Solar return temp sensor?

[Hypoxic]

I am trying to measure the temperature rise from my solar panels. I have an EasyTouch system and I am using all 3 temperature sensor inputs. I can probably use the air temp sensor input most of the season for this purpose, but I would like a more permanent solution. Is there some sort of switch that I can wire in that will allow me to have the air temp and solar return line connected to the same input and be able to switch back and forth as needed?
Is there another solution that would work better?
Thanks

 

[JamesW]

You could use a double pole double throw relay that gets triggered when you have solar on.

This will automatically switch from air temp sensor to solar return sensor.

 

[Hypoxic]

This would be perfect since the air temp is only used for freeze protection. I think I could use the Solar Boost Pump relay (not currently used) to trigger the DPDT relay. Can you recommend a relay that would work?

 

[JamesW]

If you have a 24VAC source like from the valve actuator, you can use this type of relay.

When the valve gets 24 VAC to turn, the relay will activate.

https://www.digikey.com/en/products/detail/american-zettler/AZ2800-2C-24AE/12171646

About Installing Solar Heating: First, install the solar sensor at the collectors and connect to the EasyTouch load center.

If HEAT PUMP is selected and is being used in place of a solar heating system, install Solar sensor near the EasyTouch Load Center.

Connect the wires to the SOLAR screw terminals according to the wiring diagram on page 64.

Plug the solar valve actuator cable into three-pin socket marked VLV A on the EasyTouch motherboard.

If a solar booster pump is being installed, connect the pump to a power relay and plug a low voltage cable from relay into the two-pin socket marked SOLAR on the EasyTouch motherboard.

If you have a 24 VDC source, you can use a relay like this.

https://www.digikey.com/en/products/detail/american-zettler/AZ2800-2C-24DE/12171663

https://www.digikey.com/en/products/detail/cit-relay-and-switch/J1512CF24VDC.9/14001752

https://www.digikey.com/en/products/detail/cit-relay-and-switch/J1522CF24VDC/14002253

 

[Hypoxic]

Thanks!

 

[Hypoxic]

I currently have one 24vdc (relay) source available, but I hope to use it for landscape lighting in the future. I have two 24vac (JVA) sources available, labelled Pool/Spa Return and Intake. I don't think they are programmable. Would "piggybacking" off of my Solar (JVA) work? It seems like the simplest solution.

 

[Hypoxic]

I ended up putting in a mechanical dpdt switch. Nice to be able to see how my panels are performing. Looks like I'm getting about 150,000 btu/hr currently.