Rusty/Leaking Boiler Connection

[Stevedore]

(I posted this question on another forum, but have received no responses thus far. My apologies if you're reading it again...)

We have a gas fired hot water baseboard heating system which is about 8 years old, & working fine. I noticed recently that one of the water connections to the boiler is quite rusty & has a small dripping leak. The connection is between the copper circulation piping & the boiler's iron pipe, on the water return side.

From a little internet reading, I'm guessing that the leaky coupling is a dielectric union. (Please correct me if I'm wrong.) If I'm correct, it appears that these couplings have a gasket or washer inside separating the copper side from the iron side. While replacing this coupling is within my abilities (I think!), it looks like it would be quite a job. The 2 sides would have to be separated with enough distance to allow both the threaded piece & sweated piece to be removed. Am I missing something, or would I have to separate all of the plumbing & vent connections to allow shifting the whole boiler sufficiently to provide the space I'd need? I attached pics of the leaking coupling (lower) & a larger view. There's a similar coupling on the hot (upper) pipe, which shows no sign of leaking.

Alternatively, is it possible to replace the sealing washer/gasket alone, or is that not a good idea? It seems like that could be done without moving the boiler.

Assuming the leak gets no worse, I plan to address this after the heating season. It currently leaks about 2 drips/day.

Thanks for any thoughts/suggestions.

 

[James Henry]

I have, more than once, bought a matching dielectric union and used the rubber gasket inside it to replace the bad gasket in the existing dielectric union. after you replace the gasket apply a small amount of pipe dope on threads of the union before connecting it back together. If the existing union doesn't leak then your set, if it does then you can replace it with the new one.

 

[Sponsor]

 

[Fitter30]

System has to be drained if theres no valves on mains. Most plumbing supply houses might not have high temp gaskets have be purchased off the net or order. Piping will have to come out of their supports after unions are taken apart so pipe can be spread. Spay some penetrating oil them.

 

[Stevedore]

Thanks for the replies. I'll probably try just replacing the gasket/seal, since it seems relatively easy.

If I do need to replace the union, there won't be much water to drain, as there are valves to isolate the boiler from the circulation zones. I'm more concerned about the mechanics of moving the boiler far enough to remove the union parts. From the more complete photo of the system I attached here, it looks to me that I'd have to separate the boiler from everything & slide it a bit to get enough space to get the new union pieces into place.

Thanks again.

 

[Fitter30]

Very nice boiler piping and all the conduit. Plumb level and square boiler should move enough if not boiler side piping can be removed.

 

[Tuttles Revenge]

There isn't a need for a dielectric union in that setup is there? It could be replaced with a brass union sweat x thread

 

[Stevedore]

There isn't a need for a dielectric union in that setup is there? It could be replaced with a brass union sweat x thread

I wondered about that. I see differing opinions on the web.