We have a mid-terraced house that's going to be stood empty for a few
months. It's suffered a bit from dampness in the past so I think we
should keep the heating on to some degree now that we're coming into
the colder months, but what's the best way of doing it? An hour in the
morning, an hour at night? Programmer/thermostat set to 'off' all day
but rely on a minimum temp to switch it on if necessary? And if that's
the best, what values for min/max (I think it's currently set for a min
of 11C and a max of 12C). Or some other method entirely?
I would suggest setting the thermostat for 5C, to prevent pipes
freezing and run continuously. If there is damp, I would consider
installing a dehumidifier, with a built in humidistat and a permanent
Sounds good to me. You could leave the loft hatch open if there are any
concerns about water in the loft. Perhaps turn off the water stop tap.
Could perhaps go a couple of degrees cooler if you are confident about
the thermostat. Sufficiently modern boilers tend to have their own frost
When we left my M-I-L's house empty while we sold it, the insurers wanted
the loft hatch left open and the heating left on. Good luck with that. There
We also switched off the water and drained down the plumbing.
Today is Boomtime, the 5th day of The Aftermath in the YOLD 3182
Most dehumidifiers come with a tube that can be fixed for a permanent
drain, however as the house will not be used you could sit it next to
the sink on the worksurface and just let the tube run in to the sink.
You really do need to read the small print of the policy very carefully
or you could find that when you make a claim they will not pay out if
the property was unoccupied for more than some number of days. I have
seen policies that specify 15C minimum or services all turned off and
everything drained down. You pays your money and takes your choice.
If it is unoccupied then the best strategy might well be to have the
heating come on in the middle of the night to help counteract the
coldest external temperatures around 4am and again in the early evening.
During daytime the feeble sun will provide some input.
You could probably safely set the max to 9C and leave a couple of
degrees above the frost stat which should be checked at 5C. I'm a bit
nervous of going too low since it will be the very coldest spot(s) in
the house that might freeze if you cut it too fine.
Your insurance policy may specify other limits whilst unoccupied or
require a full drain down for winter.
You might want to check the pipe and tank insulation in the loft. Make
sure there is no bare metal for drafts to play upon.
I saw the result of one of the severe winters on an unoccupied flat once
- spectacular flood when the outer door failed. Not good!!
Agreed. 9 or 10 deg is needed. 5 deg is no use for an internal frost
The pipes that froze at a house I worked at few years ago were the
pipes behind the kitchen cupboards that ran against an extarnal wal
(no cavity wall)l. Leaving the kitchen cupboards open may have saved
this from happening. Turning the stop tap off you have saved a lot of
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Thanks folks. Just FYI, there are no tanks or pipes in the loft at all.
I like Martin Brown's idea of having the heating coming on during the
night when it's coldest - seems so logical but I would never have
thought of it :')
The insurance policy for my holiday flat had used to have a clause
requiring a temperature of at least 13C to be maintained when the flat
was unoccupied during the winter months - otherwise there was no cover
for frozen/burst pipes.
I figured that this was going to cost me a fortune in gas. My solution
I duly switched my progammable thermostat to frost stat mode set at 13C
- but I wired it in series with an external stat set at about 2C. I
couldn't see how it was going to freeze *inside* unless it was freezing
*outside*. that meant that the heating maintained the internal
temperature at 13C, as required - but *only* when there was a danger of
The insurance company has subsequently relaxed the rules, and now just
requires the water to be turned off in order to limit the effect of any
I've had to do this with a few houses over the years, waiting for
probate, and in my case back when I worked for a company which liked
to send me away for weeks at a time in the early 2000's.
Leave the heating on all the time, but adjust the temperature setting
Insurance may dictate a minimum temperature, below which you are not
covered for burst pipes or consequential damage.
Otherwise, it depends on the house. A modern house will probably cope
with running at something like 8C, which should stop corners dropping
below freezing. For an older house, you may need to keep it warmer to
keep damp out - I had to go up to 12C to stop it smelling damp.
Note that ths stat is probably in the middle of a main room, but you
need to prevent obscure corners with pipework going below freezing,
so setting the stat too low will not provide protection where it's
Some other comments:
If there are water pipes/tanks in the loft, leave the loft hatch open
so some heat will get up there. If this is long term, might want to
make up a ventilated grille to go in place of the hatch so bats,
birds, etc can't come through.
If you have cupboards against outside walls with pipes in them, leave
the cupboard doors open so the warmth gets in and they don't form a
frozen cold spot.
Turn the water main off (preferably in the street), so that if there
is a leak, the volume of water which leaks is limited to what's
stored in the house. (This does raise an issue of what happens if
all the water leaks out of the radiator circuit and the boiler tries
to fire up - depends on the boiler.)
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Last winter I left a property at 7 deg for 3 months and it did suffer a
bit from damp. This winter I plan to use a higher temperature. There
are pipes but no tanks in the attic. The property is in an area where it
is unlikely to freeze. The insurance does specify 15 deg but with the
water turned off my hope is that any damage would not be to much.
At another property which has tanks in the attic and is in an area where
it freezes, I have a thermostat in the attic set to about 1 deg.
When we go away for a couple of weeks I leave the attic door open and
rely on this frost stat. I have found that on cold nights this stat
will trigger even when the property is being lived in with the heating on.
I have remote control of both heating systems and can monitor
temperatures via the Internet.
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