September 2008 Temperatures

[Ivan]

This month's been very much below average - my temperatures have been struggling between 40-45C most days this month, with an occasional day below 40. However, sun arrived yesterday and today, and both days saw tank temperatures climb from a starting point of around 40C at both bottom and top of tank to 56C all the way from bottom to top.

[garry]

Hi Ivan,

I commissioned my system last Tuesday and posted a query on the forum regarding the performance I got on that first day (hazy cloud all day, tank base raised from 13 to 29C). Since then the weather has been fine (excepting today) and yesterday the cylinder base temperature peaked at 76C. Unsurprisingly I'm pleased with this, but it is early days yet and it'll be interesting to see how well it does on more mixed days)

Garry.

(30 x 58mm tubes, 210 solar cylinder, 10mm pipe  total run approx 30 metres, panel orientation due south)

[Ivan]

Very impressive! My problem is that I have around 32m total length of pipework but ran it in 15mm (in the early days before I realised the problem with this, but now it's burried under converted attic floor, and can't be bothered to replace it with 10mm). Your 10mm system should work much better in the winter than my system, so hopefully you'll see reasonable winter performance despite the long piperun. Keep posting figures - it's useful to have benchmarks for rubbish days too, although admittedly it's difficult to find the enthusiasm to write 'today I managed 38C'!

I'll be adding another 40tubes to my system on a 1st floor East-facing roof slope in the near future - it's a much easier option. Will post pictures when I get round to installing them.....

[Gixer]

Hi Ivan,

I ran my system in 16mm armaflex at 25m.
I wish I'd used 10mm now. But like yourself, what is done is done...

[garry]

Hi Ivan,

I guess if you are going to increase the panel area then the overall ratio of water volume to capacity will improve considerably.

I know this might sound a crazy idea but many years when putting in a new ch system I considered the possibility of pushing 10mm pipe inside existing 15 mm where it had to pass through a thick stone wall and beams, though as it wasn't my own house I didn't do it. The obvious problem would be the fact that the insulation rating would be compromised by the water having to heat the old pipe as well as the 10mm pipe wall. Still it could avoid too much disruption in places perhaps?

Garry

[Gixer]

On temps, I've manage to heat 550lts in an open tank, ie no insulation on top to 45 deg for the last few days.

The open topped tank is in my basement and any heat loss easily rises up an open stairway to my living room. This has saved us putting the heating on over the last week.

End of the day temps are around 45, morning are around 28, so that makes 10kwh loss overnight.
But it will also loose heat during the day, prob more so as it's hotter.
It seems that it's giving me somewhere around 20Kwh of heating per day which seems a lot.
I must have something wrong in my thought train here, this seems to be too much?

But then our living room (no south facing windows) is a constant 21 deg with no additional heating and it's cold outside !!

[Ivan]

Garry,

Funny enough I had considered exactly the same thing myself. In the end, it's easier to just add some more on the roof of the porch (East-facing) -which will have a very short piperun -  and add these to the existing system

[NickW]

My system is run in 15mm - 16 metres in all. I have just ordered a reel of small bubble wrap which I intend to wrap round the insulated pipework to further reduce heat loss.

With 40 tubes Im getting temperature rises of at least 30 degrees with a few hours of decent sunshine.

[energy]

Not much different down here in Cornwall.  Tank temp reaching around 40 every day. Rarely more this month.

(30 x 58mm tubes, 210 solar cylinder, 15mm pipe  total run approx 10 metres, panel orientation due south)

[kristen]

Ivan, I mentioned this in another thread, dunno if it has any merit.

How about setting a bypass at the tank end so that when your dead-leg cold water arrives a valve opens to bypass the tank, and once temperature > tank then the bypass valve closes.

Also when the panel temperature sensor drops below threshold you carry on pumping as long as the water arriving at the tank is still > tank temperature.

[Gixer]

Best day I've had since I got it going

550lts, 5x20 tube 47mm, open top uninsulated tank 1m2, Start 26, finish so far 47.5 giving 13.5Kwh
Can't complain at that, must get a proper tank !!