Summer: Passive Thermal Store

A few weeks ago we started to get our glasshouse back in order and decided to employ a technique that would store and release heat in our glasshouse in a better way.

How to create a passive store in the greenhouse.

We can't afford to keep buying paraffin for heaters and run them continually through early spring and late autumn. We don't want to turn our glasshouse into a hot house, which is a problem with paraffin heaters unless you are around 24/7 to make sure the glasshouse doesn't just become a dripping jungle. Neither can we afford to run electricity up the hill to the glasshouse or the costs that come with that. Therefore we have turned to a simple technique to store passive heat and all we needed was a 270 litre water barrel, preferably black and a place in the glasshouse so it can catch the sun all day. To do the latter we extended the glasshouse path to the far end.

A water barrel in the greenhouse can mean you get more warmth.

As is the belligerent nature of greenhouses, the proportions don't fit with flag stones and we had to add a row of bricks at the end, brushing in some sharp sand. We think it looks good and we used materials we had knocking around the garden. The flag stones are from an old path we uncovered in the garden, they were about eight inches down in the soil and show just how long since the garden was maintained, all the old paths keep popping up as we continually dig the garden for planting. We have even found a barrel of lead soldiers and the remains of a shed, and the old bases of washing line posts. We then dragged the 270 litre water barrel into place.

Water barrel as a passive heat store.

It's advisable you do this before filling it with water as you won't be able to move it afterwards, just too damn heavy. Fill the barrel with water.

Water is a great resource for warming a greenhouse.

When the barrel is full put on a lid and leave. The barrel because it is black does heat up and heat up fast. We soon found the barrel was warm to the touch and the water was warm, not hot, it was the effect with the barrel being beside the staging that paid dividends. We noticed that seedlings closer to the barrel germinated faster, healthier and even the tomatoes at that end of the glasshouse are romping away. It's a cheap option and easy to do, just remember that this water is not for using in the glasshouse, you need it for the warmth it gives off! This is not an active heat store, there is no need for a catalyst, such as, a fire to heat the water, the water is subject to the weather and warm days maintain a warmth in the store over night. This is useful in early spring and late autumn when the sun is warm under glass but poor outdoors. 


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