I'm just getting started.
I'd like to try a very basic outdoor reset control.
It would monitor the Outdoor air temperature-- and adjust the boiler leaving water temperature based upon the outdoor air temperature.
From my perspective-- it is two thermisters-- one inside on the boiler supply piping and one outdoors.
A relay would be used to interrupt the call for heat as the gas valve is not modulating.
At zero outdoor temperature-- the boiler temperature will be 180 degrees
At 60 degrees outdoor temperature the boiler will be 120 degrees
In short-- there is a one degree difference in water temperature for each one degree difference of outdoor air temperature
For every degree below 60 degrees outdoor air temperature-- the boiler leaving water temperature will go up one degree
It sounds like a really easy equation
Has anybody done something like this?
Re: Boiler water temperature outdoor reset control
There are no analogue inputs on a RPi so you will need each thermistor wired to produce a varying voltage feeding an A to D converter. Then you will need to calibrate them. From there on it is fairly trivial. You will also need additional hardware to drive the relay.
Re: Boiler water temperature outdoor reset control
On no account must you you interfere with gas valves and the electrics unless you know what you are doing .
You seem to know what you are doing, writing and talking about it , and doing it are two different things
Using Thermistors are a good Idea , thy are easy to use and integrate in to a system. ..I would keep the the system
totally separate from switching gas valves , Just monitor the system and do manual controlling , Using Thermistors
to control Tempratuch valves, you will have to applied " ON and OFF " difrenshale , or the system will hunt
Regards BoyOh
You seem to know what you are doing, writing and talking about it , and doing it are two different things
Using Thermistors are a good Idea , thy are easy to use and integrate in to a system. ..I would keep the the system
totally separate from switching gas valves , Just monitor the system and do manual controlling , Using Thermistors
to control Tempratuch valves, you will have to applied " ON and OFF " difrenshale , or the system will hunt
Regards BoyOh
BoyOh ( Selby, North Yorkshire.UK)
Some Times Right Some Times Wrong
Some Times Right Some Times Wrong
Re: Boiler water temperature outdoor reset control
You could use digital temperature sensors like the common DS18B20 which is easy to interface to the Pi. They work in degrees Celsius, so you will have to either move into the 20th century or convert to old money.
They won't react instantly to temperature changes, but you can cope with that in code easily enough.
I've been using them to control my home heating with a Pi for years now. I have a list of what temperature I want certain rooms to be at specific times of day. If it drops below that it turns my boiler on for at least five minutes, or until the temperature goes above the required level. I also monitor the heated water temperature with a sensor taped to one of the heating pipes.
They won't react instantly to temperature changes, but you can cope with that in code easily enough.
I've been using them to control my home heating with a Pi for years now. I have a list of what temperature I want certain rooms to be at specific times of day. If it drops below that it turns my boiler on for at least five minutes, or until the temperature goes above the required level. I also monitor the heated water temperature with a sensor taped to one of the heating pipes.
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