Shower Cabin - Megaflo - Combi - Need more pressure

[thefishtank]

Hi all,
I've installed a new shower cabin that requires 2 bar min and 5 bar max for supply.
Currently getting about 1.5 bar out of the current system which confusses the hell out of me to be honest !
I've got a fairly large house with a lot of radiators and a huge Megaflo in the basement with a Baxi combi boiler located 2 floors up in the kitchen. I've attached pictures of the Megaflo for ease of description.
I need to get at least 3 bar to the new shower and am wondering how I can do this.
Can I install a twin pump into the system somewhere ?
Do I have to install dedicated hot and cold water tanks in the loft and a twin pump (Stuart Turner) ?

The house is only 4 years old and all the existing pipes are pretty well accessable.
Thansk

 

[scoobydo123]

I'm no expert but have read up on these things and have one (hence the reason for reading up). Pressure is dependant purely on the incoming water mains pressure and flow being suitable. I would imagine you need to get your mains pressure tested. Not sure if you can increase the water presuure by installing a pump on the cold water inlet side of the megaflo. Also it looks like the installation may be a bit suspect, the pipe from the TPRV on the side of the megaflo I believe should not have any bends for at least the first 300mm this is a saftey thing rather than affecting the performance of your system. I am sure someone will be along to help.

 

[thefishtank]

I'm no expert but have read up on these things and have one (hence the reason for reading up). Pressure is dependant purely on the incoming water mains pressure and flow being suitable. I would imagine you need to get your mains pressure tested. Not sure if you can increase the water presuure by installing a pump on the cold water inlet side of the megaflo. Also it looks like the installation may be a bit suspect, the pipe from the TPRV on the side of the megaflo I believe should not have any bends for at least the first 300mm this is a saftey thing rather than affecting the performance of your system. I am sure someone will be along to help.

Many thanks - I'll await "the experts" advice on the configuration.

 

[gavinda]

yes it seems as though your incoming mains is indeed insufficient. as for the safety pipe iirc the 'bend issue' is only relevant 'after' the tundish(airgap) as a bend to soon would cause any sudden discharge water to spray back out of the tundish rather than to outside.

 

[ChrisR]

getting about 1.5 bar out of the current system

WHere/how are you measuring that?
What's your mains pressure (no flow).
Assuming you have more that 3 bar in the street, and that the pressure reducing valve on the inlet group to the Megaflo is working correctly (3 bar), them the air bubble will charge up to 3 bar. When you open the hot tap, you'd get a burst sourced at that pressure. It would drop if the incoming pipes from the road are such that the WORKING pressure at the inlet to the M is less than 3 bar.

It would be worth buying a pressure guage (£4) like this. You can screw it in to the pressure reducing valve/group to see what's going on.
http://www.bes.co.uk/products/graphics/12149.gif

In my experience a shower designed for 2 - 5 bar, needs 5 bar! SOme fittings are amazingly restrictive. Quite often there are tiny non-return valves, which can be removed and larger versions placed in the pipes.

You Could put a break tank and pump somewhere to increase the pressure so the Megaflo isn't starved, but if it were eg in the loft, you'd hear it.
----

The discharge pipe should be metal and not plastic, because the discharge could theoretically be superheated steam. It looks like yours is a washing machine stand pipe. The risk is that it wouldn't stand the heat , and sag, etc.
If it's well supported, I'll leave it to you to judge whether to get round to doing anyting about it...

 

[thefishtank]

getting about 1.5 bar out of the current system

WHere/how are you measuring that?
What's your mains pressure (no flow).

Thanks ChrisR, I was assuming the pressure on the little guage at the bottom of the red tank was indicative of the system pressure ????? But as you can see - I know nothing about these systems !

I guess I can test the mains pressure at the incoming feed from the road by isolating the main stop cock and fitting a guage ?
if I open the two isolating valves in the "filling loop" the pressure in the red tank rises (I've not taken it over 2 bar though as I don't know what it is !)
Is the pressure reducing valve the one with the black body and brass top ? How do I know what it is set to (should it be stamped on the body?) - if it's set lower than 2 bar can I safely raise this pressure to 3 bar ???

Installing a seperate tank in the loft will not be a massive problem due to the shower being 2 floors below the loft, and the floor above the shower is actually the garage .......... garage loft will be the location of the tanks .......... the house is built into a hill and so is a bit of an upside down configuration !
Garage and kitchen on entrance level, then down a floor to master bedroom and living room etc., then down again to some more bedrooms and the Megaflo !
All a bit confusing but I'm hoping something can be done to avoid installing a seperate tank as it would involve lots of pipe routing and thus plastering etc.
Regards,