TRVs - which direction flow/return?

Not if they are truely bi-directional. They are nice to use.

Don't think it matters so long as they are fitted with the flow in the direction of the arrow marked on them .

Stuart .

The earliest ones I had, in a previous house, were very specific in which side of the radiator they were to be fitted and their orientation. The ones I bought more recently for this house state clearly that they can be fitted any which way, both in position and either inlet or outlet of radiator. So I guess the answer depends on which TVRs you have. By position and orientation I mean horizontal or vertical.

Does bi-directional not give a clue .? The make and model of the trv would be helpful of course .

Stuart .

OP here. I know the TRVs are bidirectional, and yes I do know that means that it's possible to have the flow go in each direction (!). Make and model aren't relevant to my question (not being obtuse; I can't actually remember anyway).

I can't believe that there isn't at least a convention as to which way round they go, even if it doesn't matter per se with bidirectional valves.

David

"Lobster" wrote

Historically they have been fitted on the flow end of the rad. Early models could not be fitted counterflow (ie direction of flow was important) otherwise the water flow would be assisting closure and could cause nasty shut off noise/vibration. The modern valves claim to be bi-directional, but being a traditionalist (and thinking that with some valves they will be the original design just tweaked a bit) I would fit them at the flow end and orientate the valve such that the flow of water is trying to open the valve IYSWIM. Indeed, I have just had my central heating system re-worked and insisted that they reverse the flow/return pipes to the ground floor which they had piped up wrong way round. Obviously there will be loads of others out there who DGAS which way the flow goes!

Phil

They work best on the return, as there is less parasitic heat sensing, as the return end of the rad is about ten degrees cooler than the flow end. However, considerations of decor can override this.

They are also more effective sticking out sideways (for the same reason), but look better pointing upwards.

Christian.

ROFL! I appreciate that the two replies aren't actually contradictory, but are you both sure you're correct?!!

David

Read it again - Christian is saying they *work best* on the return, whereas the Scullster is simply saying that *historically* they were fitted on the flow. So, yes, they're both right.

Incidentally, Christian also mentioned that they will also work better being fitted horizontally (which they will) however do bear in mind the temptation that this gives to kids to stand on 'em!

Mathew

Hah - read my reply again: I said I appreciated that the replies weren't contradictory... but thanks anyway.

David

said I appreciated that the replies weren't

So where exactly are you confused..?

Yes. I agree with the Scullster as well.

Christian.

Great - OK, on the returns they'll go then! Thanks David

Note some bi-directional TRVs have a setting for flow direction. One of mine (Danfoss) says that although the TRV will work any which way, changing the setting may reduce noise.

Also some TRVs are designed for horizontal mounting only. (Well, when fitted vertically the numbers are upside down!)

I tend to fit the TRV away from heat and cold sources like doors, pipes and so on. Otherwise it goes on the most aesthetically pleasing or easiest to get to side.

Just my 2p - I am in no way a plumber! (He says ruefully, 2/3 way through a boiler/rads upgrade!)