Hydronic balancing

This weekend I came to the conclusion that whatever I do, I’ll never get a well performing central heating without hydronic balancing. I’ve been watching how the temperatures in all the rooms of our house react and where the energy goes to – it’s a mess! No matter how well I’ll be able to control the kettle, temperature control in all the rooms will still be a mess without a hydronicly balanced system.

So this weekend I decided to stop what I was doing (building the Opentherm Gateway) and first try to do something about this balancing issue.

Hydronic balancing is not something I’m familiar with, and I certainly don’t have the tools for it ; but what i can do is provide enough information with these sensors; I don’t know if I’ll succeed, but it’s worth to give it a try.

Sensor for Hydronic balancing The first thing I need to know is how much energy flows through the radiators. Well, I can do that, I guess… A JeeNode with RF transmitter and 2 1-Wire DS18B20 sensors can provide me information about how much energy each radiator produces by measuring the flow- and return temperatures of each radiator.

I’ve got a bunch of JeeNode kits still waiting to be used, enough 1-Wire sensors, batteries and all other components needed, so what am I waiting for??

So this weekend I built a first sensor and a RF-to-Zigbee ‘gateway’ so I can receive all the sensors without the need of USB, RS232 or an additional Ethernet port.

The first sensor is operational now; more will follow!

Red = flow temperature, Blue = temperature drop

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12 Responses to Hydronic balancing

  1. Henk says:

    Hello Robert,

    I think that you are more equipped than the most proffesionals, you can measure room temperature, in and out going water temperature in real time. The only thing you can not measure is the real flow.
    I’m curious what the new graphs will show.


  2. Hi Henk,

    You’re right, I can’t measure the flow. Let’s hope the rest of the things I do measure can compensate the lack of experience I have in this field 😉

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  4. Henk says:

    Maybe a good start there is a procedure starting on page 6 . And there is a lot of information on http://www.klusidee.nl/Forum/ search for voetklep or voetventiel,


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  6. Henk says:

    Morning Robert,

    I was looking at the charts this morning and I was wondering what are your setpoints. The boiler starts burning at 2:00 am and only the livingroom is capable to use some power the other rooms stay ‘cold’.


  7. Good morning Henk,
    The thermostat setpoint is 19 degrees 24/7. At this moment the thermostat is located upstairs, in the passage (overloop). This is to avoid the influence of sunlight on the temperature being measured by the thermostat; although this is not a very good location either…

  8. Forgive my ignorance, but how are you actually going to do this balancing? Will you be making a guess as to where the water is flowing based on the (difference in) temperatures and then make adjustments to the valve positions on the radiators to compensate for difference between different radiators? Or are there other actuators I’m missing?

    Also, I’m not entirely sure I understand why this is needed. What’s the exact problem you’re trying to solve? Some radiators take up too much of the heat/flow so other don’t get any? Shouldn’t this be solved by the radiator knobs that automatically throttle when the room warms up?

    • You’re right, I have no means to measure the water flow. What I do have, is temperature sensors in every room and (since a few days) I can measure the difference in flow- and return temperatures of all the radiators. I like to think (until proven otherwise) that this will be enough for me to apply changes to the central heating system and create a more balanced energy circuit.

      After adding 2 radiators downstairs (in the office downstairs, which was built in 2001) and the floor heating in 2009, too much energy is flowing to the rooms downstairs. The result is that the rooms upstairs don’t get enough energy and barely heat up anymore. This can’t be fixed by automatically throttling valves (IMO), cause this would mean you’d have a central heating that will first primarily warm up the rooms downstairs to the desired temperature, and only after downstairs has been warmed up enough the second floor will get some more energy (cause those valves downstairs will close and “reroute” the heat to the 2nd floor).
      So the answer to your first question is yes. And no, there are no other actuators (I want to use or) that you are missing. Although I could switch off the floor heating pump easily. But I don’t want to do that.

      Maybe the above also answers your 3rd question? 😉

  9. I guess I have a pretty complete picture now. That only leaves me to hope that my central heating installation doesn’t suffer from that problem (so much), since I just ordered some of my first MAX stuff, but I don’t have a cool sensory network in place to do advanced balancing 😉

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