It is possible to fine tune your central heating system by balancing the radiators and applying a modulating thermostat in cooperation with a modulating boiler.  The first measurements revealed a 37% reduction in gas consumption. Read further  how I discovered this amazing fact.

The High Efficiency Boiler Setup

Mister Joep van de Ven (CV Tuning) fine tuned my central heating system. This involved lowering the maximum power-output from 11 kW (50% of maximum output) towards 40% (approximately 9 kW).  The ‘comfort-setting’ mode, set to deliver warm water instantly, had already been disabled.  The temperature on the central heating circuit was lowered from a default of 90 degrees Celsius:  I already turned it down to 65-70 degrees Celsius.  During harsh winters,  the only thing I do is change it back to 75 degrees Celsius,  so that there’s sufficient warmth.   All of these settings are quite easy to adjust and can be found in my central heating system manual.  My goal is to maintain as long as possible in the area where the boiler has it’s best efficiency:  107%  due to the energy which is stored in water vapor,  released in the emission of burned natural gas.  This heated air will settle on the condensor and transfer to the circuit to warm your house.  This process stops when the returning central heating water circuit exceeds approximately 58 degrees Celsius.   That’s why it’s important to monitor the temperatures!

The Radiators

All radiators were set up and fine tuned by Joep with the  aid of a special socket/key. After he finished his work, I could immediately feel how the bathroom got warm, while the living room and kitchen also warmed up. Before this, the living and kitchen would turn cold / cool down when the bathroom radiator was opened and got warmer.   The sound is also more noticeable:  earlier,  I could hear the ticking noises of expanding pipes,  but this is considerably less noticeable after the fine tuning. Now I could really feel  the difference in the way the  central heating and modulating thermostat were cooperating.   After all,  I didn’t change any setting on the radiators after Joeps’ work was done.

The Thermostat

When I bought this house a simple thermostat was mounted in 2006:  a Honeywell Round Modulation model.   During renovation,  I exchanged this one for a more advanced clock thermostat,  the Honeywell Chronotherm IV, which is an on/off switching type thermostat instead of a modulating one (bad mistake, as I thought it was modulating…). As the central heating is capable of modulating to the desired output, you can imagine there’s room for improvement.

So I upgraded the last one for a modulating thermostat and the old one got issued to a friend who needed one.

During selection of a matching thermostat,  I also reviewed models of ATAG (in advance of upgrading to a Qsolar system).  Though it wasn’t that obvious, the Z-protocol could cause some trouble for my OpenTherm central heating system.  Instead I opted for another Honeywell thermostat: the Honeywell Chronotherm Modulation model.

Honeywell Chronotherm CM937 Modulation Thermostat

The installation of the new thermostat was easy:    just turn off the complete system,  disconnect the thermostat and re-connect the new one. When operational, you can see on the display the modulating of the central heating:   the more ‘flames’ that are shown, the more output your heating system will generate.  After this,  it is clear the burner will start at approximately 80% and then throttle down to approximately 12,5%.   After a while, the burner shuts off and remains off until the thermostat requires more.

Last Weeks Natural Gas Consumption

The Enymate is mounted onto the main gas meter and after a week with this fine tuned and water balanced central heating system,  I collected the data from Enymate and made a graph of it.

The modulating thermostat has been mounted since January 18th, and during the period of  of January 17 & 18,  a temporary solution was installed.  Some of the  extreme figures indicate a moment where I took a shower or needed warm water or cooking (on gas).

With the gathered data,  you can visualize the behavior of the central heating system. You can immediately see the results of an optimized heating system (fine tuned and water balanced)

Here on the left side, you can see the data extracted from the Enymate. Since 12 Midnight,  the boiler/heating system is still active, while no energy is requested even though the program’s ‘sleep mode’ is active.  Take notice,  this is the night before the heating system was fine tuned and water balanced,  and a on/off switching type thermostat. Even the built-in (embedded) hot water reserve (which holds up to approximately 8 liters of warm water) was disabled.

To compare, I also used a day (December 2009) and plotted the data from the late night/early morning (until 6:30 AM) to visualize  consumption of natural gas.  In total,  that night,  2.8 cubic meters were used.

Below you see the second graph: the time during night/early morning in December 2009. A typical behaviour of an un-balanced central heating system with a switching-type (on/off) thermostat and default radiator-setup. Notice the extreme activities.

For your information, in the above graphm  the interval of measurements is set at 3 minutes (20 measurements/hour).

On Friday,  January 15th,  the company “CV Tuning” visited me and adjusted some parameters.   And what was the impact on the central heating during the night/early morning?  Sadly, there isn’t any activity at all: zero consumption!  And this is also many nights after the moment of optimization:  no activity, no consumption!  This saves me approximately 2 cubic meters of gas a day. That is about 5 kg of CO2 emission that hasn’t been expelled by 1 household,  with a one time and simple action. That’s approximately  € 1,30 you don’t have to spend on natural gas.

In my household, which uses approximately 800 m3 of gas on an annual basis,  this would imply that 150 nights (Autumn & Winter) if about 300 m3 of gas.  A reduction of  gas usage of approximately  37% (calculated/estimated).

Thats amazing, Mike!   And it is still very comfortable:  the kitchen and living room are on the same temperature when I arrive.

To make things visual again, here on the left you can see data extracted from the Enymate on the first night after fine tuning and water balanced settings.  The last moment the central heating uses some gas is on 10:27 PM,  and it returns to ‘deep sleep’ mode.  It is set to be activated at around 8:15AM  and start warming up my house, so at 10:00 AM the temperature is right where it should be (19 degrees Celsius). To conclude:  mission accomplished!

It makes you think:  if only this setting has so much effect on 1 house,  imagine the impact when you scale this up!  In my area, where about there are about 300 houses,  it could save 600 cubic meters in gas usage and prevent approximately 1.200 kg of CO2 emission every night!  On an annual basis,  it would be about 216.000 kg!

That makes you think… Think global, act local  🙂

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Niels Thijssen, Weblog: Renewable Energy: NOW!