EcoRenovator - View Single Post - Need help with Nest-HRV integration

where2 · 01-20-16, 08:13 PM

You're sure you're getting changes in current checking B and G in different modes? Can you measure resistance and check something...

The troubleshooting (Pg 14) indicated using a resistance jumper 3.9K Ohm between Black (J3-9)and Green (J3-8) to trigger LOW speed fan.

Troubleshooting (Pg14) indicated using a dead short between Black (J3-9) and Green (J3-8) to trigger HIGH speed fan.

Another tech forum indicated other brands of HRV's use different resistances between Black (Ground; J3-9) and Green (Control; J3-8) to switch modes. That would be consistent with the two carrier troubleshooting/installation guides I've been reading.

A momentary short of J3-4 to J3-5 is the same effect as the 20 minute override switch closure. The override feature runs for 20 minutes after the final moment those two contacts were closed. If you close them for 60 minutes, you'll get 80 minutes of High Speed override.

Wiring: Black = ground; Yellow = +12V (DC); Green = control; Red = ???

Now the question is how to determine if the unit is in defrost before making either of these two calls for fan. It's explicit that the unit NOT be in defrost mode when calling for either fan speed.

If you relayed the green wire attached to J3-8, open circuit appears to STOP the fan and potentially energize K5. Closed circuit appears to run low speed fan.

Reversing the current state of the damper can be modified by making or breaking the jumper JU1E.

01-20-16, 08:13 PM	#6
where2 DIY Geek Join Date: Apr 2013 Location: Sunny Florida Posts: 401 Thanks: 74 Thanked 83 Times in 73 Posts	You're sure you're getting changes in current checking B and G in different modes? Can you measure resistance and check something... The troubleshooting (Pg 14) indicated using a resistance jumper 3.9K Ohm between Black (J3-9)and Green (J3-8) to trigger LOW speed fan. Troubleshooting (Pg14) indicated using a dead short between Black (J3-9) and Green (J3-8) to trigger HIGH speed fan. Another tech forum indicated other brands of HRV's use different resistances between Black (Ground; J3-9) and Green (Control; J3-8) to switch modes. That would be consistent with the two carrier troubleshooting/installation guides I've been reading. A momentary short of J3-4 to J3-5 is the same effect as the 20 minute override switch closure. The override feature runs for 20 minutes after the final moment those two contacts were closed. If you close them for 60 minutes, you'll get 80 minutes of High Speed override. Wiring: Black = ground; Yellow = +12V (DC); Green = control; Red = ??? Now the question is how to determine if the unit is in defrost before making either of these two calls for fan. It's explicit that the unit NOT be in defrost mode when calling for either fan speed. If you relayed the green wire attached to J3-8, open circuit appears to STOP the fan and potentially energize K5. Closed circuit appears to run low speed fan. Reversing the current state of the damper can be modified by making or breaking the jumper JU1E. Last edited by where2; 01-20-16 at 08:47 PM..