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vents for new shower supply pipes

Postby soundant » Fri Sep 28, 2007 9:20 pm

Hi all,

I'm installing a salamander (RSP50) pump at the base of my hot water cylinder which will supply a shower on the same floor - I intend to use speedfit pipe (15mm) 'up and over' via the loft and back down to the shower.
The manufacturer specs vents on the hot and cold side above the shower - how do I do this? is a simple T fitting OK with a length of pipe above (how long) or do I need a special valve of some sort?
I also need a non-return valve on the pump outlet (hot only) - any suggestions?
Many thanks for your thoughts and advice.
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Simply Build It

Postby rosebery » Fri Sep 28, 2007 11:50 pm

Don't understand (perhaps it's just that time of night) what you are saying about vents - can you provide details of manufacturers spec?

I only trust Hep2O but that's my personal preference.

Non-return valves are to prevent syphonage. Single and double check vvs available at all good plumbers merchants. Presume you are pumping both hot and cold to a thermostatic valve so why only on the hot?

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Postby bobplum » Wed Oct 03, 2007 6:23 pm

hi i am slightly confused as well regarding the need for vents
also if with non return valves you only need them if the pressure of one water supply is stronger than the other and the risk of back flow occurs
the water from the cold tank will be gravity as will your hot i dont see the real need for them
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Postby richieplum » Sat Oct 06, 2007 10:40 pm

The vents mentioned in your question are irrelevant as you are fitting plastic pipes, and I've never seen any sort of aav (automatic air vent) or even finger vent fitted to any plastic pipe. The dcv (double check valve) is also certainly not required as double check valves are only ever used on electric mains hot water heaters, large scale industrial supplies or outside taps.....oh, and filling loops into combi boilers. Their purpose is to stop any contaminants being pulled back into the mains supply in case of a sudden and catastrophic drop in the mains pressure (perhaps due to a fracture in the mains pipe). In the installation you are proposing, assuming both supplies start from the tanked water in your loft, and that you are going to use speedfit you need neither air vents nor check valves, but do remember to fit some sort of isolation to the supplies to the pump to aid service.
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