What have I done here ? I only wanted to change a faulty zone valve

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Hi All.

I have a S plan system where the boiler serves underfloor heating, cylinder and radiators. For some time now, we have had this loud noise when the hot water 2 port zone valve stops, i.e when the stat tells it to stop, we have a loud clambering noise that always wakes us up, and my next door neighbour has complained to me also.

I was brave enough to attempt to change it, however I made my first mistake by changing it with a 3 port zone valve, rather than just a like for like 2 port zone valve. It was later on that I realised my mistake but I already opened the pipework at that stage, so I just used a 22mm end feed to block off the redundant output on the new zone valve.

The zone valve was supposed to be a straight swap, but after changing the plumbing aspect of it, a friend of mine did the electrical as I had to attend to an issue at work. Now I don't know what he did, but below is what is happening now.

When we call for heat on the radiator, it fires up the boiler but the zone valve isn't opening unless I set it to manual then our radiators work. This zone valve was working fine before the works/changin the hot water zone valve, we had no issues with the CH circuit. How do I know if the zone valve is bad or something with the wiring has been tampered with ?

Right now when we call for heating, the boiler fires but zone valve doesn't open.
When we call for hot water, its hard for me to tell if that's working because of the 3port zone valve, and being a cylinder I have no way of knowing if its working unless the hot water is exhausted then I know that it hasn't been replenished.
Underfloor heating takes time, for that as well I will need to let it run for a few hours then look at the temperature on the UFH gauge, is there a better way to tell ?

Thanks in advance.
 
Right now when we call for heating, the boiler fires but zone valve doesn't open.

You have things wired wrong...

The sequence should be - Timer> stat > zone valve > triggers boiler to on. Only when the zone valve is open, should the boiler receive a signal to run.

The pump, in older systems, was powered from the zone valve. More modern systems, have the boiler providing power to the pump - so that the boiler can get rid of its heat, after it has shut down.
 
Ask your friend how it was wired/get them back or as per @Exedon change it for a 2 port.
 
As above incorrectly wired.
I take it your 3 port is a Y plan mid position valve?
Maybe clear picture of what's happening in junction box?
To be blunt I would just fit a 2 port wire it correctly and move on.

3 port valves are cunning enough when installed in a Y system, they will be delighted to be installed in a S system, but you won't.
 

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