Installing a mixer shower - advice needed!

[DIY_Dean]

Hi

Sorry this post is quite long, but there are a few questions I need answers to!!

- I want to install a mixer shower above my bath (there is no shower there at the moment), but I need some advice on how to do it. I've got a hot water cylinder on the same floor.

My plan - as in the pre-school drawing in this link - is as follows:

Drawing


1. Take feeds off of the copper hot & cold pipes underneath the bath (which currently go to the bath taps) using compression 'T' fittings

2. Connect the bath taps from the 'T' fittings to go to the bath taps.

3. From the free branches on the 'T' fittings, connect longer flex hoses running up behind the wall to the shower valve



Questions:

1. Will this work?? !!!!!
2. My shower hasn't been delivered yet, but do they generally accept tap fittings or does it need to be copper pipe? If the latter, how do I get around this?


Of course, I'm probably barking up the wrong tree completely, so If anyone can suggest 'ANY' viable solution which doesn't involve soldering, please let me know. As I'm a novice (can't you tell !), as much detail as possible would be great!!


Many Thanks in advance

Dean

 

[B&Qsuck]

No No No No, are you planning on using flexi hoses from these new tee's to the shower? that would be some length flexi hose.

I am sure you would get a lovely cold shower if you use this configuration, with very low flow as flexi hoses invariably restrict flow due to smaller bore internals.

The correct way to plumb in a shower, would be a direct feed from the hot water cylinder to the hot connection of the shower via a Surrey flange or similar. Then a direct feed from the cold water tank in the loft to the cold connection on the shower. This can be done with compression fittings if you don't want to solder, but from your post, I am assuming you do not have the skills to do this, so I would highly recommend getting a plumber in, or you will end up with at best a poor performing luke warm shower and at worst getting very wet and costing yourself more getting a professional in to fix your mess

 

[DIY_Dean]

Ok, thanks for the advice - I guess that's what these forums are for - to prevent idiots making a mess!!

Your solution would cause a whole lot of problems for me as alot of floorboards would need to be lifted, etc., to get a feed from the hot tank.

Presumably it would just be alot easier for me to fit an electric shower as the cold water supply is fairly close to the bathroom.

Oh well, worth a try!

 

[B&Qsuck]

Always worth a try, an electric shower does sound your best option, as you say. You will need to get a direct mains connection the an electric shower, rather than from your cold water storage tank. Get a good quality high rated electric shower and you should get a decent flow of hot water this way. Electric is never as good as a mixer shower, but needs must I'm afraid. You will of course need a seperate electrical feed for the shower, which should be installed by a part P qualified person. All these new regulations are a pain, but as you will be mounting an electrical appliance in Zone 1 of your bathroom (i.e. directly above your bath) you really want it done properly, of you may turn your bath into a giant cooking pot.

 

[TicklyT]

Looks like it should work ok IF

1.The existing 22mm feeds are both at the same pressure. Are they fed from the cold water cistern in the loft, and hot water cylinder (which is also fed from the same cistern)?

2. the cold cistern is, say, a metre or so above the position of the shower head when it's in use. if the cold cistern is built into the top of the hot cylinder you are probably on a loser here. Water doesn't run up hill!

3. The valve and shower head you select are suitable for the pressure available. (If your cold cistern is 1 Metre above the shower head the available water pressure will only be 0.1 Bar).

You use 'proper' pipe to the shower valve (plastic or copper - I don't want to start that debate here again) instead of flexis. if it is all gravity fed there may be benefits to using 22mm pipe up to the valve even if the valve connectors are only 15mm.

Remember you may get temperature fluctuations if anyone uses another tap elsewhere in the house while the shower is in use.

Extra flanges on the hot cylinder and new cold feeds etc. would be required, if you want a pumped shower, mainly to protect the pump from damage by drawing in air.

It should be possible to set up a perfectly adequate shower on a gravity system. It won't pin you against the wall with a high-powered jet, but it will certainly get you wet.

It's all down to selecting the right components for the job, not just what 'the sheds' want to try and sell you.

