central heating - which is flow, which is return?

[StephenStephen]

Hi all

I'm feeling a bit silly...

- I've drained the central heating (sealed system heated by combi boiler), and cut the 22m flow and return pipes ready to put a new radiator loop in.

-I want to run the flow an extra metre or 2 under the floor to give it a bit of warmth (I suppose you could call it informal underfloor heating!) but...

-I forgot to check and mark which was flow and which was return before I cut the pipes.

oops

Is there a way I can tell? (without installing temporary stops on the pipe tee's I've cut - refilling the entire system, bleeding, turning heating on, marking the pipes, letting it cool, re-emptying, taking off temporary stops)

For example - do the thermostatic valves on the radiators tend to be installed on the flow side?

thanks for your help

in slight embarrassment...

Stephen

 

[AlF2008]

If you check the flow direction on the valves (usually marked with an arrow) it should indicate the direction of flow.

 

[kev_1911]

why dont you re-align the pipes you cut then just follow them back to the boiler and check which is which,your manual will tell you the sequence of order for the inlets/outlets on the boiler,the thermastatic valves coould be bi-directional and on either flow or return.failing that carry out all your work then when you re-connect everything back up and test,when you light the boiler feel which pipe gets hot first, this is the flow then if you have them crossed simply uncross them again.

 

[StephenStephen]

Hi all

thanks for your help

So far I've not found any arrows on radiator valves (I have one more to check)

The route of the pipes from the boiler includes a lot of inaccessible long boxed and behind walls sections, so I'm unfortunately not going to be able to route with any accuracy.

Yes I may well end up tossing a coin, connecting, refilling bleeding, checking and possibly draining swapping etc.

To give me my best chance of guessing accurately - most of the radiators have thermostatic valves. Is there an accepted practice as to whether they are on the flow or return side of the radiator?

cheers

Stephen

 

[AlF2008]

do you have a manual for the boiler? If so have you checked whether it shows which is which?

 

[StephenStephen]

Following the pipes to the nearest radiator, I found that some gorgeous person (bless their cotton socks) has put mysterious symbols on the joist above the pipes: 'F' and 'R'

fantastic

thanks for all your support

Stephen