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Author Topic: Home made Thermal store  (Read 17068 times)
Jonah
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« Reply #15 on: September 27, 2011, 09:37:26 PM »

Thanks guys, not a problem renewable j, they've only had orange juice in them....

What do you think of a 22mm coil? And what length do you think is best?
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dhaslam
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« Reply #16 on: September 27, 2011, 10:40:23 PM »

22mm  copper doesn't sound very easy to work with.    Although it would be much more expensive perhaps 22mm flexible stainless steel.   

The calculation of coil length is quite complicated  but the coil does need to be quite long if you want a good watyer flow. 

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3156
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DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
2807
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« Reply #17 on: September 28, 2011, 01:08:34 PM »

Hello Jonah


What do you think of a 22mm coil? And what length do you think is best?

I think 22mm copper is both hard to work with and very expensive.  Which is why I went for the cheap & easy option of 100m of 22mm plastic pipe.  It is relatively cheap - around 42 from memory and has a large volume - over 30 liters - which gets hot whilst the taps are not running & is ready for immediate delivery.

2807
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Jonah
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« Reply #18 on: September 30, 2011, 07:38:32 AM »

The only trouble isthat mine is a heating coil so heat transfer is more of an issue than having 30l of water, I have read some where else that it might be better of using 4 x 10m coils of 10mm pipe then back into manifolds inside the tank so I only have2 x 22mm ports coming out of the tank.
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knighty
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« Reply #19 on: September 30, 2011, 11:05:07 AM »

Jonah, I think it would be easier for you to do it the other way around...

have the ray burn heat the tank water directly

and then use the coil to take heat out of it....  that way it can be plumbed in directly to your heating system so you don;t have to worry about heat/pressure etc.. ?
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Jonah
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« Reply #20 on: September 30, 2011, 11:29:02 AM »

Yes mr knightly thats the way I'm going to do it, what I'm on about above is the others are using dhw coils so 30l of hot water is good for them but my coil will have the radiator water being pumped through it which is why I'm more concerned on the heat transfer, what do you reckon to the 1x22mm coil or 4x10mm coils? Which would you go for?
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dhaslam
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« Reply #21 on: September 30, 2011, 12:03:08 PM »

The four smaller pipes have twice the surface area  for the same volume  of water so they should double the heat gain.    You will need to confine the radiator  take off to the approximately the bottom two thirds of the store  and have a greater proportion  of the  DHW coils in the remaining  part.   

There is still the problem of using  copper pipes in an iron cylinder which I think would corrode the copper pipes.  However inclusion of some zinc might  stop that happening.

http://en.wikipedia.org/wiki/Galvanic_anode
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DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
Jonah
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« Reply #22 on: September 30, 2011, 12:45:00 PM »

Thanks for the info on the zinc I'll look into that.

I'm not planning on taking any hot water off this at all as we have a LPG combi which I'm quite happy with paying for the gas at the moment, so this one is heating only, do you think I should aim to have the coil as high as the water when cold or raise it out of the water slightly so when I gets hot the coil is in the very top? (there isn't an f&e tank on this, it'll just be fill low to allow for expansion with an overflow just in case)
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Jonah
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« Reply #23 on: September 30, 2011, 12:54:17 PM »

Ignore the last bit about height of coil as I think expansion is only about 8L (ish)
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skyewright
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« Reply #24 on: September 30, 2011, 02:36:17 PM »

Probably a bit late to raise this option since a solution has already been found, but has anyone considered or tried one of these DIY tanks:

http://www.builditsolar.com/Projects/SpaceHeating/DHWplusSpace/TankConstruction.htm

i.e. wooden construction with an EDPM liner?

The example on the above page is ~620 litres.

The following example is just short of 1900 litres!

http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/Tank/Construction.htm

That's serious capacity!
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Regards
David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
EccentricAnomaly
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« Reply #25 on: September 30, 2011, 04:00:44 PM »

EPDM (not EDPM, I keep making that mistake, too) like that was my plan A. The tanks would be along the bottom corners of an east-west A-frame - intended to give a large flat fairly-steep south facing surface (see piccy).

However, I'm moving away from the idea. Partly because the outline planning permission for plots I've been looking seem to be really keen on vertical aspects to the windows (hence A-frame not so good) and partly because making a store like this would be a bit intricate and being really really sure it's watertight (and going to stay watertight) would be a bit of a worry.

Current thinking is a more standard house shape with IBCs (about 10, two rows of 5 on top of each other) for the thermal store.


* sketch.png (83.65 KB, 330x213 - viewed 683 times.)
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skyewright
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« Reply #26 on: September 30, 2011, 05:32:30 PM »

EPDM (not EDPM, I keep making that mistake, too)
Thanks for the correction.

Current thinking is a more standard house shape with IBCs (about 10, two rows of 5 on top of each other) for the thermal store.
Insulated IBCs do sound like an interesting option, especially as it's a case of "reuse". The tricky bit would probably be negotiating the carriage terms to these far flung reaches...

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Regards
David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
Jonah
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« Reply #27 on: September 30, 2011, 10:24:33 PM »

Insulated IBCs do sound like an interesting option, especially as it's a case of "reuse". The tricky bit would probably be negotiating the carriage terms to these far flung reaches...


[/quote]

I know, I have bloody loads of them, but they've usually had fibreglass resin in....
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EccentricAnomaly
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« Reply #28 on: October 01, 2011, 01:19:00 PM »

Yes, transport of the things is disproportionately awkward for their weight. I guess the trick is to find a local user of something not too noxious. For a thermal store which is more or less sealed [1] it wouldn't have to be food safe but you wouldn't want weed killer or anything like that in the house. Still, ones which have had resins or oils or something would be OK if cleaned and left to vent any remaining contents for a while.

[1] I have in mind an FE tank in the loft, above the level of the solar tube manifolds. If there's any doubt about the contents of the tanks it could have a sealed lid and a "breather" pipe to outside.
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skyewright
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« Reply #29 on: October 05, 2011, 05:54:44 PM »

Yes, transport of the things is disproportionately awkward for their weight. I guess the trick is to find a local user of something not too noxious. For a thermal store which is more or less sealed [1] it wouldn't have to be food safe but you wouldn't want weed killer or anything like that in the house. Still, ones which have had resins or oils or something would be OK if cleaned and left to vent any remaining contents for a while.
Thinking about this and considering that there don't seen to be many obvious local users of IBCs (except, I wonder if the distillery might...) the thought of fish farms crossed my mind.
We may not have much in the way of factories around here but we do have fish farms & hatcheries. I wonder if they might have the odd redundant, large, liquid holding large container? I've certainly seen trailers full of what look like pallet size plastic 'tanks'. No idea what plastic they would be made of, but perhaps worth investigating?

Just a thought...
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Regards
David
3.91kWp PV  (17 x Moser Baer 230 and Aurora PVI-3.6-OUTD-S-UK), slope 40, WSW, Lat 57 9' (Isle of Skye)
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