Alternative way to heat

[carly]

So, finding out that a paraffin heater will cost far too much to run we have done up with an idea.
We will have 3 water butts in the greenhouse at the back. My husband is on about using the one on the left to feed tubes of warm water ( he has seen a system I think) and these will be laid directly under the lining for the soil so they heat up the soil
Thoughts?

[Cadalot]

Great in the summer when you don't need it but what warms the water in the colder weather when you do? Cost of pumping, wait use solar but along with colder weather comes more cloud and less sun.

[Mr Bones]

Just having a full water butt in the greenhouse will help maintain the temperature, especially if it's a dark colour. You must have plenty of space Carly, lucky you.
There was a company at one time that made flat water butts to go behind sheds etc. Don't know if they're still going.

[chris_m]

There was a company at one time that made flat water butts to go behind sheds etc. Don't know if they're still going.

Haven't seen any, best I could find (at an acceptable price, that is) was 100 litre slimline ones, which I have set up in banks of 4 and 5, each bank interlinked via hoses on the taps feeding a manifold.
Larger butts, whilst cheaper overall, would stick out too far from the walls against which I have them unfortunately.

[bario1]

Hi Carly, are you talking about heating in the winter? I'm sure under-bed hot water heating would help with germination, but won't the air temperature still be too low for strong growth?

[Jay22]

What about the terracotta plant pot and tealight idea...does that actually work or does the tealight run out too quickly?

[roitelet]

What about the terracotta plant pot and tealight idea...does that actually work or does the tealight run out too quickly?

I**a sell some tea lights that burn for 9 hours.

[SarrissUK]

I**a sell some tea lights that burn for 9 hours.

I can vouch for the bags of tealights you can buy there in bags of 100 for less than £2. Amazing and far better than any other tealights I have found anywhere.

[Jay-ell]

Thoughts and questions :-

1. How big is the greenhouse (has it already been built)?
2. What is the purpose of heating the green house?
3. When do you want to heat it?
4. What crops are you expecting to grow then?
5. Hot water rises, cold water sinks so if you have the butt connected to pipes under the beds you're going to have to pump the water to circulate the heat and have non- return valves to make sure that it doesn't suck heat out of the bed when the pump isn't on.
6. If it's a BIG greenhouse and hasn't been built google "rocket mass heater".
7. If you're looking to give some heat to seedlings early on in the season can you construct a hot compost pile inside and put the seed bench on top?
8. Can you use cloches inside the green house to extend the season in either direction?
9. Can you grow more cool weather crops at either end of the growing season which will still get a milder environment than outdoors?
10. Would the use of fleece/bubble wrap be easier/cheaper/less chance of burning the place down and still give the desired results?
11. If you did want to go down the plant pot route search utube for 100 hour candles

[Jay-ell]

Another way would be to use the ground as a heatsink - during the day hot air from the top of the greenhouse is blown into underground tubing which would warm up the soil a little. Cooler air can be blown through to get some of the stored heat back. Not sure how much piping you'd need or how much heat could be stored.

By the way, the butts of water themselves will act as a themal store - raising in temperature during the day and releasing that temperature during the night. Not heating but it can keep the temps a degree or two higher that normal if there's enough. It takes a lot more energy to raise water 1 degree than to raise the same amount of air 1 degree so when the water starts releasing its energy to the the air and cooling down it can raise the temperature of a lot more air per degree of change.

For the same cubic space water holds more heat than stone, brick or concrete.

[veggiechicken]

This is Carly's GH http://www.growfruitandveg.co.uk/gra...ml#post1540736
Its 20x10 with a paving slab floor (I think).

Key question I'd like to ask, is why do you want to heat it? is there something speial that you have in mind?

Over the years, I've used paraffin heaters and electric tube heaters - and lined it with bubble wrap. Now, I don't do any of it, but I still grow salad leaves and a few other bits and pieces over winter.

[carly]

Hi Carly, are you talking about heating in the winter? I'm sure under-bed hot water heating would help with germination, but won't the air temperature still be too low for strong growth?

We are still thinking about this. Will let you know of any developments

[carly]

This is Carly's GH http://www.growfruitandveg.co.uk/gra...ml#post1540736
Its 20x10 with a paving slab floor (I think).

Key question I'd like to ask, is why do you want to heat it? is there something speial that you have in mind?

Over the years, I've used paraffin heaters and electric tube heaters - and lined it with bubble wrap. Now, I don't do any of it, but I still grow salad leaves and a few other bits and pieces over winter.

Hi,
I would like to grow all year around if possible.... we want to try and be as self sufficient as possible... it may not be possible. I a, looking up all vegetables that could be grown in cooler weathers.
If it is not possible then I would like to start quite early on like February, which can still be quite cool here. So looking to use it February -novemeber if I cannot produce over novemeber to February

[carly]

Another way would be to use the ground as a heatsink - during the day hot air from the top of the greenhouse is blown into underground tubing which would warm up the soil a little. Cooler air can be blown through to get some of the stored heat back. Not sure how much piping you'd need or how much heat could be stored.

By the way, the butts of water themselves will act as a themal store - raising in temperature during the day and releasing that temperature during the night. Not heating but it can keep the temps a degree or two higher that normal if there's enough. It takes a lot more energy to raise water 1 degree than to raise the same amount of air 1 degree so when the water starts releasing its energy to the the air and cooling down it can raise the temperature of a lot more air per degree of change.

For the same cubic space water holds more heat than stone, brick or concrete.

We have 3 brown rain butts ( planning on painting black) we will be able to hold 660 litres between them all..... I have also thought about putting up some of that heavy duty plastic flap that you see on doors sometimes to create a hothouse within the greenhouse. This area will also be where the 3 rainbutts are stored.

[veggiechicken]

You should have no problems growing salady things through winter. You'll be growing in pots I guess since you have a solid floor - as do I.
You could buy a cheap blowaway at the end of the season, when they're even cheaper, and put it up inside your GH to create a warmer spot.