Faulty TRVs

[bfdyorkie]

Hi
I have recently replaced my CH boiler and have started using some radiators which I didn't use before. Two of the TRVs are producing vibration and juddering noise which I can temporarily stop by slightly adjusting them.
However the noise returns in about 10 minutes time. They are Danfoss valves.
I wonder whether it is possible to replace the head of the valves to remedy the problem or whether it will be necessary to drain the whole system to replace the valves completely?
TIA
Bfd

 

[45yearsagasman]

Check the arrows on the valve body and see if they are fitted correctly in relation to the water flow direction.

 

[1983]

The flow direction through valve is wrong. Causes them to knock as they are about to shut off, depending on style of trv you can simply turn them round otherwise you will have to swap them to the other side.

Beat me to it!

 

[bfdyorkie]

Hi Pete
This gets confusing.
I can't see any arrows on the valve body but on the T-piece to which the valve is attached. There is an arrow pointing towards the rad on the union attached to the rad and on the union attached to the pipe there is an arrow pointing towards the pipe. Next to the arrow are the characters G3.
Does that mean the valve is designed to cope with either flow direction?
By the way on the other rad the T-piece is facing the wall but appears to have marks in the same places.
I can't help feeling I face a drain down but controlling the flow roughly now by gradually adjusting the exit valve
Bfd

 

[45yearsagasman]

A picture of the valve would help.

 

[CBF]

if they look like this, you need to turn the grey ring at the bottom of the head & remove the head, you will then see a grey ring with two arrows on it turn this ring so you have the arrow facing the other way & re-fit the head.


http://postimage.org/

 

[1983]

Edit

 

[bfdyorkie]

I'll start working on a picture - not easy for a complete technophobe but I have all the equipment needed.

 

[bfdyorkie]

Here's the picture, hopefully
I inherited the valves with the bungalow about 10 years ago so they will be older than that.

 

[Agile]

It could be that the new boiler was installed by a nupty who changed over the flow and return!

Was it "professionally" fitted by a Gas Reg installer?

Tony

 

[bfdyorkie]

The new combi boiler was installed by British Gas.
BTW - didmy picture show on the post?
Bfd

 

[JimCrow]

.


The valve you have is the older Danfoss type which were not bi-directional,

remove the whole valve and turn it so the thermostatic head sits horizontally

and the arrow on the valve body is pointing to the rad.

 

[bfdyorkie]

Jim Crow's view sounded pretty authorative and I'll follow the advice but will probably fit new valves after some research.
Many thanks for the help of all posters.
I'm still not sure if my picture appeared.

 

[ianmcd]

even if you do fit new valves you would be well advised to make sure they are the correct way round as earlier advised some need the direction of flow to be set when the valve is installed (nothing difficult about it though)

 

[bfdyorkie]

Thanks for that - I'll bear it in mind.