Well, I spoke to E.ON again and it turns out I somewhat misunderstood the deal they were offering
. It's the unit prices for both gas and electricity that will be fixed for two years but I still will have to pay for what I use (it would have been too good to be true). But I asked a colleague (the company I work for is a finance company that invests in renewable energy so I'm in the right place to ask at least
) and he very highly recommended going for the fixed prices as he is very very certain the energy prices will be going up; so I've gone ahead and done that.
Also, re the heating on or off thing, I checked with another cat friend who is a building surveyor and this is what she replied;
Re heating, it depends a bit on the building. If it's a well insulated modern building, then intermittent heating isn't too much of a problem. But in older buildings, solid brick and/or stonework are slow to warm up, so all you're doing with short bursts of heat is warming up the air, and not the walls. The warmer air will hold more moisture, then when you go out for the day and shut the building up, this moisture condenses out on the cold walls, windows etc, resulting in condensation, possible mold growth, and certainly a higher moisture content in the walls. This reduces their temperature and means some of the next burst of heat is wasted just drying the walls out before they warm up again. Even if you don't have a condensation problem, with buildings like this using continuous low levels of heat means the walls not only have a chance to warm up, but they also hold the heat and act like a storage heater, keeping the house warm for longer.
So yes, in older buildings, continuous low levels of heating are better for keeping the building warmer and drier, but tbh I haven't tested it on the fuel bills. I know others who have, who say it pays off, but at the very least it's better for the building, and warmer.
There endeth the Building Science lecture! Hope that helps!
Once temperatures are more settled (it's still quite warm during the day) I am going to give it a try and see what happens and I'll definitely let you know.