My plan at the time was to take the opportunity to make the jump to a heat pump, but that proved far from simple. Firstly, I would need cavity wall insulation and the company advising me on that said it was not feasible without about £5,000 of extra work because the bricklayer had been very sloppy, leaving heaps of mortar on the wall ties which would cause cold spots no insulation could reach. Even without that, including government grants, it would cost about £20,000 to buy and install the thing and that wasn’t straightforward as the only place it could sensibly go would need planning permission. Reluctantly, I gave up and had a new boiler instead. It’s working well and due for its second service, but I’m hanging back on that for a while because I’m exploring other options.

The problem is, although it works well as a boiler, the central heating as a whole doesn’t. That might be partly the result of the lack of insulation, but it uses huge amounts of gas and does not heat the house well. The kitchen, in particular, is almost always cold except in the mildest weather. I have had the radiator doubled in size but that still isn’t enough.

Then I heard about far infra-red panels. These are radiant heat, as our grandparents would have known, only not as our grandparents knew. The old radiant heaters were partially visible light and partially near infra-red. They ran hot enough to start fires if inflammable items got too close. The current heaters use far infra-red radiation. To understand the difference I need to digress slightly into the electromagnetic spectrum, so here goes.

Infra red sits in the spectrum between microwaves (1-10GHz) and red light (500GHz). We all know microwaves have warming properties and can penetrate below the surface. That is why microwave ovens can cook food more deeply in a shorter time than either hot air or traditional radiant heat, which is near infra red and the red end of visible light. The shorter the wavelength (or higher the frequency since wavelength and frequency are inversely proportional), the less they penetrate and the more the heat is concentrated at the surface. This partly accounts for the more intense surface heating from near infra red. The other factor is the higher temperature required to produce shorter wavelengths, since microwaves are currently the highest frequency normally produced electronically rather than by raising the temperature of the source. As radio waves are used mostly for communication a coherent source at a specific frequency is generally required rather than random radiation over a broad spread of frquencies. Coherent radiation at a higher single frequency can be produced by optical oscillators such as masers and lasers but those are for special applications and warming people in buildings does not require that sort of precision. The spread of frequencies generated simply by warming the source up is quite adequate and much simpler to achieve.

Far infra-red heaters work at a temperature closer to a radiator than an electric fire but have a much larger surface area to compensate so they can emit a gentler more penetrating heat which travels further across a room and warms surfaces and objects rather than air. That’s important because air has a low heat capacity and can easily lose heat to a cold surface, requiring good insulation to prevent that happening. Warmth absorbed by walls and furniture is less easily lost by contact with cold air and will start to heat the air instead. This ought to make insulation less critical than it is with air-warming heating. That, at least, is the hypothesis.

There is one other inefficiency with heat mediated through hot water, and that is caused by the need to put a lot of heat into the water to raise it to a temperature where it can usefully heat anything else. In a typical house, this amounts to around 3kWh each time the heating is switched on. If the heating is used twice a day for 200 days in the year, that’s around £100 every year just to switch the heating on, before it can do anything useful, which must come on top of that. That cost is likely to be similar whether the water is heated by an inefficient boiler using cheap gas or a more efficient heat pump using expensive electricity. With direct heating that system-warm-up energy cost does not exist.

So much for the theory, what about the practice? Well, since it’s still early Autumn and I’ve only had the panels a week or so, it’s too early to tell. I will know in the Spring when I have had bills and been able to tell how effective the panels are in the cold weather, but they have held up well so far and my house is currently warmer than it’s ever been, so long as I remember to switch the units on before I plan to sit in a room. I have not used my central heating for six days now and I feel warmer. I’ll see how things go, but I’m quietly optimistic. At about £250 each the panels are much cheaper to install as a simple DIY job than any kind of central heating and certainly much cheaper and easier than a heat pump.

I wonder whether those who’ve gone for heat pumps have backed the wrong horse.