 

[DIY_Dean]

Thanks guys, but I'm confused now!

Is my original plan a complete no-go, or would it do the job if I use 22mm copper pipe & 'speedfit' push-fit 'T' connectors instead of flexi hose?

My reasoning was that you can buy bath taps with the shower attachment built in (you know, the type where you push/pull a button to switch between taps & shower). I thought there would be little difference between that and my plan as surely the pressure would be the same (?). Wouldn't the pressure just be similar to that I get from the taps themselves (which is pretty good)?

My cold tank is in the loft, probably about 1.5 metres above where the shower head would be. The hot comes from a cylinder which is fed by the same tank in the loft, and it doesn't need to be pumped. While I don't need a powerful shower (it's a 'spare' bathroom and won't be used much) I would want one which is ok to use, not just a dribble. The flow from both hot & cold bath taps is pretty good, and I'm not too bothered about any potential temperature fluctuations as no other taps, etc. will be used at the same time.

Here's my amended plan for your consideration/potential ridicule ........

Version 2

Obviously I don't want t spend time & money doing this if it's not going to work, so your help would be much appreicated!

Thanks again

 

[B&Qsuck]

You're right, there is little difference between a bath shower mixer and what you plan, but it is all to do with the height of an outlet in relation to the store of water. i.e. the head.

I am still of the opinion it's not the best set up, but provided you are sure no other outlet will draw hot or cold water while the shower is in use, and you buy a shower valve suitable for low pressure, you will probably get a similar outcome to an electric shower.

There are plenty of valves available suitable from 0.2 bar upwards. Another option would be a venturi shower, like the Trevi boost, which uses the pressure from cold water mains to boost the flow of hot water giving a more powerful shower. This would, of course, need a feed from the cold mains side, and a tee into your bath hot supply.

The trevi boost is a great shower and can be upgraded to a regular thermostatic mixer if you change to a high pressure system in the future.

 

[Zoltan G]

Hi Dean, have you decided whether your plan to run a mixer shower off the bath tap supply is viable? I am considering exactly the same thing - i am a total novice but also can't see how this differs too much from a normal bath tap / shower mixer.

The difference in my gaff is that I have no tanks at all as we had a combi installed fairly recently. But I don't know how to tell how good the pressure is, and I don't know how to make sure the hot and cold water supplies going into the mixer are of similar pressure.

Can anyone tell me if Dean's idea will work on my system?!!!

 

[DIY_Dean]

Zoltan, no I haven't decided. Too many things to consider at the moment!..........

1. Install mixer and run the risk of ending up with a dribbling shower
2. Install electric shower, but no power in bathroom so would need new cabling al the way to the consumer units AND a plumber to take feed from loft

I just don't know what to do! I think I might risk #1 but not sure yet.

I think things might be a bit different for you having a combi boiler, but....hey..... I'm no expert

 

[B&Qsuck]

but also can't see how this differs too much from a normal bath tap / shower mixer

Neither of you seem to understand the principle of gravity fed systems.

In very basic terms, a gravity system relies on the weight of the stored water to "push" the water through the bottom of the store to whatever is calling for water, i.e. a bathroom tap.

If the stored water is nice and high up, with no taps or outlets above it, then you will get flow from the tap. If however the stored water is not so high, and the tap is above the tank, you will get either no flow of very poor flow.

If you try and imagine a bucket with a hose pipe coming out of the bottom... if you point the hose pipe straight down from the bucket, the water will flow fast and empty the bucket. If you point the hose off to the side and about an inch lower than the bucket, the water will flow slower, but still empty the bucket. If you take the hose around the bucket and straight up to above the rim of the bucket, the water will probably not flow at all, depending on certain other factors.

I hope this helps understand why you may not get a good flow from a shower outlet that may be higher or level to the stored water...

Zolten, you have a combi shower, which is completely different, your water is not stored and will be mains pressure, so you could fit a shower valve suitable for a combi without a problem, you should still ensure you don't have too many restrictions in the pipe work, like non-full bore isolating valves. The actual flow you will get from the shower will be dependant on the dhw flow rate of your boiler.[/quote]