UFH Mixer Valve Whining.......

[Rob99]

I've recently started using my Wunda UFH which works very well but it has a high pitched whine most of the time when it's running. 
The noise comes from the mixing / temperature setting valve on the manifold and is at quite a high pitch. If I slightly adjust the setting, the noise stops, until (presumably) it comes back to the new set point, when the noise starts up again. Changing the manifold pump speed just changes the pitch but the noise is still there.

Has anyone else experienced this with their system? Is it a faulty valve or could it be something else?

[ProDave]

What make pump?

 

I had a similar issue (different manifold) and solved the whine by changing the IBO pump for a Wilo pump

[Rob99]

Its a grundfos UPS2 which came with the manifold set

 

Curious as to why changing the pump would make a difference? The pump is virtually silent.

[dpmiller]

is there a bypass valve on the manifold?

[Rob99]

There's no bypass valve on the manifold. I didn't think one was needed and the manifold set didn't come with one and the documentation doesn't mention a bypass.

At the moment there are 3 UFH circuits in use, all of which are permanently open as I haven't set up the controls yet.

[PeterW]

Open the valve all the way, pump on high and let it run for 1/2 hour. Then close down the valve to the correct setting and turn the pump down. It should clear it. 

[Rob99]

Thanks Peter,

Did all that and now all nice and quiet.

Hopefully won't have any more issues but at least I know what to do now.

Thanks again.

Rob

 

[Rob99]

Spoke too soon, the whining started again after a few hours and now the heating is on again this morning it's still there ?

 

I'll try again with your suggestion Peter but if that doesn't work I'm a bit stumped. Could it just be a faulty valve?

[Temp]

I've heard this isn't an unusual problem. Sometimes changing the pump speed can alter the noise the mixer makes so it's probably due to turbulence in the mixer? Perhaps try sound insulation? Perhaps _lightly_ clamp some mole grips onto it or adjacent pipework to see if adding mass to it helps? Not too tight mind.

 

Edited February 21, 2019 by Temp

[Nickfromwales]

Its because the flow temp is set too low for a conventional blending valve, and the return temp is coming in at a point where the acceptable ratio for hot / cold is outside its acceptable working parameters. When I say too low, I mean you need it to be that temp as opposed to you using it incorrectly, and the only real cure for you, short of changing the pump / blender arrangement will be to turn the pump down to its lowest setting and seeing if that will still have acceptable flow to the floor loops ( eg it'll still maintain room temps ).

The flow gauges will drop off but you'll still get flow, so don't automatically think it wont work just run it and see. Turn it down, run it for 48 hrs and report back here  

[Nickfromwales]

It the shitzen hits the fan, it's one of these you'll need to replace it with.

[dpmiller]

or one of these if you're short on funds-

 

https://www.ebay.co.uk/itm/Universal-Underfloor-Heating-Thermostatic-Mixer-Mixing-Group-without-pump/112017177467?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

[ProDave]

I go back to the pump. I changed my other noisy one yesterday for a Wilo and the silence is bliss.

 

Re low temperatures, I am running mine lower than the mixing valve is calibrated to go, but I found taking the knob off, rotating it a quarter turn on the splined shaft and putting it back enabled the valve to go to a lower temperature setting than it is quoted to do, though  of course the temperature graduations on the knob are now even more a work of fiction.

[PeterW]

I doubt this is the pump as the noise goes when the valve is altered. It will be a harmonic of the flow through the valve .. other option is decrease temperature but increase flow, rooms getting hotter slower. 

[Nickfromwales]

11 hours ago, PeterW said:

I doubt this is the pump as the noise goes when the valve is altered. It will be a harmonic of the flow through the valve .. other option is decrease temperature but increase flow, rooms getting hotter slower. 

Its running too close to its stated tolerance IMO. When the return temp gets close to the flow the valve tries to go into 'anti-scald' and squeezes partially shut. That's where the noise is emanating from eg the water squeezing through a nearly shut valve. Open the valve up to 10oC more allowance and the noise will stop temporarily, but then will start again when the new flow temp is achieved and the return catches up.

[ProDave]

10 minutes ago, Nickfromwales said:

Its running too close to its stated tolerance IMO. When the return temp gets close to the flow the valve tries to go into 'anti-scald' and squeezes partially shut. That's where the noise is emanating from eg the water squeezing through a nearly shut valve. Open the valve up to 10oC more allowance and the noise will stop temporarily, but then will start again when the new flow temp is achieved and the return catches up.

If that is the case it is a badly designed valve as it will always reach that equilibrium, and only a swap for a different valve would fix it?

[Nickfromwales]

10 hours ago, ProDave said:

If that is the case it is a badly designed valve as it will always reach that equilibrium, and only a swap for a different valve would fix it?

