Replacing Badly Rusted Tankless Coil on Weil Mclain EG-45 - NSFW

ScottSecor

If properly sized, I would recommend a new EG-45, with tankless coil for hwbb heat.

Unless you have a lot of free time, I would suggest cutting your losses and replace the boiler. Hate to see you spend more time, only to learn you cannot get the plate to stop leaking. Worse yet, one of the sections cracks.

hadeone

STEAM DOCTOR said:

If the baseboard is all in the basement, and the piping is all below the water line, then there is no reason in the world to use a coil. 

Its all in the basement but the piping travels up from the boiler, not along the floor, into the ceiling then drops down and back up in each room.

ScottSecor said:

If properly sized, I would recommend a new EG-45, with tankless coil for hwbb heat. Unless you have a lot of free time, I would suggest cutting your losses and replace the boiler. Hate to see you spend more time, only to learn you cannot get the plate to stop leaking. Worse yet, one of the sections cracks.

I measured approx 340 sf of radiation based on some old literature.  I have Aero convector radiators, looks like one was removed, 1700sf house, plaster walls with no insulation.  So it seems the EG45 was properly sized at 390sf.

If I ditch the baseboard in the basement do you still recommend the EG-45?  Im weary of the same failure happening with the tankless coil.

Thanks everyone!

mattmia2

If it is hot water you size it based on the heat loss of the house, not the amount of radiation (assuming the heat loss is <= the radiation)

mattmia2

Or is this steam with a hot water loop?

hadeone

mattmia2 said:

Or is this steam with a hot water loop?

Yes it’s steam and the tankless coil (hw loop) heating some baseboard radiators in the basement.

Intplm.

Hey there @hadeone

You are so deep into it now just go ahead and see it through. Clean the face where the gasket will be and be sure to drill and tap all of those pesky bolts. Use a center punch to start then a small drill bit then move up to the final size needed. Have some extra drill bits ready for when the first few brake. Just go for it.
Give us a look with some pictures of your successful repair when you are all done.

STEAM DOCTOR

I would stay away from the coil. They really are the weak point on an otherwise Grade A boiler. At only a few feet of elevation, very easy to keep water in the loop, without a coil. Using what we call the fishie method (Dan has a chapter on this in one of his books and I thing there are articles about this somewhere on this site). 

STEAM DOCTOR

If you ditch the baseboard, then you definitely do not need the coil. 

STEAM DOCTOR

The Weil Mclains come with or without the coil option. And of course if you're going without the coil option, there are other options besides for the WM. 

hadeone

STEAM DOCTOR said:

The Weil Mclains come with or without the coil option. And of course if you're going without the coil option, there are other options besides for the WM. 

Right so I’m trying to figure out the best way to ditch the coil and keep the baseboards.  If it’s not feasible then I’ll do without the baseboards.  

ScottSecor

https://heatinghelp.com/systems-help-center/how-to-run-a-hot-water-zone-off-a-steam-boiler/

Not a bad way to go with your situation, single small zone in basement.

Ironically we've had good luck with using tankless coils for heating on Weil McLain EG steam boilers. We've used them with indirect dhw tanks, radiant heat and hwbb loops with few problems. I always considered the "clean" water of the tankless coil a huge advantage. Pumps seem to last a long time, as do the other components as it is a closed system.

hadeone

ScottSecor said:

https://heatinghelp.com/systems-help-center/how-to-run-a-hot-water-zone-off-a-steam-boiler/ Not a bad way to go with your situation, single small zone in basement. Ironically we've had good luck with using tankless coils for heating on Weil McLain EG steam boilers. We've used them with indirect dhw tanks, radiant heat and hwbb loops with few problems. I always considered the "clean" water of the tankless coil a huge advantage. Pumps seem to last a long time, as do the other components as it is a closed system.

Thanks for this.  My system worked well besides the leaking.  I’m not sure how old this boiler is but I’m guessing 10 years+ and doesn’t look like much maintenance has been done.   

