balancing radiators with two lockshield valves

ROSENMARSH

I have not noticed that radiators are warmer at top than at the bottom so I thought I would try rebalancing as a first measure. However the instructions that I have downloaded assume that the radiator has a lockshield valve and a TRV valve. However mine are old radiators with lockshield valves at both ends. So how do I work out which lockshield valve to adjust?

Many thanks

Matthew

Avoriaz

The valve on the return side is the one that should be adjusted.

The valve on the flow side should be fully open.

Turn on the heating from cold or cool and see which valve or pipe gets warm first. That is the flow side. The cooler end is the return.

Southend1

Avoriaz wrote: »

The valve on the flow side is the one that should be adjusted.

The valve on the return side should be fully open.

Turn on the heating from cold or cool and see which valve or pipe gets warm first. That is the flow side.

Avoriaz, I don't disbelieve you but could you explain the logic behind this. All the guides I can find say adjust the return but as OP says, these relate to rads with TRVs.

keystone

Avoriaz wrote: »

The valve on the flow side is the one that should be adjusted. The valve on the return side should be fully open.

Sorry to be picky but thats 180 degrees out of phase. OP wants to balance his rad. Flow side should be fully open (if a TRV just take the head off). Rad needs to be cool/cold. Fire up heating. Open up LSV a quarter of a turn. When rad starts to heat up then adjust the LSV setting bit by bit until there is an approx 12 degrees C difference between flow and return pipe temperature at the base of each valve. It needs to settle with each adjustment so don't try and get it done in 30 seconds. Once achieved then the LSV cover can be put on and not touched whilst the flow side whether manual or TRV is used to control heat in room. The only circumstances where you are correct is with a single pipe system where, inevitably, the LSV on the rad furthest away from the boiler will be wide open.

To balance the system this needs doing with each radiator in turn starting with the one that gets warm first then in sequence with the one that gets warm last being done last. Pump speed also needs adjusting when balancing system to get the correct temperature gradient between flow and return pipes at the boiler.

Turn on the heating from cold or cool and see which valve or pipe gets warm first. That is the flow side.

Is the correct answer on that one.

Cheers

keystone

Southend1 wrote: »

Avoriaz, I don't disbelieve you but could you explain the logic behind this. All the guides I can find say adjust the return but as OP says, these relate to rads with TRVs.

See post 4. TRVs or not its still done the same way.

Cheers

Avoriaz

My apologies, my memory isn't working properly today.

I got it the wrong way around.

I'll revise my post.

Avoriaz

keystone wrote: »

Sorry to be picky but thats 180 degrees out of phase.

There is no need to apologise for pointing out my stupidity.

In my defence I was multi-tasking and my brain was confusing the end where a TRV should be with the end that should be used for balancing.

ROSENMARSH

Thanks everyone for getting back. I think I understand that the valve on the side that gets warm first is the flow side and that should be left fully open. The LSV is the valve on the other side and that is the one I adjust to get 12 degree temperature difference. Do I put the thermometers on the horizontal pipe between valve and radiator or the vertical pipe underneath the valves (I assume on the horizontal pipe..)
Also in terms of doing each radiator in turn I assume the best way is to go around manually checking which are warming up first although I guess I can assume that the radiators furthest away from the boiler in the kitchen (it's a two bed room flat) will be the ones to heat up last.
Finally I had a new Valliant boiler installed in the summer but have no idea about adjusting pump speed. Is this something I should attempt?

Many thanks again

Matthew