Pipe Diameter Advice

[shorky]

looking at the times of the postings that some of you have made, do you not need sleep

 

[mysteryman]

A little summary for anyone who may find it helpful: [If you know it all already, please do not reply!]

If it is a separate low head gravity shower, 22mm pipes are likely to be better. 0.2 bar is 2 metres of water above the shower. Everywhere except the UK will be mains fed; they don't use gravity systems, and imported kit is not likely to be happy on tank fed supplies.

If it is a bath shower mixer, it needs to have both supplies at the same pressure, either both tank fed or both mains fed, meaning the hot from a combi or unvented cylinder. If mains fed, you must have double check non-return valves. You cannot and must not supply these from mains cold and tank hot.

As in the case of the resin shower tray, always install to the manufacturer's instructions!

 

[securespark]

looking at the times of the postings that some of you have made, do you not need sleep

Up at 7.30. Lie-in...

Right. So, if I can get a decent flow without the pesky NRV's, fine, but if I need a pump, they need to say in? In which case I can't pull them out first as they may not go back in?

The internal hose dia. looks like 8mm. Better change for 12mm, no?

There is no restrictictor.

Realistically, if removing the NRV's and replacing the hose will not double the dribble, then I may as well leave the mixer valve alone and just fit a pump.

But then the pipework may need rerouting. Surrey flange etc...

And, horror of horrors, I've just looked again at that piccy of the tank. Is it leaking???

 

[sooey]

Yes it is, all the more reason to blank the hole off and relocate it to the correct height.
And is that chipboard which it is supported by? Can't really tell from the pic.
If it is that should be replaced with either close boarding or strong plywood, I don't like the look of that meccano set type frame either.

 

[securespark]

You're doing a good job of cheering me up.

Oh, dear.

 

[sooey]

Is that chipboard, because it's already wet.

 

[doitall]

Is that chipboard, because it's already wet.

It's boards on my computer.

Take the checks out sparky

 

[sooey]

Well if an old b*gger like you can see it and I can't...I'll have to go to specsavers.

 

[doitall]

Well if an old b*gger like you can see it and I can't...I'll have to go to specsavers.

Less of the old, I'm a Senior now.

FinL is 91 and a bit and still drives a car.

 

[shorky]

Ss, take out the check valves as advised, within the valve, there crap, they are needed to comply with water regs but will hinder the flow under gravity, they can be put back if a pumps fitted but i would fit separate ones in the pipework at the pump. That base is well suspect, it looks like fibre board, should be marine ply really, easily replaced so i would do that in the near future. Back to the pressure, you will only now how reasonable it is once you use it, you can do all the calcs you want, nowone knows the restriction through the valve, etc, it might be fine if you lay in the shower tray with the shower head a foot off the floor, as soon as you raise it, it will for sure be worse, i would seriously consider sticking a pump on it and be done with it.

 

[ChrisR]

Contradicting, um, someone, the level of the outlet from the cistern won't affect the pressure/head. That's still going to be what you would measure from the water level.
( Although, yes, instructions always talk about the bottom of the tank)

There's a good chance the leak was started by yer man wiggling the pipes below, so might stop if the nut's nipped up. It is too high though. And it should be WBP ply ( doesn't) need to be Marine, which is silly expensive. Or plain floorboards are OK.

And the NRVs - it's normal not to have any fitted if a pump's used, I can't see right now why there could be a need for them. That could be merlot induced brain fade though.

The internal hose dia. looks like 8mm. Better change for 12mm, no?

That would make more difference than changing those 2 x 15's for 2 x 22s.

Again - call Triton to ask what the differences are between this tesla and one designed primarily for gravity. Trouble is you'll probably only get someone reading the brochure at you of course! The shower head will make a large difference I expect.

It's interesting to measure the flow, then take the shower head off and measure it again, then take the hose off and measure it again, and so on.
But if you've changed from 6l/min to 8 l/min and they both feel "perfectly OK" then it's academic!

 

[shorky]

Hi chris, mi's normally specify nrv's so back syphonage does occur if the head is left in the tray if it fills up, never gonna happen but breaches water regs if not fitted, although being a hippocrit i dont use them on a gravity system, normally put them on the inlets to a shower pump though cos 1 their specified and 2 to stop the pump kicking in if another outlet is opened as it can happen.

 

[ChrisR]

if the head is left in the tray

Oh yeah that - if you don't use the little loop things (which we all do, of course...).

Haven't come across the other problem on a shower, ever, but never say never. Trapped air can cause funny things like that with combis...

 

[sooey]

Contradicting, um, someone, the level of the outlet from the cistern won't affect the pressure/head. That's still going to be what you would measure from the water level.
( Although, yes, instructions always talk about the bottom of the tank)

That would be me.....and dammit, you're right of course. , though it's still wrong for safety reasons.

 

[securespark]

Is that chipboard, because it's already wet.

Will take out the "checks". But the shower install is on hold. The nightmare plumber has gone. We came back on Sunday to find a wet dribble down the moisture-proof plasterboard............

Turned off the gates in the loft (fitted at my request ). Whole thing quaratined.

Now the tank is in question. The boards are actually T & G.

I went to look at the "leak". Gingerly pressing loo roll against the "wet" produces no water on the paper, though in the photo it looks shiny on the tank and the wood. Could it be some kind of compound?

As for the head, it does seem that the higher the shower head, the worse the flow.

You were right, Triton were not a lot of help. 'Cept they recommended fitting a 550i...

Just had someone have a look.

They reckon the pump and fitting will be around £400. BUT, we need a new tank. Not because of the "leak", or the badly-placed pipe (although these would be good to eliminate) but because the tank is too small to feed the shower.

NOW.

Here's a poser.

Just had a word with Aqualisa. They tell me the Midas 300 LP is made to ru on Gravity systems with poor head and turn out double the flow rate of competitor's showers.

They recommend 22mm pipe, reducing down to 15mm (like the piccy I posted). I said the old shower just went straight in with 22. Apparently the old ones did but the new ones are all 15mm now.....


So.

Dilemma time.

I know the pump plus the tank will give an A1 shower. BUT it will cost a packet.

I don't mind at all if the shower is the same as the old one, flow-wise.

Aqualisa thinks the Midas 300 LP will equal the old Aqualisa unit I had for flow. Because it is especially designed for low pressure gravity fed systems.

Do you think Aqualisa can be trusted when they say it would be twice the flow of the Triton I have now?

Thanks.