That's a lot of compression fittings

[MortarThePoint]

Below if a rough out of the fittings I plan to put in before the 22mm copper that the plumber used for my tank, manifolds etc install. It works out as a hell of a lot of compression fittings, no pipes shown. I'd rather go with Pressfit, but don't have the expensive tool and if done carefully (inc Jet-lube V2), hopefully I'll have no leaks. I could only use solder fittings for tees and elbows so wouldn't actually reduce the number of compression joints as much as you'd think. 39 + 12 = 51 compression joints in total including the softener pipework.

 

Singe check valves (aka non-return valves) are highlighted with blue stars. Double check valves (DCV) are highlighted with pink stars. I've heard conflicting things abut whether a DCV is required first thing, but I do know I am supposed to have at least a single check valve before the water softener. I am effectively creating a double (DCV) by using two in series, hence the 15mm single on the unsoftened (drinking and garden) branch. I've put a drain off between these check valves to allow verification as you'd have with a DCV. Contaminating outlets are protected against by DCVs.

 

I should have a second branch like the garage one (inc isolator, DCV, drain) for machines (dishwasher, washing machine).

 

Can anyone confirm that the long tail type A drain off cock  is OK for compression fittings?

 

Would have been good to notice you can get a DCV with isolator [link1] and that would have saved cost and joints. Likewise, you can get drain tees [link2] [link3]. The ultimate would be a combined DCV, isolator and drain off, but I haven't seen that at a sensible price and link1+link2 is a great option.

 

 

[Russell griffiths]

It only looks a lot because it’s all in a small space on the floor, spread it out into it’s correct location and it will look different. 

[JohnMo]

Should be this order, stop cock, then immediately after a double check valve.

 

Then you can tee to hard and soft water routes 

 

Hard water add isolation valve, drain cock, tee to house drinking water (no check needed), outside tapp needs a double check - but outside tap, you have a tee and a drain, the drain will not do anything the tap doesn't do already when you open it, so delete the drain and make tee and elbow. Use Tectite push fit for elbows or solder.

 

Garage if it also connects to hose pipe etc, you need a double-check, if it's going to say a washing machine it doesn't need a check valve.

 

Drinking is that just going to the kitchen?

 

 

[MortarThePoint]

11 minutes ago, JohnMo said:

Should be this order, stop cock, then immediately after a double check valve.

 

Then you can tee to hard and soft water routes 

 

Hard water add isolation valve, drain cock, tee to house drinking water (no check needed), outside tapp needs a double check - but outside tap, you have a tee and a drain, the drain will not do anything the tap doesn't do already when you open it, so delete the drain and make tee and elbow. Use Tectite push fit for elbows or solder.

 

Garage if it also connects to hose pipe etc, you need a double-check, if it's going to say a washing machine it doesn't need a check valve.

 

Drinking is that just going to the kitchen?

 

I think I recall that you're in Scotland and my 'research' suggested DCV are required by regulations in Scotland, but not in England. I am attempting to make the lowest sacrifice (in terms of flow rate) alternative out of single check valves. That's why there is a single check valve on each branch thus making a pair of check valves between branch and main. The intermediate drain allows verification testing.

 

The outside tap drain allows air in to drain the pipe through the wall. Without that drain, the water would just stay in the pipe.

 

Garage will have a hose on for washing the car with softened water.

 

Drinking is just going to the kitchen. It's OK to drink softened water as far as I understand so not the end of the world if someone drinks water from a bathroom tap.

[MortarThePoint]

@Nickfromwales In the photo layout I've shown the drinking water and garden tap branching off before the PRV. Is that a good idea or not. It has occurred to me that some some kitchen sink taps may have a maximum working pressure that could mean it wants to be downstream of the PRV. A high pressure for the garden tap feels a good idea as it will help with the garden hose etc, but I guess there could be a similar issue there. What would you recommend?

[Nickfromwales]

14 hours ago, MortarThePoint said:

@Nickfromwales In the photo layout I've shown the drinking water and garden tap branching off before the PRV. Is that a good idea or not. It has occurred to me that some some kitchen sink taps may have a maximum working pressure that could mean it wants to be downstream of the PRV. A high pressure for the garden tap feels a good idea as it will help with the garden hose etc, but I guess there could be a similar issue there. What would you recommend?

