New bathroom questions

JF77 · 22 Jan 2011

I am putting in a new bathroom and moving things around to get a shower in.
Ive taken out the old suite and are a bit confused from what Ive found.

The cold water to the bath comes from the header tank in the loft, I presume so you can drain it. Does this need to go back in as found or can I re-route this in to a waste pipe?
Second do I need to connect the bath with 22mm pipe or can I feed it off a 15mm supply? the taps are 22mm but I could use a reducer.

Thanks

Jules

TicklyT · 22 Jan 2011

If your hot water system is fed from a gravity tank, feeding the cold from the same tank gives balanced hot and cold pressures at the outlets.

Most shower valves work best with balanced water pressures, but you will need one suitable for the low pressures from a gravity system, or install a pump to boost the pressure. It is usually easier to pump both hot and cold gravity supplies than to pump the hot only to try to match the higher cold mains pressure.

Gravity systems are generally plumbed in 3/4" / 22mm to achieve good flow rates with the limited water pressure available.
Bath fillers with 1/2" / 15mm connections are typically designed for mains pressures. Their performance on a gravity system can leave a lot to be desired.

The pressure range for your chosen brassware is usually on the packaging or in the instructions. The pressure in a gravity system may be as low as 0.1 or 0.2 Bar, but a lot of brassware on the market has a minimum working pressure of 1 Bar

xr4x4 · 22 Jan 2011

JF77 said:
I am putting in a new bathroom and moving things around to get a shower in.
Ive taken out the old suite and are a bit confused from what Ive found.

The cold water to the bath comes from the header tank in the loft, I presume so you can drain it. Does this need to go back in as found or can I re-route this in to a waste pipe?
Second do I need to connect the bath with 22mm pipe or can I feed it off a 15mm supply? the taps are 22mm but I could use a reducer.

Thanks

Jules

i dont understand the first point.

cold water from a cold water storage tank for the bathroom is common, why would this be becasue you can drain it?

what do you re-route into a drain pipe?

gravity fed systems are better off in 22mm pipe, due to better flow.

15mm for sinks and mains water pressure.

JF77 · 22 Jan 2011

when I took the bath out there was still water coming from the cold pipe that was connected to the bath altough the mains was off. I traced the pipe into the attic and to the header tank. on this pipe is a shut off valve. when I closed it the flow into the bath stopped. so I presume this pipe from the tank is so you can drain the header tank if needed. i dont want to use it as the bath is now the other end of the room so I was going to divert it into drain and keep the valve closed.

Looking at some of the some of the pipes under the floor there are a mix of plastic 22 and 15 with reducers so I dont think it really matters which I use on the bath. It is a gravity feed system but there seems to be ample pressure on the hot side.
There is very litle brasswear mainly plastic fittings.

Ta

xr4x4 · 22 Jan 2011

i think im gonna leave well alone, because talking about putting a cold fed pipe in a drain is just madness.

if your not using the pipe, it needs to be sealed with a water tight cap.

Bahco · 22 Jan 2011

JF77 said:
when I took the bath out there was still water coming from the cold pipe that was connected to the bath altough the mains was off.

Your cold water bath tap is being fed from the tank in the loft. Even if the mains is off water will still come out of the pipe until the tank is empty.

How do you propose to feed your tap if you put this your waste?

JF77 · 22 Jan 2011

Its not a cold feed pipe, its from the header tank in the loft.
I can use another feed to connect the bath. I just need to run this pipe to somewhere so if I need to drain the header tank there is an outlet.
Is this pipe from the header tank unusual? because the way its been plumbed in looks like an after thought. I have pipes coming thru the floor with caps on!

I'm not mad I understand the schematics!

GodKnows · 22 Jan 2011

Hi all,

Please read carefully what TicklyT has posted

You obviously don't understand schematics as you haven't grasped the principles between the difference of "Gravity" and "Sealed" systems....

The cold feed from the F & E tank is required with your system, and not "An after-thought!" Suggest you listen/read above a few times, or seek a local competent plumber/RGI who could furnish you with the correct specification and offer you a comprehensive plan for your new bathroom, with prior consultation between you both

Bahco · 22 Jan 2011

JF77 said:
Its not a cold feed pipe, its from the header tank in the loft.

Is it the overflow pipe from the tank that is being (incorrectly)routed to your bath instead of going outside your house as a warning pipe?

JF77 · 23 Jan 2011

No there is an overflow on the header tank which is routed to outside.

what I m trying to say that the cold bath tap is gravity feed from the header tank not from the mains cold water. Is this nomal?
The rest of the bathroom and the rest of the house is fed from the mains.

Bahco · 23 Jan 2011

JF77 said:
the cold bath tap is gravity fed from the header tank not from the mains cold water. Is this nomal?

Can be. You can change it to mains fed if you are handy.

You should cap this feed at the tank so as not to leave a dead leg.

xr4x4 · 23 Jan 2011

xr4x4 said:
cold water from a cold water storage tank for the bathroom is common, why would this be becasue you can drain it?

Nige F · 23 Jan 2011

Just go to BG - they look after your world

and get a brand new combi from them

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