Single/Double/NRV Check Valves Query

[BobbyJoe]

Good morning,

I have a query about single check valves/double check valves/non return valves and their purpose.
I moved into a flat built in the 1960s and I think the bathroom was last upgraded around 2007 perhaps even before.

I am going to get it completely redone next week (new suite/ taps etc) and want to have single check valves installed in the bathtub water pipes and the basin pipes because the pipes don't even have isolation valves or anything.
Could someone advise if check valves of any kind are mandatory to have installed and if so their purpose and how many are necessary. My main concern is ensuring their are no back flow water issues, fresh water is always flowing in the correct direction and would appreciate advice from experts so that I can then inform the workmen what extras I need for the bathroom revamp, thank you.

 

[Burger]

Check valves are if I recall correctly, for situations where backflow (a flow unintentional of original direction) may occur, an example is where it's not possible for a shower head to maintain an air gap above the bath spillover level. Does this make sense?

 

[Chuck]

You appear to be in the UK. As long as the bathroom is being installed to current Building and Water Regulations appropriate measures are standard not extras.

If you are designing the bathroom yourself there is no substitute for studying and understanding the applicable Building and Water Regulations, which are available on line. These cover the necessary backflow and cross-flow prevention measures.

Arrow Valves have some useful guides to the Water Regulations:

Arrow Valves

www.arrowvalves.co.uk

that cover washrooms, shower / bath / bidet, isolating valves, notification, etc.

If in doubt, consult a qualified plumber, fixing mistakes after the bathroom has been finished can be painfully expensive.

 

[BobbyJoe]

Thank you for the advise and yes I am in the UK. I am not designing the bathroom myself but a family owned business is going to do a complete installation next week, I was just curious if I had to ask the workmen to install check valves or would everything comply in meeting Building and Water regulations because the current pipes don't have any valves or even isolation valves in them.
[automerge]1569061792[/automerge]

 

[centralheatking]

Generally non return valves, single check & double check valves are not fitted in bathroom or shower rooms. The risk is to prevent dirty water backflow into the cold water drinking supply. This generally is not a risk in a bathroom as the greywater in the bath is below the taps and even if you have a deck mixer leaving the shower head in the bath water will not back siphon as the supply will be on or shut off. Same applies to showers as the risk is even less. However I can see a rare situation in multi occupancy buildings eg tower blocks where a flat at high level might eg due to being a void or poorly maintained might back siphon
but the chances are rare. I suppose I could quote chapter and verse of this aspect of wras but above is an honest working interpretation
others might add ...so dont worry....centralheatking

 

[BobbyJoe]

Thank you I appreciate your advice very much. I used to live in a multi storey tower block and the water supply did have siphoning issues.
Now I live on the 3rd floor of a 3 storey flat and am just trying to be cautious and doubt I will need valves and don't want to pay for anything which isn't required. Lastly would the kitchen sink ever need a valve attached to the pipework?

 

[Burger]

Thank you I appreciate your advice very much. I used to live in a multi storey tower block and the water supply did have siphoning issues.
Now I live on the 3rd floor of a 3 storey flat and am just trying to be cautious and doubt I will need valves and don't want to pay for anything which isn't required. Lastly would the kitchen sink ever need a valve attached to the pipework?

If the kitchen sink isn’t a balanced supply, and a mixer tap then it’s a fluid category risk 2 and would need single check valves.

A balanced supply would be a mains fed cold with a combi boiler of equal pressure.

 

[BobbyJoe]

Thank you very much it is much appreciated

 

[OffshoreGas]

Generally non return valves, single check & double check valves are not fitted in bathroom or shower rooms. The risk is to prevent dirty water backflow into the cold water drinking supply. This generally is not a risk in a bathroom as the greywater in the bath is below the taps and even if you have a deck mixer leaving the shower head in the bath water will not back siphon as the supply will be on or shut off. Same applies to showers as the risk is even less. However I can see a rare situation in multi occupancy buildings eg tower blocks where a flat at high level might eg due to being a void or poorly maintained might back siphon
but the chances are rare. I suppose I could quote chapter and verse of this aspect of wras but above is an honest working interpretation
others might add ...so dont worry....centralheatking

I’d always fit a double check valve on a mixer tap/shower where hot and cold water may mix. My understanding is this dates from vented tanks in lofts etc and possible legionella risk.

 

[ShaunCorbs]

What is your hot water system

If it’s gravity hot water then a single or double check is required on the hot to stop the cold overpowering the hot and back flowing

If it’s mains pressure eg same as cold water then there is no backflow risk so you don’t need to allow for anything unless your taps are below the spill level

As for iso valves always fit them on toilets basins and kitchen sinks

Type of iso full bore iso valves are the best

Don’t fit the cheap ones as they have a smaller internal dia around 10mm

Eg

Small dia

Isolating Valve 15mm 10 Pack

Full bore

https://www.NoLinkingToThis/p/full-bore-isolating-valve-15mm/46860

 

[Harvest Fields]

Always go with full bore,

 

[Ben-gee]

I think it’s a great idea to use full bore on gravity systems but in most instances (ie taps, inlet valves) not necessary on a pressurised/Combi system.

