Empty house: draining down system and heating advice

Adaline

I'm going away for 10 days in February, and am concerned about leaving the house empty when there might be a spate of cold weather due. I had frozen pipes (but luckily no burst) last year, so am really cautious. I was going to drain down the water system completely (switch of stop !!!! and open taps), and then leave the central heating on the timer to come on for a couple of hours in the morning and evening. It's a condensing boiler, so I know I can leave it on if the water is switched off. But someone mentioned about the radiators, and thought they might run dry with the water turned off. Can anyone advise me on this? Thanks.

keystone

Perhaps you could describe your system in a little more detail. Thanks.

Cheers

Adaline

It's a baxi condensing boiler 100 HE, which does the whole house. Radiators throughout the three floors. Is that enough to go on?

cosworth_monkey

A system boiler is a sealed system and the volume in that system remains the same regardless of whether the mains stop !!!! is open or shut. So radiators running dry will not happen.

If the boiler has a frost stat fitted it will kick in once the desired (or undesired!) temperature is detected.

In response to draining the domestic water (hot and cold water) more information would be handy. Do you have a cold water storage tank in the loft?

Adaline

No, no tank in the loft. After switch off the stop!!!, should I just open the bath and sink taps and flush the loos? How long might it take to drain it down? Thanks for help!

paulsad

Bit of overkill draining the system - just check pipes in exposed cold places ie loft near the tank are nicely lagged and with heating coming on as you've said you should be fine.

cosworth_monkey

So you have a unvented cylinder somewhere in the house?

I'm not so sure why you'd need to drain the domestic water if the heating will be kicking in everyday. Anyway, shut the mains and open the taps. It should only take a few seconds and then you'll have no water (although there will still be water in the pipes) leave the taps open and you'll have no problems.

Adaline

It's because last year the pipes froze when the heating was on, and the house felt quite warm. It was the night it had got down to minus 14, which hopefully it won't again! But even so. I've had several people round to see what happened, but it's strange as all the pipes in the loft are lagged. So it may have been an outside pipe rather than an internal one that froze. Anyway, I'm very nervous about it after that, which is why I want to make sure I've done everything possible!

cosworth_monkey

If you have an outside tap you'll need to isolate that internally and open the outside tap. They are the most likely pipe to freeze and burst.