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Author Topic: Green house heating  (Read 703 times)
billi
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« on: December 26, 2018, 12:26:46 PM »

Hi there , just visiting my folks in south germany and the garden I build with dad this spring , its the warmest area in germany , but ocassionally it gets to minus 10  degrees  now letuce spinach etc still grows and basically  need perhaps 7 nights per month  a small heating idea ,   at the momant  4  candles during the night  seem to make a diffrence  , no idea how much watt a bigger tealight gives , but I asume  about 100 watt to 200 would be sufficient , under ground half in the greenhouse  there is a 5000 l rainwater tank , so maybe that could be utilized as a heat store during sunny days in winter to store  heat  as a buffer  ...  sure a battery maybe and a el heater ....   anyway ,maybe someone has an idea  , would be good to find a renewable idea....   thats how it looks now




« Last Edit: December 26, 2018, 12:40:21 PM by billi » Logged

1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
Countrypaul
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« Reply #1 on: December 26, 2018, 01:49:23 PM »

Can we assume the water in the tank is at about 10C (if you are using it as a heat store it maybe higher of course)?

1g of water requires 4.2J to raise it 1C, or gives out 4.2J per 1C drop in temperature. For 100W you therefore need about 25g with a 1C drop per second. Converting to Kg and hrs, suggests 100Kg per hour losing 1C. In practice it will depend on how large your heat emitter is as to what the temp drop might be, but if you just used some copper pipe around the greenhouse that might be sufficient to both emit enough heat and to spread it around (several small pipes in parallel?). A pump to do that should be fairly small and run off a battery quite easily (which you would charge with a PV panel of course). You do not say if mains power is available, but if it is then the battery could be charged/pump run off mains in the few occasions when it is both too cold and too miserable to get anything out of the PV. Otherwise you might be lugging a battery back from the greenhouse to the main house to charge it occasionally.
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billi
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« Reply #2 on: December 26, 2018, 02:33:15 PM »

Thanks paul ,  I guess I  should measure the water temperature  , kind of makes sense  if  its warm enough to use that underground tank as a heatstore  its minus 2  ,,now outside and in the greenhouse its  plus 3 now .... amd when sun comes out it heats up  that one might be able to circulate that heat back into the ground  ....
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1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
knighty
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« Reply #3 on: December 26, 2018, 06:18:40 PM »

I can;t find it now but I watched a youtube video where they were growing veg year round in greenhouses somewhere in american... where it was too cold to normally grow most  of the time

the had a fan and a coil of pipe underground under the greenhous... they blew air through the pipe and it was enough to keep it warm year round


the underground water tank might well harvest enough heat for you... you just need to pump it around something to warm the air up a bit... some kind of little radiator and fan


if the water did start to cool too much you could leave it going 24/7 so the greenhouse heated the water a bit during the day?
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stannn
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« Reply #4 on: December 26, 2018, 08:04:31 PM »

That could be this video from Nebraska.
https://www.chonday.com/30978/nebaoran6/
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« Reply #5 on: December 26, 2018, 10:14:03 PM »

http://www.greenhousegarden.com/thermal-massheat-storage

I'm just away to move my greenhouse, and will be adding water storage.
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billi
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« Reply #6 on: December 27, 2018, 08:11:03 AM »

Hi  , we lit 4 candles , this evening  and temp rose from 0 to 3 degrees in the glasshouse in 2 hours  ,  i estimate, read, each candle has about 30-50 watt  

Went through  the last years weather info and there  where 30 days below 0   highest low -10

Guess  for this winter we get a gas greenhouse heater  ,    a fill of  5 kg  propane gas costs  about 10 euro  here  so i estimate  20 euro  to  keep it constantly above 0  

Still have to  check the  underground  water tank temp

Billi
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1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
knighty
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« Reply #7 on: December 28, 2018, 12:33:35 AM »

That could be this video from Nebraska.
https://www.chonday.com/30978/nebaoran6/


that's the one!
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chasfromnorfolk
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« Reply #8 on: December 28, 2018, 09:12:07 AM »

hi Billi, maybe with the Navitron mantra ‘insulate, insulate, insulate’ you could get down to 2 candles...

Following this with interest.

Chas
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billi
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« Reply #9 on: December 28, 2018, 09:55:20 AM »

 Smiley  yeah sure .... , was a great visit to my parents over christmas , we theee built that whole garden  on sloping slippery ground , last year , average age between us threee was 70 .'.. lot of intense fun , and this christmas , exclusivly ,  vegetables from our garden , joyfull ...heart full ....love 😇😁
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1.6 kw and 2.4 kw   PV array  , Outback MX 60 and FM80 charge controller  ,24 volt 1600 AH Battery ,6 Kw Victron inverter charger, 1.1 kw high head hydro turbine as a back up generator , 5 kw woodburner, 36 solar tubes with 360 l water tank, 1.6 kw  windturbine
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