Please can some one tell me which is most efficient if you want to get the central heating up to say 22 degrees in time to get up in the morning....
Leave the thermostat on 22 degrees and have it come on earlier for longer or Put it on 26 &/or turn up heater temperature and let it come on later.
I've puzzled so much I'v econvinced myself both ways, but there must be a scientific answer... cheers
"keith" wrote | Please can some one tell me which is most efficient if you want to | get the central heating up to say 22 degrees in time to get up in | the morning.... | Leave the thermostat on 22 degrees and have it come on earlier | for longer or | Put it on 26 &/or turn up heater temperature and let it come on later. | I've puzzled so much I'v econvinced myself both ways, but there must | be a scientific answer...
Turning the thermostat to 26 will make no difference to how much heat the boiler will put out and thus no difference to how long it takes to heat the room. It only affects at what degree of warmthness the CH turns off.
The only ways to get the room warmer earlier are:
Owain
The thermostat only switches the heating on or off. So, if the temperature is below the set point, it runs until the set point is reached. Turning up the thermostat does not make the boiler run any harder.
Ergo, the answer is "longer".
Not sure it's a question of efficiency! With the system running flat out it will take a finite time to reach your desired 22 degrees. If you start it too late to achieve this, you can set the stat to 50 if you like - it ain't going to make any difference - 'cos if it doesn't even get to 22 it isn't going to get to a level where the stat operates.
The problem is that the starting time needs to be different depending on how cold it gets over night. The way to deal with this is to replace your manual stat with a programmable stat such as the Honeywell CM67 with optimum start. You tell that what temperature to achieve by when - and it works out for itself when to start. You won't get much more efficient than that!
Assuming the boiler thermostat isn't already up full of course, and the OP did say "increase the heater temperature" - which suggests it isn't ;) Albeit the effect of flow temp on warm up time depends on the Kw output of the boiler, amount of water and number of rads in the system...
Lee
Doh!, meant "is" not isn't.
Lee
That must be the most convoluted way of typing 'temperature' I'm ever likely to come across :)
"Lee" wrote | Assuming the boiler thermostat isn't already up full of course, | and the OP did say "increase the heater temperature" - which | suggests it isn't ;)
That would only make a difference if the boiler is cutting out whilst there is still a demand for heat. That's possible with hot water only once the cylinder reaches 50--70degC, but unlikely with heating as if the rooms are still below 20deg and the radiator stats are open there should be ample dumping of heat from the boiler to keep the boiler stat on even at low settings.
Owain
That is only true of an old style non-modulating boiler that has been sized to the house requirements. A modern modulating boiler is so overpowered (typically 28kW) that it will very quickly be able to reach the set output temperature, and bring the radiators up to temperature. Then the boiler stat will act almost as a power setting for those radiators, long before the room temperature rises anywhere near the room stat setting.
Christian.
Thanks to all for replies,
So it sounds like the most cost efficient way to wake up warm is to put the gas burner temp high (setting water tank thermostat medium for hot water) put the CH thermostat on the temp i want to be at when we wake up, and experiment with how early this has to be until it's right.
cheers
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