What does the team reckon about this:
https://ibb.co/XZQ10FQ

I know the conventional wisdom is to leave a patch of ceiling uninsulated
under your cold water tank, but the tank is 3 foot in the air! There's
completely free airflow from the patch of ceiling under the tank to the cold
loft. The site is quite windy so convected heat is unlikely to make it to
the tank.

It appears to have had 1-2cm polystyrene attached to the outside (not sure
if also to the bottom, I forgot to look).

To allow me to insulate underneath while avoiding the risk of freezing the
tank, I suppose the options a

- add a better jacket to the tank
- add a heater on a frost stat inside the tank
- add a heater on a frost stat to the side/bottom of the tank
- something else?

Would tank lagging be sufficient for a tank in a cold loft, without
additional heat flux from the house?

Thanks
Theo

Theo wrote:
What does the team reckon about this:
https://ibb.co/XZQ10FQ

I know the conventional wisdom is to leave a patch of ceiling uninsulated
under your cold water tank, but the tank is 3 foot in the air! There's
completely free airflow from the patch of ceiling under the tank to the cold
loft. The site is quite windy so convected heat is unlikely to make it to
the tank.

It appears to have had 1-2cm polystyrene attached to the outside (not sure
if also to the bottom, I forgot to look).

To allow me to insulate underneath while avoiding the risk of freezing the
tank, I suppose the options a

- add a better jacket to the tank
- add a heater on a frost stat inside the tank
- add a heater on a frost stat to the side/bottom of the tank
- something else?

Would tank lagging be sufficient for a tank in a cold loft, without
additional heat flux from the house?

Thanks
Theo


Could you not box in the area under the tank? Then insulate the sides of
the box (and tank) but leave the base uninsulated.

Tim

--
Please don't feed the trolls

On 30/12/2020 16:11, Tim+ wrote:
Theo wrote:
What does the team reckon about this:
https://ibb.co/XZQ10FQ

I know the conventional wisdom is to leave a patch of ceiling uninsulated
under your cold water tank, but the tank is 3 foot in the air! There's
completely free airflow from the patch of ceiling under the tank to the cold
loft. The site is quite windy so convected heat is unlikely to make it to
the tank.

It appears to have had 1-2cm polystyrene attached to the outside (not sure
if also to the bottom, I forgot to look).

To allow me to insulate underneath while avoiding the risk of freezing the
tank, I suppose the options a

- add a better jacket to the tank
- add a heater on a frost stat inside the tank
- add a heater on a frost stat to the side/bottom of the tank
- something else?

Would tank lagging be sufficient for a tank in a cold loft, without
additional heat flux from the house?

Thanks
Theo


Could you not box in the area under the tank? Then insulate the sides of
the box (and tank) but leave the base uninsulated.

Tim

That's what I would do. You could even make the box from Celotex
extending up the sides.

Could you not box in the area under the tank? Then insulate the sides
of the box (and tank) but leave the base uninsulated.

Tim

That's what I would do. You could even make the box from Celotex
extending up the sides.


That would be so easy to do and very neat.

JohnP wrote:
That would be so easy to do and very neat.

Hmm... an interesting thought.

I hope to in future run some data cables underneath the tank parallel to the
joists (since there's no insulation there at present), but maybe I could add
a drainpipe to run the cables in before I celotex it all up...

Theo

Theo submitted this idea :
Would tank lagging be sufficient for a tank in a cold loft, without
additional heat flux from the house?

It would only be OK, providing a cold spell wasn't too long, plus the
mains flow into the tank was regular.

Insulating will help keep the heat in, but only for a while. I would
suggest nailing carpet around the frame of the support stand and
leaving the area over that ceiling uninsulated.

Another way, would be to add a source of heat to the tank. Can a cheap
test tube type heater, with a built in stat, be set to operate at 5C?

Harry Bloomfield, Esq. wrote:
Insulating will help keep the heat in, but only for a while. I would
suggest nailing carpet around the frame of the support stand and
leaving the area over that ceiling uninsulated.

I doubt carpet would help much, but celotex as suggested would.

Another way, would be to add a source of heat to the tank. Can a cheap
test tube type heater, with a built in stat, be set to operate at 5C?

That was my thought: don't waste heat for the 99% of the time it's not at
risk of freezing - and also avoid transferring heat from the hot loft to the
house on a summer's day.

There are things like this:
https://www.tankblanket.co.uk/why-tankblanket/
but that's for motorhome (12V/8.5A) use. There doesn't seem to be an
equivalent for domestic use that I can find.

