Hot water issues with running bath

[dl1973]

Hi
We have the following problem when we run the hot water tap on our bath. Basically it starts to come out hot then after a few minutes it goes lukewarm and I'm not sure why. When I try the hot water tap on the kitchen sink it comes through a lot hotter and there are no problems with running the hot water on our shower either - sometimes it's too hot. Our hot water comes via a thermal store cylinder. Cold water inside a coil is heated by the body of hot water inside the thermal store. It was set up like this as we have a wet based underfloor heating system and I think the idea was that it might get connected up to a renewable energy in the future. Any thoughts on what might be causing this and how to fix this would be much appreciated.
Thanks in advance for your help.

 

[Roy_66]

Dont know about Thermal store cylinders, but have seen them working fine in places I've stayed.

Just to help understanding - if you run the bath real slow does it stay hot ?

Roy

 

[dl1973]

Hi Roy
Haven't tried that, so I assume open the hot water tap less so the water flows through slower. Why might that help?
Thanks

 

[steadyon]

Because the slower flow of water through the coil surrounded by the hot water in the cylinder allows more heat to be transferred, raising the temperature of the water flowing through the coil.

 

[Roy_66]

Hi Roy
Haven't tried that, so I assume open the hot water tap less so the water flows through slower. Why might that help?
Thanks

Its just an experiment to understand whats happening. Yes open the tap less e.g. 25%. Also turn off for a bit if goes cold.

Hopefully a Thermalmstore expert will give you a reply.

Roy

 

[Stu-B]

What make of store is it?

 

[dl1973]

Unbranded

 

[Harvest Fields]

Is it a mixer tap?

 

[dl1973]

No, there are separate hot and cold water taps on he bath

 

[Stu-B]

Maybe there’s a blending valve under the bath

 

[Harvest Fields]

Maybe there’s a blending valve under the bath

Possibly

 

[dl1973]

I don't think there is one, it's a fairly simple tap/pipework set-up.

 

[Riley]

I’d call tmv

 

[Stu-B]

I don't think there is one, it's a fairly simple tap/pipework set-up.

Have a look for something like this

Thermostatic Mixing Valve TMV 2/3 - 15mm - 12162 | BES.co.uk