Cold Rad, Hot Pipe

[Brownstone1892]

Nothing wrong with Tee'ing off a single pipe system BUT there needs to be some distance between the tee's (normally the width of the rad), as such a system relies on the pressure drop between the two tee's (due to the pipe friction) to get the water to start circulating around the rad.
Perhaps something like this would be better. The S shape pipe retains the flow of the single pipe system if the rad is shut off and the length of the S pipe provides the distance between the tee's.

View attachment 172446

This may be where I'm going wrong. This, and the fact that I'm using a standard TRV and not one designed for single pipe systems (if indeed it is a single pipe system).

So, take a look at this picture, to see my incredible work for yourselves:

Here's some context:

Red is the "single pipe"
Blue goes to the flow TRV (the pipe leading into the TRV gets hot)
Green is the "return" which does not get hot
The dashes are where the pipe used to go to the old rad.

The reason it's so elaborate, is the two sets of pipes are on different levels. The green and blue going to the new rad are lower than the feed pipes.

I really hope I'm making sense here.

Hopefully, someone has the answer to my prayers, as I only have a week to sort this before I'm away for work.

Cheers,

Carl...

 

[Brownstone1892]

Anyone? I'm getting quite desperate here.

Cheers,

Carl...

 

[ServiceNumpty]

Could be an airlock, with the pipes connected that way.

 

[terryplumb]

You have quite a few things working against you ,that pipe layout is too restrictive ,you have a one pipe system ( very inefficient at the best of times ,and often a pain in the ass to balance).
One pipe systems and narrow vertical radiators are not a brilliant idea, the distance between the inlet and outlet ports are two close together. Ideally the " flow" pipe should be horizontally below the rad ,and a vertical T up to each valve ,and to a conventional panel radiator.
I am surprised the pipe to the TRV is even getting " hot". When you removed the radiator to check for a baffle ,you looked through the two bottom valve ports and told us there wasn't one. Is the rad upside down . can you post pic of the rad.
When you removed rad ,and it was still removed ,did you open the TRV to make sure that water flowed out if it ?

 

[Brownstone1892]

Thanks for the replies fellas, you've confirmed what I suspected all along, I'm out of my depth. I've arranged for a heating engineer too come take a look and price it up.

Thanks guys,

Carl...