controlling water valves for heating system

[pascalspits]

I just found out that all the radiators in our newly bought house are individually connected to collectors in the boiler-room, so instead of using the FHT8V3 radiator valves I would like to use normal water valves on the different water circuits to all individual radiators.
this way I only need to have Domoticz monitor temperatures in all the rooms, and let it open the valves towards radiators in the rooms where heat is needed ...
as the boiler is located in the garage, and so will the Domoticz server be, we could use a wired solution for controlling these valves ?
which valves do I need exactly to control the water circuits to the radiators ?
which controller (wireless or wired) do I need to let Domoticz take control of these valves ?

[deennoo]

Depending of your collectors / manyfoilds, what brand it is ?

You can use thermal actuators with m30x1.5 plug (like this :http://www.eberle.de/product.aspx?id=2384 ) and a wiring
Connection strip (like this : http://www.eberle.de/product.aspx?id=757)
And a relay board to plug each relay instead of each room thermostat

[pascalspits]

I will need to control 10 water valves + circulation pump + boiler burner ... so 12 outputs
and also, to be complete, I would need to monitor the water temperature as well ...
so how is the best way to control these (slave Pi ? Adruino ? some other Ethernet wired device ?)

please advise ...

[pascalspits]

I'm thinking about using Arduino with Ethernet shield and a 16 relay board (or a Triac board ?) ...
... and using 1 input on the arduino to read the water temperature in the central-heating-boiler

This will then be connected to the LAN and controlled by Domoticz (setting up devices through the Lan on the Arduino ?) by programming rules and scenes ...
-> Does this make sense, or am I overthinking it, or are there better/easier/cheaper ways ?

And a second thought : if I use the Ethernet shield on the Ardiuno, will I still have enough GPIO left to control all the relays and the temp sensor ?
maybe use an Arduino Mega to make sure that I heve enough GPIO ?
-> or am I, again, overthinking thing ?

You guys here have tons of experience with this stuff, and I'm a complete newbie ... so asking for advice ...

Thanks in advance
Pascal

[TallGuy212]

When each radiotor is connected to a distributor you can use an actuator from Watts, the 22c which comes in nc and no versions. They can be conrolled with a simple switch, the watts controller on 433 or via a relais.

What this basically does is open or close the flow to the radiator by plugging the actuator in an electrical oulet for the nc (normally closed) version. A simple cresta thermometer in the room and every room can be individually controlled. What is missing is the control over the central heating, you will need an OpenTherm Gateway for this if your central heating works with opentherm. The OTG is however in short supply and the heatcontrol from benext does not work with domoticz. I am looking at a similar setup, but controlling the central heating is still to be solved.

[jkimmel]

Why using an OTG?

Why not controling room temperature (as described) by actuator and temp sensor and setting temperature by thermostat setpoint. Look in the hardware section for dummy >>> thermostat setpoint.

Thermostat setpoints can be set by their timers or likewise by lua scripts.

The pity is that thermostat setpoints are not (yet) usable with blockly but lua scripts are an easy way.

Look here:

Code: Select all

-- script_time_HeizungSchlafzimmer.lua

function TimeElapsed(s)
   year = string.sub(s, 1, 4)
   month = string.sub(s, 6, 7)
   day = string.sub(s, 9, 10)
   hour = string.sub(s, 12, 13)
   minutes = string.sub(s, 15, 16)
   seconds = string.sub(s, 18, 19)
   t1 = os.time()
   t2 = os.time{year=year, month=month, day=day, hour=hour, min=minutes, sec=seconds}
   difference = os.difftime (t1, t2)
   return difference
end

debug_option = 1
TemperatureUpdateElapsed = TimeElapsed(otherdevices_lastupdate['Schlafzimmer'])
sTemp = otherdevices_svalues['Schlafzimmer']
-- sTemp = tonumber(sTemp);
setpoint = otherdevices_svalues['Setpoint Schlafzimmer']
--  setpoint = tonumber (setpoint);
if 
		debug_option == 2 then
    		print("Schlafzimmer script Starting..." )
		print("Schlafzimmer TemperatureUpdateElapsed is " .. TemperatureUpdateElapsed)
		print("Schlafzimmer = " .. sTemp .. " degrees.")
		print("Heizkreis Schlafzimmer " .. otherdevices['Heizkreis Schlafzimmer'])
		print("Thermostat Schlafzimmer = " .. setpoint .. " degrees.")

end

commandArray = {}

if 
		(TemperatureUpdateElapsed > 600 and TemperatureUpdateElapsed < 700) then
		commandArray['SendNotification'] ='Schlafzimmer Temp sensor has not sent an update in 10 minutes. Disabling Domoticz temperature control.'
    		commandArray['Heizkreis Schlafzimmer'] ='On'
end

if		setpoint < sTemp and otherdevices['Heizkreis Schlafzimmer'] == 'On' then
   	if     debug_option == 1 then print("Temperature Schlafzimmer above thermostat set point. Turning central heating OFF." ) end
   		commandArray['Heizkreis Schlafzimmer'] = 'Off'
else
     
if 		sTemp < setpoint and  otherdevices['Heizkreis Schlafzimmer'] == 'Off' then
     if 	debug_option == 1 then print("Temperature Schlafzimmer below thermostat set point. Calling for heat." ) end
        	commandArray['Heizkreis Schlafzimmer'] = 'On' 
   end
end

return commandArray

Of course you can omit the time function.

[ThinkPad]

When going this way i would always build in a backup manual function.
What are you going to do when your domotica controller dies at Christmas evening? It will take a few days to receive spare parts then....

[jkimmel]

When going this way i would always build in a backup manual function.
What are you going to do when your domotica controller dies at Christmas evening? It will take a few days to receive spare parts then....

Second RPI is waiting for that

[MikeBass]

Well, I say that this is really a good idea. Now I am planning to put up a better water heater system in my home.
http://www.bestsellingreviews.com/Home/Water-Heater/

Thanks for sharing!

[ThinkPad]

I see i had already posted in this topic. But an extra addition: for a system like this you also need to have a so called 'bypass' installed in your system. Otherwise if all valves are closed the pressure will rise inside the system, and your heater can get damaged. The bypass prevents this. It is installed between the outgoing and incoming pipes of the heater and it will open at a certain waterpressure. The heater will see that too hot water is coming back and turn it's flame off.

[jkimmel]

This thread is quite old nevertheless here is one mmore point:

instaed of installation of a by pass you can control your pump.

If all valves are closed shut down pump