I could drop an immersion in, but I can't find a suitable frost stat that
will measure the temperature of the water (not the air temperature).

The only other kind I can find are fish tank heaters, which don't go cold
enough. 'Pond ice heaters' may do but it's not clear they have thermostats,
rather than things you just put in on cold days.

Theo

On 30 Dec 2020 16:08:10 +0000 (GMT), Theo wrote:

I suppose the options a

- add a better jacket to the tank
- add a heater on a frost stat inside the tank
- add a heater on a frost stat to the side/bottom of the tank
- something else?

No.4 Insulate underneath and leave tank as is (I assume it's properly
covered to keep evaporation in summer, in and wildlife, out)

Would tank lagging be sufficient for a tank in a cold loft, without
additional heat flux from the house?

Is the tank freezing going to be a problem? There is little to
constrain the required expansion, it can just expand up the tank.

Our tanks are stood on boards about 18" above the ceiling joists. The
Ceiling is insulated. Not noticed any problems in the "cold" loft.
Remember mains water will still be above 10 C or so even in winter(*)
and there will be some heat coming through the insulation.

We have had a couple of pipe bursts due to freezing. Same pipe, in
the garage with no heat and only when its been down to -10 C ish for
several days.

(*) PL footy grounds use this "warm" mains water to thaw the pitch
surface on days when it's close to or just below freezing.

--
Cheers
Dave.

Dave Liquorice wrote:
No.4 Insulate underneath and leave tank as is (I assume it's properly
covered to keep evaporation in summer, in and wildlife, out)

I think so, but I should check.

Would tank lagging be sufficient for a tank in a cold loft, without
additional heat flux from the house?

Is the tank freezing going to be a problem? There is little to
constrain the required expansion, it can just expand up the tank.

Why is there all this stuff about leaving under the tank uninsulated then?
Or is the concern pipes freezing? (The pipes are all in clip-on lagging
jackets, although not sure how effective those are).

Our tanks are stood on boards about 18" above the ceiling joists. The
Ceiling is insulated. Not noticed any problems in the "cold" loft.
Remember mains water will still be above 10 C or so even in winter(*)
and there will be some heat coming through the insulation.

I suppose the worst case is going away for Christmas when there turns out to
be a cold snap - heating down low and no water drawn from the tank.

As it happens I have one of these (2ft 80W version):
https://www.dimplex.co.uk/product/ec...ter-thermostat
and I suppose I /could/ mount it inside the tank insulation somehow,
controlled by a socket controller:
https://www.amazon.co.uk/KETOTEK-Tem...dp/B085Q2NDP9/
(many others available)

Not entirely convinced that's a good idea (what if the thermostat jams on?)
Feels like heaters next to foam insulation isn't a great plan, although
maybe rockwool would be ok.

Theo

On Thursday, 31 December 2020 at 10:42:38 UTC, Theo wrote:

Not entirely convinced that's a good idea (what if the thermostat jams on?)
Feels like heaters next to foam insulation isn't a great plan, although
maybe rockwool would be ok.

Self-regulating heating cable under pipe insulation should be OK, with a frost
thermostat to activate it when temperature is just above freezing.

John

On 31 Dec 2020 10:42:33 +0000 (GMT), Theo wrote:

Is the tank freezing going to be a problem? There is little to
constrain the required expansion, it can just expand up the tank.

Why is there all this stuff about leaving under the tank uninsulated
then?

Gawd knows, which is partly why I described the tanks here that have
never had a problem even when it has been cold enough to burst a pipe
in the unheated garage.

Or is the concern pipes freezing? (The pipes are all in clip-on lagging
jackets, although not sure how effective those are).

Pipe work is probably more of a problem but again no problem with
insulated pipes freezing in our loft.

I suppose the worst case is going away for Christmas when there turns
out to be a cold snap - heating down low and no water drawn from the
tank.

Heating down low, something that never happens here. Stone walls give
the place massive thermal inertia, let it get cold and it takes days
to warm back up.
--
Cheers
Dave.

John Walliker wrote:
Self-regulating heating cable under pipe insulation should be OK, with a frost
thermostat to activate it when temperature is just above freezing.

I suppose I could wrap some trace heating cable around the tank, under some
(rockwool) insulation. On a score of 1 to terrible, how bad an idea does
this sound?

(is trace heating cable rated for being exposed to moisture?)

Theo