Renewable Energy Questions/Discussion > Solar (heating or electric)
New Electric Booster Boiler
rossw:
--- Quote from: oztules on October 27, 2016, 02:05:27 pm ---It's taken 10 years to see you fluff your lines like this.... so I'm gonna make the most of it
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It's a fair cop! Yes, of course I "meant" MJ/H but it's not what I said - well picked :)
--- Quote ---Actually we have propane, (LPG not LNG) here, so really only CO2 and H2O....
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Same here, and probably explains why I see far far less issue than we did at our old place, which had town-gas (LNG). The old pool heater (gas) rusted up in very short order.
--- Quote ---We can thank vultures for this... it was noticed that vultures would circle around areas that had gas leaks
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Well there you go, I've learned something :)
--- Quote ---It is still a big whack of power in a little box... just for a shower......
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Absolutely :)
.............oztules
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rossw:
--- Quote from: DJ on October 27, 2016, 05:53:14 pm ---I'm on the lookout for a 400L unit to convert. With this I would only need to do a fire up every 2-3 days on what we use on average.
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I have two, 2000 litre tanks. They are heated by whatever "available heat" we have. A 60-tube evac tube solar collector feeds directly to one. The generator (complete with exhaust heat recovery) and the 50kW wood-fired boiler both heat both tanks (via heat-exchangers in the bottom).
You'll want to super-insulate your tanks. We seem to lose a fair bit of heat - even if you use almost none, if we don't add heat at all, we only get about 4 days storage of water hot enough for normal domestic use. (I'll just add in here - that we don't actually store any "hot" potable water. Our domestic "hot" water is the domestic "cold" water passed through a copper coil in the top of each storage tank).
DJ:
The tanks I was referring to were actually gas hot water heaters which will already be Insulated... to a point anyway.
I see a gross inefficiency in them being the tube that runs through the centre where the flame/ vent normally is. On my 125 heater, you can feel the thermo siphon effect once the flame is off with the air being drawn through which would be a heat loss. I have read that is significant which I don't doubt for a second and also that the pilot light normally running when they are on gas is a significant amount of energy a day that compensates.
I was thinking I would need some sort of Solenoid operated shutter on the top of the flue for this to seal off the vent and stop/ significantly slow the draft losses.
I did think about insulating regular IBC tanks. Do you think a layer or 2 of house fibreglass roof batts would be sufficient? I guess there is going to be a point where the heat loss happens no matter what you do. The thing would be to get as neat that as cost effectively as possible.
I have been looking at the evacuated tubes as well. Here they are not economical compared to used PV I can backfeed and use a normal cheap heating element but I am interested in them none the less. What I can't seem to find is any sort of specification on their output.
Panels are all rated so I know how much power they produce but I can't seem to find anything that tells me what a Tube does.
All I have found is something that says the output of a 10 tube collector is equal to 648W. this is bugger all and seems to conflict with my other belief from what I have read that these things are super effective at heating water. Is there something else at play here? The same article said a 30 Tube collector had a 2Kw output. Given the cost of that and the cost of even a new installed PV system, there has to be something else or why would you even think of Tubes for water heating?
At least with PV, once the water is up to temp the power can go to other things. With Tubes it just does nothing..... which is something else I can't figure, how does the thing shutdown or stop heating once the water is up to temp or do you get 150o Water at 30PSI in the right conditions?
eraser3000:
The specifications on mine show differently:
Category(Ti-Ta), Clear Day 2000Btu/ft2/day, Mildly Cloudy 1500 Btu/ft2/day, Cloudy Day 1000 Btu/ft2/day
A (-9F) 47,000 36,000 24,000
B (9F) 46,000 34,000 22,000
C (36F) 43,000 31,000 19,000
D (90F) 36,000 25,000 13,000
E (144F) 29,000 18,000 7,000
(Ti) – Temperature Inlet: Refers to temperature of fluid entering manifold.
(Ta) – Temperature Ambient: Refers to the ambient temperature, or the outside air temperature.
(Ti-Ta) – Refers to the inlet fluid temperature subtracted from the outside ambient temperature. For example, if the temperature
entering the manifold is 100F, and the outside air temperature is 80F, the Ti-Ta would be 20F.
http://www.solarpanelsplus.com/pdfs/spec-sheet-spp-30a-revb.pdf
From experience I think that is pretty accurate. I am normally in the D Category. So for me 36K btu each is great. That 10.5 KW. It really starts adding up when you have several in series as you can get huge deltas at fairly substantial flow rates.
eraser3000:
A little more progress.
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