Register with us or sign in
in Tools and techniques
I am wanting to purchase a heater for my greenhouse 6' x 4' its aluminium and polycarbonate. I'm not really keen on the paraffin heaters as I have a 3 year old son. I have seen online the tubular heaters but are they any good? If so what size would be best?
I'm wanting my grape vine to finally produce grapes this year and just can never get it warm enough thanks to our great British weather!
I have a small generator and a mate of mine adapted it to work a small tubular heater.
I really can't believe no one has come up with a suitable "green" solution for greenhouse heating.
Solar i get, it would only work during the day when the greenhouse is "heated" anyway.
However you'd think you could charge some kind of battery during the day to run a small tubular heater off during the night.
Then again wind would seem the most obvious, if you can get a small wind turbine to run the leccy in a caravan you'd have thought someone would have made one for a greenhouse heater, must be an obvious reason why no one has done this but i don't see it!
This wouldnt solve your dilemma, but may help. Try putting a layer of bubble wrap in you greenhouse (which is what I did last year), then it retains the heat from the daytime much better than usual. Thats the greenest way I can think of, but may only raise the temperature by 5 degrees or so
On another thread someone suggested 'can furnace'. If you google this you will get to an inventors blog which tells you exactly how to make it. The principle is; lots of aluminium cans painted black, stacked inside a box covered in glass or plastic. Cold air enters at the base and travels up through the cans which have holes at both ends, and exits at the top as warm air, through a hose into the G/h
As an old gardener always had a greenhouse and tried them all nothing will give you more than a frost guard.Paraffin is costly gives off moisture and needs constant attention if you do not wish to find all your glass black with smoke.A gas heater costly gives off some moisture although will not be as bad as Paraffin.None of those will ever pay their way, while you are eating your £1 per carrot salad the shops will be selling them by the bag full.My Father built a stove to burn rubbish outside the greenhouse with large pipes running through it worked well and cost nothing H&S plus green laws would frown on that now.I have a South Facing Wall Mounted GH now and ran electricity to it. The wall on even sunless days takes in heat and gives it back at night.A Sand-bed with warming cables and thermostat with shelving above allows for seeds to be sown and then put on the shelves with a bubble wrap curtain around that section, add a Fan Heater with Frost guard and that does nicely.Saying all that over the last three months here in the Northeast none of them have been switched on yet and will not be until we have more light, very important and the outside temperature raises above freezing, at the moment it is minus 2.You will do your own thing and find the cost prohibitive depending where you live I would say let nature do it naturally.
I have a good gardening friend who swears by his 12ft heated bench in his greenhouse this is backed up by a frost biter - electrical heater that comes into action when the temp freezes, i hope to do the same this year with my greenhouse as i would hate to think next spring 2014 is anything like this one !
My greenhouse base is of 3"x2" paving slabs, they warm up during the day through natural radiation. (Keep your glass clean for maximum effect) I have not recorded specific tempereturs but it is noticably warmer inside when entering in the morning.
Starting my early seedlings I have an plastic box with water in it and insulation round the outside. using a 100 watt thermostaically controlled fish tank heater keeping the water warm. The top has a plasic lid with small holes drilled it. I place my seedling trays on this lid and cover the whole thing with a home made mini greenhouse, this keeps the warmth and humidity up at minimum cost. I have for the past four weeks had this in operation for the past four weeks during the feezing March weather. The tempereture inside the mini greenhouse is kept at 60F.My Tomatoes and Lettuce love it. Checkout the picture.
i'm hoping to have a new greenhouse in the next couple of months and intend building a 'rocket mass heater'. They seem to work for not much money and theres loads of info available online
Solar is a possible if you look at solar water systems there is some interesting stuff around. About the best seems to be sydney tubes these are are glass tubes made of pyrex with an inner tube which is metal coated inside a vacumn sealed clear outer tube being circular they always face the right way. The heat captured is quite incredible and can boil water.
while domestic water systems can be very expensive. The tubes themselves can be quite cheap. (i've seen smallish tubes on the internet at $99 for 10 only problem import duty) Theres a couple of methods for transfering the heat the simplest just requires a pipe leading down from a tank the hot water in the tube will rise into the tank while cooler water replaces it , thermo syphoning. another type of transfer is the heat pipe where a sealed pipe has water under low presssure. This causes the water to boil at relatively low temperature and rise up the pipe where it is again into a tank of water which cools the water vapour releasing latent heat and heating the water in the tank. Once the sun goes down the hot water generated in the day could be used to provide heating at night. I'm still at the experimenting stage but i was quite impressed with the heat pipe i made even thou i was forced to test it with a fire. I'm looking at ordering a small sydney tube for experimenting with from canada tomorrow. Its about €15 plus postage but i'm not expecting to heat much water with it. I just want to see how hot it can get on these cold days.
We've actually got a solar water heater on the house, it works surprisingly well. Even in the middle of winter if if the temp is -5 outside as soon as the sun comes out you start getting plenty of hot water generated.
Problem with a greenhouse heater based on solar i guess is when you really need it you won't have solar power, ie cold wet, dark winter months. As unlike solar leccy, we don't seem to get much when it's dull.
In the summer you'll have to watch overheating, as the water litterally just keeps getting hotter and hotter very fast. Our boiler has a safety trip but the temp in the pannel can very quickly hit boiling once the tank is hot.
I have found a cheap free method to heat a greenhouse and it's so simple.
cut the grass. Stuff clippings into a compost or coal bag put bag(s) in the greenhouse.
you might want to just pile them up initially to get them brewing.
Grass as it rots generates heat, once your into the first few inches the heat is massive. google "jean pain method"
This is a bit extreme but this guy is actually generating hot water from compost, basically running about a 100 foot of pipe through his compost pile.
I guess once the pile cools off it can become part of your regular compost heap or used as a mulch or soil enricher...