STEAM DOCTOR

I have also used the coils for such applications. Many times. But my personal opinion is to avoid when possible. 

hadeone

I am now boiler shopping and did a EDR calculation. I’m calculating 280 SF of radiation using the tables for Aero convector radiators and it turns out the EG45 installed was somewhat oversized (388 sf capacity).   It seems like a new EG40 would work (321 sf).  I understand it’s the same boiler as the EG45 but with 5 burners instead of 6.  

A local plumber is proposing a Crown replacement because they have tappings high on the sections which can be used for the baseboard zone.  That would keep the zone water cleaner than lower tappings.  Does this make sense?  Using the boiler water directly seems like it will have the same effect on the zone pumps regardless of tapping.  They are against WM because of the rubber seals.

Thanks for reading.  Any more insight is appreciated.  

STEAM DOCTOR

Peerless also offers tappings a bit higher up. Perfect for your application.

STEAM DOCTOR

And for what it's worth, when given the choice between WM and crown, I would take the WM 10 out of 10

hadeone

STEAM DOCTOR said:

Peerless also offers tappings a bit higher up. Perfect for your application.

I was looking at the Peerless 03.  So using the higher tappings to avoid using a tankless coil is worth not having “clean” water in the zone?  

Ideally I’ll avoid the coil but if the alternative will create other issues before a new coil does than is it worth it?

Just thinking out loud.  Thanks for reading.

BobC

Increase the PH of the boiler water and you won't have to deal with corrosion and everything will last longer.

Bob

STEAM DOCTOR

I think that you are overthinking this. There are many thousands of people who feed their basement baseboard systems, with boiler tappings using regular boiler water. Worst case scenario, you will need to replace your circulator every once in awhile. Not a big deal. On the other hand, if you ever need to replace your coil, it can be a very big deal.

hadeone

STEAM DOCTOR said:

I think that you are overthinking this. There are many thousands of people who feed their basement baseboard systems, with boiler tappings using regular boiler water. Worst case scenario, you will need to replace your circulator every once in awhile. Not a big deal. On the other hand, if you ever need to replace your coil, it can be a very big deal.

You’re right.  I don't have any experience except for what was installed in this house so since I’m replacing it I want to make sure what I do is equivalent or better.  Thanks for clearing up that the tappings method is more commonly used.  I’ll most likely go with that on a Peerless like you recommended.  

STEAM DOCTOR

Peerless has 1" tappings intended to used for indirects. They are perfect for this application. Well below the boil the water line but not quite the bottom.

EBEBRATT-Ed

@hadeone

The problem with the coil is not the coil itself but the gasket and the mounting bolts.

The original installer should have removed the bolts and put never seize on the threads and then retorqued the bolts. Then they should be checked every year or two retorqued the bolts.

The problem is no one ever does this and then you start to get leaks around the gasket.

If the leak is attended to promptly it's a non-issue remove the coil new gasket retorque and clean up and your fine.

When it gets neglected it turns into a mess.

realliveplumber

The original installer should have removed the bolts and put never seize on the threads and then retorqued the bolts.

The manufacturer should have put never seize on the threads

STEAM DOCTOR

I agree but the coils themselves do have a tendency to leak as well. Not common but does happen. And when  that does happen you will have a royal mess. There is a potential for water coming out of every single radiator in the house.

mattmia2

realliveplumber said:

The original installer should have removed the bolts and put never seize on the threads and then retorqued the bolts.

The manufacturer should have put never seize on the threads

Should have used antiseize and stainless or brass bolts or studs and nuts.

pecmsg

The biggest issue with stainless steel bolts is No Stretching. All they do is snap. 

Grade 8 bolts with never seize. 

ethicalpaul

In my case, the Peerless ports work great for my hot water loop. I keep my ph at 11 to minimize corrosion and feed my boiler water through a screen filter, into a bypass loop, and into regular cheap grundfos iron circulator. The water is very clean and all is well after 3 years. SS circulators are quite expensive so I rolled the dice.

hadeone

Just as closure to this thread and some more data, I found a 2016 manufacturing date on the section of the old boiler.  7 years old…