a question for techies

[snake the squadie]

i inted to build my own green house on my lottie using thick clearish bags and clearish corrogated plastic for the roof. its all to min done at zero to min cost. the questions i have are how to prevent heat loss and the big one is i intend to build my own solar central heating system out of scrap but how do i get the water to flow around the system if any one has even the slightes idea please let me know

[roitelet]

Heat loss can be prevented by double glazing for the winter with bubble plastic but it can present problems with condensation.

Bit concerned about the plastic bags though. They will breakdown quickly if they are not ultra violet resistant. The plastic will be OK but how will you block the corrugations?

No ideas about the water circulation though.

[Paul Wagland]

Solar hot water systems (for heating household water) usually have a small solar-powered pump, which runs faster the brighter the sun. So on a sunny day, when the water is getting hot quickly, the pump is running at max speed.

I have seen plans for a non-pumped system... I think it relied on the 'hot water rises' principle to move cool water into the bottom of the solar array and hot water out of the top.

If it's not a big greenhouse you would probably be ok with a solar battery, rather than a central heating system. Just fill a large, dark-coloured container with water and put it somewhere in the sun. It'll soak up heat in the day and release it at night.

Alternatively, build a chicken house along the north wall of the greenhouse. The chooks will warm the greenhouse with their body heat. Give them access to the greenhouse in winter (as a warm indoor run) and they will eat all the pests and manure the soil for you. They even breathe out carbon dioxide, which is good for your young plants!

[snake the squadie]

thanks for all of that. i am only using the thick pags cos they are free(dont realy wont to use them) and thought about using a solar panel and pump but this has got to be a no to minimem cost project. i was thinking about using the hot water rise principel but didnt know if it would work. and would love the chicken idea but sadly i am not at home during the week to feed them. but thanks for all the advice

[Snadger]

Alternatively, build a chicken house along the north wall of the greenhouse. The chooks will warm the greenhouse with their body heat. Give them access to the greenhouse in winter (as a warm indoor run) and they will eat all the pests and manure the soil for you. They even breathe out carbon dioxide, which is good for your young plants!

I like that idea!

Seen a guy in US of A who zig zagged a large bore hosepipe in an enclosed area then tipped tones and tonnes of fresh steaming manure on it. Connected pipe to his water main and wallah! He had hot water for his home!

[Maf]

i intend to build my own solar central heating system out of scrap

Solar heating for your greenhouse or your home ?

A greenhouse would act as a solar store in it's own right.

Are you thinking of something like a solar heated propagation bed (bottom heat) ?

Please clarify

[snake the squadie]

Solar heating for your greenhouse or your home ?

A greenhouse would act as a solar store in it's own right.

Are you thinking of something like a solar heated propagation bed (bottom heat) ?

Please clarify

i wasnt but i am now. the system i had in mind was a very simple one for the green house. build a water solar panel on the roof of the green house out of a old radiator and bits and bobs then use it to heat another old raditor inside the green house. i just wanted to know if ant one had any ideas how to move the water around

[esrikandan]

An old radiator might be too heavy on the roof of the greenhouse. What about some hosepipe in a glass fronted box? As far as moving the water around, I'd imagine the hot water rises principle would be sufficient. Otherwise perhaps a smallish solar cell and an old car water pump?

[heebiejeebie]

The convection current from the water should be quite effective. I'd love to try out solar heating in the greenhouse - I was thinking of having an old radiator painted black outside the greenhouse and some hosepipe underneath the floor zigzagging through gravel or something. Idea is to warm the gravel during the day and heat the greenhouse at night. I need a permanent place for the greenhouse first (and a better quality greenhouse to make it worth the effort).

As soon as I get my hands on a freecycled radiator I'll give it a go. I have a small solar cell pond fountain that might do for a pump if convection isn't enough - the pond fountain came to grief when the mr mowed the cable.

[Maf]

I think you will need some type of heat store so that you don't cook your plants during the day.

Something that holds a lot of water (preferably in black)

Garden Warehouse: Water Storage and Watering Accessories - 1520ltr Water Storage Tank

Good old Dickie has an idea here

Solar Greenhouse Heat Sink - Solar

Clever that the solar panel runs during the day and the heat rises at night !

Here's another idea (personally i'd paint the copper collectors mat black. Maybe line some guttering with foil as a concentrator )

DIY Solar Water Heating - Heating