Greenhouse heating

[gaz1]

alaska

for me paying for fuel was a bad thing and not welcomed on an alotment, high risk of fire

building a double greenhouse was much cheaper for long term use not short term and using passive technology was better option heating water by the sun or even rocket stove and a water back boiler plate was cheap

 

[Wozzaaah]

I give up, wish I hadn’t asked now.

 

[roofman]

 

[minimutly]

It's a very big space for a candle to heat.
I've just found a website that suggests putting a rabbit in it.

Put two - three times the heat..

 

[roofman]

Put two - three times the heat..

Put two in and end up with thirty three

 

[CompoSimmonite]

Source an old storage radiator and use the bricks for a heat store by sucking the warm air from the top of the greenhouse (computer fan ?) during the day so it'll then give out heat at night. Power the fan by a small solar panel so when sun goes in the heat will start to come out of the heat store

 

[Migmac]

My FiL used to put a 60w light bulb under a plant pot to keep rooms frost free, a more modern version of the candle. It does work

 

[voipio]

This is all a bit back of a fag packet, calculations-wise, but, for a 10' x 10' glass greenhouse, a rough ball-park figure seems to come out at around 300W of heat beng required to raise its temperature by 1 degC above where it would have been with no heat.

Using the above figure, we can work heating requirements out. So, the average figure for the heat a candle puts out is around 60-70W, thus raising the temp by about 0.2degC. A 2.5kW paraffin heater would raise the temperature by about 8.5 degC. If the night time low temperature forecast is around -8 degrees, then the paraffin heater should keep it frost free.

 

[Bullet2012]

I give up, wish I hadn’t asked now.

“Oh” I thought we were all being extremely helpfull.

 

[8ob]

There is probably more heat inside a compost heap than a lightbulb, might be worth looking at tapping into that or a bit of geothermal.

Bob

 

[ukracer]

I'm not a gardener but my missus is, she tried it over winter and it kept whatever plants were in there ok - the addition of the pot makes a big difference apparently as it traps the heat from the candle and radiates it off slowly, it's not a lot of heat but it's constant. Ours is 6 x 6 so not as big as yours though...

2 x candles and 2 pots then?

 

[DanZac]

I'd heard about the candles thing for protecting grape vines from frost before. Seems like it's actually a thing though according to Google.

I'm guessing that if a few candles can keep a vineyard frost free, a couple in a greenhouse might work.

Either way the boilers getting ripped out tomorrow and I'm investing in bees wax, got to be cheaper than the cost of gas.

How candles and propellers protect vines from May frost

Wine growers use a variety of ingenious techniques to guard vulnerable vines from sudden temperature drops

www.theguardian.com

 

[anto44]

There is probably more heat inside a compost heap than a lightbulb, might be worth looking at tapping into that or a bit of geothermal.

Bob

Compost bin would work perfect. This is a pic of mine from last year. It holds that temp pretty consistently.

 

[magnet]

Ive used a couple of the old chalwyn roadmans paraffin lamps i know paraffin aint cheap but they'll run over a week on one fill i used to put one under the bonnet of my old sherpa van when we got the hard frosts back in the day saved her popping a core plug

 

[gaz1]

a greenhouse wont heat up at all unless it has a good heat store in the first place thats red hot to start with

so if you think candle power forget it

a parafin heater will do it or another type but it wont go over a certain temp due to heat loss from the greenhouse glass and outside temps

the main thing with a greenhouse is double its cover to stop the loss of heat for start off and covering the inner side with an insulator

either 2 ways around this use poly tunnels inside of the greenhouse or create an external cover

then insulate over them a parafin heater is better under the beds as long as it can heat all of the bed up underneath it before the heat escapes

but you will need to create longer drop down sides for both beds

i can tell you now your not going to want to do this one

 

[gaz1]

like ive said for free

so if i was heating water up id use a back boiler and a rocket stove type of design

i wouldnt make it that way as it can be made out of channel and fillers inbetween in 5mm will last longer

this rocket stove is wrong you will only get heat until the wood runs out

this is all you would need can be made of steel or bricks but better if firebricked


this would give you 3-4hrs worth of heat to water then your heated water would continue to heat the greenhouse

with it being outside it wouldnt bother it but the closed door gives longer burns as your burning the gas off from the wood on a rocket stove

as the top part would then connect up to the chimney as the boiler part is sat on the hotplate

like this rocket stove below heating the hotplate up then fumes going up the chimney great for cooking on with very little wood
but wrong type as you need a door on and to burn the gasses via secondary air vortexing to slow the wood burning away fast

as a point of reference heated water for a shower heated by a rocket stove up to the boiler tank then up to the chimney

only the same as putting a pan or kettle on a stove

 

[Keith 66]

Our greenhouse is 11' x 7' last winter i dug out mums old parafin heater, small pancake tin type with two wicks.
It will run for 7 days on 1 gallon of parafin, or a gallon a fortnight if you only have it on at night.
It had no problems keeping the frost at bay.

 

[Gareth J]

Can you include some thermal mass in there? A few layers/stacks if old storage heater bricks would be great, they'll soak heat in the day and let it out at night. Will help buffer temperature swings a bit

 

[James1979]

I had (dunno what happened to it or you could have it) a small parrafin heater in the ‘machine room’ in the last workshop to stop condensation on the machine tools. It was basically a 10x10 shed in the corner of a big workshop which was clean and kept crap off the mill and lathe.

Anyway. This heater was about the size of 2 toilet rolls and hung from the ceiling on a hook. Paraffin lasts a while in it. It was never toasty in there but it stopped condensation.

 

[The_Yellow_Ardvark]

@Wozzaaah
Do you have a compost bin/heap?
If so, make it a hot composter, Googlr will show you many ways.
Place a old car radiator inthat heap.
Pipe it to a second one in the green house. The heat will travel through the water, by convection and keep it above 0deg C
In the day it works backwards and heats the compost, allowing it to break down faster.