? and if there is an electrolysis condition, what do I do about it?

Kafox15

Kafox15 said:

How much voltage is "too much"? and if there is an electrolysis condition, what do I do about it?

Following up on my last comment above.

I'm peeling back the jacket today and doing another overfill test.

Kafox15

No other leaks besides the ones around the tankless coil. I added some high temp RTV silicone and it seems to be holding, but I don't know how long I can expect it to last.

I contacted a contractor from this site and he recommends waiting until spring as its too risky to attempt now. What does everyone think?

MikeAmann

Cold weather winter weather is nearly here. If the silicone is holding, wait until spring.

Kafox15

Resurrecting an old thread, but finally working on this now that summer is upon us. I managed to easily remove the 5 bolts that were still intact and get the coil out. Still need to remove the 3 bolts where the heads broke off, but I'm not expecting it to be too difficult as the other bolts came out very easily.

With the coil out, I can see inside this boiler section and its not pretty. Is this typical for the inside of an 8 year old boiler? Do I have some other problem going on that I should address now?

MikeL_2

   I've been grinding the heads off coil plate bolts for about 25 years. After removing the coil plate, I heat the remaining studs red hot & let them cool. They always back out easily with a tiny pipe wrench........
  
    

Kafox15

Yea, I don't have concerns about getting the broken bolts out as long as I can get a grip on them. More concerned at this point with how the inside of this thing looks.

EBEBRATT-Ed

The inside looks pretty normal.

Kafox15

Finally got this taken care of - removed the remaining bolts, two of them I was able to grab with vice grips and turn out and just one I had to use a bolt extractor, but it came out easy once I got a grip on it.

Cleaned up the mating surface the best I could and installed the blank plate - made sure to use never seize on the new bolts. torqued them to about 20# but will retorque as needed during the heating season.

Anything else I should take care of now? I will probably do a skim at the beginning of heating season.

Thanks all!