Unoccupied house - leaving heating/hot water turned on with mains water turned off?

Padkir

Hi - just looking for some advice on this from someone who knows more about it than I do!

We may be leaving our house unoccupied next year - possibly up to 5/6 months, including over the winter. Subject to insurance company being ok with this, it would be my intention to leave the heating coming on once or twice per day/night to ensure the place doesn't go to ruin and hopefully stop any pipes from freezing, but equally I'd like to turn the mains water off in case the worst should happen and at least water damage would be limited to what's in the tank. We have an oil boiler (Warmflow) with standard heating system (cold water tanks in the attic, hot water cylinder, and rads in each room) - house was built in 2006. Due to a quirk (according to my electrician) the central heating can only be switched on when the hot water is on, so we would need to leave both the heating and hot water coming on together during this time. He mentioned some way of fixing this, but it would cost a bit to do and we decided to leave it like that.

From reading up on this across a few old threads and some other forums, my understanding is that the heating system will continue to work even if the mains is turned off, as it shouldn't lose any water unless there are some leaks I'm unaware of. Equally, the hot water cylinder will remain full at all times, even if the tank drains. It would be my intention to have someone call to the house once a month to check up on things, so I could get them to turn on the mains for a while when they are there to re-fill the tank if level has dropped.

I suppose I have two questions:

1) Is my understanding generally correct above, that the heating system can still work away with the mains being turned off?

2) If the worst happened, i.e. there is some leak that I'm unaware of and the water tank was drained before the mains was turned back on, what would happen? Will the boiler just not fire if there isn't enough water in the system, or is there a possibility of it trying to run and potentially causing a fire risk?

Thanks in advance!

Wearb

Most of what you understand is correct. If it runs dry, the high limit thermostat on the boiler should activate and turn off the boiler (this is assuming everything is working ok. ) In your situation, I'd like someone calling once a week, but "needs must". Are you sure that one of the attic tanks is for the heating. If so you could isolate the water supply for a while to see if the level fall significantly. You'll need to do this during the heating season as temperature changes can reveal or conceal leaks.

Your whole assumption is based on not having leaks, so I'd try an make sure of that before going. Give your regular boiler service person a call. They'll know your system and be able to give more accurate advice.

monseiur

There's a holiday home next door to me which I keep an eye on for the owners (they live in USA) It has a similar heating set up to yours, built 2000 and is unoccupied for 11 months of the year. The mains water is always turned off from October to end of March and half the water in the attic storage tank is drained. The expansion tank, the small tank beside to bigger one in the attic, ensures that the heating system has ample supply of water if required say in the unlikely event of an untraceable tiny pinhole leak underfloor etc. A good time clock on your oil fired heating systme is the key, you can set it to kick in for an hour from say 7 pm to 8 and again 1 am to 2 etc. depends on your location, the weather is normally milder by the sea than inland. Leave all doors open to ensure a good air circulation, that includes wardrobes etc. Ensure that all pipes in attic are well insulated and that there is no insulation directly under water storage tank. Empty, clean and unplug fridge, freezer etc. and leave doors open. Ensure that oil tank is full and secure.

Leave key with someone local that you trust.

1874

room & tank thermostats? should save a fortune

Padkir

Thanks all - good tips here!