Andrea Leadsom has just appeared on the news saying that if people turn down the thermostat on their combi boilers (we all have one of course) it won't reduce the temperatures of the radiators and the house will stay at the same temperature but they will save money.
Has she found a way round the law of conservation of energy?
The logic, I suppose, is that this will make a condensing boiler run a tiny bit more efficiently, (even if for longer) provided there is enough capacity to bring every room up to the point where thermostatic radiator valves are governing the temperature.
In *my* house, where the conservation officer won't let me replace Critall windows, I have to wind the boiler up in cold weather to stay comfortable. In fact in mid-winter I had it powered up 24/7 for some of the time.
I think that's some sort of cack-handed attempt at explaining weather compensation. Unlikely to work if people do as she suggests.
Of course, politicians know everything and always tell the truth. Actually, turning down the room 'stat would still allow the rads. to get to max. flow temp. but there's be a lot more overshoot, so the time between firings would increase. It is so marked that I have throttle the rad. in the room with the 'stat to get enough heat into other rooms.
But we?re not talking about the room stat, it?s the boiler stat under discussion.
As has already been explained, it?s about encouraging the boiler to spend more time in condensing mode (and hence higher efficiency) due to lower return flow temperatures.
Tim
Would she know the difference? That's why I assumed she meant the room stat. There was a chap on Look East last night who specifically said boiler and condensing - that's the sort to ask. My new boiler was set to 60 by the installer. In the first day I realised that it didn't need to be that high. I'd had the old boiler at 60 because it went to temperature and cut out so if set lower it never put out enough heat as it spent too long off. The new boiler eases back as it approaches set point and stays there, modulating right dow, until the room stat cuts it. Rather less overshoot and more comfortable. It's now set to 50C and, after a cool day and frosty night, the room warmed up just as fast as with the old boiler.
FFS you don't think she came up with that herself, do you? I'm pretty confident that anyone who gets to a level in the Civil Service where there briefs actually reach a minister will understand the technology. Even if they only read PPE.
I suspect someone, somewhere, has pointed out that if the system (not just a combi) is set so it ?over shoot? the target temperature, rather than creeping towards it, it is probably more efficient. Ideally, systems would have a three term, PDI, controller rather than turning the boiler on/off.
Losses do increase with temperature, so avoiding overshoot avoids losses directly.
I think you will find the ?modulating? function in boilers is controlled by the boiler stat, not the room stat.
Room stats tend to be on/off devices. If the system is churning away it is quite possible it could keep on going until the room stat ?catches up? and even keeps increasing as the air circulates etc.
Reducing the boiler stat mitigates this.
Of course, the chances that Ledsom knows which stat is which ?.
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