Flow and Return mix up?

[picasso]

Its a combi boiler so do not slow the pump down, the vast majority of trvs are now bidirectional, I cant remember the last time I saw a unidirectional trv, the only rads I have installed that need the flow and return in a certain direction are column rads but thats because of the baffle in the flow to force the water up the rad, apart from that your post is spot on.

 

[halfway]

Why have you been changing rads?

 

[motorbiking]

Its a combi boiler so do not slow the pump down, the vast majority of trvs are now bidirectional, I cant remember the last time I saw a unidirectional trv, the only rads I have installed that need the flow and return in a certain direction are column rads but thats because of the baffle in the flow to force the water up the rad, apart from that your post is spot on.

I stand corrected. thanks for the point on baffles.

 

[Agile]

Even so, most column rads will work either way round but the makers usually specify that the flow just goes up to the top on the first section only. That is probably because it prevents gravity effects causing differences between different tubes on the return side.

But I did see one that would not allow any circulation if piped wrongly but I have forgotten why it would not. But it could be simply reversed in the brackets by the builder who had fitted it wrongly !

 

[motorbiking]

that is not so easy to do on a single column radiator..

I've yet to find out if this one installed by my plumber will work as I've no way of knowing if the flow is on the left or right given the bidirectional TRV.

 

[Razor900]

Its a combi boiler so do not slow the pump down

That certainly applies to most but not all combis

 

[just pumps]

Some TRV`s become noisy (rattle) if fitted on the return side but in general they can be fitted either way.

 

[picasso]

I stand corrected (you intergas freak)

 

[Razor900]

I stand corrected (you intergas freak)

 

[Agile]

that is not so easy to do on a single column radiator..

I've yet to find out if this one installed by my plumber will work as I've no way of knowing if the flow is on the left or right given the bidirectional TRV.

Why not just turn it on?

But he has fitted the TRV on the return side which will still work but is contrary to what most plumbers usually do.

There can be good reasons for putting it on the return said, easier to get to to adjust, closer to an opening door etc.

Tony

 

[motorbiking]

If the TRV and return valve were closed would I still get enough heat in the flow pipe to be able to work out which side was which? I'm assuming No? I'd rather not fill the rads as I have to take it off to decorate anyway. I'd have preferred plumber not to have actually fitted the rads and just left me to do it after decoration.

 

[Agile]

Unless you actually let flow through the rad you will never know.

But if you did open the valves but not bleed the rad it will not fill completely and limit the amount of water you need to drain to remove it.

I have to drain so many rads that it is a chore but only a 10 minute task on average size rads. So if it were mine I would certainly be testing it !

I am not sure why your type is marked as flow and return. One I have recently fitted had an internal allen key plug which had to be inserted on one side to set that as the flow.

Tony

 

[motorbiking]

My conclusion was there was some sort of baffle to make it flow up, or simply that it only has a bleed nut on one side and this needs to be on the flow.

On my more expensive column rads each column has alternate welded pipes connecting them to the next so that the water is pushed to flow up - down - up down etc across it. These cheaper ones I think just have vertical tubes welded to two horizontal tubes.

 

[Agile]

I expect they do have some baffle but it may be fixed.

The bleed point can usually be fitted either side.

Tony

 

[halfway]

Join the two rad valves together if you need to find which side heats first