 

[OffshoreGas]

I think it’s a great idea to use full bore on gravity systems but in most instances (ie taps, inlet valves) not necessary on a pressurised/Combi system.

Completely agree, if anything I find myself throttling the flow back so it doesn’t result in a torrent of water then you open the tap too enthusiastically.

I know you’re not supposed to throttle a ball valve obviously but there don’t seem many alternatives in plumbing.

 

[BobbyJoe]

Hi and thank you all for your great insight. I have a new combi boiler (gas) pressure is at the 1.2 bar and the water is fed via the mains supply for both hot and cold.
I thought I would get as much information as possible as the bathroom is being upgraded next week and I don't want to pay someone to come back and redo anything. The workmen said they would install isolation valves and flexi hose pipes to the copper ones and install a thermostatic shower with mixer taps for the bathtub and basin, therefore I won't require check valves unless I am mistaken.

Lastly my kitchen tap is going to be replaced with a lever mixer tap, should I get a double check valve and isolation valve installed on the one kitchen pipe under the sink as their is only one pipe connected to the tap?

 

[OffshoreGas]

Hi and thank you all for your great insight. I have a new combi boiler (gas) pressure is at the 1.2 bar and the water is fed via the mains supply for both hot and cold.
I thought I would get as much information as possible as the bathroom is being upgraded next week and I don't want to pay someone to come back and redo anything. The workmen said they would install isolation valves and flexi hose pipes to the copper ones and install a thermostatic shower with mixer taps for the bathtub and basin, therefore I won't require check valves unless I am mistaken.

Lastly my kitchen tap is going to be replaced with a lever mixer tap, should I get a double check valve and isolation valve installed on the one kitchen pipe under the sink as their is only one pipe connected to the tap?

Some would probably disagree but if they say they will fit flexi hoses I’d tell them to beat it.

At home or jobs I’m likely to come back to I install service valves like confetti. They are cheap and easy to fit, it saves a massive amount of hassle when you go back to work on them.

I assume some plumbers choose not to to guarantee future work as it’s a lot more intimidating to a home owner etc even to do basic repairs if they have to isolate/drain a whole system.

 

[Ben-gee]

Bobby as you have all water from the mains then isolating valves are not needed for maintenance purposes, however they should be fitted so that a faulty item can be isolated whilst parts/plumber is sought.

The exception is that a “ball valve” ie lavatory inlet valve Must have an isolating valve by regulation.

I would ask the plumbers to hard pipe the bath taps rather than use flexis, this is due to massive restrictions in flow rate and also the fact that they are hidden away and so in my opinion require a more robust installation as problems will not be spotted until too late.

 

[BobbyJoe]

The plumber said he was going to hard pipe the bath taps but use flexis for the basin, does this seem right?

 

[Ben-gee]

Yes that sounds par for the course and better than a lot of them do to be honest.

Some basin mixers can only be fitted using flexis, they come with factory fitted captive ones that don’t unscrew.

I wouldn’t worry unduly, and please allow them to get on with their work unhampered - except with enforced tea and biccy breaks!

 

[Chalked]

Most modern shower mixers have them built in.

 

[BobbyJoe]

Thank you all very much but one thing about water pressure in the flat. I had a new gas combi fitted last week and the hot water pressure flow is not as high as it was before but actually much better at a lower rate, the cold water has really high pressure but I would prefer it at the same flow rate or near about as the hot water is it possible and if so what needs to be done?
Any advice on this would be appreciated so I can understand how things work and am better informed .

 

[centralheatking]

Hi and thank you all for your great insight. I have a new combi boiler (gas) pressure is at the 1.2 bar and the water is fed via the mains supply for both hot and cold.
I thought I would get as much information as possible as the bathroom is being upgraded next week and I don't want to pay someone to come back and redo anything. The workmen said they would install isolation valves and flexi hose pipes to the copper ones and install a thermostatic shower with mixer taps for the bathtub and basin, therefore I won't require check valves unless I am mistaken.

Lastly my kitchen tap is going to be replaced with a lever mixer tap, should I get a double check valve and isolation valve installed on the one kitchen pipe under the sink as their is only one pipe connected to the tap?

Read above if the system has balanced hot and cold pressures as yours does there is no problem with a kitchen mixer tap. You have checked with us and the project to my mind is absolutely fine now.
Worry not ....and when its finished let us know how you got on
please...feed back is nice . centralheatking