Balancing Rads with 2 way trvs

[Irie]

I've been playing about trying to balance our heating system and I'm now a bit confused about what to do.

If I've understood everything, when balancing rads with no TRVs, the return is left fully open and it's the flow side that is adjusted. If TRVs are installed they are normally installed on the return side of the rad and the lockshield on the flow is adjusted.

Our system has 2 way trvs and I was trying to establish which side was which so I opened all valves and turned the heating on to find which warmed up first. Turns out most of the trvs are fitted on the flow side, how would this affect balancing? 2 rads didn't heat at all, even with the flow to all others shut off and no air in them...

 

[Nige F]

Just adjust the lockshield - irrespective of which end it's on .

 

[Agile]

Have you actually read the FAQ instructions on this site about balancing?

Did these two rads ever heat up?

Why did you decide you wanted to balance the rads?

A good starting point is to close all lockshields and then open just each of them just one turn!

Tony

 

[D_Hailsham]

A good starting point is to close all lockshields and then open just each of them just one turn!

Half a turn is a better starting point as some LS valves are almost fully open at one turn.

I have Honeywell VT200 TRVs with integral balancing on most of my rads. Balancing is achieved by removing the head and then turning a plastic dial round the spindle which limits the stroke of the valve. The dial is marked from 0 to 9. Honeywell instructions say that the dial should be turned until it stops and then opened to no more than 4, i,e 4/10ths of a turn. Maximum opening is at 17.5, i.e 1¾ turns.

Drayton TRV4 also have an integral balancer, which is initially set to 6 - fully open. Drayton recommend a starting setting of 3 when balancing a system. This is not related to the settings on the thermostatic head.

In both cases the LS valve is left fully open.

 

[Agile]

I asked the professionals here how many actually used the integral setting in the TRV4s and it was virtually none.

For a DIYer I would always say one turn initially because some types have about a quarter turn before they start opening and that could confuse them.

Its difficult giving general advice when there are so many different types. Some only have about one turn.

Tony

 

[D_Hailsham]

I asked the professionals here how many actually used the integral setting in the TRV4s and it was virtually none.

That doesn't surprise me. I expect those who do are mainly working on commercial installations where flow rates and differential pressures are specified and a proper control system is installed.

 

[Irie]

Cheers for the help everyone, all sorted.