Working out flow and return

[Riley]

Right I know this is a Mickey mouse question but I've wasted enough time on it today.

Trying to re-pipe a number of rads for a customer but their flow and returns are all over the place some left some right on existing rads

new rads are very specific in that flow must be left and return must be right. Posh upright rads.

I cant have floor up or ceilings down as all new (I know!!! Why not sort the rads first) cust thought it would be ok as all pipework was to be in the walls. The only way I can think of to work out which is flow and return is to gradually fill system and open the rad valves. Old rads are all off so there are no links on the system. So logically if I close the flow valve at boiler And fill at the return at the boiler and then open valves then the returns should have water at them? I tried this a mo ago and yes definitely got a greater flow at one side but unfortunately still got a small trickle at the other tail too. I assume one of the zone valves must be letting by ️️ever so slightly.

Do do you guys have a better way of testing this??? Or is my logic reasonable that the return would have the greater flow?

sorry for length of post.

 

[Leo21]

Couldn't you isolate flow at the boiler, like you have. Turn every rad valve off, make sure any bypasses are shut, pressurise or fill and see which valve has water/flow?

 

[Riley]

Exactly what I did do. But the issue was that the other tail at each rad was dribbling too making me think that something was letting by.

 

[josh]

Sounds a bit of a job mate, depends how accessible but take pipe out of zone valve to heating and make sure any bypass/other rads that are left are of and blow down the flow at zone valve and have one end open at rad at a time? Saves putting water back in it to then fight to get rid of it to solder again.

 

[Lee]

How about using wet and dry vac to determine which is which.... no risk of flood.

 

[Riley]

Cheers all. Yeah I have a wet vac I place Each time I test just no matter what I do I struggle to get water at only one tail. Weird. I will have to just persevere