Strange hot water cylinder!

sillygoose

I have a traditional vented indirect heating system, tank in the loft, copper cylinder in the airing cupboard.

I am removing an old mixer shower which had its own direct hot water feed from part way down the cylinder - obvious enough. But the cold supply to the shower was taken from a 15mm rising supply that - also has a branch off into the cylinder! (via a gate valve)!!!

I though the point of the loft tank was to give the hot water some pressure and it feeds into the bottom of the cylinder as expected.

So why the extra direct mains feed? curiously it doesn't seem to do much on or off! all the taps seem to flow with same pressure but the mains riser is definitely live as I can get mains cold out the shower branch of it.

Its a 15 year'ish old Supercal Herculag cylinder, label is faded but has something about double feed and a big 'power shower from a conventional system'.

I can only think its some attempt to boost hot pressure by combining mains and tank pressure at the same time?? - if so its dud!

1984ReturnsForReal_2

It is so the hot water supply to the shower remains constant if someone uses more hot water elsewhere in the house.

And the cold water pipe you see will not be mains but a gravity feed. (gate valves do not go on mains).


And if you arent keeping the feed from halfway down the cylinder (essex flange) you will have to partially drain the cylinder.

sillygoose

Thanks but its definitely mains, just turned the mains off and its killed it. I don't know why I said gate valve, it is actually just a stopcock looking again :embarasse.

I understand where your thinking :beer:, but if it was tank fed it would only have the same pressure as the main 28mm feed from the loft tank.

- have drained the tank enough to cut and stopend the old hot water outlet

1984ReturnsForReal_2

In that case if you added a pump to the existing hot through the essex you will have a pretty powerful supply.

brig001

Sounds like an early thermal store to me. The mains cold feed to the side of the tank feeds a coil of pipe inside the cylinder. This is heated by the water in the cylinder and comes out as potable hot water at mains pressure. A bit like this http://www.redwoodsolar.co.uk/sidbar%202/thermal_stores.html (picture half way down).
HTH, Brian.

keystone

Does your tank look a bit like this?:



Cheers

keystone

brig001 wrote: »

Sounds like an early thermal store to me.

Mmm - yes - thats possible too. OP lets have a pic if you can. If it is and its 15 years old it will be full of carp. They are not called sludge buckets for nothing.

Cheers

sillygoose

Here she is....

The 22mm running down left goes in the bottom from loft tank. 22mm out top supplies all hot taps. Top right 15mm was hot to mixer shower I just stop ended it. second down 15mm is mystery cold mains feed, also went to shower mixer cold. Under that are the 2 28mm coil ends fed from the boiler via the 3 port. (The electric immersion is just backup)

Very odd the mains feed into it! it did have a label going on about 'power shower from an ordinary system'



I am thinking the stopcock in this mains feed into the cylinder is actually blocked up, if I turn off the gate from the loft tank tap the hot taps dry up - surely if mains pressure cold were being forced into the cylinder it would force water out to the hot taps? - I may replace it tomorrow out of curiosity.

Got a more annoying problem now - I need to drain down the central heating a bit to remove an upstairs radiator - sadly some Muppet (me) had a small radiator in a utility room taken out a couple of years ago with a wall move. doh! it was the low point with the drain off valve right next to an outside door. No other radiators has one. Tricky.

sillygoose

Ah! now I am getting it... the two 15mm are in/out of another coil! to pick up heat from the tank and supply mains pressure hot at balanced pressure to the shower. eureka! - it wasn't a bad shower but it was rubbish for duration, only lasted a few minutes often. I am going for a 10.8kw electric, I know its not anywhere as good as a plumbed shower but at least its there when and as long as you need it.

1984ReturnsForReal_2

sillygoose wrote: »

Ah! now I am getting it... the two 15mm are in/out of another coil! to pick up heat from the tank and supply mains pressure hot at balanced pressure to the shower. eureka! - it wasn't a bad shower but it was rubbish for duration, only lasted a few minutes often. I am going for a 10.8kw electric, I know its not anywhere as good as a plumbed shower but at least its there when and as long as you need it.

You only had a 15mm hot supply. carp.