Boiler supply / return connections

CBRob

The connection here seems to be one that is prone to leaking.

I've also seen different connections used here. Black iron pipe, copper and brass
Is there a preferred fitting here that is least likely to leak over time?

hot_rod

Is that a brass BSP to NPT adapter? Is that the leaks point?

CBRob

Bob, I think it's just a 1 1/4 female adapter.

The leaks I've been seeing are at the brass to copper threaded connection.
This is one of the triangle tube boilers in the homes I manage.

DZoro

I don't know what TT does different with there adapters but they have always been troublesome. Besides the fact that they make it 95% impossible to put 2 pipe wrenches inside that space to tighten them up.
I always use a union Just because of the issue, and so many times one has a hard time sealing up the union. Tape, dope, repeat, tap toes together 3 times, sign of the cross, and maybe...

D

CBRob

Here is another, little bit different.
Still a tri tube boiler

BillyO

junk

hot_rod

cut them off and solder onto the copper.

Zman

Those really like to leak. I have suspected that the machining is off. Cutting it off and sweating would solve the problem, I wonder if it would create a warranty issue.
I have used these with good success. https://www.supplyhouse.com/Elkhart-56686-1-CxF-Union-Lead-Free

hot_rod

If it is a Euro built connection they tend to over-think the NPT thread sometimes They machine a NPTF thread and it may not work so well with the fittings common over here, the standard NPT.

On one of my own boilers I cut the copper tube up inside the cabinet, soldered a copper coupling and copper tube the length I needed. As Z mentioned it may void warranty.