I want to install a basic shower by way of bath mixer tap. I don't want a proper shower - I've been quoted about £1000 for the electrical work and that is overkill on a ridiculous scale - so I realise it is a compromise (aka dribble) situation, but I want to buy a mixer set-up that works like a hand held shower but can also fix on the wall above us.

I have got an immersion heater downstairs with a header tank in the loft. The cold runs off mains pressure. I haven't got any sort of pump and I don't know what the hot pressure is or how to measure it. I don't really want to replace any of the pipework if I can help it, I am very stingy and normally buy everthing secondhand and I would rather spend my time gardening than plumming. You can see I am a bath lover myself, but the kids would like a shower, and the WWOOFers, so I would welcome some advice about:

1. The best type of mixer tap set-up to buy (and anything to watch out for);
2. Whether it would make an appreciable difference to have a pump for the hot, and if so what sort of thing I am looking for, and
3. Is there anything else I can do easily/cheaply to make it work better.

Thanks for your help, kindly plummer-types.

Cathy
www.permaculturehouseintotnes.co.uk
Followingthe evolution of a council house on its quest to become a farm

How much plumbing do you feel happy with doing yourself and can you gain easy access to the underside of your existing bath taps?

If you can gain access to the underside of the taps easily enough, then swapping them over for a shower mixer should be pretty straightforward. If the taps are conventional, then just find a mixer tap that will fit the existing hole centres on the bath (they are usually standard, but worth checking). A look around your local DIY store should give you an idea of what's available at a reasonable price. Thermostatic shower mixers are more expensive, but help to control shower temperature more easily, whereas non-thermostatic mixers can be fiddly to set the temperature.

You will need a tap wrench, a special spanner that fits up under the end of the bath to release the nuts that hold the taps in place and the pipe unions under there too. You'll also need new sealing fibre washers for the tap unions, usually they are 22mm pipe fittings.

Turn off the water (including releasing the pressure on the hot system, by opening the taps after turning off) making sure that the boiler and immersion are turned off. With the system drained you can remove the old taps by undoing the pipe unions and pulling the pipes free, making sure not to damage them, just move them to one side (it will be a bit of a faff!).

Next, undo the nuts that physically fasten the taps to the bath. These are usually under the pipe unions. With these removed the taps will come free. Clean up the bath where the taps fit and fit the new mixer tap. Secure the tap with the nuts, then remove the old fibre washers from the pipe unions (if they are still stuck to them, which they normally will be), clean up the sealing faces, fit new fibre washers and refit the pipe unions, making sure that they fit squarely and that the nuts don't get cross threaded (it's fiddly, as you're often working in a restricted area under the end of the bath underside). Tighten the pipe unions securely, but not overly tight - just enough to get a good seal. Turn the water back on, open the taps and let the air bleed out. When water flows cleanly, close the taps and, with a torch, carefully check the underside of the taps for leaks around the pipework. Leave the bath panel off for an hour or two, then double check that the tap unions aren't leaking. If all is well refit the bath panel.

The shower head will need it's bracket fixing to the wall, which will mean drilling through tiles in all probability. Use masking tape to cover the tiles where you need to drill (it helps stop the drill slipping around), use a percussion drill and masonry drill bit to carefully drill through the tiles and into the wall for about 40mm. Before drilling check for hidden pipes and cables with a pipe/cable detector unless you are in no doubt whatsoever that there is nothing in the area. With the shower head bracket holes drilled, fit plastic wall plugs and screw the bracket into place.

That's pretty much all there is to it, but it can be a bit of a fiddly job because of the limited space you have to work in.

Posted By: tonyWith mains cold and gravity hot you will never get a nice shower as the temperature will fluctuate too much for comfort and safety.

If you have a simple (cheap) mixer then you cannot use mains pressure (cold) and gravity fed (hot) together. What happens is that you pump cold back through the hot pipe to the cylinder and up to the header tank. This can become very dangerous.

You will have to fit a new cold feed from the header tank to the bath tap.
This means you will have to blank off the existing mains pressure cold feed near the bath taps.
Plastic pipe (that blue stuff) is alright for this, as are the correct pushfit couplings (I bought 20m of the stuff as it was cheaper than getting the correct length cut, I still have 15m left going begging).

