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Thread: Home Heating Automation - which system

  1. #1
    Automated Home Lurker
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    Default Home Heating Automation - which system

    Hi all,

    I am hoping to get my house central heating system to the point where it is all controllable via a pc.

    Looking around the "Heatmiser" stuff looks pretty good,but damn expensive.

    Is there a way I can do something similar on the cheap.

    What I want is a way to stop/start the flow to a radiator, using something like the heatmiser valve, http://www.heatmisershop.co.uk/Heatm...e-p-16203.html
    by reference to the temperature in that room. (I am not bothered about being able to alter this from within each room so just a thermometer would be ok)

    I envisage the pc would know the temp in the room, which it would reference against a set of criteria such as time of day, day of week etc such that just before the kids go to bed it ramps up a few degrees, but then whilst they are in bed starts to drop it down.

    Similarly when the main heating comes on via timer, only certain rooms are heated e.g downstairs until an hour before first bed when upstairs can start being heated. Once we are all in bed then no poinnt heating downstairs anymore etc.

    Does anyone have details of what sort of system I would be best using ? Has anyone used the heatmiser inline valve - before I saw these tonight I always thought the only thing I could use is a 2 port motorised valve. Do you need a constant current to keep the wax valve above the temp required to close it.

    Any pointers in the right direction would be welcomed.

    Thanks
    Stuart

    P.S. Also keen one day in the future to add in cctv pc surveillance with internet alerts, and to connect the alarm system up etc - so much to do and so little time in life !

  2. #2
    Automated Home Sr Member NeilUK's Avatar
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    The Heatmiser prices are actually a lot lower than many other systems around - the price they quote for the valve/thermal actuator is actually less than many plumbers merchants would charge for the actuator alone! I don't think you will find anything cheaper that will give the the features you are looking for unless you make it yourself - possibly using Dallas 1-wire sensors along with a suitable home automation controller such as Homevision perhaps?

    You are right about the thermal actuator - it needs to be constantly powered to keep it open. It opens and closes very slowly, several minutes in most cases. Having said that it is also silent which is useful if you fit thermal actuators onto radiator TRV valve bodies rather than cutting an in-line valve into the pipework.

  3. #3
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    I do like the look of the Heatmiser actuators. How would you fit the actuator onto an existing TRV body, would the trv stay as is with the white plastic dome on top, or would you remove the temperature knob etc and just screw the actuator on top where the brass pin needs depressing ?

    Is Homevision the best sort of controller for something of this nature. Reading up on it a little it only has 8 inputs/outputs unless expanded. Are there any alternative controllers (cheaper) ? I am happy to have a pc running 24*7 to control the system.

    Would I be right to think I would take a temp sensor in as an input, have the if then else logic built around time and temperature of that sensor, and then trigger a relay(s) to open the necessary radiators when required ?

  4. #4
    Automated Home Sr Member NeilUK's Avatar
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    You need to check the existing make of TRV that you have. There are plenty of thermal actuators that are matched to the valve characteristics of TRV valve bodies, for example Honeywell have several different models in their range. You need to make sure the actuator is matched to the valve body, both for stroke (amount of movement from fully open to fully closed) and for torque (effort required to clost the valve). If the torque is too high you will quickly damage the valve seat and the valve will no longer stop the flow of water when closed. Cleverer actuators such as the Honeywell HR80 used in the CM zone system and Hometronic measures the stroke length and has torque limiting built in. Unfortunatley they can only be used as part of a complete system and are much more expensive than conventional thermal actuators in any case.

    Cannot give you any other leads for alternitive controllers, just know there are plenty of HV users successfully automating heating already.

    Simple logic control will give you something that is a little better than conventional thermostats due to the potentially more accurate temperature measurement. More complex control algorithms can add anticipation for closer control or optimum start/stop to automatically calculate the preheat time or shut down time depending on the difference between room temp and setpoint.

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