Bath/Shower mixer taps - fitting advice please & are they legal for my setup?

cahjubb

Hi, I was thinking about fitting bath/shower mixer taps in our bathroom (supply = hot water cylinder on landing/cold water tank in loft), and taking the water supply off the tap pipes, as I'm doing our bathroom on a tight budget precluding expensive showers.

However, reading into it, I can see a problem if the cold water is used elsewhere in the house, so presumably I need to take a pipe from the cold water tank direct to the mixer taps?

BUT, reading a DIY book (pub. 1997), it talks of it being illegal to mix low pressure hot water from a cylinder and high pressure water from the rising main due to the chance of contaminated water being drawn back into the mains. (What is the rising main? Water from the cold water tank??)

So - can anyone please tell me how I can get round this? The taps I have my eye on have the BS1010 kitemark - what relevance is this?

Do I bite the bullet and save up for a shower unit?

Oh, and with the water pressure, if I rent/buy a device to check on what pressure I get from the taps, how should I use it correctly??

Many, many thanks if you can shed light on these queries for me, HJ

Canucklehead

Hi

I take it you have mains cold and tank fed hot. The two are at very different pressures so your plan to run a pipe (22mm) from the tank in the roof is the best. The downside is that the pressure for a shower will be quite poor if your bathroom is directly below the tank .
If you used the mains for cold then you would need a double check valve on the cold mains the prevent back flow. It would also push the low pressure hot back making it very difficult to get the water to mix.
BS1010 is the standard for that type of tap ie a low pressure tap with a screw down washer, it also covers stop c*cks , ballvalves etc.
If you want better pressure then an instant electric shower is the way to go.
There are small booster pumps on the market that pump a bath mixer but they involve electrics and IMO are noisy and not much use.

HTH Corgi Guy.

jennifernil

The rising main is the main water pipe into your house that feeds the cold water tank. It is not the pipe from the CW tank.

The best way is to run a new pipe from the CW tank to supply the cold to the shower and take the hot from the HW pipe already running to the bathroom.

However, unless you fit a thermostatically controlled mixer tap, which is quite expensive to buy, any use of hot or cold water elsewhere in the house could easily upset the temperature of the water for the shower.

If you have only one bathroom then this is not so much of a problem, as presumably nobody else will be using it at the same time. A friend of mine had a little sign saying "shower in use" that she placed on the kitchen taps while showering to try to avoid temperature fluctuations!

cajef

cahjubb wrote: »

so presumably I need to take a pipe from the cold water tank direct to the mixer taps?

BUT, reading a DIY book (pub. 1997), it talks of it being illegal to mix low pressure hot water from a cylinder and high pressure water from the rising main due to the chance of contaminated water being drawn back into the mains. (What is the rising main? Water from the cold water tank??)

The rising main is the high pressure water supply coming into your house to the cold water tank, water from this tank is low pressure supply and goes to your hot water cylinder.

The rising main is the pipe that goes to the ball valve in your cold water tank, also some houses depending on the area of the country have all the cold taps and toilets fed from the mains. Others have a low pressure system where the cold taps and toilets are fed from the cold water tank.

You can check by turning the mains stop off, turn your cold taps on if no water flows out of the taps they are fed from the rising main, if you still have water coming out of your cold taps then you are on a low pressure system and you can use a mixer tap/shower in the bath.

If you are on mains pressure cold system, then you will have to run a pipe from the cold water tank to your bath mixer so that the supply to the mixer taps is from the same tank and the pressure will be equal.

cahjubb

Thanks all of you for the info. The cold IS fed from the mains (now I know what that is!), as I turned it off to fit the new kitchen & sink etc last year. Changing the bath tap washers also showed me where to turn off the cold water feed into the hot water tank!
Also, my OH wants an electric shower now instead, as she has the same thoughts as you about water pressure.

A friend is a qualified electrician, so am I right in thinking I need to get him to wire this into the consumer unit instead of a circuit/spur? Our current consumer unit looks to have a trip fuse (RCD?) and 3 other large fuses, which has never been criticised by the annual checks on our home care package, which means I think it's ok. Even so, should I expect to replace this to accommodate the shower, or will it cope? (I'll ask my friend for advice, but want to figure out as much as poss beforehand.)
Thanks again for any advice, HJ

EliteHeat

An instantaneous electric shower will require it's own 45amp supply from the consumer unit.

Another way of doing it would be to install a power shower. This utilises the gravity feeds from the CW cistern and the HWC and simply pumps the water out. The performance will be superior to an electric shower and will not be affected by any other taps running - if installed properly.

Whilst there are of course regs covering the electrical aspects of a power shower, you will not need a dedicated power supply to it.

A decent power shower will give you a flow rate of about 14 litres of water per minute. An electric shower will give a dribble in comparison, especially in the winter.

Canucklehead

Good evening: The Bathroom Manufacturers Association has produced an excellent series of free guide books (downloadable PDFs) .... http://www.bathroom-association.org/training/guides.asp
We recommend the site as a research tool to our customers as the guides provide good explanations of the wide range options for bathrooms/shower rooms.

HTH

Canucklehead

amcluesent

I fitted a shower by running a dedicated cold pipe from the loft tank and dedicated hot pipe from the hot water cylinder - there's a fitting called an 'essex flange' for the tank. That way, peeps running taps elsewhere in the house won't cause sudden temperature changes. Plastic pipe was fine and much easier to work with on DIY. I used an shower with an in-built electric pump as the water pressure from a loft tank was nothing like enough.

cahjubb

More useful info, especially those guides. More food for thought as I look round screwfix and those other online stores. hmmm, more belt-tightening for a power shower but would prevent dribbles in Winter. (How does a shower's L/minute compare to a bath's.) Thanks, HJ.