Shall just reiterate, do not combine mains and gravity pressure.

Oddly enough, if you fit electrical gear under the bath and behind a fixed panel, then it is considered outside a wet zone (cant remember the Zone numbers) and may be also be 'minor work' and not covered by the scope of Part P, so depending on the installation may be done by a competent person. I fitted my pumped shower this way (though it is RCDed and Fused correctly as well.

Yes you can get pressure reducers (not the same as flow reducers) and NRV, the trouble is that they reduce the flow to a tiny trickle (a typical British shower). Saves a lot of water, but leaves a lot of soap under the arms. If you like a powerful shower try one on a channel ferry, they can pin you to a wall
I put in a shower to 'save water' (6 quid a tonne here now, but no need to tell you that John). My lodger, who likes her showers can spend 40 minutes, at 11 litre a minute, under it. Think that is the real reason to fit the switch gear outside the bathroom

You can get a reasonable fits-on-the-wall type of thermostatic shower mixer for about £120 or so, and install this above the bath - if you do this, go for one of the types which have separate controls for flow and temperature (others just have one control, and are either "off" or "on full blast" - you only then get to change the temperature.

Spending another £20 to £30 over a no-name thermo-mixer can get you a named brand with a 5 year guarantee - so this may be worth considering.

Unfortunately, the fits-on-the-bath-where-your-current-taps-are type (as opposed to the normal on-the-wall sort) of bath+shower thermo mixers are a bit more of a niche product, and often seem to be twice the price...

Whether you can get away with a £30-or-so manual mixer tap or not depends on your plumbing - or rather you probably can, but it may well be that the extra plumbing necessary to ensure that when someone turns on the cold tap downstairs, whoever is in the shower doesn't get scolded may not make it worthwhile - i.e. no or minimal shared pipework between the shower and other stuff...

Easy to see if this'll be the case with your current plumbing layout - if turning on a tap elsewhere or flushing a loo etc. makes the flow out of the bath taps reduce appreciably then you'd need to be changing around some of the plumbing or just going for a thermostatic type.

In either case, the "aerating" type of shower heads seem like they may be worth a try - from about £25. The Mira and Ecocamel seem to be the main ones. Reviews here:

http://www.daisygreenmagazine.co.uk/reviews/the-eco-camel-shower-head/

Tim.

Thanks. I'm reading through and digesting all this...

Good plan to get a quote from a plumber for fitting it, as if you've not worked under a bath before you will probably find it a frustrating and awkward job to do!

That shower mixer looks to be just the job, but you will need some pipe, fittings etc to couple it up to the pipework under the bath, a suitable shower head, hose and rail or fixings, a shower outlet connector that goes on the wall (if you want a flexible shower hose arrangement) and you'll also need to think about the work needed to make good afterwards. That's a flush fit shower unit, which needs to be recessed into the wall, with the pipe work also recessed into the wall. This will mean a fair bit of disruption, as the tiles will have to come off at the end of the bath, the wall will need to be channelled out and the whole lot re-tiled afterwards.

I had a quote for tiling about a year ago and it came to around £40 per square metre for labour, plus the cost of the tiles. That didn't include making good the wall first.

Google suggests the Trevi boost might be a bit fussy about pipe diameters. Perhaps try and get the fitting instructions before you buy in case you have to re plumb the run from tank to bathroom.

I've emailed the seller to ask if he would scan and send the instructions.

Thanks for this. I've just been talking to my plumber who didn't think they were still made. He put in a few (not Trevi) for customers in the past and they were all dissatisfied with the result. But now he knows they are made by Trevi (who he rates as good quality) he is going to get them to fax him the details and give me a quote. He thinks it might be a problem with the built in one - he says they are designed to be built in to the wall of a shower cubicle not the exterior wall of the house. He thinks I might be better with an external one so I think I won't buy the eBay one - especially if I need the full kit. If they are supplied with them, maybe the £250 trade price includes everything which would be better.

Anyway, thank you all very much for your input. It was exactly what I needed.

Cathy