Hi, I currently have separate hot & cold taps on my bath, the hot is fed from the water tank (water cylinder with storage tank in loft) and the cold is fed directly from main. I would like to replace these with a single mixer tap but think I recall reading somewhere that both hot and cold had to be either low or high pressure and could not be mixed. Is this correct? Thank you for any advice.
Can I use mixer tap with mixed pressure hot/cold
- Thread starter hztm2008
- Start date
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You can but ideally require one that deals with low pressure systems, so you need to know your head of pressure from the storage cistern to the tap.
That would be 0.1 bar per vertical metre.
That would be 0.1 bar per vertical metre.
Thanks for the info. Tank is above bathroom so probablly about 2.5m. I think the article I read mentioned something about the high pressure cold could force the hot water back towards the cylinder and so was dangerous. The article mentioned having to run the cold feed from the storage tank instead of the main. I cannot find the info now so maybe i have it wrong. I just want to be sure that it is allowed and will be safe. Thanks again.
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If you have a 'mix in the body' mixer tap then significant differences in pressure between hot and cold, when both taps are open, can have one restrict the flow of the other. In extreme differences you can have one force itself up the pipe of the other.
Is it dangerous? Not necessarily, more inconvenient IMO.
Is it dangerous? Not necessarily, more inconvenient IMO.
Whilst I do agree that check valves should be used in a mains pressure situation (on the cold) it could cause issues with flow on a low pressure system IMO.
It will protect the cold from backflow but would it stop the lower pressure side being restricted in an unbalanced supply, not too sure about that.
The simple solution is to feed a mixer tap from a balanced supply. Run a cold from the cistern if you wish to minimise any supply issues.
Thanks for all the info. If there is no regulations around this then I guess we are free to fit the mixer and see how well it works. If there are regulations saying that we need valves and things then it is probably easier to keep separate taps. We do not really want to run a cold feed from the tank. Thanks again for the info.
Strictly regs speaking, you should have single check valve on the cold to avoid the hot contaminating the cold. Unless you have the regs police in though does it need it, not really.
Though putting a single check valve in is relatively straightforward.
Though putting a single check valve in is relatively straightforward.
Water Regs would want a NRV on the cold.
But YOU should want a NRV on the hot to prevent cold forcing its way into the loft tank.
But a better solution is to use a pressure reducing valve on the cold supply to reduce the pressure. A 15 mm will suffice as not a lot of flow of cold is needed. ( Unless you take cold baths ).
Tony
But YOU should want a NRV on the hot to prevent cold forcing its way into the loft tank.
But a better solution is to use a pressure reducing valve on the cold supply to reduce the pressure. A 15 mm will suffice as not a lot of flow of cold is needed. ( Unless you take cold baths ).
Tony
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