Drying clothes = price + running costs (when will it pay off)

Running cost per year= price per kWH * kWH per cycle * 365 / 2 (i recon we'll run it once every other day)
price per kWH = 13.7p
362 / 2 * 13.7p /100 (convert to pounds) = 25

Tumble dryers:

A++ energy rating
Cost = £599
Running cost = £46

A+ Rating
Cost = £479
Running cost = £73.75

B Rating
Cost = £299
Running cost = £85

C Rating
Cost = £150
Running cost = £91

You could work out how many years the more economic will start paying off over the other by doing some algebra:

A++ energy rating cost + (running cost * years) = C energy rating cost + (running cost * years)

a + (b * x) = c + (d * x)

a - c = dx - bx
a - c = (d-b)x
(a-c)/(d-b) = x

A++ compared with C
(599-150)/(91-46) = 9.99 years

A+ compared with C
(479-150)/(91-73.75)= 20.1 years

B (other) compared with C
(299-150)/(91-85) = 24.8 years

A+ compared with B
(479-299)/(85-73.75) = 17.6 years

So, it looks like C rating is better then all of the above up until 9 years. How long will we have it for? I guess the washing machine has lasted 10 years so far and it's still going strong.

Of course if you double the amount of time you use it, you half the number of years. So after 5 years A++ will be paying off better.

Lets compare to some interesting inventions:

JML Dri Buddi
Cost = £45
running cost = (1.2kW * 3 hours = 3.6kwh) * 25 = £90

Lets compare with C rating:
(150-45)/(91-90) = 105 years

Compared with A++
(599-45)/(90-46) = 12.6 years

It's basically the same running costs as the C energy rating, but 1/4 the initial cost. Probably double up as a heater. Must be noted that it probably isn't as good as a tumble dryer though.

Because of the price difference, I think it doesn't hurt to try the Dri Buddi first. If it's rubbish, I've only really lost £70 inc running cost at most.

Another problem is the humidity problem, and we get very bad damp problems. With a dryer it gets dealt with by either vent or internally condenses it. An idea I've had is to put the JML Dri Buddi in the greenhouse. The humidity will escape through the many gaps in the greenhouse. The only problem is that it'll be colder in the winter, what will happen is the clothes will be warmer then the surroundings, and the main points are that the humidity will be low, and the surroundings will want to 'steal' the warmth via evaporating the water. Still worth giving it a go.