Heatbank F&E tank - pipe sizes?

[Tim S]

Hi,

Just buying the fittings for the F&E tank for a 250l DIY heatbank.

Any reason to take 22mm for the fill and vent/expansion connections? Most smaller F&E tanks I've seen have had 15mm for both.

The only think I can see is air might clear better with a 22mm expansion pipe. On the fill pipe, though I have mental water pressure on the mains, I doubt a standard ballcock could much exceed the capacity of a 15mm fill pipe.

Any thoughts gratefully received before I hit Toolstation...

Ta

Tim

[Tim S]

Tim S coughed up some electrons that declared:

I'll quickly add of course, that the expansion connection will overhang the tank in the time honoured fashion, not use a tank connector - but killing birds etc...

[YAPH]

I think the general rule is 15mm feed, 22mm vent.

[Tim S]

YAPH coughed up some electrons that declared:

Thanks for the confirmation John. I'll do exactly that...

Cheers

Tim

[David Hansen]

On Wed, 03 Jun 2009 22:18:19 +0100 someone who may be Tim S wrote this:-

One pipe, generally 15mm, allows water to flow into the system and also allows water to expand back into the tank. After the system has been filled water flows up and down this pipe as the water in the heatbank expands and contracts. This is the feed and expansion pipe.

The other pipe, 22mm, allows air and water to escape from the pipework during filling and afterwards. If water flows over the top of this pipe [1] then the system is designed or installed wrongly. This is the vent pipe.

Those pipe sizes are house and other small building ones.

[1] during filling a large air bubble may force water over the top.

[Tim S]

David Hansen coughed up some electrons that declared:

Thanks David. Have ordered parts...

Now for the joy of hole drilling a GRP tank :-ooo

Cheers

Tim

[John Rumm]

I think the logic of using 22mm for the vent is to make it much harder for this to get blocked by scale or other obstructions...

[Tim S]

John Rumm coughed up some electrons that declared:

Good point - hadn't thought of that...