Thermostating Mixing Valve Query

Flood

I recently fitted a mixing valve into my hw system as the hot water was too hot and kids getting to the age of being able to turn on taps i was getting afraid they would get burned as childrens hands can burn easy.
The problem i have is the pressure in the hot taps in upstairs bathrooms has dropped, downstairs is little bit back on pressure but ok. The non returns in the valve is where im loosing the pressure no doubt.
Im wondering is there a mixing valve available with weaker non returns or other alternative. The supplier i bought it off suggested removing the valves but i would have hot water mixing over into the cold supply then i imagine.
Its a gravity system, storage tank 6 feet up in attic. Cylinder is sitting on floor on first floor. The mixing valve is suitable for gravity according to the installation instructions that came with it.

freddyuk

Which brand, which model? PM if you don't want to advertise....we can check if it is low pressure or high pressure

jimmy180sx

I usually specify the rada meynell mixing valve as these have very low pressure drop and are suitable for gravity systems. Usually spec them for schools, as they are tmv3 certified also

Flood

Its a Titan-ozimix2, according to its specs the working pressure dynamic = low pressure is 0.1-1.0 bar.
Am i right in saying im losing 0.1 of a bar pressure by having this fitted?

youtheman

I have a gravity system in my house. A few years ago I upgraded to solar with a dual coil cylinder. As part of the solar system I had to install a thermostatic mixer valve as the hot water in the cylinder can be very hot. As it is a gravity based system I was afraid of a pressure drop through the valve so I was advised to 'go up one size'. So my piping is 1/2" (I think) so I installed a 3/4" thermostatic valve. There are no NRVs (non-return valves) in my system. I did initially have a problem where the hot water was reverse flowing back through the thermostatic valve and eventually into the tank in the attic. This was solved by running the cold feed from the attic tank down to the hot-press floor and then up to the thermostatic valve (hot water will not flow downwards). Problem solved. So I would consider this, bigger thermostatic valve and no NRVs (no pressure drop and no reverse flow).

Flood

youtheman wrote: »

I did initially have a problem where the hot water was reverse flowing back through the thermostatic valve and eventually into the tank in the attic. This was solved by running the cold feed from the attic tank down to the hot-press floor and then up to the thermostatic valve (hot water will not flow downwards). Problem solved. So I would consider this, bigger thermostatic valve and no NRVs (no pressure drop and no reverse flow).

That is an interesting point, i have often seen mixing valves fitted in places and the non returns that come with the valves not used so using a technique the way you brought the cold feed to floor and back up to stop the hot expanding back up the cold pipe.