Flow & return valve positions

pyounger · 6 Oct 2011

Since embarking on my journey to replace a radiator I have been taking a more in-depth look at my system and notice that some radiators have the lockshield on the flow whilst others have them on the return. Surely this can't be right and must affect the ability to correctly balance the system especially as most have TRVs.

Should I swap over the incorrectly fitted rads?

Dan Robinson · 6 Oct 2011

Depends what trvs you have.

kevplumb · 6 Oct 2011

if you restrict it going in or out it dont make any odds

if as dan suggests odd / old trvs they might chatter

pyounger · 6 Oct 2011

Th TRVs are quite new Drayton TR4s. I also notice that the bleed valves are oddly mixed - some on the side of the TRV others on the side of the lockshield

kevplumb · 6 Oct 2011

so it makes no odds

Dan Robinson · 6 Oct 2011

Well either you had different fitters (right or lefthanded) or like me he was trying to place them on the least intrusive side of the Rad.

pyounger · 7 Oct 2011

Ok thanks. And the same goes for the bleed valve - doesn't matter which side that's on (as long as it's on the top!).

RonO · 7 Oct 2011

Surely if the lockshield is on the flow it messes up balancing? I was told to balance you open up bothe valves then adjust the lockshield on the return so it is approx 12c lower than the flow.

If the lockshield is on the flow you'd have to have that wide open and use the TRV to shut off - which you couldn't do

Dan Robinson · 7 Oct 2011

Think you need to be told things by someone who knows what they are talking about Ron

Some radiators have baffles in them that DOES affect the direction of flow. However, most rads are universal.

RonO · 7 Oct 2011

Maybe, but that is how it is described in many books and on-line tutorials.

D_Hailsham · 7 Oct 2011

RonO said:
Surely if the lockshield is on the flow it messes up balancing? I was told to balance you open up both valves then adjust the lockshield on the return so it is approx 12c lower than the flow.

If the lockshield is on the flow you'd have to have that wide open and use the TRV to shut off - which you couldn't do

All a lockshield valve does is control the flow rate though the rad. The slower the flow rate, the greater the temperature drop across the rad. It does not matter which end the LS valve is placed, the effect is the same.

Read How to balance a CH system

Dan Robinson · 7 Oct 2011

RonO said:
Maybe, but that is how it is described in many books and on-line tutorials.

And most of those are based on incorrect, out of date and often both, information.

I have several books written for the industry that I gave up reading due to the woeful inaccuracies and terrible writing/spelling errors.

RonO · 7 Oct 2011

Fair enough Dan thanks

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Flow & return valve positions

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