Thermostatic shower controlling hw in house

[monte]

hi all

I have a thermostatic shower in my bathroom. we have to keep the shower set at a certain point. if we turn the temp one way the hot water for the whole house becomes cold and we turn it too far the other way the shower becomes too hot

Any ideas as to why the shower seems to be controlling the hw temp for the whole house.

House is 3 storey, with condensing boiler and ventilated cylinder

any advice welcome

 

[SimonG]

Yep.

Sounds like the shower could be fed from the vented hot water and mains cold water.

Really needs to be fed from tanked cold water to equalise the pressures, plus double check valves fitting to prevent what is happening.

If you are lucky you might get a pressure reducing valve on the mains cold supply and get it adjusted to somewhere close. Still with double check valves though.
[automerge]1577654270[/automerge]
Sorry bud, misread your first post on the unventilated water tank.

Showers goosed, needs replacing. Still think the double check valves are required though

👍👍

 

[monte]

f

Yep.

Sounds like the shower could be fed from the vented hot water and mains cold water.

Really needs to be fed from tanked cold water to equalise the pressures, plus double check valves fitting to prevent what is happening.

If you are lucky you might get a pressure reducing valve on the mains cold supply and get it adjusted to somewhere close. Still with double check valves though.

thanks for that

your correct hw comes from cylinder and all my cold is mains fed. 2 questions - check valves on both hot and cold water and if I can fit the pressure reducing valve do I fit it on the section running up to the shower. finally what's the option of I cant fit the pressure reducing valve
[automerge]1577655004[/automerge]

Yep.

Sounds like the shower could be fed from the vented hot water and mains cold water.

Really needs to be fed from tanked cold water to equalise the pressures, plus double check valves fitting to prevent what is happening.

If you are lucky you might get a pressure reducing valve on the mains cold supply and get it adjusted to somewhere close. Still with double check valves though.
[automerge]1577654270[/automerge]
Sorry bud, misread your first post on the unventilated water tank.

Showers goosed, needs replacing. Still think the double check valves are required though

👍👍

thanks this is appreciated.

the hw is unventilated and not ventilated assume that doesn't make a difference.

 

[SimonG]

Forget the first part of my reply with the prv. It's all mains pressure so new shower and double check valves on feeds to shower.

 

[monte]

Forget the first part of my reply with the prv. It's all mains pressure so new shower and double check valves on feeds to shower.

that's great. thanks for your help