lockshield valves

[pritsuk2002]

hi im going to be put a few rads on a sealed system with new trvs. i wanted to know
1 if i should also put a new valve on the other end?
2 am i right in saying its called a lock shield valve?
3 are they bi directional?
4 once fitted should i position the valves to open position then use filling loop to fill system? or should they be closed?

thanks

 

[Bahco]

1 if i should also put a new valve on the other end?

Only £2 so why not

2 am i right in saying its called a lock shield valve?

yes

are they bi directional?

I suppose so

4 once fitted should i position the valves to open position then use filling loop to fill system? or should they be closed?

Not much good to you if closed.

 

[TicklyT]

It's not usually necessary to change the lockshield valves, but some might for cosmetic reasons.

LSVs are used to control the heat input to each radiator, and TRVs control the final room temperature. The system should be balanced by setting the LSVs to throttle the flow so each radiator gets it's fair share of the boiler output.

LSVs are bi-directional. Usually the only difference between an LSV and the wheelhead valve on t'other end of a rad. is the plastic cap. Swap the caps over, and the wheelhead becomes an LSV, and vice versa.

If you close an LSV, count how many turns and fractions of a turn it takes so you can open it to the right setting without upsetting the rest of the system. If you change one, it will need setting up from scratch.

Some erroneously believe balancing isn't necessary if TRVs are fitted. Without balancing, the system will tend to heat up one or two rads at a time, with some not heating at all until the TRVs on the working rads start closing. There is information on balancing systems in the FAQs.