Hole in my shoes?

[PaulAH]

Do Danfoss two-way valves (shoe type) have a habit of leaking? (At least I think it's shoe type - its stoppers are shaped like a section of cylinder backed by a spring).

I've fired up our new CH system and, while all is generally well, there seems to be a lot of heat getting to the rads when that zone is closed. After an hour or so, the pipe from the "out" side of the valve was too hot to touch, and some of the rads were almost that hot too. (The return was barely warm, however).

I cannot see how so much heat is getting to that side of the system with the valve closed unless it's passing water.

Another zone with a similar valve remains stone cold when it's shut off.

Please don't make me take it off. I've already drained down five times to cure a leaking joint!

Paul

 

[oilman]

Please don't make me take it off

OK, you can dismantle it in situ to see if the shoes are scored, but you will still have to drain the system. When you have drained the system, you might as well take it off instead.

If I was putting the system in, I put service valves on the pipes that connect to the valves, so when they need fixing, I can take them off without draining.

 

[PaulAH]

I put service valves on the pipes that connect to the valves

Great. Now you tell me.

Is this because they have a habit of leaking? Is the shoe-type particularly prone? (these are brand new). Would you say the symptoms indicate a leak? I can't see any other path through which the heat is being transferred.

Meldrew.

 

[PaulAH]

Oilman, I have wasted your time. A whole evening's investigation has revealed that some Scunthorpe plumbed a rad wrongly. If my theory is correct, he has taken the feed from the DHW flow and connected it back to the CH return.

The error became clear when I fired up from cold with just the HW valve open. Defying the laws of physics, the RETURN from a pair of 15mm pipes disappearing into the ceiling became hot, the flow remaining cold.

Eventually every other rad in the house heats up, presumably fed by the one wrongly-configured rad. Shutting it off cures the problem.

So revisiting the original question: When the flow pipe from the two-way valve became hot, I assumed it was because the thing was leaking internally. It's now fairly clear that the heat was backing up from elsewhere in the system, fed by this rogue rad.

And I know who this bar-steward is. He was the guy who built our extension. It fell down half way through the job, taking half the house with it. The plumbing seems to have been of a similar standard. It was not evident when the CH was a single zone with gravity fed HW. The whole thing just "got hot" or "got cold". Now it's pretty obvious. So it's up with the floorboards...

Why oh why didn't I keep the old Redfyre going? It was only 30 years old. We'd have been none the wiser.

Paul

 

[doitall]

Thanks for taking the time to help, I really apprciate it.

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