Not quite. I have found that there is a slightly higher flow rate with higher temps, strange as it sounds, and as the heat loss is slightly higher at higher temps they seem to work fine when not set to minimum. More plumbing voodoo for you  

FWIW I do not fit the conventional blending valves any more, and instead I'm sticking to the Ivar kit as posted above. So much easier to commission and far better degree of temp / slab control vs the conventional types. They do not rly on a return flow to function so are IMO a no-brainer.

For higher temp / mid energy consuming installations the conventional type should suffice, but if the target flow temp is at or very close to the lowest setting of the TMV then you shoud change types to mitigate against this problem.

[Rob99]

On 23/02/2019 at 22:04, Nickfromwales said:

Its running too close to its stated tolerance IMO. When the return temp gets close to the flow the valve tries to go into 'anti-scald' and squeezes partially shut. That's where the noise is emanating from eg the water squeezing through a nearly shut valve. Open the valve up to 10oC more allowance and the noise will stop temporarily, but then will start again when the new flow temp is achieved and the return catches up.

Hi all, thanks for the useful comments, am only just getting back online after a few weeks out of action.

 

Nick, that's exactly what is happening, turn the valve temp up or down and its fine until the temp gets close to the set point again. I have reduced the boiler temp down to about 40-45 and run the system for a few days with the valve open to maximum (i.e. 60deg) and not a peep from it, presumably as its not trying to close off.

 

So how does the Ivar valve set up work which is different to a normal blending valve?

[Nickfromwales]

On 08/03/2019 at 16:00, Rob99 said:

So how does the Ivar valve set up work which is different to a normal blending valve?

The Ivar doesn't rely on returned cool water to function and does not 'have to have' a return to operate at all. The opening of the valve, for heated water to be introduced to the recirculating UFH loop water, relies on a thermo probe which sits in a wet pocket and references 'post mix' flow temp. That connects hydraulically via a capillary wire to the valve which operates like a TRV radiator valve. The temp is very reliably controlled and you can operate at temps as low as 20^oC and as high as 60^oC with near pinpoint accuracy. I've ditched the TMV blending sets altogether now, particularly for 'passsive' builds where temperature hysteresis is critical. 

[Apr0327]

Rob99, did you manage to solve this? I have same problem and its driving me mad!! Plumber can't solve it and has gone awol!.

[Nickfromwales]

3 hours ago, Apr0327 said:

Rob99, did you manage to solve this? I have same problem and its driving me mad!! Plumber can't solve it and has gone awol!.

What’s the boiler flow temp vs UFH flow temp? Is it quiet when starting from ‘cold’ then gets progressively noisier as the UFH temp rises to the TMV set point?

[AdamSee]

Right, I had the exact same problem which I've just managed to sort out.

 

Long story short, I set my boiler to the same temp and the mixing valve (50c) because I don't have rads. Noise be gone.

 

Long story continued;

So i have a omnie manifold with a grundfos pump, the thermostat is set to 50c and the boiler set to 65c as per omnies instructions and my plumbers. Problem was that the boiler would send hot at 65c to the manifold which would mix with existing water raising the temp and cause the thermostatic valve to slow the water comming in. But it eventually balances out to a semi open status. Open enough for the boiler to keep supplying water. But not shut enough for the boiler to stop. So the water rushes through a tiny gap was causing noise. I did fit a external bypass which helped and changed the pump speed which also helped. But the biggest and most importantly change.....I set the boiler to 50c. By the time the water gets to the boiler it's now 47c roughly. Valve stays open and there's no noise. Boiler will fire for about 10mins at a time I think. Then shut off for 10 mins or so. Only noise now is abit of vibration from the pump. Not sure how the affects the economy of the gas use, but it can't be worse.....either way it's quiet here.....kinda.....I have tinitus.......never really that quiet. I also talk to the dog alot..

Edited February 11, 2020 by AdamSee
Edit

[Apr0327]

Thanks Adamsee, so what you are doing is making the mixer value redundant, its constantly open.  Unfortunately I need to keep boiler temp higher for upstairs radiators, and therefore need mixer to do its job (wish my plumber did!) for reduced temperature in underfloor. 

[AdamSee]

Yea my mixer is pretty much redundant now as our system has no rads or any plans for them. 

 

You said that when yours is fully open it dosent make any noise so it probably is the same issue. Does it always make the same noise even when the rads are warming up? I remember mine became quieter when I installed the bypass. I would have thought that your rads would act as a bypass. 

 

I would keep a ear out for times it's making noises compared to times the rads are warming up. See if there's a difference between ufh running with the rads and without the rads warming. 

Im assuming you have motorized valves that can control the two systems independently.