Why don't I have a cylinder stat?

[JayJay1978]

I've just moved house and I'm getting to know my system, I have:

regular boiler

Indirect cylinder

Sealed central heating with external expansion vessel

The cylinder has an imersion heater with integral thermostat but I cant see a strap around cylinder stat?

The cylinder is one of those ones with the tank sitting on top, I think its called a combination cylinder.

So why don't I have a cylinder stat?, When does the boiler know when to stop heating the water?

 

[Kingsway]

You probably on a gravity system

 

[JayJay1978]

Thanks for the reply, I have a pump in the airing cupboard though.?

 

[gas_man_gaz]

doubt it, not on a sealed sys... prob a fully pumped sys withe a single motorised valve for the central heating, could do with some more info tho! what boiler ya got? have ya got any valves? (norm in airing cupboard) if yes how many and how many ports?

if it hasn't a stat on the cylinder the only thing that determines the temp is the boiler stat and the water will be heated up all the time it is set to be on. not very efficient and no longer aloud to be installed that way (if it is)

 

[JohnD]

you may have pounped CH and gravity HW. It used to be quite common but is obsolete now. It is wasteful esp in summer. You could have it upgraded, I would have thought it would cost a few ££hundred.

Post some pics of the pipes around boiler, cylinder and pump and we will probably recognise it.

I am a householder not a pro.

 

[JayJay1978]

There's a 2 port motorised valve in the airing cupboard, pump, expansion vessel, indirect coil in cylinder and an immersion heater which is in the bottom of the tank??

This is what I don't understand as hot water rises?

 

[D_Hailsham]

There's a 2 port motorised valve in the airing cupboard, pump, expansion vessel, indirect coil in cylinder

Which circuit is the valve in - the cylinder or the radiator?

Does the pump serve both radiator and cylinder circuit?

immersion heater which is in the bottom of the tank??

This is what I don't understand as hot water rises?

Correct.

If the immersion was in the top of the tank, it would just heat the water at the top. By having it in the bottom, the heated water rises to the top and all the water in the cylinder gets heated. Cold water enters the cylinder at the bottom and hot water leaves at the top.

 

[petit_pablo]

You dont by chance have a brass 3 port blending valve about 1/2 way up the outside of the tank do you? If so its a thermal store

 

[JayJay1978]

No blending valve.

So since we moved in we've had the heating on and there's been hot water as a result but when summer comes and we don't have the heating on how will the boiler no when to turn on to heat the water in the cylinder if there's no stat?

Also how hot will it be? The boiler is an old Stelrad? or something with a high and low setting but no temp gauge or anything.

What do I have to do to put a cylinder stat on?, As there's no wiring center as such just a 13amp socket where the pump plugs in and the lead from the 2 port MV.

Thanks for the replys so far, I've been viewing this forum for about a year now, but never had to ask anything until we moved here!

 

[D_Hailsham]

Can you post some pics showing the airing cupboard (use the upload photos button at top of page). Also how about more details about the boiler, pump, motorized valve, timer etc?