CWST temperature advice please

[Mary Mcnab]

Hi all, first time posting, looking for advice regarding a CWST.

I was asked to look at a system where the customer couldn't get below 25degree at cold taps. The building is predominantly unused at the moment, it is going to be used as a holiday let soon.
It has 8 ensuite bedrooms, a main kitchen and a second sitting area which has a sink in it.
The CWST is in the basement, in a plantroom off the swimming pool area, also in the plantroom is the swimming pool boiler (Room Sealed) and associated kit. The CWST outlet goes into a booster pump set to feed the cold outlets and also feeds the unvented Hot Water cylinders also situated in the plantroom.
There is no ventilation in the plantroom and no means to run any (being in the basement under the house) Not the best of designs I must say!
The humid air temperature in the plantroom is 28degrees and due to the building being unoccupied at the moment water wasn't being drawn off which had caused the temperature inside the tank to rise.

We have tried emptying the tank completely, and refilling, incoming water temp is 10degrees, newly filled tank temp was then 15 degrees, 24hr later it was 19degrees and a further 24hr later 23degrees.
My question is if the fibreglass tank was insulated would it keep the water cooler for longer or cause the water to heat quicker?
I informed my client that a full chlorination will be required once we find a suitable solution.

All advice appreciated

 

[Stigster]

Insulation keeps cool things cool and hot things hot. If the cistern was properly insulated and the turn over of water sufficient, you will hopefully be able to maintain a more acceptable lower temp at the cistern and therefore the outlets. Many people have their CWSC in their lofts and as you are probably aware, they can also be very warm places in the hotter months. Insulation is not just a nice thing to have, it is a regulation. A bye-law 30 kit contains all of the items required to keep a cistern hygienic, including an insulating jacket.

Ultimately, if the water cannot be maintained at a suitable temperature because of the siting, it would have to be moved.

 

[Burger]

I wouldn’t know with these, it’s beyond my general knowledge. However it sounds plausible that the tank is being unduly warmed, but I’m not sure about insulating a booster tank. Have you ruled out any backflow from a faulty mixing valve?

 

[Millsy 82]

Insulate the tank correctly.

If it's that really warm in there as well you could build an insulated cupboard within the room with Celotex or something like that.

The problem you may have is the tank will have to be sized for 8 bedrooms but how often is the house going to be fully occupied. Make sure the tank is not oversized as you will just have water sat around longer than it needs to be.

 

[Mary Mcnab]

Thanks everyone for your replies

 

[Chalked]

We have boxed them in before ,with 50mm kingspan insulation. Foil tape the joints.

 

[Brambles]

A couple of points:

Is this in the Uk? If so there are regulations on forced ventilation for chlorinated water systems in confined spaces. I assume it is not a brine system.

It is not unusual to have an A/C unit in an underground pool plant room - to deal with the above and lower the ambient temperature and humidity.