My understanding is that if you fit a single flow mixer tap (kitchen or bathroom), i.e. where the water is mixed in the tap, then you have to fit single check valves (non-return valves) on both the hot and cold supplies (in addition to service valves). The check valve on the cold side prevents contamination of the cold supply and, on the hot side, it prevents cold water at a higher pressure being forced down the hot supply pipe. Fair enough.
If this is the case, then
1. Why don't tap sellers make it clear on their sites whether a tap is single or dual flow? Several of them point out that if you fit single flow taps then you must fit single check valves but they don't point out which taps are which.
2. Why don't people like Hep2O or Speedfit supply single check valves? Their catalogues only list double check valves.
I am currently trying to plan the plumbing for my new house and, either I'm missing something (more than possible!) or it seems that nobody seems to bother to obey the rules.
Can anybody sort out my confusion?
If this is the case, then
1. Why don't tap sellers make it clear on their sites whether a tap is single or dual flow? Several of them point out that if you fit single flow taps then you must fit single check valves but they don't point out which taps are which.
2. Why don't people like Hep2O or Speedfit supply single check valves? Their catalogues only list double check valves.
I am currently trying to plan the plumbing for my new house and, either I'm missing something (more than possible!) or it seems that nobody seems to bother to obey the rules.
Can anybody sort out my confusion?