Does a shower need an independent cold water supply?
Discussion
Short version:
Can I tee off the cold water supply to my downstairs bathroom to supply the utility room?
Long version:
Water supply comes in to the house under the kitchen sink. One copper pipe goes in to the concrete kitchen floor and supplies the tank in the loft and the utility room. The copper pipe is now leaking somewhere under the concrete floor (1970s house, copper appears to be embedded direct in to the slab. Neighbour had a similar problem a few years ago).
Option 1 is to dig up the slab and repair the pipe.
Option 2 is to cut off the pipe through the slab, run a new pipe to the header tank in the loft , plus a new supply to the utility room.
The downstairs bathroom is supplied by a pair of 22mm pipes to the bath taps, with 15mm pipes off those to the thermostatic shower valve. The 22mm pipe supplying hot water has a tee off it to supply hot water to the utility room. Can I take a tee off the 22mm cold supply to the utility room too? Utility room has a sink (only used occasionally) and the washing machine.
The photo shows the 22mm supply to the bath taps - RH pipe is the hot water, with a tee off it to supply the utility room. LH pipe is the cold supply. Gash looking 15mm pipe is the other end of the cold water pipe coming under the concrete floor and supplying the utility room. LH 22mm pipe is the cold supply which I could tee off.
If I can't do that then I could run a supply around the top of the wall, but it would be a lot more effort and wouldn't look great.
Can I tee off the cold water supply to my downstairs bathroom to supply the utility room?
Long version:
Water supply comes in to the house under the kitchen sink. One copper pipe goes in to the concrete kitchen floor and supplies the tank in the loft and the utility room. The copper pipe is now leaking somewhere under the concrete floor (1970s house, copper appears to be embedded direct in to the slab. Neighbour had a similar problem a few years ago).
Option 1 is to dig up the slab and repair the pipe.
Option 2 is to cut off the pipe through the slab, run a new pipe to the header tank in the loft , plus a new supply to the utility room.
The downstairs bathroom is supplied by a pair of 22mm pipes to the bath taps, with 15mm pipes off those to the thermostatic shower valve. The 22mm pipe supplying hot water has a tee off it to supply hot water to the utility room. Can I take a tee off the 22mm cold supply to the utility room too? Utility room has a sink (only used occasionally) and the washing machine.
The photo shows the 22mm supply to the bath taps - RH pipe is the hot water, with a tee off it to supply the utility room. LH pipe is the cold supply. Gash looking 15mm pipe is the other end of the cold water pipe coming under the concrete floor and supplying the utility room. LH 22mm pipe is the cold supply which I could tee off.
If I can't do that then I could run a supply around the top of the wall, but it would be a lot more effort and wouldn't look great.
Where does your hot water come from? Vented/gravity fed cylinder, unvented cylinder or combi boiler? My understanding (although I’m not a plumber) is that 22mm pipe in used to aid flow on gravity fed hot water as the pressure is low, and as you’re going to a shower mixer, the cold may be from the cold water header tank to be at a similar pressure and flow to the hot. If that’s the case, I wouldn’t take that cold anywhere near a sink tap.
If the cold is direct from the mains, I don’t see an issue.
Maybe I misunderstand the post question and post title. Just answering the thread title, with a gravity fed hot water supply, if the cold is direct from the mains you can have a notable pressure difference so the cold is fed from the cold header tank, ie the tank that then feeds the hot water cylinder.in effect it is a different supply as the header tank creates a buffer, but can also introduce stuff you don’t want in drinking water.
If that is the setup, you should have mains pressure cold water going to the header tank which you could use.
If the cold is direct from the mains, I don’t see an issue.
Maybe I misunderstand the post question and post title. Just answering the thread title, with a gravity fed hot water supply, if the cold is direct from the mains you can have a notable pressure difference so the cold is fed from the cold header tank, ie the tank that then feeds the hot water cylinder.in effect it is a different supply as the header tank creates a buffer, but can also introduce stuff you don’t want in drinking water.
If that is the setup, you should have mains pressure cold water going to the header tank which you could use.
Gone fishing said:
Where does your hot water come from? Vented/gravity fed cylinder, unvented cylinder or combi boiler? My understanding (although I’m not a plumber) is that 22mm pipe in used to aid flow on gravity fed hot water as the pressure is low, and as you’re going to a shower mixer, the cold may be from the cold water header tank to be at a similar pressure and flow to the hot. If that’s the case, I wouldn’t take that cold anywhere near a sink tap.
If the cold is direct from the mains, I don’t see an issue.
