Cylinder thermostat and valve.

[Matthew]

Hi All,

The new cylinder has arrived and I will be fitting it this weekend. The only problem is that I dont kow how high up on the new cylinder to fit the thermostat!

From top to bottom the height is about 1.2m and

its got a substantial quick recovery coil.

Im going to refit the existing British Gas thermostat so wanted to know where to put it.

BTW Ive noticed on the boiler return from the cylinder (next to the cylinder) is a 22mm gate valve. At the moment this is fully open. Is this needed for anything particular?

Thanks, Matthew

[EricP]

Don't know anything about the cylinder but if you do need a valve on it, dump the gate valve. They are total crap and will seize up after a short time and need replacing. (Always in the emregency you need them).

Replace it with a full bore guarter turn lever valve.

[HLAH]

I fitted ours at a height halfway between the flow and return for the coil. It was specified thus on either the cylinder or thermostat instructions.

H

[David Hansen]

On 5 Dec 2006 04:22:24 -0800 someone who may be "Matthew" wrote this:-

Half to two thirds of the way down. The best position depends on your particular circumstances.

[David Hansen]

On Tue, 05 Dec 2006 12:31:23 GMT someone who may be EricP wrote this:-

Will they? Provided such valves are maintained properly (fully open and close them, leave them a quarter turn instead of fully open) they remain workable for decades.

[Roger Mills]

The stat needs to be lowish - mine is about 1/3 of the way up from the bottom - otherwise it will turn off too soon while the water in the lower part of the cylinder is still cool. [Convection will ensure that there's a temperature gradient from top to bottom].

The gate valve was probably for balancing - to stop the HW from hogging all the boiler flow when HW and CH are on at the same time. With a fast recovery cylinder, this isn't really an issue - it doesn't matter if the CH is reduced for a few minutes while the HW heats up. Better still use independent timers on HW and CH and try to contrive that they are mormally

*not* both demanding heat at the same time.

[Matthew]

I guessed the valve may be something to do with balancing.

Our surrent system is a Y plan with a 3 way valve. I have often wondered whether there is a mid posn i.e. CH and HW at the same time.

Presumably you could have a situ in which the CH switches to HW if there isnt any and your piping hot CH water would then be coming out ofyour cylinder boiler return cold again which presumably is ok? I think Im rambling but you know what I mean hopefully.

We just have our HW and CH coming on at the same time although they can be called individually. What is the best and most efficient way to configure it?

Thanks, Matthew

[EricP]

Not in my experience. They are utter crap and to be avoided at all costs, particularly when more efficient alternatives are available at same cost.

[Roger Mills]

If it's Y-Plan, there *is* a mid position. The alternative is W-Plan, which uses a diverter valve which gives either HW or CH but not both together.

Sorry, you've lost me!

Do whatever works for your lifestyle. My HW is timed to come on an hour or so ahead of the CH each morning - so the tank is hot before the CH starts, and they are rarely both on together.

[David Hansen]

On Tue, 05 Dec 2006 18:18:48 GMT someone who may be EricP wrote this:-

That perhaps tells us something about your experience. However, others have such valves which were installed nearly two decades ago and which work fine.

[Matthew]

[EricP]

LOL

My experience with gate valves would be considerably greater than yours, you can trust me on that point. But I doubt you will because you always seem to have a deep rooted need for The Last Word. Feel free. :))

Of course they do. :))

[David Hansen]

On Wed, 06 Dec 2006 13:40:11 GMT someone who may be EricP wrote this:-

I prefer to make up my own mind thank you.

[Ed Sirett]

A key aspect is that gate valve should only be installed in a vertical section of pipe so that debris cannot collect in the gate-way.

[manatbandq]

Three decades+ in my case.