Unvented system wiring help

[Leesparkykent]

Lol if it's not connected to a boiler then why have a two port valve? The Plumber can't have his G3 ticket as he has the very basic principals of how the system works wrong.

 

[Taylortwocities]

So, its a direct system with the ONLY source for heating the vessel is from the immersion???

Hi you normally have the overheat stat and the standard stat in series as an extra safety precaution.

Not just normally, this is an absolute requirement. The overheat cylinder control MUST be wired in series with the heat source (the immersion).
They are the things that stop the vessel boiling and squirting super-heated water over everybody should the immersion's temperature controls fail.

Installation of unvented heated water vessels is notifiable to the local authority and you need a G3 qualification to do it.

you need to get someone in who knows what they are doing.

EDIT:
Extract from guidance
The Local Authority Building Control must be notified of the installation of an unvented hot water storage system as they are subject to the legal requirements of Building Regulation G3. The system must be installed by a ‘competent person’ who holds the relevant qualification for the installation of unvented hot water cylinders. The installer must be able to provide a card issued by a body such as the Institute of Plumbing (IoP) or the Construction Industry Training Board (CITB).

 

[Taylortwocities]

So, its a direct system with the ONLY source for heating the vessel is from the immersion???

Hi you normally have the overheat stat and the standard stat in series as an extra safety precaution.

Not just normally, this is an absolute requirement. The overheat cylinder control MUST be wired in series with the heat source (the immersion).
They are the things that stop the vessel boiling and squirting super-heated water over everybody should the immersion's temperature controls fail.

Installation of unvented heated water vessels is notifiable to the local authority and you need a G3 qualification to do it.

you need to get someone in who knows what they are doing.

EDIT:
Extract from guidance
The Local Authority Building Control must be notified of the installation of an unvented hot water storage system as they are subject to the legal requirements of Building Regulation G3. The system must be installed by a ‘competent person’ who holds the relevant qualification for the installation of unvented hot water cylinders. The installer must be able to provide a card issued by a body such as the Institute of Plumbing (IoP) or the Construction Industry Training Board (CITB).

 

[andyb]

Looking at the 2nd picture it would seem that it's plumbed as indirect. The valve is on the flow. You need to wire the tank stat to controll the valve. The immersion will just be a back up and not the primary heating source.

 

[buzzlightyear]

that boys is pullin evolution cylinder .Pullin Evolution Unvented Cylinders - http://www.evolutioncylinders.co.uk/
indirect model he has. I think looking at his pics.

 

[davesparks]

Hi, this system is not connected to the boiler, it's stand alone hot water, does that not make it a direct system as the water is heated directly by the source ( element).

If it's not connected to the boiler then why does it have a flow and return pipe connected to it, and a two port valve?

That is an indirect cylinder, not a direct one.

 

[davesparks]

Every unvented has a 2 port, fail safe / safety device

Only indirect cylinders do. There is nothing for a valve to operate on in a direct system.

The safety cutout on a direct system is incorporated in the immersion heater thermostat.

 

[Sparkgap]

Every unvented has a 2 port, fail safe / safety device

All unvented cylinders have mechanically operated temperature/pressure relief valves. I have also seen more recently cylinders with two-port motorised valves on the hot water outlet with an over temp thermostat which shuts it if the water gets too hot. This is because even if the overtemp cutout on the immersion heater works you still have a cylinder full of too-hot water.

 

[Toneyz]

Reading this post has not answered the OP question.
These unvented cylinders should have immersion heaters with H/L stat built in.
How is the domestic hot water being heated the impression I get is direct from the immersion heater in which case as Davesparks posted the pump is secondary hot water pump via time clock which makes sense. What is the valve for ?.

 

[davesparks]

Reading this post has not answered the OP question.
These unvented cylinders should have immersion heaters with H/L stat built in.
How is the domestic hot water being heated the impression I get is direct from the immersion heater in which case as Davesparks posted the pump is secondary hot water pump via time clock which makes sense. What is the valve for ?.

That is an indirect cylinder, the motorised valve is on the flow connection.
The yellow pump is a secondary pump,