New Mixer shower install...

I was planning a new complete shower with cubicle but that is going to be one hell of a big job routing the pipes and what not so Have decided to opt for a mixer shower to go where the bath is for the meantime.

My current bath is in a corner, see poor effort of an illustration below



My proposition is to create a stud wall behind the front of the bath where the mixer shower can go, and tile it all up then stick the mixer shower on and this will give me good access round the back to get at the plumbing.

Now my questions are for the plumbing side of things.

Would I be able to run a feed off the bath's hot/cold taps straight to the mixer shower? There are about 3 connections to the main cold and hot pipes from the boiler already i.e. two toilets, second sink...

After having a comi boiler fitted, has left a very poor flow for hot water, the pressure is so bad that I can only turn one tap on at a time.
I'm assuming this will be an issue with a new mixer shower but wondering if i would be able to get away with it as I know many people with combi boilers using mixer showers fine.
What other options are there for me if the pressure is not enough? Pump?

Any tips help and advice would be most appreciated.

Cheers

if its of any use:

our shower is connected the way you suggest (we have a combi)


you cant legaly pump mains water


is there a gate valve / tap in line with the boiler feed? (our has one) is it 100% open

Hmm not sure about the gate valve, where can i find that?

Also I i was thinking of one of these shower pumps, is that not legal?

http://www.screwfix.com/prods/46231...ower-Pumps/Salamander-Shower-Pump-1-5bar-CT50


The only worry I have is that there is one single feed from the boiler to the upstairs bathroom, then off that main feed is a fair few other feeds. I'm just wondering if there is some sort of limit as to how any feeds I can take off that main feed?

our valve is just under he bioler, i am not saying you will have one, but if yoiu habve is it open.

the pump you liked to clearly says "suitable for gravity fed systems" which yours isnt.

I think the pump part has to do with being able to suck water in faster than it can be supplied. but then again i may have that bit wrong.

But there have been mentions on this forum of the possibility of pumping from a hot water cylinder (which you and i dont have) and the pump could in theory empty the tank, so air pressure will literaly cause the tank to colapse.

Best wait for a pro to answer regarding pump.

neds said:

My proposition is to create a stud wall behind the front of the bath where the mixer shower can go, and tile it all up then stick the mixer shower on and this will give me good access round the back to get at the plumbing.

Click to expand...

Nice illustration, and a good idea about the wall.

Would I be able to run a feed off the bath's hot/cold taps straight to the mixer shower? There are about 3 connections to the main cold and hot pipes from the boiler already i.e. two toilets, second sink...

Click to expand...

Yes you can, since you won't be using the shower and running the bath at the same time.

After having a comi boiler fitted, has left a very poor flow for hot water

Click to expand...

In that case you were mis-sold the combi, because they require a good mains flow rate, and you require one powerful enough to heat water at the rate you use it.

the pressure is so bad that I can only turn one tap on at a time.

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That's extremely common for a combi installation, but you should determine your mains water flow rate to see how big a problem you have, before deciding on the solution to that problem.

Please measure the rate at the kitchen cold tap and post your result here.

Please also state the make, model and power output of your combi boiler.

I'm assuming this will be an issue with a new mixer shower but wondering if i would be able to get away with it as I know many people with combi boilers using mixer showers fine.

Click to expand...

You might get away with it, because a shower uses a fairly low flow rate forced through small holes, but success will depend on your mains pressure and the restrictive effect of the combi.

What other options are there for me if the pressure is not enough?

Click to expand...

You could fit an electric shower over your bath. If you get a powerful one (like 10.5kW) and install a dedicated cold feed to it, then you might (depending on various factors) get a better shower than if fed from your combi.

For this you would need a registered electrician to install a new 10mm² (preferably) cable, which would in turn require enough capacity at your consumer unit, and require your existing installation to be safe or to be made safe.

Pump?

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You'd need permission from your water authority, and would be unlikely to get it if your incoming mains flow rate is already poor. And it would be extremely unwise to do it without their permission, because (a) it wouldn't work very well, and (b) you'd create wide-ranging health risks that would expose you to liabilities that could, in extreme circumstances, either bankrupt you or put you in prison.

Any tips help and advice would be most appreciated.

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The best tip is to get better plumbing/heating advice next time you have work done. If you've had a combi installed instead of replacing an existing open-vented boiler, then you now know what that's a bad idea.

breezer said:

if its of any use:

Click to expand...

It isn't.

you cant legaly pump mains water

Click to expand...

A little knowledge is a dangerous thing.

is there a gate valve / tap in line with the boiler feed? (our has one) is it 100% open

Click to expand...

Is there a guide to English grammar on your desk?
Is it 100% open?

breezer said:

our valve is just under he bioler, i am not saying you will have one, but if yoiu habve is it open.

Click to expand...

Masterful use of the language. All hail.

I think the pump part has to do with being able to suck water in faster than it can be supplied. but then again i may have that bit wrong.

Click to expand...

It's a mystery to me why people guess at bits of knowledge. If you don't know, then don't post.

But there have been mentions on this forum of the possibility of pumping from a hot water cylinder (which you and i dont have) and the pump could in theory empty the tank, so air pressure will literaly cause the tank to colapse.

Click to expand...

This is so stupid that I can but assume that you're ill. Please don't post anything else in the plumbing forum until your doctor says that you're well enough to understand that an open-vented cylinder can be emptied of water without it "literally colapsing" (sic.).

softus, the great taker of ****

Hm. The flow rate of p**s on this forum far exceeds my ability to take it.

now that was amusing (almost funny)

You could fit an electric shower over your bath. If you get a powerful one (like 10.5kW) and install a dedicated cold feed to it, then you might (depending on various factors) get a better shower than if fed from your combi.

Click to expand...

Perhaps misleading. The lowers power combis are 24kW, so supply far more than the electric shower. The electric ones feel reasonable because they have shower heads to suit, which means very small holes, so quite fast jets of water.

Measure some flow rates, as Softus says, to get an idea where your problem is, ie if it's more than just a lowish power combi. If you have less than around 18 litres/minute at your kitchen + garden taps combined, (both on at the same time) then your supply is limited.

ChrisR said:

Perhaps misleading. The lowers power combis are 24kW, so supply far more than the electric shower. The electric ones feel reasonable because they have shower heads to suit, which means very small holes, so quite fast jets of water.

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Quite right. Good call.

Thanks for the excellent advice guys, It has answered some of my main questions. I think i may have been exaggerating a bit about the flow but it seems really pap. Also dumb question am I measuring the cold water flow rate as well?

Was thinking about electric shower route and would definitely get a spark to fit the cable in, but was wondering the most simple way for now would be a mixer if I could get away with it. I will get some flow rates and report back.

Cheers

neds said:

Also dumb question am I measuring the cold water flow rate as well?

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A question worth asking.

The cold flow rate is really the only relevant one - if that's OK but the hot not what it should be then you have a boiler problem, not a shower problem.

OK just measured the cold coming out of the kitchen sink and that about ~10Litres/Min. Doesn't sound very good? The hot is about that much too. I remember last time i called the guys who fitted the boiler and told them about the loss of flow they said it was due to the flow from outside and nothing they could do about it.

Combi boiler is a Vaillant ecoTEC plus. Cant find any power figures for it though...

Before the thread dies a death any more feedback?

Cheers