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How to use heating controls to reduce your energy bill

Posted by Tim Pullen on 15 February 2010 at 9:27 am

The importance of good controls on the heating system cannot be over-emphasised. There are two main reasons:

1. An analogue room thermostat in the lounge or hall will make the heating system heat the whole house to the same temperature as the air around the thermostat, for the whole time the heating system is on. So the bedrooms will be nice and warm all the time you are sitting in the lounge watching telly.

2. An analogue room thermostat gives only an approximation of the desired temperature. It is not uncommon for older thermostats to be as much as 4oC out.

There is a much publicised Government statistic which suggests turning the thermostat down 1oC will reduce the heating bill by 10%. We have no argument with that, except that most analogue thermostats are not that accurate.

What can be fitted will depend on the situation. A pre-existing heating system is likely to be divided into 2 circuits at best; ground floor and first floor. In that case 2 thermostats are better than one and digital is better than analogue.

The best option is a good quality digital zonal control system. This is best suited to new build and will allow different temperatures for each room and, perhaps more important, different timing for each room. So you won’t have to have the heating on in the bedrooms when you have no intention of going there.

If that is not possible then radiator thermostats at least allow different temperatures in each room. If you want to control the bills, you have to control the system.

About the author: Tim Pullen is eco-editor for Homebuilding & Renovating magazine, author of Simply Sustainable Homes and founder of sustainable property consultancy WeatherWorks.

If you have a question about anything in the above blog, please ask it in the comments section below.

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7 comments - read them below or add one

MGH Trading Ltd

MGH Trading LtdComment left on: 15 April 2010 at 10:53 am


I am an advocate of the Househeat system. These use digital thermostats mounted on the wall (away from the radiator) that wirelessly control motors that replace the heads of TRVs on the radiators. They allow accurate and timed control of the temperature of each room independently.

 I also use the window sensor in our bedroom, so that when my wife opens the window to air the room, the system automatically switches off the radiator - which she doesn't  :-(

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Tim Pullen

Tim Pullen from Weather WorksComment left on: 4 March 2010 at 2:39 pm


Which heat pump is it? And why the Honeywell, which I belive is intended for zone control. It is likely that radiators are on ring circuits rather than zone, so it may be that the control is kicking the heta pump out because one room is up to temperature.  

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Monica B

Monica BComment left on: 26 February 2010 at 1:19 pm

I have a water source heat pump which is heating radiators - a retro conversion. We have a digital thermostat/timer in the hall - Honeywell CM907 and TVRs on all radiators. The CM907 is too accurate for the system despite being set at a minimum on time of 4 mins and cycle rate of 3 per hour, which are the oil boiler settings. The heat pump frequently fires for only a short time before the thermostat clicks off again, rather than running for longer and letting the temperature fluctuate more. In principle we like the flexibility of the CM907, (such as allowing the setting a higher temperature during periods of economy 10) which a separate room thermostat and timer would not have. Does anyone have any ideas for a better system of control?

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Tim Pullen

Tim Pullen from Weather WorksComment left on: 20 February 2010 at 10:51 am

Alec is absolutely right. Weather compensation is a good idea and a requirement for some local authorities. It becomes virtually mandatory under 2010 Building Regs (to be published in October). But it does not take away from the idea that we need to control the temperature of each room.

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alec Morrow

alec MorrowComment left on: 20 February 2010 at 9:38 am

Tims comments are perfectly valid for old systems, but if you are installing a condensing boiler it is advisable to instal it with modulating controls which tell the boiler from either inside the house or outside how much heat is required at any one time, avoiding wasteful over heating. This means the radiator temperature varies.

All boilers have this technology, its called open therm compatibility or weather compensation or modulating controls, its mandatory in Germany and Holland as it saves energy and makes TRVs and on-off controls redundant saving on the install cost.

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Tim Pullen

Tim Pullen from Weather WorksComment left on: 18 February 2010 at 4:04 pm

The Watersure scheme looks good. It is amazing the number of similar schemes and grants out there for heating, insulation, and the like that all seem to be well guarded secrets. Maybe we should start a campaign to get them all publicised.

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HeatandEnergy.OrgComment left on: 18 February 2010 at 3:56 pm

Hi Tim,

Very interesting - old thermos 4 degrees out, will certainley be checking mine!

Not quite the same subject but we have discovered a scheme the water companies are offering to families to reduce their water bills called Watersure. Just a pity they are not advertising the fact.. more details can be found here ...

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