Ecobee acc with older lifebreath HRV

Calcafada · October 21, 2025, 05:45:21 PM

I have an older lifebreath HRV. I tried wiring it to my ecobee premium acc terminals. My life breath has 4 wires running to a dehumistat with fan speed control. The wires are only labeled by color. Red, black, yellow, and green. As per instructions I found online I wired red to acc+ and green to acc- and just eliminated the other two wires. I blew a fuse on my HRV 155 max circuit board. Can anyone explain how I can wire this so my HRV will turn my furnace fan on I need the interlock because the HRV uses my air return.

Admin · October 21, 2025, 06:23:14 PM

If you can, post a picture of the wiring at the HRV.

Once you add the equipment to the Ecobee it will start the furnace fan anytime the HRV runs, so no interlock wiring is required.

Calcafada · October 21, 2025, 07:06:54 PM

Sorry I can't seem to add a photo. I'll share photos as soon as I figure it out

Calcafada · October 21, 2025, 07:12:52 PM

Try this https://www.dropbox.com/scl/fo/55voufda2078ia3td7pkx/AG1Q-MslbtuaTn1NL0jMDck?rlkey=yekwbh0clpok0xbkoue0l6wzn&st=yaxqmkmd&dl=0

Admin · October 21, 2025, 08:27:56 PM

You need to follow the mecanical timer wiring. See the attached picture. Install a jumper between ON and RED. Then wire the Ecobee ACC wires to HI and ON. The HRV will run in high speed when it's turned on. You could also use low speed instead. Just connect the ACC wire to LOW instead of HI. The Ecobee can only control one speed and not both.

Levistras · February 04, 2026, 01:00:04 PM

Quote from: Admin on October 21, 2025, 08:27:56 PMYou need to follow the mecanical timer wiring. See the attached picture. Install a jumper between ON and RED. Then wire the Ecobee ACC wires to HI and ON. The HRV will run in high speed when it's turned on. You could also use low speed instead. Just connect the ACC wire to LOW instead of HI. The Ecobee can only control one speed and not both.

hey there, sorry to jump on a thread that isn't mine but I have the exact same issue and am not sure that the response answers the question. Like the OP I have a 5 terminal block on the outside of my 155MAX that runs up to a controller with dehumidistat dial next to my thermostat. the 5 wires are labeled "BLK, RED, ORG, GRN, YLW". in my existing setup the orange terminal is not connected, the other 4 wires run upstairs.

in your response you have a 10-terminal block which I'm guessing is from newer HRVs? I definitely don't have that on mine and I'm guessing OP doesn't either as my situation matches his pictures.

Given that there is no ON or HIGH or LOW or any of that.. is there a known solution for which two of those color coded wires from the 155MAX become ACC+ and ACC-?

Admin · February 04, 2026, 03:39:18 PM

I couldn't even see the terminals in the above picture, so thank you for listing them!

I would jumper BLK and RED on the HRV, and if the HRV starts those are the 2 wires to connect to the Ecobee ACC terminals. The other wires would not be needed.

See the wiring diagram below. The Ecobee would be considered a toggle switch (dry contacts)

Levistras · February 05, 2026, 03:56:54 PM

thanks! I will definitely try that. seems I blew the fuse in the 155MAX and will try again once I source a new one.

Gemini chatbot suggested this is the wiring:

Color Function Terminal #
RED 12V Power 3
ORANGE ON (Control Signal) 2
GREEN LOW (Low Speed) 1
YELLOW HI (High Speed) 6
BLACK COMMON 10

and suggested I jumper red to orange, and then connect acc+ to orange, and ACC- to either green (for low speed) or yellow (for high speed).

I'll report back on which wiring yields the correct result in case others are curious. I'll make sure I have a few fuses just in case!