If ‘drinking water’ means you have unregulated cold mains going to one side of a mixing body of the kitchen sink tap? 
 

You need to be specific here as the tap is the crux; you can buy a mixer tap which is good for cold on mains and hot on gravity, where the two waterways are entirely separate until they come out of the spout (typically a coaxial outlet where hot is in the centre and cold is a ring around that). You otherwise will (most likely) have a true mixer body tap, where these meet and mix before entering the spout, with that then being the blended ‘sum’ of x amount of hot and x amount of cold ‘seeing’ each other when the flow is open. 
 

The issue with the latter is that higher pressure cold mains can actually partially push back down the hot line which is called “reverse pressurisation”. That causes EV’s to pop, PRV’s to open and let by (discharge out of tun-dish at D1 off the UVC) and more.

 

So, any mixer body outlets should be fed off a balanced supply, after the control group, so these possible conflicts cannot occur.

 

If it’s a new install this should all be followed religiously, or if it’s a retro fit you can do some ‘work arounds’; for eg you’d fit a single check non return valve on the hot outlet of the UVC (making sure the EV’s are on the protected side, and an additional SC would be put on the kitchen sink hot supply as a failsafe.

 

If it’s just the kitchen cold then err on the side of caution and avoid that being before the control group.  

[MortarThePoint]

1 hour ago, Nickfromwales said:

If ‘drinking water’ means you have unregulated cold mains going to one side of a mixing body of the kitchen sink tap? 
 

You need to be specific here as the tap is the crux; you can buy a mixer tap which is good for cold on mains and hot on gravity, where the two waterways are entirely separate until they come out of the spout (typically a coaxial outlet where hot is in the centre and cold is a ring around that). You otherwise will (most likely) have a true mixer body tap, where these meet and mix before entering the spout, with that then being the blended ‘sum’ of x amount of hot and x amount of cold ‘seeing’ each other when the flow is open. 
 

The issue with the latter is that higher pressure cold mains can actually partially push back down the hot line which is called “reverse pressurisation”. That causes EV’s to pop, PRV’s to open and let by (discharge out of tun-dish at D1 off the UVC) and more.

 

So, any mixer body outlets should be fed off a balanced supply, after the control group, so these possible conflicts cannot occur.

 

If it’s a new install this should all be followed religiously, or if it’s a retro fit you can do some ‘work arounds’; for eg you’d fit a single check non return valve on the hot outlet of the UVC (making sure the EV’s are on the protected side, and an additional SC would be put on the kitchen sink hot supply as a failsafe.

 

If it’s just the kitchen cold then err on the side of caution and avoid that being before the control group.  

 

Thank you, very useful

 

It's a new build. I think my best solution is probably to have a separate dedicated drinking water tap in the kitchen separate from the mixer. The mixer can then be fed by softened balanced hot and cold.

 

That dedicated drinking water tap could then be fed from upstream of the main PRV, but there feels little point since the most that will need to happen is filling a jug which should be quick anyway.

 

That leaves just the garden on unregulated pressure. I checked a Karcher washer manual and they support 12bar max feed pressure. Really it's going to the be garden tap that would be the worry point, but hopefully that is PN16 though I can't see any such markings.

Edited 11 hours ago by MortarThePoint

[JohnMo]

Our incoming main from a borehole pump has a PVR downstream of outside tap take off. This is set to around 2.5 bar.  Now the whole house including the UVC is at that pressure - you can then do what ever want with mixer taps as everything is at the same pressure. The UVC has the normal pressure regulator but it effectively doesn't need to do anything.

[MortarThePoint]

1 hour ago, JohnMo said:

Our incoming main from a borehole pump has a PVR downstream of outside tap take off. This is set to around 2.5 bar.  Now the whole house including the UVC is at that pressure - you can then do what ever want with mixer taps as everything is at the same pressure. The UVC has the normal pressure regulator but it effectively doesn't need to do anything.

I'd love to go the borehole route but the only people I have spoken to suggest it will cost something like £15k which seems crazy. £5k and I'd go for it

[JohnMo]

All depends on depth of water, I was near £5k all in.