TRV puzzling problem

I have had a few issues recently with my boiler (see my previous threads) but the one which is niggling me most is a trv I have fitted onto a new radiator. Essentially, I have replaced an old radiator with a new slightly larger radiator. The old one worked perfectly. When the heating kicks in the lower part of the radiator and the TRV remain cool. Now, according to the box it is a bi-directional trv so I have it located on the right hand side of the rad for easier access. I have tried the following so far :

- isolated the new rad and put the heating on. Eventually the bottom of the rad and the pipe gets warm but I think that is more heat spreading rather than hot water flowing through. It's not proper hot.

- isolated the new rad and flushed through using the filling loop and a hose on my drain valve. I did get an escape of air and black muck come out.

- undone the trv nut and drained the radiator. I then put a bucket under the trv and turned it on. Water flowed but I am aware that the water flowing into my bucket was actually flowing the wrong way when its attached onto the radiator.

- I have put a cleaner in but that had to be drained out due to the pump stopping and air building up in the boiler.. my intention is to put another cleaner in in the hope the trv issue is sludge. On that note what brands do people use?? I did try the no nonsense from screwfix but wondered what other peoples experiences were.

I have tried pressing the pin down on the trv and it does move, and with the heating on, I have tried pressing the pin down and releasing a few times but no flow.

Could it be possible my bi directional valve is not bi directional or the bi directional feature isn't working, I'm almost tempted to switch the trv and lock shield round and see what happens.

Does anyone have any more ideas I could try please? Many thanks

I take it you replaced the valve and not just the head? Have you tried bleading when the system is off, sometimes you can think you've got the air out when you haven't

Thanks for your reply. It was a whole new valve and when I unscrewed the valve and turned it on I kept the head on and confirmed water ran through, although it did have to get to number 3/4 of 6 before water came through, and due to it being on the right my test only proved water passes through but the wrong way I need it to. I have tried bleeding it with the CH on and off.

does it work with the valve head off and the pin exposed?

No it doesn't, I've had the head off and pressed it down and nothing. It only goes down a little and springs back up.. I've held it down and nothing.

It's airlocked or you've bodged it. How have you confirmed water is passing through it? A simple job. If the old rad performed good and hot as you say, it's what you've done.

Turn off TRV.
Fully open lockshield valve
Bleed 2 pints out of radiator into bucket
This will confirm water flows through the pipe connected to the Lockshield

Now turn on TRV fully
Turn off lockshield fully
Bleed another 2 pints out of radiator again.
This confirms water flows through the pipe connected to the TRV side

You'll probably need to re-pressurise as you go.
Report back when done.

Dougie212 said:

It only goes down a little and springs back up.. I've held it down and nothing.

Click to expand...

down = off, up = on.
They only move a small distance.

How would I have bodged it Gas2air?? I've not had an issue with the trv's that I've done since, which is why I'm baffled.

Phod, I shall give that a go. I have undone the trv valve before and pulled it off the rad and turned it on and water does come out of the valve, my only concern is that all I proved then was that water passes one way through the valve, I'm thinking that as it's on the right side of the rad the trv is on the flow out side, the water passing from rad out of the trv I haven't been able to check. I know it should be on the flow in side but I'd read that it didn't matter as long as the valve was bi directional, and the right hand side is easier to access in the room.

There are a few valves that can work both ways but you have to turn something around to set the direction. Others are fully bidirectional without doing that.

I don't recall reading anything on the valve about changing something to determine direction. It's a Drayton valve that screwfix were giving away with every rad sale.

Dougie212 said:

It's a Drayton valve that screwfix were giving away with every rad sale.

Click to expand...

Were they doing it for the love?

Well...... I did wonder if they were just giving away problematic stock but surely they should work...

phod said:

Turn off TRV.
Fully open lockshield valve
Bleed 2 pints out of radiator into bucket
This will confirm water flows through the pipe connected to the Lockshield

Now turn on TRV fully
Turn off lockshield fully
Bleed another 2 pints out of radiator again.
This confirms water flows through the pipe connected to the TRV side

You'll probably need to re-pressurise as you go.
Report back when done.

Click to expand...

Going to give this a go now Phod... 2 pints from the bleed valve with one side open, then the other..??