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Trv pins only move 2mm. Head moves much more.

Discussion in 'Plumbing and Central Heating' started by carl0s, 28 Dec 2020.

  1. carl0s

    carl0s

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    In the house we've moved in to, I'm trying to get to grips with the heating system and some issues with heat from radiators in a downstairs room (almost like cellar level, but it's not, it's just that the house is on a hill so theres a room down there).

    Anyway to cut to the chase, my question is about trv bodies. The pins on a lot of those here only seem to move about 2mm while the head actuator pushes about 5mm or more. Basically on the 1 - 5 or 6, anything above 3 doesn't do anything, and spins freely.
    Does this mean the bodies are some old type of on/off body and should be swapped for ones that have more progressive control?
    Next question is that I have ordered a Drayton Wiser system and a few extra trv heads to go with it, but a quick look online doesn't show a recommended trv body to go with them. We certainly have some misbehaving TRVs.. one where there is no flow on 5 or full on, but there is if you nudge it down a little, to 4.5 i.e. just push the pin slightly. That one doesn't have the aforementioned problem of only 1 to 3 acting on the pin obviously. I had a look on Toolstation last night but seemed like they were just selling complete sets.

    Oh and lastly.. we've got these weird TRV heads that seem to have an adapter fitted to them. They have a collar that you spin to loosen-up a clamp then you just pull them off. Rather than them being screwed straight to the body.. one of those is one that the pin barely moves in. It also seems to be turnable as well. The pin seems to be coming through a hex that can be used to turn the flow on / off. Could it be that these used to be on/off hand valves, that are poorly adapted to TRV heads?
     
    Last edited: 28 Dec 2020
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  3. ianmcd

    ianmcd

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    just post pics of what TRVs you have
     
  4. lloyda

    lloyda

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    The last one sounds like danfoss ras-c2.
     
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  5. carl0s

    carl0s

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    We seems to have a right old mix.

    There's a bulldog one in one room that looks like it might have leaked some of its liquid. That one has a button rather than a pin internally.
    We have various Westherm Fours. One of which seem to be on what looks like 10mm pipe instead of the 15mm elsewhere in the house, although it might be sleeved-up, or have a special olive inside to make it fit.. not sure.
    Then there's the Danfoss in the toilet - this is one of those with the wacky adapter on it.

    Apart from the Bulldog, most of them seem to be Westherm Fours and the Danfoss ones.
    Many of them seem to be OK. Some of them clearly do not do anything above '3' on the head though.. there's just no physical contact with the pin there.

    Oh, and we have the horizontal one in the downstairs room (last photo). This is the radiator that's putting up a fight in terms of getting warm. It looks like a balancing issue. I broke the head on this and bought a new Drayton one to fit it last week, after we took the radiator outside to hose through it. It has a different thread size to almost all the others in the house. This one doesn't have any head-to-body connection (i.e. no pin-contact) above '4'.. even though the dial goes up to '6'. This horizontal one looks like the body/valve would have to be replaced with a Pegler B4451 if it needed changing. I can't see any other horizontal ones available.

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  6. carl0s

    carl0s

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    Yes you're correct. They're certainly Danfoss anyway.

    Oh by the way, I found that Drayton are selling the body-only, to go with the Wiser heads. The plastic cap on them made me mistake them for locksheild valves. So they are suitable for almost all of my radiators except for the horizontal-head one, and possibly the smaller-pipe-fed ones (there are a couple of those).
     
  7. ianmcd

    ianmcd

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    It isnt a horizontal one, it has been installed Horizontally, can easily be installed vertically
     
  8. carl0s

    carl0s

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    The TRV head is in-line with the radiator output. They're usually 90 degrees to eachother aren't they?
     
  9. denso13

    denso13

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    Normally easily changed, have you got a photo of this one?
     
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  11. carl0s

    carl0s

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    Yep it's the last photo in my post above. As I say, it looks like Pegler do the only matching one. The model screwfix have called a Pegler VB1390/4P looks like the same style.
     
  12. ianmcd

    ianmcd

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    Nope completely wrong
     
  13. carl0s

    carl0s

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    Ok, thanks for the explanation.
     
  14. carl0s

    carl0s

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    So I guess that the flow lines (denoted with the arrows) can be flipped by unscrewing the fitting, so that the rad inlet can be moved?

    I'm going to buy some more stuff then..
     

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  15. ianmcd

    ianmcd

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    no you simply turn the grey plastic collar 1/4 turn, no tools needed , hardly a chore , you are looking for a problem that doesnt exist
     
  16. carl0s

    carl0s

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    Think there may just be a simple language barrier here, but thanks all the same.
     
  17. ianmcd

    ianmcd

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    OK will do it in English, you see that little arrow pointing upwards ? that means that the valve SHOULD be on the flow, if you turn it then the arrow will point downwards meaning it should now be on the return, tell me if you want the explanation in another language

    TRV10.jpg
     
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