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Plumbing

22mm hot to 15mm for shower.

Anonymous user 17/03/2024 - 2.30 PM

I am renovating my bathroom. The hot and cold feed for the bath comes from 22mm copper pipework under the floor and comes up with isolating valves on each end. On the hot there is a tee fitted with its end at 15mm which I plan to have the shower run on. The thermostatic shower valve I have bought takes hot at 22mm.. Is it safe / ok and won't reduce flow rate if I fir a 15mm adaptor to 22mm off this tee piece? It seems silly to have the water come up in 22mm, be brought into roughly 15cm of 15mm l, then be stepped up to 22mm again... Not professional I imagine but will this be ok to do? If not, looking for suggestions if possible? Additional info that I am not sure is important. - hot pipes from the tee to the shower will be roughly 3.5m - Recently had a new boiler fitted into the loft which was previously ground floor and is stronger so we have better water pressure than standard. 28 psi/ 2 bar. - I plan to use push fit pipes and used previously in the other bathroom. Help or comment would be much appreciated.

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3 Answers

Colin Melhuish

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Camberley

15mm to the shower will be fine on a pressurised system. When you say the connections to the valve are 22, are they actually for 22 or are they 3/4 female threads, in which case you can just use a 3/4 to 15mm male iron to copper. Hope this helps and good luck

Answered17 September 2023

Anonymous user

It's generally not advisable to reduce the pipe size from 22mm to 15mm right before the thermostatic shower valve, as this can significantly reduce the flow rate of hot water to the shower. Reducing the pipe size can increase the pressure drop in the system, which will result in reduced flow and potentially affect the performance of the shower. Thermostatic shower valves are designed to work optimally with the specified pipe sizes, and deviating from those sizes can lead to issues with water pressure and temperature control. If your shower valve requires a 22mm hot water supply, it's a good idea to maintain that size from the tee piece to the valve. If you do decide to use a 15mm adaptor, it's important to consider the following: Flow Rate: The 15mm pipe will restrict the flow of hot water compared to a 22mm pipe, which can result in lower water pressure and a less satisfying shower experience. Temperature Control: Reducing the pipe size may affect the thermostatic valve's ability to maintain a stable and accurate water temperature, as it relies on a consistent flow rate for precise control. Potential for Future Issues: Over time, sediment and mineral buildup can occur inside pipes. If the pipe size is reduced, these deposits may accumulate more quickly, further restricting flow and potentially causing maintenance issues. To ensure the best performance and safety, it's recommended to maintain a 22mm hot water supply to your thermostatic shower valve. If necessary, you may need to consult a professional plumber to modify your plumbing system to accommodate the valve's requirements without reducing the pipe size immediately before the valve. If you're confident that the reduced pipe size will not significantly impact water flow and temperature control, and you've successfully used push-fit pipes in your home before, you can proceed with this option. However, if you have any doubts or concerns, it's always a good idea to consult with a professional plumber who can assess your specific situation and provide expert guidance on the best approach for your bathroom renovation.

Answered10 October 2023

Curtis Carpentry

Rating: 5 out of 5

Wallingford

Fit an equal t and run in 22mm

Answered17 September 2023