On Dec 21, 11:38*am, Tim Watts wrote:
On 21/12/10 08:22, wrote:



I'm about to go away for a few days, and usually I would switch the
central heating thermostat down to the frost setting.

That of course will be sufficient to ensure that the pipework inside
the house won't freeze, but my feed& *expansion tank is in the loft -
and with the exceptionally cold weather, I could imagine that might
freeze.

My system is a thermal store (i.e. large volume of water), so hot/cold
cycling actually results in a fair bit of movement of the water level
in the f&e tank. I'm guessing that because it's never off for more
than 8 hours on the current timer settings, that any ice "skin" in the
tank gets broken up by the movements in water level.

So I think I'm going to play safe as temperatures are remaining below
freezing for days - and leave the system on its normal settings.

But I'd like to hear - are f&e tanks freezing a real problem?

Are burst pipes elsewhere in the system (due to inadvertently creating
a "sealed system") a possible outcome?

If you are that worried, leave the heating on a normal or slightly
reduced cycle - if it is only a few days.

That's exactly what I have done, although I have a conventional large
cold tank and small CH header tank mounted directly on the floor
joists. I also opened all the bedroom doors so that the heat from the
bedroom radiators should waft up into the loft (left hatch open). I
set the radiators to "medium", so they get fairly warm. And the hot
water in the airing cupboard will also throw off some warm air to
permeate the loft a bit.

I've been leaving the loft hatch open for a few days and placed a
thermometer in the loft. Even when the outside (garden) temperature
was reading -7C the loft measured +2.

I also ripped up some of the loft insulation covering the joists and
placed it around the pipes. The pipes all have the foam rubber tubing
around them, but sinc I was going away I thought an extra bit of
insulation can't do any harm.

But for next year I am deffo going to investigate warming
possibilities, for example greenhouse-type propagation heaters. I'm
also going to get a wireless thermometer to put in the loft that I can
monitor from the comfort of my living room. Thing to do is see what
they do in e.g. Canada and Russia.

Re the light bulb idea, I had also heard of someone using a 100w bulb
suspended from a loft beam to just take the chill off. Presumably this
would be hung within a few inches of the tank or pipework, but I, too,
would be worried about fire risk. In fact, although I had been leaving
the light in the loft on for the past few days (it's only 60w filament
and mounted on a rafter), I debated whether to leave it on while I was
away and in the end just couldn't do it. Let's hope that the CH
doesn't fail! Mind you, the weather appears to be getting slightly
warmer right now anyway. For example, the BBC weather page for
Spalding says the min temps for Wed, Thu, Fri, Sat, Sun are forecasted
to be -1, 0, 0, -2, -1

MM