Groaning mixer valve

[AliG]

Hi,

 

I have a mixer valve that "groans". I think this issue has come up before as kind of fluttering in the system. It was fine for three or four years before it started to do this.

 

You can temporarily fix this by adjusting the temperature but then it gets to the new temperature and does it again.

 

I was thinking of getting the boiler serviced and asking them to replace it when they are here.

 

Can you just replace the 4 way mixer or does it only come as a unit with the pump? Looking online i suspect it was all supplied as one with the manifold and I cannot see a make on the actual mixer. 

 

Are general heating engineers a bit wary when it comes to messing with UFH?

[jayc89]

Mixing Valve Unit is the part you're after, you can buy them separately. 

 

The guy who fitted our new boiler and UVC didn't want to touch our UFH system, he ran the flow/return to the manifold and that was it. Other Heating Engineers are happy to do it all though. 

[AliG]

Thanks

 

Sorry meant to include a picture -

 

I think it says TH MIX on it as well as made in Italy.

 

 

[Nickfromwales]

If you’re looking at a replacement then I’d switch to the Ivar set and lose the basic TMV. I’ve never heard or had a noisy unit tbh, and they are very reliable and super accurate.
Had one fail once, and it was out of warranty, but still got replaced for free when I said it was a rare occurrence etc (which they agreed with). Sticky cartridge, but may have been just a ‘Friday unit’ as I’ve been fitting them for years without issue. 

 

Ivar

 

Cheaper Emmeti 

 

Not sure what the difference is to justify the prices, but nothing wrong with Emetti either tbh. 

[AliG]

Thanks @Nickfromwales

 

I realised last night that there might be something in all the manuals etc I was given.

 

It appears that I have this unit -248TH MCE2014.pdf248TH MCE2014.pdf248TH MCE2014.pdf

 

This has been replaced by the 248N and the technical data for this says that the primary flow should be at least 15C higher than the set temp of the mixer. When I was looking for replacements, some of them said 20C. A while back, trying to optimise boiler efficiency, I turned the boiler down to the high 50s. The flow in that manifold is set I think at 42C, so I have turned the boiler up into the 60s to see if in fact the problem is being caused by the low temperature differential.

 

 

[Nickfromwales]

Just now, AliG said:

Thanks @Nickfromwales

 

I realised last night that there might be something in all the manuals etc I was given.

 

It appears that I have this unit -248TH MCE2014.pdf248TH MCE2014.pdf248TH MCE2014.pdf

 

This has been replaced by the 248N and the technical data for this says that the primary flow should be at least 15C higher than the set temp of the mixer. When I was looking for replacements, some of them said 20C. A while back, trying to optimise boiler efficiency, I turned the boiler down to the high 50s. The flow in that manifold is set I think at 42C, so I have turned the boiler up into the 60s to see if in fact the problem is being caused by the low temperature differential.

 

 

A good place to start the process of elimination tbh, as there’s nothing worse than changing stuff to then arrive straight back at the original fault. 

[JohnMo]

The good thing if you do change the mixer for an Ivar, there are plenty of adjustments and fine tuning you can do. You can actually reduce the dT down quite a bit, think I managed to get the dT down to 5 degs across the valve.

 

The mixer may be gummed or scaled up restricting internal parts moving and you are getting under and overshoot or generally worn.

 

I moved to an ASHP and as I only have UFH eliminated the the pump and mixer all together.

[AliG]

So far it seems quieter since I turned up the boiler, but the heating has only been on for a few minutes.

22 hours ago, JohnMo said:

I moved to an ASHP and as I only have UFH eliminated the the pump and mixer all together.

This now has me thinking. At some point I plant to switch over to an ASHP. I would probably have to take out the mixers as they won't be required and likely won't like the low flow temperature.

 

I have 4 manifolds, so won't be in a hurry to do that!

[John Carroll]

Can you remove the shuttle, clean it up, apply a bit of silicone grease and see how it goes.

[AliG]

Since turning the boiler up it is still groaning although maybe less than before.

 

I could put Star Wars on as it sounds quite like Chewbacca!

 

@John Carroll you have me there. Is the shuttle the trv?

[John Carroll]

9 hours ago, AliG said:

Since turning the boiler up it is still groaning although maybe less than before.

 

I could put Star Wars on as it sounds quite like Chewbacca!

 

@John Carroll you have me there. Is the shuttle the trv?

Yes, it's the thermostatic mixing valve,TMV, generally contains a plastic piston/shuttle which can be removed.