On 16 May, 12:42, fred wrote:
In article
,
Bodgit writes

I installed a Pandora heatbank from DPC about 2 years ago. It's always
worked well but I've always been concerned that it seems to leak a lot
of heat, but I've never got round to actually measuring it until now
(had 2 kids in the meantime that took all my time!)

The design code is CPC-150-ABBDA-AAJA-H (150 litre Pandora)
At 10.30pm the temp was 78 deg.C.
At 8.00 am the temp was 64 deg.C.

It was completely powered down overnight, so the loss can not be due
to a dripping tap etc.

I work that out as 8.8KJ over 9.5 hours, so an average heat loss of
about 250W, which seems very high!

I'm wondering if such a high loss could be due to the fittings etc. or
if it's likely that the insulation is compromised.

I emailed DPC a week ago but haven't received a reply as yet.

My 205L cylinder (not heatbank) quotes a loss equivalent to around 132W
so your 250W for a smaller cylinder does sound a bit high but I could
see a lot going through the extra pipework associated with a heatbank.

Are all the pipes around the bank fully insulated? I have 19mm walled
pipe insulation on mine. Cylinder insulation is a fairly basic 35mm.

I don't think it's a major convection loop though, you'd be losing heat
a lot quicker than that.
--
fred
BBC3, ITV2/3/4, channels going to the DOGs

Hi All,

Thanks for the replies - some useful information there.

There are 4 pipes connected to the heatbank: boiler flow & return;
mains cold water in and DHW out. The whole thing is in an airing
cupboard under the stairs on the ground floor. I'm not sure how thick
the insulation is - it's all enclosed in a plastic casing so you can't
actually see the insulation. The surface temperature doesn't feel much
above ambient though. It's sat on a piece of 18mm plywood, on a solid
concrete floor, so there may well be some losses there. I don't
suppose there's much I can do about that though.

The boiler flow & return are insulated inside the cupboard (first 4
feet), but they go through the wall and behind some built-in cupboards
in the bathroom, so they're uninsulated for the next 6 foot or so,
then they're fully insulated in the boiler room. The F&E tank connects
to the pipework in the boiler room, on the other side of a motorised
valve, so I really doubt there's a convection current running - the
pipes in the boiler room are pretty cool anyway.

The heatbank came with a small amount of insulation on some of the
heat exchanger pipework, but there are a fair amounts of elbows &
unions that are uninsulated. I might try Tim's suggestion of
insulation using Celotex - I'll have some left over in the next couple
of months. Thanks for the suggestion.

I'm actually using the airing cupboard to dry clothes with the aid of
a small dehumidifier (I got the idea from this NG), so the leaking
heat is not going entirely to waste!

Thanks again,
Dave.