Mains water pipe size and taps fed from tank or mains

[onabudget]

All the plumbing is stripped out of my house and I'm having the following fitted (I'm not doing any of the gas work)

Three bed terrace 1920's with bathroom downstairs and an onsuite upstairs, both showers are standard fed from cylinder but being replaced.

The mains into the house is approx 22mm plastic which is currenty going to 15mm copper.

Planning to fit a heat only worchester bosch 12ri or 14ri mated to a hot water cylinder with a cold tank in the loft and header tank for rads. Not doing a sealed system on the advice on the site from miketheboilerman and a corgi engineer. I want a simple system that won't need topping up and will allow both showers to work at the same time (i.e. not a combi), so opting for open vented and will make sure all tanks well insulated.

Can you advise on where I should take the cold feed for the taps (on suite/bath downstairs, kitchen and the two toilets) and washing machine. And also is there any advantage to running 22mm cold from the inlet or is 15mm fine.

The options I have are run the cold for all items from the cold water tank in the loft or run everything from the mains feed except for the cold tank which will then only feed the hot water cylinder. And should I leave as 15mm or use 22mm as far as possible).

The sort of concerns I have re using the mains for the cold are getting the showers balanced but maybe I should not worry about this any comments?

thanks

 

[TicklyT]

Your kitchen tap should be supplied direct from the mains, as should any other potable supplies. Supplies from the cold storage tank are not considered drinking water.

For showers, balanced hot and cold pressures usually gives the most predictable performance.

WCs, washing machines etc can usually handle either mains or gravity supplies. Some WC float valves are happier supplied at mains pressure, and others are just noisier at mains pressures.

So, ideally, you end up with three supplies, Gravity hot and cold supplies, and potable mains water.

 

[jono_h]

I'd go for the same as Tickly, but if you're putting a bath in and can't feed it with 22mm from the tank, it might be worth using mains cold for a faster fill.

 

[onabudget]

thanks I understand that,

So where I have a wash basin I'll run mains 15mm for the cold and hot from the cylinder, and where I have a shower I'll run from the cylinder and cold from the tank to give an equal presssure.

Is there any advantage to trying to get 22mm hot to the showers and the bath tap as well as 22mm cold from the tank or shall I make do with 15mm. I'm at the stage where it's possible but I don't want to cause problems by not having too large a pipe and reducing pressure.

It looks like most bath taps take 22mm but most showers take 15mm.

Also what should the washing machine feed be (tank or mains), I'm thinking it may get a faster fill with mains?

thanks very much

 

[JohnD]

I'd go for the same as Tickly, but if you're putting a bath in and can't feed it with 22mm from the tank, it might be worth using mains cold for a faster fill.

only if you like having cold baths. it will also be unsuitable for a shower mixer.
22mm tank cold and hot will fill it fast enough. You might consider plastic pipe if the pipe route is tricky.

So where I have a wash basin I'll run mains 15mm for the cold and hot from the cylinder,

which will be unsuitable for a mixer tap. If it is in the bathroom you will have a tank cold supply for the shower and bath, so you may as well use it for the basin and WC cistern (which will be quieter) too

Also what should the washing machine feed be (tank or mains), I'm thinking it may get a faster fill with mains?

your washing machine is probably in or close to the kitchen, where you have the mains cold tap for drinking. this will also be fine for the washer and dishwasher.