On Feb 7, 7:23*pm, Fredxx wrote:
On 07/02/2012 12:52, Roger Mills wrote:









I think that most people's response to yesterday's thread about an
external stat to control a pond heater was "I wouldn't start from here!"
- and no-one identified any suitable stats.

I have another application for one - but Google hasn't come up with
anything sensible.

The insurers for my holiday flat are tightening up the cover for damage
due to water escape - and require either that all water is drained when
the flat is unoccupied between November and March, or that the heating
is left on all the time in order to maintain a temperature of at least
13 degrees. We use the flat for about one week in four - even in the
winter - and it would be totally impractical to drain the sealed CH
system and unvented HW cylinder after each period of occupancy. The
heating is controlled by a wireless room stat with a frost setting which
I *could* set to 13 degrees - but that would cost a fortune in gas. [Our
practice so far has been to turn off the water and gas, and to rely on
the fact that the flats below and above are permanently occupied and
heated - thus reducing the risk of out flat getting cold enough for the
pipes to freeze and burst].

If I go down the road of leaving the heating on, I can't see any point
in running it unless it is freezing outside. It seems to me that what I
need is an external thermostat - switching on at (say) 1 degC - wired in
series with the roomstat. It would, of course, need a by-pass switch for
when the flat is occupied - but this could be separate and not part of
the stat itself.

I think that what I actually want is a manual stat with an operating
range of a few degrees either side of zero, and with an external sensor..
[The stat itself doesn't need to be weather-proof as long as the remote
sensor is.]

Any idea where I might find such a beast?

TIA.

1 *Has the flat got any water storage? *If the water to the flat is
turned off after you leave the flat, what's the most damage that could
be done?

2 I presume the boiler has a latching over-temp cut-out and is a sealed
system, such that if there was any water loss, the boiler wouldn't fire
up from *reduced pressure? *So inherently a safe system, or as safe as
can be.

For one year I might be tempted to leave the stat at 13degsC just to see
how much gas is actually used, and keep a log. *Another alternative is
to find another insurer, but the cost of water damage to your flat, and
to ones below would be not inconsiderable, so I don't blame them for
making such stipulations.

Personally I leave my stat at 10degsC.

Are you suggesting it is cheaper to run your heating all day rather
than just in the mornings and evenings?

Jonathan