‘Wet’ TRV

Hi all,

So far I have fitted 2 trv’s without problem and they have all been dry. However when I started to unscrew the one in the family room it was leaking and had I completely unscrewed it there would have been a water flow.

So I am guessing this rad has been set up differently to the others ? Does anyone with plumbing knowledge know what I need to add in order to make it dry as the others are so that I can add a Tado trv (as I am guessing it can’t be installed in a wet environment !)

Thanks

Chris

Comments

  • samdsamd ✭✭✭

    It sounds as though the valve itself has leaked and needs replacing.

  • Thanks Sam, it doesn’t leak as long as the trv is screwed on but as soon as I start to unscrew the trv then it flows strongly until I tighten it up again.
  • samdsamd ✭✭✭

    Chris

    You will remember when you did the first two TRVs that there is a pin which moves up and down due to it sitting on a plug of wax. That part of the TRV can leak around the base of the pin. You may have noticed some rust there on those you have done. I cannot think of any other reason than that and, if so, it would require the valve body to be replaced. There are two ways of doing that viz drain down the system and replace or using a pipe freezing kit.

  • GrilledCheeseGrilledCheese ✭✭
    edited November 2019

    As mentioned above the O ring around the pin can pass water if it becomes worn. However, you will only get a dribble of water leaking out, never a strong flow. I suspect the gland nut on top of the O ring has come loose. When the TRV head is attached it is pushing the gland nut down but it lifts up when the head is removed.

    Some brands of TRV have a combined lockshield in the valve body which makes things more complicated as you have an outer locking ring which must be done up tight.

  • Thanks for your help guys .. So in terms of resolving the issue, apart from a pipe freezing kit I essentially need to drain the systems down and replace the valve.

    Thanks


    Chris

  • Draining down is the safest way to replace the body of a TRV. To save time you can freeze the pipes or pull a vacuum, but if it goes wrong you will mess up your flooring. If you do drain down then make sure you add new inhibitor to the system, else the fresh oxygenated water will start to corrode the steel radiators.

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