polytank - what's the vent pipe for?

I expect it is meant for the vent pipe from your indirect hot water cylinder, as it is described as a sleeve?

Toby...

aha - that's where overflow from the hot water goes back into the cold tank is it?

that's the one!

Looking at the pictures below, pucture number 18 does support this theory!

I assume the breather one has a mesh or somthign to stop anything but air getting in or out?

if so, this sleeve will then seal around the expantion pipe, so there isnt a hole around it to let dirt in to the tank..

Toby...

It is a warning pipe, which means it needs to be run to somewhere that you can see water coming out of it if the cistern overflows. On domestic size cisterns, the warning pipe usually also doubles as the overflow. On anything above 1000 litres, the overflow will be a separate pipe and may be run straight to a drain. The warning pipe / overflow should have a fine mesh insect screen fitted, which is at least 2.5 times the area of the pipe.

This should also be fitted with a fine mesh insect screen, with an area of not less than 2.5 times that of the hole.

It takes the the expansion pipe from a hot water cylinder. There should be a close-fitting sleeve, again to stop the ingress of insects.

Colin bignell

Not if this is your cold water cistern.

MBQ

it is for cold only so i wont drill a hole or fit the vent pipe 5.

thanks

Where would you put the vent pipe from an indirect hot wather cylinder then?

Toby...

Ah. I was thinking central heating vent pipe.

MBQ

I have bought a polytank

The instructions (7) say to drill the inlet and outlet at opposite sides of the tank to create a circulatory flow of water, but it would be much simpler to put them both at the same side, this would mean less joints and curves in the blue plastic pipe.

What shall I do? opposite holes and a bent pipe, or 2 right angle joints, or holes at the same side?

You could do them both at the same side but extend the actual outlet to the far side internally with a bit of pipe? It wouldn't need to seal well since it's inside the tank, it just has to grab the majority of the incoming water from the far side.

On Fri, 26 Jun 2009 13:49:38 +0100 someone who may be "george (dicegeorge)" wrote this:-

As do the regulations. This is to avoid dead areas of water in the tank, where legionella and other little nasties may rapidly multiply to dangerous concentrations.

I cant imagine how to do this- if I stuck a pipe inside the outlet to extend it wouldnt it cut down the flow significantly?

presumably the circulation is wanted so the water doesnt get stale.. it's used for brushing teeth...

sunny day so i've been up ladders repairing rotten windows, still havnt drilled holes in the tank yet, thinking about it in 'background mode'...

If there are regulations i'd better follow them.

(I didnt find anything about cold water plastic pipe systems or regulations at

Some, yes. You didn't really say what the tank was for - is it the loft header tank for your domestic cold water?

tomorrow it will be for 3 toilets, 4 sinks and a bath but one day I may use it to feed other circuits so as someone's made me paranoid about legionnaire's and regulations I'll put the holes as they say in the instructions and bend the outlet pipe (as it has less pressure)

thanks

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "george (dicegeorge)" saying something like:

Go up a fitting size for the outlet flange, so it will take a pipe being inserted in the tank side, and reduce it back to your normal size on the external side.

You definitely do need to keep the flow up for a bath filler...

Try and avoid right angle bends, use formed bends or gentle curves in polypipe. You lose a *lot* of flow at a right angled bend. (Says he who just replumbed the hot feed in formed 22mm all the way from the cylinder up to the loft and across to the shower just to get enough flow... )

will it be totally within regualtions if i fit an internal pipe like you suggest?

TBH I don't know the regulations well enough - you'll have to wait and see who else answers.

I believe regulations in each area are down to the local Water Board, but there is an overall body called the Water Regulations Advisory Service that aims to keep them consistent.

They say this on their website:

========= Further information on any topic may be obtained from the Water Regulations Advisory Scheme, Fern Close, Pen-y-Fan Industrial Estate, Oakdale, Gwent NP11 3EH. Telephone, 01495 248454. Fax 01495 249234. E- mail: snipped-for-privacy@wras.co.uk =========

So you could always drop them a line?