If a bathroom has: a) one toilet, b) one basin (with mixer tap), c) one bath with mixer bath filler, d) one hand shower, and, e) one shower over bath, how many single check valves and/or double check valves are required? A combi boiler is used in case that makes any difference. Thanks.
A double check valves protect against category 3 liquids, might cause gutrot, upsets, etc, where as a single only protects against category 2 liquids that cause bad taste strange,warm, like from washing machine hose, whether Cat 2 or Cat 3 neither fluid would kill you. https://www.wras.co.uk/consumers/resources/glossary/fluid_categories/
So with regards to the bathroom applications above, is there any disadvantage in simply using double check valves for all where required instead of single?
Also, am I correct in thinking that six check valves are required for the aforementioned setup? a) one toilet, one valve b) one basin (with mixer tap), two valves c) one bath with mixer bath filler, two valves d) one hand shower, one valve before it reaches the two way diverter e) one shower over bath, (valve for 'e' same valve as for 'd')
With regards to the shower setup, which consists of an overhead shower, a hand shower and a two-way diverter, would any possible internal check valve be within the two-way diverter, the overhead shower, or the hand-held shower?
So far I've discovered that the Fluidmaster Pro45B brass shank fill valve which will be in the toilet cistern has an anti-siphon / backflow design which prevents contamination. So it looks as if I only need to get a full-bore isolation valve for the toilet, no other valve required. Also, the 2-way diverter for the overhead and hand showers has an internal check and non-return valves, located on the hot & cold inlets to the valve. So again, I think it's only two full-bore isolation valves I need for this. Just have to hear back about the basin mixer tap and the bath mixer filler...
Apparently the Hansgrohe basin mixer tap does not have an internal check valve. So I'll require two isolators and two check valves for this. The bath mixer filler also does not have a non-return valve. So, I'll need the same. I did read on the Q&A for a product somewhere on the ScrewFix website that double check valves do not have the same flow rate as full bore (though I don't know to what extent the double slows down the flow rate compared to the single). Although on the upside the double protects against category 3 liquids as KIAB stated above. Would it be standard practice to install double or single check valves on a domestic bath filler and hand basin?
On a domestic installation check valves (non return valves) and other back flow prevention devices are not required on wras approved bath fillers or basin taps. so buy wras approved taps is the answer.
That's good to know. I've just checked and apparently the Hansgrohe tap is WRAS approved. However, the mixer bath filler is not. It was the only model of this type (of the type required) which I could locate, and is sold by several retailers. Therefore, I'll need to purchase two check valves for this. The retailer did suggest double check valves.
Which bath filler do you have ? can you post a link,its most probably a clone and OK. Not all tap manufactures say their product are wras approved (they seem to miss that out on their internet adverts/flyers,especially the imported Chinese products)
As far as I'm aware there's no internal non-return valve. http://www.bathshop321.com/hudson-reed-e304-single-lever-freeflow-bath-filler/
That bath mixer would require check valves,unless they state otherwise. Although many would not fit any
Isolator valves will need to be fitted to the pipes to the bath filler in any case and, interestingly, I did locate the product linked-to below which combines the double check valve with the isolator valve: http://www.altecnic.co.uk/images/products/info/98_info.pdf It's interesting that, since it is WRAS approved, check valves are not required for the Hansgrohe basin mixer tap, even though it does not have an internal check valve.
Would anyone happen to know the purpose of the black cap underneath the double check valve with isolator, pictured below? It appears to be referred to as a 'test plug'. http://www.altecnic.co.uk/images/products/info/98_info.pdf
Thats to do with the tap spout/outlet is not in contact with stored dirty water in the basin,if the basin fills to its highest level it will overflow via the overflow or spill over the basin rim so the tap is never in contact with dirty water. Your fancy pants bath filler is different,you can fill the bath to the overflow level (which is very close probably adjacent to the water flow inlet) the mixer flow into the bath could be more powerful than what the overflow will accommodate so now the tap outlet is in dirty water,so back flow prevention is required. Dont worry about that and dont use them,it will drastically reduce the flow of water.its main use in the uk is part of a filling loop.Ask your installer to specify check valves that will suit your tailor made system.
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