Anyone know a suitable TMV?

[Countrypaul]

This should be simple, but I cannot find a suitable Thermostatic Mixer Valve for use on a bath.

The cold and hot pipes are 22mm both mains pressure (the hot via a Thermal Store). Typically (in winter) the HW is at about 45C, but for the bath we need that mixing down to about 40C which seems like a trivial task. All the TMV's I can find so far either require the HW to be 10C or greater than the output temperature, or require the HW at 50+C.

The showers that have the TMV built in rather than a separate fitting seem to have no problem working with the HW as less than 10C higher than the output - so I know it can be done.

Can anyone point me at a suitable 22mm fitting?

[spread-tee]

I have used these several times in the past with good results, I cant remember the exact specs TBH but they seem to be reliable and decent quality, and have been infinitely adjustable over a fixed range subject to fitting the correct cartridge.

https://www.intatec.co.uk/product/intamix/

We did have one that would "sing" while it was settling down to find an equilibrium on a UFH system that drove me nuts, we ended up soundproofing it to the customers satisfaction in the end but never did work out why it did it!

Desp

[ecogeorge]

Hmmm ........ your requirement to reduce 45c to 40 is difficult as you have found .......
Silly question but run bath , add cold ??
45c seems low for dhw - I can wash up with 46c water ...... is it not cold after reaching sink ??
but some googling found these .......file:///home/chronos/u-cb8767ec99fae7874470798d7e2df151c98c3f7c/MyFiles/Downloads/VTA370_VTA570_en_M_LR.pdf
Can't see what temp differential is the min tho ??
rgds George.

[Countrypaul]

I have used these several times in the past with good results, I cant remember the exact specs TBH but they seem to be reliable and decent quality, and have been infinitely adjustable over a fixed range subject to fitting the correct cartridge.

https://www.intatec.co.uk/product/intamix/

We did have one that would "sing" while it was settling down to find an equilibrium on a UFH system that drove me nuts, we ended up soundproofing it to the customers satisfaction in the end but never did work out why it did it!

Desp

The spec sheet for those has "Minimum Temp. Differential (Mix to Hot) to Achieve Failsafe 10°C", it also says "Inlet temperature range 55-65C Hot" which is the same spec as the ones I have. Based on that spec, my experience is that the outlet water is reduced to 35C after a couple of minutes.

They don't appear to have separate cartridges - have you mixed your TMVs?

[Countrypaul]

Hmmm ........ your requirement to reduce 45c to 40 is difficult as you have found .......
Silly question but run bath , add cold ??
45c seems low for dhw - I can wash up with 46c water ...... is it not cold after reaching sink ??
but some googling found these .......file:///home/chronos/u-cb8767ec99fae7874470798d7e2df151c98c3f7c/MyFiles/Downloads/VTA370_VTA570_en_M_LR.pdf
Can't see what temp differential is the min tho ??
rgds George.

The problem is the little ones getting scalded which can happen quite easily if the HW temperature is much higher as it tends to be in summer, I should have said minimum HW temperature (which is typical in winter) rather than just typical, in summer it easily reaches 70+C.

The ESBE spec sheet also indicates a minimum temperature difference between HW and mixed of 10C

[John_S]

Think outside the box.

How about installing a bath/shower thermostatic mixer and fit a blanking cap on the shower outlet They are usually set to 38 degrees with an override button.

I have found the following spec for a Grohe unit and it states that the hot water temperature at the supply connection should be at least 2 deg C above the desired output temperature.

https://cdn.cloud.grohe.com/tpi/2000/21 ... 190558.pdf

[Countrypaul]

Think outside the box.

How about installing a bath/shower thermostatic mixer and fit a blanking cap on the shower outlet They are usually set to 38 degrees with an override button.

I have found the following spec for a Grohe unit and it states that the hot water temperature at the supply connection should be at least 2 deg C above the desired output temperature.

https://cdn.cloud.grohe.com/tpi/2000/21 ... 190558.pdf

I have been trying to think out of the box and wondered about UFH mixer valves since in many cases the UFH needs to deal with quite a low temperature difference between the warm supply and cool recirculating water (thnking Heat pumps) but I nnot find any of those suitable yet.

A quick look at the link you suplied ans it seems to need a thermostatic mixer valve on the HW before the actual unit I need to ensure I have read that correctly as it sounds pointlees to me.