Author Topic: Pek adapter, ecobee and HRV hookup  (Read 4942 times)

Offline Sergroum

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Pek adapter, ecobee and HRV hookup
« on: June 07, 2015, 09:45:05 PM »
Heya folks.

So I'm pondering on a puzzle, trying to figure if it's possible, if I'm missing anything.

So.

I would like to install an ecobee thermostat. It's a wi-fi remote sensor thermostat that requires a common to work properly and can control 1 accessory, humidifier for example.

I've got six wires ready for the thermostat and an optional adapter that would allow me not to have a common wire.

The appliances I need to hook up are the furnace, ac, humidifier, and an HRV. And there lies my problem.

If I hook up the humidifier to the thermostat, I use up my 2 extra wires and I'm out of one for Common. if I use a PEK adapter, I dont need a common, I believe it uses G wire as a common from thermostat to adapter and then onto the common of the control board.

Which works superb, except ... the HRV. If I hook up the HRV in a way that it's connected with the furnace's continuous fan and relays out the G from the thermostat whenever HRV is on, then I lose Common for the thermostat whenever HRV turns on.

That's my puzzle. Let's just say I hope to avoid running another wire.

Does my description make any sense at all? Anyone caught a problem like that before in their experience?

I know I feel like I'm trying to bake the cake and eat it too, but I'm wondering if I'm missing something very obvious.

Offline Admin

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Re: Pek adapter, ecobee and HRV hookup
« Reply #1 on: June 07, 2015, 10:46:54 PM »
Is that the Ecobee3 thermostat you're using?

You should be able to use only one wire for the humidifier.  Use the ACC+ terminal to send 24V to the humidifier solenoid then connect the other solenoid wire to C on the furnace control board, instead of using a second wire to connect to the ACC- terminal at the thermostat.

You will need to make sure you set the other ACC terminals, you use to control the HRV, to the dry contact timer configuration option in the thermostat menu.

I think you will end up needing the following wires,

W (Heating)
R (Power)
G (Fan)
Y (Cooling)
C (Common)
ACC+ #1 (Humidifier)
ACC- #1 (Unused)
ACC+ #2 (HRV)
ACC- #2 (HRV)

That's 8 wires but you only have 6 wires?

I have never seen the Ecobee controls before.  I installed a Honeywell Prestige 2.0 because it could control the HRV and humidifier.  The newer style controls like the Nest and Ecobee3 are nice looking for sure.  I would have upgraded to the Nest but it couldn't control an HRV and humidifier.  The Ecobee3 looks like something I could upgrade to.  It's better looking than the Honeywell Prestige 2.0.  I believe Honeywell has a Lyric model that looks like a Nest but can control an HRV.  I'm not sure if it can control both the HRV and humidifier or just one or the other like the Nest.  Looking at the Lyric manual it appears to control either the humidifier or HRV but not both.

Offline Sergroum

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Re: Pek adapter, ecobee and HRV hookup
« Reply #2 on: June 08, 2015, 08:00:34 PM »
Ecobee3 is exactly what I'm using. It cannot control HRV and Humidifier 'both'. Only one of them. But the HRV never had a humidistat to begin with, so it's been controlled by the 'botton' control on the body of the HRV itself. I'm not too worried about controlling it, I just dont want to lose a common and ... I think you helped me with that. Yes. Externally powered humidifier would work out with just one wire from ACC +.

Then I do not need to use G for common down to adapter and can hijack it for my HRV. It works out. Thanks, man.

The main thing I like about ecobee3 is that it's got a remote sensor and the wifi app to control it the thermostat. Amongst all the 'fancy' thermostats that I encountered, I personally like Lennox Icomfort the most (especially now that it can be adapted to any furnace make if you 'really' want to) and Carrier Infinity Control the least. But neither one of those have a remote sensor, so that's out.

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Re: Pek adapter, ecobee and HRV hookup
« Reply #3 on: June 09, 2015, 07:47:07 AM »
I just re-read the manual.  There is only the one set of ACC terminals.  I guess I will hang onto the Prestige 2.0 awhile longer.