Heating - cheaper on all the time or when needed ?

[ALEC1]

energy efficiency and the application of heating technology is poorly understood in this country...

1)its related to usage patterns... houses have people in them usually 16 hours of a day...but many have people in them 20 hours a day or more...for them on all day will be less wasteful.

2) its related to how you use the boiler...if the boiler is set up with compensation controls and the house is occupied say 16 hours or more it may well be more efficient to leave the heating on.

3) it depends on the level of insulation and the thermal inertia of the building...if you have to heat up a large thermal mass (which most houses are) twice a day then you will use more energy than leaving it running..or at least its marginal

its worth bearing in mind that all boilers accept compensation controls that match heat demand to heat generated...thus ensuring less wastage...

 

[Agile]

Again, largely, physics says it doesnt really matter what the rate you feed the energy in is to the amount you use.

Daniel

An average three bed semi needs about 10 kW to heat it.

So if you warm it up at a slow rate of say 12 kW in the morning over and hour it will lose 10 kWh.

BUT if you can turn on the heating half an hour LATER so its only warming up at say 24 kW the it only loses 5 kWh. So thats more efficient.

However, the boiler efficiency has to be considered and that may be less delivering 24 kW than 12 kW when it might be more condensing and saving perhaps 15% more.

A few minor variables but generally the heat loss is 10 kW all the time its hot inside!

Boiler makers dont give efficiency curves for part loads! Most boilers deliver less than 50% of their maximum all their life! Many oversized only about 33%.

Tony

 

[ALEC1]

the trouble is Tony, that heating systems have to "over shoot" to put more heat into the building that has been lost to trip the thermostat. Then they shut down, and the radiators keep emitting unwanted heat...


thats why compensation controls that wind down the heat emmission of the radiators before shutting down the pump and boiler in the case of internal sensing only enhance efficiency...other variations try to put enough heat into the building to maintain a stable temperature...