plumbing help!

[Joe Shmoe]

Guys,

I am adding another radiator to my existing central heating system. The new rad I am fitting has a special value inside which dicates how I should connect the flow/return pipes.

The problem is, I don't know which pipe is the flow and which the return. I have already cut pipes and removed another rad, so I cant even fire the system up and see which gets hot first. Silly me.

I have turned the fill-tap located near the bioler that presurises the central-heating system up with water, and I can see that one of the cut pipes gushes, so I am guessing this is the flow. Is that def the case, or could it be that pipe is gushing because its lower that the other etc etc....

The other reason why I am still doubtfull is the TRV value his been fitted on the other pipe. I always thought they should be stuck on the flow pipe, but maybe the previous plumber just stuck it on the return side as its easier to reach ?


Any advice would be good?

 

[sparkymarky]

the filling loop is normally fitted on the return of a central heating system, is your trv bi-directional of can it only go on the flow? (they sometimes have arrows on the trv valve body, what brand is the trv??)

can you remove the central heating zone valve or the connection on the mid position valve / combi boiler and get someone to blow down the flow pipe, make sure all the other rads are turned off though so it doesnt cross over to the return.

hope this helps.

cheers, mark.

 

[OLD]

Modern trv's work in flow or return. Try blowing into the flow of adjacent rad and see which cut pipe the air comes out of.

 

[RogerS]

Yebbut...he's got a special valve inside his rad and so it's not a TRV issue..as far as I can see.

Get a flexible pipe with 15mm compression at either end, connect up the flow and return on the pipes you've disconnected and then fire up the heating system perhaps?

Sounds like a combi system and so the pressure is going to be the same in flows and returns...so water is going to take the line of least resistance..so no guarantee your flow check has picked up on the flow.

 

[jasonB]

Roger you don't need to check the direction by pressure you just feel which side gets hot first but thats the way I check if the rad is not there just tails, put a flexi or bit of pipe with a couple of push fit fittings between the tails and see which end gets hot first.

Its not really a valve inside the rad, just a baffle to make sure the water does not take a short cut, usually sends it up one vertical pipe and down the rest.

J