Maybe I misunderstand the post question and post title. Just answering the thread title, with a gravity fed hot water supply, if the cold is direct from the mains you can have a notable pressure difference so the cold is fed from the cold header tank, ie the tank that then feeds the hot water cylinder.in effect it is a different supply as the header tank creates a buffer, but can also introduce stuff you don’t want in drinking water.
If that is the setup, you should have mains pressure cold water going to the header tank which you could use.
The cold supply is from the header tank in the attic. The hot supply is from the hot water tank, which is in turn supplied from the header tank.If the cold is direct from the mains, I don’t see an issue.
Maybe I misunderstand the post question and post title. Just answering the thread title, with a gravity fed hot water supply, if the cold is direct from the mains you can have a notable pressure difference so the cold is fed from the cold header tank, ie the tank that then feeds the hot water cylinder.in effect it is a different supply as the header tank creates a buffer, but can also introduce stuff you don’t want in drinking water.
If that is the setup, you should have mains pressure cold water going to the header tank which you could use.
My question is - is it OK to use the 22mm pipe which supplies cold water to the shower to also supply the utility room? Is there anything in the regs which says that doing that isn't allowed? For reasons unknown the original installer used the hot water supply to the shower as a source for the utility room but used a different source for the cold water supply to the utility. I don't know if that was because it was easier or if there is a regulatory reason for it.
Sounds like the utility room has been plumbed correctly. The hot supply has been used to feed the utility room, but as already been said the cold in the utility will be mains pressure "fresh" water rather than water that has been sitting in the tank in the loft.
Don't use the header tank cold for the utility.
Don't use the header tank cold for the utility.
GasEngineer said:
Sounds like the utility room has been plumbed correctly. The hot supply has been used to feed the utility room, but as already been said the cold in the utility will be mains pressure "fresh" water rather than water that has been sitting in the tank in the loft.
Don't use the header tank cold for the utility.
That's great, thanks for the info. Looks like I will need to replace the underfloor supply then!Don't use the header tank cold for the utility.
this is my username said:
GasEngineer said:
Sounds like the utility room has been plumbed correctly. The hot supply has been used to feed the utility room, but as already been said the cold in the utility will be mains pressure "fresh" water rather than water that has been sitting in the tank in the loft.
Don't use the header tank cold for the utility.
That's great, thanks for the info. Looks like I will need to replace the underfloor supply then!Don't use the header tank cold for the utility.
If there's a sink in there that might be used to supply water for drinking or cooking then the cold should be direct from the mains.
If all you've got in the utility room is appliances and there's no sink in there then it shouldn't matter.
FWIW some people will happily drink water from a bathroom tap that's fed from the cold water tank in the loft. I'm not one of those people.
omniflow said:
FWIW some people will happily drink water from a bathroom tap that's fed from the cold water tank in the loft. I'm not one of those people.
A lot of people who happily drank water from the cold tank in the roof stopped doing so once they found their first dead squirrel or pigeon in there. Still ok for cleaning one's teeth though...
Not sure I'm keen on washing in 'mouse and pigeon soup' either.
The houses I've had with tanks in he loft, I've had to clean out the tanks and fit covers.
A shower mixer has more chance of working well if the cold is at the same pressure as the hot, so feeding it from the tank makes sense.
A 22mm pipe from the tank may fill the bath quicker than the mains via 15mm.
Ideally the rest of the cold system would be direct from the mains.
The houses I've had with tanks in he loft, I've had to clean out the tanks and fit covers.
A shower mixer has more chance of working well if the cold is at the same pressure as the hot, so feeding it from the tank makes sense.
A 22mm pipe from the tank may fill the bath quicker than the mains via 15mm.
Ideally the rest of the cold system would be direct from the mains.
A thought.. if you’re in for big spend digging up floors, maybe invest in going unvented hot water instead, especially if your mains pressure is decent. It’s the best thing we did, gets rid of the cold water header tank, and makes both hot and cold mains pressure (more or less) throughout the house, although it does expose any issues you have on pipework currently fed from the header tanks and any thermostatic mixers may need to be changed. If it’s a small place then a combi would be an option but might need a lot more plumbing changes.
Yes, an unvented system is on the cards if/when we go for a heat pump. If I need to I can run a cold supply without having to dig the floor up.
The good news is that the house insurance company sent a guy out this morning who has fixed the leak - so I can avoid doing anything about it for the time being ......
The good news is that the house insurance company sent a guy out this morning who has fixed the leak - so I can avoid doing anything about it for the time being ......
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