Is there any way to sense, electronically, if a Raypak pool heater is heating?

[wayner]

I am working on setting up a Raspberry Pi for next year to monitor my pool system, including logging temperatures and heating.

I would like to know when my heater is running. Is there any way to tell this by sensing an open or closed circuit on the heater's electronics? I could put a temperature probe and measure the temperature, but that would have lags and would also heat up or down slower or faster depending on the ambient temperature, wind, rain or other conditions.

Presumably the gas valve gets opened when the control unit tells it to turn on. Is there any way that I could monitor a signal on the valve or something from the control board using something like a Raspberry Pi?

In doing this I could monitor how much gas my heater uses on a regular basis. My heater uses 6.5 m^3/hour when running.

My heater is a Raypak Natural Gas unit.

 

[Rancho Cost-a-Lotta]

Check out the unit linked below. This switch, coupled with a temperature probe, would provide control of the heater in addition to providing remote access and heater status. The unit also provides historical data. You would connect this unit to your heaters fireman's switch using the dry contacts on the Sonoff switch.

Amazon.com

 

[wayner]

Great thinking as I am actually using a different Sonoff switch, the POWR3, to have smart control of my pool pump, and a different dry contact relay to control the fireman's switch. I just bought another Sonoff switch similar to the one you mentioned, the THR20 which I may use instead as it has a "wet" switch that I could use for the pump, plus the dry contact relay to use for the fireman's switch. But with the stock firmware on the THR20 the wet switch and relay are tied together. I plan to flash this device with Tasmota firmware which should allow me to control them separately. And I will have to add some logic as you always want the pump to run for 10-15 minutes after the heater is shut off so that you don't have water boiling in the heat exchanger.

But I would also like a way to directly tell when the heater is on, so I know how many minutes per day it is running. With the thermometer I could indirectly try to figure out when the heater is on or off, but if you could just sense a contact that is open or closed then you would know for sure.

One minor issue with the temperature probe on that device is that is is only 50cm long. But you can buy generic DS18B20 temperature probes very cheaply and wire them up, or just splice into the short one with any wire.

 

[hexabc]

I am working on setting up a Raspberry Pi for next year to monitor my pool system, including logging temperatures and heating.

I would like to know when my heater is running. Is there any way to tell this by sensing an open or closed circuit on the heater's electronics? I could put a temperature probe and measure the temperature, but that would have lags and would also heat up or down slower or faster depending on the ambient temperature, wind, rain or other conditions.

Presumably the gas valve gets opened when the control unit tells it to turn on. Is there any way that I could monitor a signal on the valve or something from the control board using something like a Raspberry Pi?

In doing this I could monitor how much gas my heater uses on a regular basis. My heater uses 6.5 m^3/hour when running.

My heater is a Raypak Natural Gas unit.

You could do some testing to check how much AC current flows into the heater's controller when the gas is closed and how much when it's open. If there is a significant difference (let's say, at least 50mA), you can find a sensitive current sensor converting current to, for example, 0-10V voltage, add a HAT doing ADC conversion, and you are done.