what is the last valve for? PICS

[fuzzyone]

hi all,

just want to know if someone can tell me what this last valve is for? Do i need to turn it on or leave it off? Currently its leaking at the valve so might try and see if i can tighten it somehow.

Cheers!

 

[moggridgeplumbing]

It is a motorised valve which switches the flow between hot water and or central heating depending on demand. If it is leaking at a joint then you may need to drain down the system to that point to rectify the problem.

 

[fuzzyone]

i'm talking about the red valve, not the box on the 3 valve pipe.

 

[mickyg]

its a bypass, although with a Y plan as you have its unlikely you need it on unless you have TRVs on every radiator in which case it should be open a little

 

[fuzzyone]

well upstairs theres 5 rads, i think 2-3 have tvrs, then other are normal.

I found it in the closed postion initially.

Whats this bypass for? Shall i just leave it closed as the rest of the rads in the house are normal plastic turn valves.

 

[fuzzyone]

been reading a little and seems the bypass should be off because there are 3 ports for the water to flow? I think this is for the over-run?

I just need know should this be open or closed and why.

 

[Dan Robinson]

Closed - because you don't have 100% trvs

 

[fuzzyone]

Dan your the man! Oh and i got my PCB for the boiler, going to wire it up this sat and post back.

Ok why closed and what does it have to do with TRV? upstairs are not all on TRVs, only 2-3 have the out of the 5 rads. This is just for my knowledge as I'm a noob with these....for now.

 

[Dan Robinson]

Because not all rads are trv'd you will always have (in principal) one Rad on, which will act as a by pass and not waste heat on a circuit back to the boiler.

Trvs can self close so in theory when heat only is called for by the controls you'd have no circuit for the pump.

With a y plan, you will always have one circuit open ...

 

[seasickstevie]

What always puzzles me, is that even when TRVs are open and asking for heat, the by-pass is still going to let hot water take a 'wasted' trip back to the boiler, and presumably waste efficiency.
Or am I misunderstanding the principal?

 

[Dan Robinson]

You are misunderstanding the fact that on this system it should be turned off, and on an S-plan it should be a differential valve.

Roll one next January - then it will be REAL fun