My clay flower-pot room heater

Hi Friends,
Well, it's a bit of basic experimental science from me today, as I've been trying out a low-tech DIY room warmer. I was able to put it together using only items I already had and if anyone fancies experimenting further with this, there are plenty of instructional websites & videos online. I'll admit you won't get many physics-based blog posts from me......decades later, I still recall the words of my 3rd year physics teacher, the aptly named Mr Newton all too well.........

"Despite her obvious lack of interest in this subject & extremely inconsistent approach to handing in homework, Cathy somehow managed to achieve 31% in her end of year physics exam"..........

Well, take this, Mr Newton, because Cathy of the 31% has constructed a flowerpot room warmer, willingly, of her own volition, following online instructions from Those Who Know!!

Aim of the experiment:To find out whether a flower pot room warmer will have any effect on the chilly temperature of 'Cathy HQ' (my small upstairs office). 

Equipment required:

Two clay flower pots, 1 2lb metal loaf tin, 4 tea-lights & a 10p coin or similar metal disk. (I used an irritating Canadian coin which some skanker managed to offload in my change the previous week!) 

For safety, you will also need something heat-proof on which to stand your contraption, & a box of matches. This is basic, but doesn't involve rubbing 2 sticks together while appealing to the Elements.

Arrange the 4 tea-lights in the tin as above, then light them..

Place the smaller clay flower pot over the tea-lights, then block the hole in the top with the 10p coin.

Now carefully place the larger flower pot over the smaller one, & stand your completed room warmer on a heat-proof surface or trivet & site it where you want a little extra warmth. 

A couple of the online instructions I found suggested using a squidged-up (genuine scientific term) aluminium tea-light case to block the hole in the smaller flower-pot. I tried this initially, but found that more heat built up when using the 10p coin, presumably because it's heavier.

Now, as Ms 31% in Physics, I'm not about to astound you with a full scientific explanation of how this contraption works, but I do know it is to do with convection. The heat from the tea-lights builds up in the smaller pot, heats the space between the two pots & flows out of the hole in the outer top & from underneath. Clay pots seem to have good heat retention properties as the outer pot gets nicely warm, but when I removed this to investigate the smaller pot, I found that this was too hot to touch.

So, did it make a difference?

The results: Having installed the only temperature-taking device in the house (a Gallileo thermometer!) on a shelf in 'Cathy HQ', sufficiently far away from the flower pots as to avoid skewed results, I can report that after 2 hours of burning time, it progressed from this.......

i.e all glass globes clustered at the top, therefore 'Room is cold'...........

......to this......1 globe dropped to the bottom of the tube, meaning room has started to warm up. There was no other heating on at all in the room at the time, neither was I executing manic star jumps with a view to influencing the results. The room definitely felt a little warmer. Using tea-lights purchased from a well-known Swedish Purveyor of Household Goods, total spend is 8p per four hours.....plus 1 match! (Please note, I don't require any maths geeks to supply me with the cost of one matchstick!!)

Conclusion: Cathy HQ is a small room & I think that the clay flowerpot room warmer could have a role to to play in helping to keep the temperatures up in winter. Our heating goes on in November, but I think I will continue to experiment with my flower pots, to find the optimum spot to site them for extra heat while I'm sitting at my desk or playing the piano. I may check out some of the additional online modifications (some people use 3 flower pots plus tech it up with, nuts & bolts!), but I like the thought of keeping it basic.......& of potentially paying a tiny bit less to energy companies. In the continuing words of Mr Newton, as he summed up my physics prowess at the end of the third year,

 "This is not a subject I would recommend Cathy to consider taking at O-level"................

...........which was absolutely fine by me, as there would actually have been fractionally more chance of me opting to become a tarantula trainer!

Till next time,
C x