TRV hissing?

Discussion in 'Plumbers' Talk' started by dbrb2, Dec 1, 2019.

  1. dbrb2

    dbrb2 New Member

    I have just fitted smart TRVs in my house. All seems to be working, but the bedroom radiator hisses fairly loudly when it comes on....which is a bit of an issue since it is in a bedroom....

    Audio recording below:

    Any ideas if there is a solution to this...? The pump speed on my combi is fixed, which seems to be a suggestion often given....
  2. MGW

    MGW Screwfix Select

    Have you got a by-pass valve fitted? My valves from time to time adjust, and you can hear the motor run, but other than that no sound, I have two different makes, wifi Energenie MiHome down stairs, and eQ-3 stand alone blue tooth upstairs and kitchen. Not set up A1 yet in this house, last house took some time, work better if on the supply side, if on the return setting the lock shield is critical. We found if on return, radiators gets hot, then valve closes, but radiator is still pumping out heat so it over shoots, but slowly a bit each day, turning the lock shield to give less and less flow, got the temperature not to over shoot, and once done it did not need touching again even as the summer arrived.

    As to noise, if it's the valve motor then nothing you can do, if the water, then maybe reducing the pressure at which the by-pass opens would help. On old house two by-pass valves one in boiler, and one outside boiler, this house pump is on the return, so no by-pass valves. However the DHW is thermo syphon and boiler in this house oil not gas, so boiler not modulating, so not the same need for a by-pass valve.
  3. dbrb2

    dbrb2 New Member

    Cheers - the boiler is an ecoTec Pro 24 - which I am pretty certain has an internal bypass valve. As I understand it, that is so that the water has somewhere to go if the TRVs are off and the motor is still on...?

    The noise in this case is not the valve motor - is is definitely a "water rushing" kind of noise.
  4. The Teach

    The Teach Screwfix Select

    Do all your radiators have E trv's ?

    The internal by pass can be adjusted to allow more pumped water bypass the radiator circuit,maybe that's been done already.

    Ecotec boilers are fairly standard the radiator circuit will be bespoke,hopefully its all installed & set up correctly ;)
  5. dbrb2

    dbrb2 New Member

    Cheers - yes, they all do. I can reasonably happily change a valve, but would be very nervous about changing the bypass settings in the boiler, both for legal reasons, and because I assume if I got it wrong I could cause my pump to burn out were the TRVs all to be closed :)

    Functionally all seems to be fine...just the quieter I can make it the better. I should probably "solve" the problem by ensuring the bedroom TRVs never open at all at night!
  6. Hans_25

    Hans_25 Screwfix Select

    I have a similar issue with iTRVs, what make are yours? Got Drayton here and have two root causes I think:
    - if the Dryton TRV is not adjusted precisely (settings 1-6 on the valve portio) then you end up with a much smaller hole than you should; result is higher water pressure squeezing water through this hole generating noise. The reason being that with Drayton TRVs, there are 6 different sized retangular holes to allow 6 different flow rates, but these rectangular holes need to be perfectly lined up.
    - the other issue, related to the smart system is that where as before all radiators would be on to some extent, with a smart system you can have the situation where only 1 or 2 rads are on - with the full force of the pump pressure acting on just 1 or 2 rads hence higher flow rates and more water noise.

    Fitting a bypass with a lowish setting would help to some extent, also if your pump has different settings then lower the setting to reduce the head generated. Another option is to have your hot water cylinder on all the time which will dissipate some flow and/or more rads on which are not on TRVs. Have got the hall rad on lockshields so its on whenever heat is called for, and also a bathroom towel set as a summer rad so its on whenever the boiler is on.
  7. dbrb2

    dbrb2 New Member

    Yes, they are Drayton wiser TRVs
    I hadn't noticed any mechanical calibration on them when fitted... I'll take a look when I get home

    What should I be looking for?
  8. Hans_25

    Hans_25 Screwfix Select

    This should give you an idea. I've got most of mine at 6 now, so fully open, only a couple of the furthest rads are turned down to 4. I also have a digital differential thermometer!

  9. The Teach

    The Teach Screwfix Select

    Then it becomes an alteration that needs other considerations. Relying 100% on the internal boiler bypass could be a costly mistake,doubt any blame ofthe boiler installer,warranty or any home insurance product would be of any assistance when it goes **** up :)

    You need an external bypass,the internal bypass could be disabled ie shut. hey been there seen new boilers destroyed by diy alterations.

    Said t-I-t-s ffc page 3 items
  10. Hans_25

    Hans_25 Screwfix Select

    I'd have one radiator without a TRV e.g. hall rad, ensures there's always somewhere for the water to be pumped if everything else is off.

    Have Drayton Wiser setup here, had quite a few teething issues but fingers crossed, all working as intended now.
    The Teach likes this.
  11. The Teach

    The Teach Screwfix Select

    most boilers that have a pump over run facility will need an open pipe route/open valve route to satisfy the pump over run requirements, relying on an internal boiler bypass will have other considerations to consider although Its possible :).

    Vote labour :)
  12. dbrb2

    dbrb2 New Member

    Ah - the config is on the TRV valve body itself. My TRVs are <random> - it is only the actuators that are Drayton Wiser

    I might try changing one TRV body out and see hat effect it has

    The boiler is an ecoTec Pro 24 - It /seems/ to have a internal bypass, but I'd hate to accidentally blow up the system!
    No obvious "always on" rad unfortunately....I suppose the Wiser config could include logic to never close all TRVs whilst there is still a demand in for heat....I wonder if they do though...
  13. Hans_25

    Hans_25 Screwfix Select

    Pretty sure thats not the case if the boiler has a pump overrun thingy...pump keeps going after boiler is turned off by the Hub and all TRVs are closed.

    Check that your rad lockshields on the other end of your rads are fully open - it could be them causing the noise not the TRV body.

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