honey well motorised valve without a manual lever

[Inverness]

As anyone came across a motorised valve without the manual lever? I had one with was a honey well 28 mm the merchant said it's for back boilers and they open up when a power cut has occurred. They are hard wired in.
Can someone explain there purpose and where there location is on a heating system.
Great thanks too you all.

 

[Geyser]

Normally open valves that power close, so in a power cut they will remain open and be safe. Usually ive seen on solid fuel installations.

 

[Best]

They allow gravity circulation on a solid fuel system to a circuit in the event of a power cut to let the excess heat go somewhere. Depends on the design of the system. I will see if I can find an example

 

[Inverness]

Thanks

 

[SimonG]

You will have a power closed, normally open, on your heat leak rads and a power open, normally closed, on your cylinder. Power cut = fails safe.

 

[Inverness]

I don't understand what you mean. The heat leak rad will have the zone valve on it and we'd only open when power cut happens. How does it get warm when there isn't a power cut?

 

[MC_Bob]

If there's a solid fuel stove boiler, it'll carry-on burning etc

 

[snowhead]

Where there's and uncontrollable heat source, solid fuel, the circulating pump will move the heat to Rads or cylinder in normal circumstances.

Control of those circuits (or part of for heat leak)will be with a Normally open, powered closed (no lever to fix it closed) Valve.

To close the valve the thermostat puts power to it unlike a normal valve where it takes the power off.

In the event of a power cut, the valve opens and gravity circulation takes place.
This couldn't happen if the valve was a normal powered open valve.

 

[Inverness]

Can someone show a diagram of location of this type of motorised valve. Chers

 

[SimonG]

I don't understand what you mean. The heat leak rad will have the zone valve on it and we'd only open when power cut happens. How does it get warm when there isn't a power cut?

It opens once cylinder is up to temperature.