Can mains stopcock be switched off, leaving combi boiler ON?

[HNev]

My house is unoccupied at the moment during all this frosty weather. I have left the Worcester Greenstar 24i Junior combi boiler switched on using its * 'Frost' setting, and the same on all radiators. As I understand it, this will fire up the boiler when temperature approaches freezing, and prevent damage to the system. However, I am worried about the cold water pipes in the house during the extended hard frosts we are warned are to come.
I would be much happier if the mains water were switched off, but doesn't the Worcester Greenstar 24i Junior need a constant mains water supply?

Thanks to anyone who could suggest the best protective measures.

 

[stem]

The permanent cold supply is for the supply of water that is heated by the boiler to supply hot water to your taps.

The supply that actually feeds your radiators has a manual isolation valve that is always closed anyway. The only time it's opened is when you repressurise the system.

So feel free to turn off your cold water main while you are away.

 

[HNev]

I'm obliged for your advice: I had thought the Worcester Greenstar 24i Junior needed to constantly be 'topping up' with water to replace the puffs of steam it sends out of the flue when the CH is operating.

If anyone could clear up another question regarding the * FROST setting on this combi boiler?
The electronic timer thermostat in the hallway is, of course, permanently on and I've left it at its minimum setting of 7degrees, which is designed to keep the house from freezing, but is this going to be negated by my having left the boiler itself at the * position, and all radiators also at *.

Have I safeguarded the system itself, but left the property vulnerable to burst pipes?

 

[Agile]

The boiler frost stat is only designed to protect the boiler!

Its better to leave the boiler on heating for 24 hrs but with the heating temperature knob on the boiler set at the lowerst point where its is still operating.

That will take the chill of the whole house and usually prevent anything from freezing.

Tony

 

[stem]

I'm obliged for your advice: I had thought the Worcester Greenstar 24i Junior needed to constantly be 'topping up' with water to replace the puffs of steam it sends out of the flue when the CH is operating.

The steam is a by-product of a condensing boiler, produced by moisture laden fumes that have had most of the heat removed. The moisture condenses into vapour, hence the term "condensing boiler".

The water that is used to heat the radiators is a closed system that contains anti-corrosion chemicals, similar to that in a car, the radiator / heater system is filled with antifreeze which is only lost in any quantity if there is a leak.

 

[HNev]

I am grateful for the knowledge passed on so quickly from all of you. This encouraged me to make the journey yesterday, dodging the snow, and found the house chilly at 2 degrees internally prior to the evening's predicted hard frost. I switched the boiler from * FROST to '1' and it fired up immediately, no doubt responding to the 7 degrees minimum on all timing points. I set all the radiators at 4, and switched the water stopcock off completely.
Peace of mind!
Thanks again guys.

 

[Agile]

I'm obliged for your advice: I had thought the car needed to constantly be 'topped up' with water to replace the puffs of steam it sends out of the exaust when its running

The water that is used to heat the car is a closed system that contains anti-corrosion chemicals, similar to that in a house radiator / heater system which is only lost in any quantity if there is a leak.

 

[stem]

Indeed, it seems to work both ways