LSV / Control knob - Feed or return

[garrymum]

Hi

Am about to fit TRV to the upstairs rads and am wanting to fit them to the feed. I know the feed pipe is the one which gets hot the first but which side is the control / LSV. Should the control knob be on the flow side and the LSV be the return. My rads are all mixed up with the control on the feed on some and the return on others.

 

[kevplumb]

normal practice is to put the lsv on the return but it dosent really matter

 

[PEDANTICVINDICTIVEMAN]

If you have bought cheap trv's fit them on the return with the arrow facing in the correct direction of flow, less chance of whistly noises as the valve shuts down.

 

[garrymum]

thanks to you both for replying.
They are cheap TRV's, £5 from B&Q. The arrows in the 90 degree bend indicate that they can only be fitted on the return then as the arrow on the horizontal points to the left, ie out of the rad and the vertical points down. Does this mean they can only be fitted on the return????

If the TRV is fitted to the return, will they still give the same performance as the hot water will still be getting into the rad?

 

[kevplumb]

yes

 

[garrymum]

now I am confused....was speaking to the plumber at work and he said if you fit the TRV to the return pipe the radiator will still get heat due to convection and heat rising up from the downstairs rads and up the flow pipe. He said it would be best to fit TRV to feed to stop this happening???

Any ideas?

 

[IanDB]

No, think about it. The TRV will control the flow rate through the radiator. Unless you have it turned off there will always be a bit of flow. Now, the reason a radiator exists is to radiate heat (it follows doesn't it!), so it will always be cooling down only to be replaced by hot water and heating up to the level DEPENDING on the flow. There may be a tiny amount of convection up through the pipe but it will be really minimal compared with the flow rate and in the nearly closed position the radiator will remain cool because of what it's meant to do.

They wouldn't make TRV's that fit on either end of a radiator if it made that much difference.

Well, that's what I reckon anyway.