I broke the ERV by trying to install an automated control system with the Nest to the Boost control and with Lutron devices to the 0-10 variable control system. The support for the Recouperator was very helpful and sent a new fuse and transformer.
ERV Boost Wiring
Luckily the new transformer and fuse fixed the ventilation system. I brought it all back to factory settings to be sure I was not breaking it again and will start again with connectivity.
I had the Nest connected to the ERV boost by wiring a direct wire from the Nest to the ERV. There are two wires, red and white. But the ERV connections are Boost, Line, and Rtn. Which is think is return or negative. The ERV uses 24 volt AC same as the Nest common and I had the Nest wired white to common and red to G Fan. At least I think I did. I was uncertain of the wiring I used that allowed the Nest to control the ERV!
Recouperator Boost Wiring to NEST
If I connected the Nest common wire to the ERV 24 volt line, then it may have been sending 24 volt from the ERV to the Nest. Probably not a good idea to double the positive inputs to the Nest. If I connected the white wire from the common to the Rtn. Then there would be no connection from the ERV’s 24 volt power which is necessary for the boost to run according to support. So my guess is I used common which allowed the Nest to act as a switch which is what I wanted. BUT support also said that doubling that common wire at the Nest could have caused the issues with the ERV transformer.
There is another option to connect the HVAC system to run the ERV with a furnace blower. Since I have a radiant system that does not use a blower, the furnace control that is typically connected to G on the Nest thermostat, I connected the G and Common wires to the ERV.
ERV Forced Air Connection
Unfortunately, I removed the wrong jumpers and blew the fuse again! I removed JC #6 and 7 when I was supposed to remove #2 and 3. I didn’t see the smaller jumpers and removed the two I saw. So easy to make a mistake when you are unfamiliar with the circuit board.
The air handler/blower connection allows the ERV to run at less that full speed-t0 whatever is set by the variable control that came with the unit. Or with a setting that is controlled by the 0-10 vdc input. Boost runs at full speed only.
I found a way to hook up the Nest to Boost at the same time as the blower connection. There are instructions on the Nest pro installers guide for hooking up a two wire humidifier. The star connection is for a humidifier but I can use the same type of relay to connect to the G fan connection with two wires that come from the ERV. That means I can use a variable speed blower input with one Nest and wire the family room Nest to turn on Boost speed. I also want to have a humidstat in the guest bathroom to turn on Boost when the bathroom is fogged up.
Nest to Humidifier Connection
Here is an explanation of how it was set up by another user at Wrightfuly.com And there is a good explanation about how this works on that site.
Nest with Relay
I ordered more fuses–two packages of the 1/4 amp glass slow blow type and the new fuse fixed the ERV again. Now I have enough to make more mistakes. I also received the relay for the boost control to the Nest and I bought the humidistat for the bathroom. But the completion of the controls will have to wait until after the drywall job.