Rad valve on flow or retuen pipe - which is best?

Henrik · 13 Jan 2014

Hi,

System was initially installed with all rad valves on the flow pipe, air vent valve at the return side. This was logical to me and allowed balancing of the system.

We've just completed an extension, with additional radiators, and I notice the plumber has fitted some of the new valves the other way - with valve on the return end, and lockshield on flow.

I have 2 questions:

1 - does it matter which way the valves are fitted
2 - how do I balance the radiators when valves are on the return side - do I leave the lockshield end fully open and use the 'valve' end (now fitted to return piping) as the 'balancer'?

Hope this makes sense, and all help much appreciated.

Henrik

p.s. don't reply telling me the plumber should look after balancing - I'll be glad to see the back of him given he's left us without heat 3 times in the last 3 weeks!

Blagard · 13 Jan 2014

Henrik said:
Hi,

System was initially installed with all rad valves on the flow pipe, air vent valve at the return side. This was logical to me and allowed balancing of the system.

We've just completed an extension, with additional radiators, and I notice the plumber has fitted some of the new valves the other way - with valve on the return end, and lockshield on flow.

I have 2 questions:

1 - does it matter which way the valves are fitted
2 - how do I balance the radiators when valves are on the return side - do I leave the lockshield end fully open and use the 'valve' end (now fitted to return piping) as the 'balancer'?

Hope this makes sense, and all help much appreciated.

Henrik

p.s. don't reply telling me the plumber should look after balancing - I'll be glad to see the back of him given he's left us without heat 3 times in the last 3 weeks!

Generally with old systems the valves could be either way round and OK, but with TRV's you have to be careful, some are only OK on the flow. They will often be called reverse flow if suitable for use on the return. What TRV's are fitted ?

Balancing always uses the lock shield irrespective of whether it is on flow or return.

It is always "best" to use lockshield on the return if you can

mogget · 13 Jan 2014

Also known as bi-directional valves.

Lockshield valves will work on the flow but can be noisy if air bubbles are passing into the rad for whatever reason.

Henrik · 14 Jan 2014

Thanks Blagard,

No TRVs are fitted on the new rads, but as stated in the post the plumber has fitted some rads with the lockshield on the flow. So, to balance these rads, how do I go about it? Do I leave the lockshield (now fitted to the flow) fully open, and adjust the flow through the rad with the 'valve' which is now fitted to return end?

All help much appreciated

Thanks

Henrik

Blagard · 14 Jan 2014

I did say that

Balancing always uses the lock shield irrespective of whether it is on flow or return.

However if no TRV is fitted you may find that the caps on the valves can be switched over effectively reversing them.

If you can't do that, then just balance with the lock shield on the flow and adjust as normal. So in your case leave the return with the wheel head fully open.

MJN · 14 Jan 2014

Henrik, if it helps you get your head around it, balancing is merely adjusting the resistance to flow through each radiator. Whether this is done by restricting the flow in to the radiator or out of it doesn't matter - the end result on the flow through it is the same. Hence, always use the lockshields regardless of their location.

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Rad valve on flow or retuen pipe - which is best?

Henrik

Blagard

mogget

Henrik

Blagard

MJN

DIYnot Local

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