Shower thoughts

[Multiplex]

I want to install a shower in my bathroom for the first time. An electric shower is sadly out of the question according to my electritian (bad wiring).

We have a slightly unusual system as the cold water tank and the hot water tank are next to each other, as we live in a flat. This means we have almost no pressure at all, but the flow is okay.

Here's my setup:

What's better, a power shower unit or a shower pump? I really really don't want the hassle of installing an essex flange...is it really necessary as nothing else would be using the tank when the shower is running?

Also, I timed my hot water tank as running hot for just 7 mins 20 seconds at around 9 litres per minute. Would that be good enough to install a shower?!

Thanks for any advice.

Simon.

 

[oilman]

What is the detail of the "bad wiring" according to your electrician. I can't see any reason that an electric shower can't be fitted with appropriate changes.

 

[Multiplex]

I'd rather not turn the thread into a discussion of something I can't do, but would prefer to talk about options that are available to me. The CUs are outside...running a cable through down three flats isn't going to happen.

Talk to me about my other options!!

 

[breezer]

i was always under the impression that a power shower gets its pressure from............. a shower pump

 

[Multiplex]

Power showers have a pump built into the shower unit. The alternative is a mixer shower and a seperate pump.

Question for you:

From what I've read, a shower pump will pump upwards something like 40 feet (my understanding anyway). A power shower, which like you I thought was more or less the same thing has a problem:

Why, does there have to be head between the top of the shower and the bottom of the cold water tank??? If the unit is pumped, surely it should overcome the head issues?

As you can see from my setup my cold tank is really low. So it would be great if someone could tell me if a power show unit would work!!

Simon.

 

[breezer]

Why, does there have to be head between the top of the shower and the bottom of the cold water tank???
Simon.

if there was no difference then the cold water would not flow, the greater the difference the higher the "head pressure"

 

[AdamW]

Well, the shower head should be below the bottom of the cold tank. The reason for this is that it means when you open the shower valve (whether you have a separate pump or integrated power shower), water will start to flow out due to gravity. The pump senses this and switches on. If you don't have this "head" that is not the end of the world.

If you have "negative head" then you can get special pumps, some pumps have additional kits for negative head. These (from what I understand) just manually switch the pump on.

1 bar of pressure is equivalent to about 30 feet of head, so a typical 1.5 bar shower pump is equivalent to a 45 foot head.

I prefer separate pumps myself.

1) It means you can have a more aesthetically pleasing shower mixer
2) The pump is located remotely and is thus quieter
3) You can get more powerful pumps than you can integrated power showers.

Your hot water tank stays hot for 7 minutes and 20 seconds at 9l per minute. Well, remember that when you shower the hot water is mixed with cold water at a ratio of between 2:1 and 1:1. So, that 9l of hot water translates into a total shower rate of between 13.5l per minute and 18l per minute. Personally I take forever in the shower (15 minutes is about my minimum, there's a lot to wash - damn you Fray Bentos! ) But if you reckon you can shower in 7 minutes and 20 seconds you should be OK.

 

[ChrisR]

The flow you measured is probably at the bath tap?? It will be much less at a rasied shower head. If you're going to empty the hot quickly, check the CW tanks fills quickly or you'll have annoying behaviour to say the least.

Main problem here is that pumps suck. SO you get air down the hot pipe from its vent over the cold tank. Your cold feed pipe diameter, to the hw cyl, is v important to keep the resistance down.

But Essex flanges help a lot with that and are easy to fit. 5 minutes once you've drained some water from the cylinder. A 22mm one needs a 1 1/2" hole, 15mm 1 5/16" which is harder to get. Put a bit of pipe on the flange bit (as you will connect anyway) before you fit it or you have nothing to hold onto when doing the nuts up.



If neg head is a prob, lowering the shower head will cause a flow which will start a +ve head pump, which will then stay on.

Turn HW stat up to get a longer shower, but not over say 60º or you risk cavitation. We all shower at 38-40 btw.

If you do fit a pump and you get problems, one soluton is to limit the flow to what works - often the only way. Watch the flow rate - an Aquastream will dump 11 or 18l/min, nothing less unless you fiddle with it. They just turn on without testing for flow,- so will work in neg head situations quite well. New Team's "power shower" is probably better suited and miles cheaper. If you don't mind a box on the wall, installation is simpler than a pump though you have to run pipes to the box. Use chrome pipes to be flash git.


Glad the new timer you bought from me works well by the way!