Can heating be run on timer if water mains turned off?

We will be away for a while shortly and were advised to turn off the mains water supply. My query is can our oil-based central heating system be left to run on a timer (we propose to have the heat come on for an hour or so a couple of times during each 24 hour period)? It was suggested to me that the heating system would need a continuous supply of water. Hope not!

As far as I know, and I am no expert, your central heating system is a closed system. Barring a major leak it should not be a problem. Might be worth getting a plumber to advise.

Yes, you can safely run the heating while the mains is turned off.
Leo

Great - thanks for that, Leo.

Hi - just my opinion, but note that if you have a leak in your heating system, you may cause issues to your boiler, even a small leak over an extended period of time can mean than the level of water drops significantly. If you are confident that you have no leaks, then it will be ok, but if not... Personally, I wouldn't risk it. Are you going away for an extended period of time? Are you expecting freezing weather where the house is situated?

We'll be away for about 6 weeks and if the weather that hit Europe is on the way here, then we could have that blasted white stuff back again in the next month or so.

What model boiler do you have? Most have low water level cut-offs to prevent issued if the water levels drop.

Also, if you have a feed & expansion tank in the attic, this will supply enough water over that period to deal with all but significant leaks.

It's a Grant Module 50/70 - it's out in the back garden. House built 7 years ago, so relatively new.

You could drain the heating system completely and re-fill upon your return. Alternatively, if there is not one already fitted, you could fit a frost thermostat to the boiler. Also wire in a pipe thermostat (set to 30C) fitted to the return pipe in the boiler casing, wired through the frost stat, so when the frost stat turns the boiler on the pipe stat will turn off the boiler when the water temperature in the system returns at 30C. It will prevent the system over-running in very cold weather but still prevent the water in the system from freezing.

Note: If your system is zoned, you must fit an automatic bypass valve in the circuit to prevent the pump pumping against a closed circuit as this will lead to pump failure and/or the boiler going out on the high limit stat which must be re-set manually.