Author Topic: Ecobee3 Lite + HRV wiring blew furnace fuse  (Read 9287 times)

Offline redkulat

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Ecobee3 Lite + HRV wiring blew furnace fuse
« on: June 29, 2017, 10:57:14 AM »
I recently installed the Ecobee3 Lite and had everything setup the way it was instructed. Everything worked perfectly, it was working for the first 3 days I installed it. The A/C and fan were turning on correctly and it was all good.

However yesterday I turned on my HRV unit as I didn't test that to see if everything was working correctly. It was not…the HRV turned on, but the fan on the furnace did not. I checked, and my Ecobee was off. I took a look online and someone said to check if the furnace board fuse blew…and it did. There was a big black mark in the middle of the 3 amp fuse.

When I was first wiring the PEK from the Ecobee3, I did notice there was only one "G" wire to control the furnace fan which I found very odd.

The original HVAC company (Applewood) seems to have connected the fan wire running from the thermostat with the fan wire running from the HRV together with a wire nut and jumped it with another wire straight to the control board.

I called Ecobee support before installing and they said there should be no issues.

Well clearly something happened, because the fuse blew on the board. There are two things I think that may have caused the fuse to blow.


1) The HRV and PEK are both connected to the "R" terminal on the furnace control board. When I opened up to take a look, I noticed the HRV wire (in the "R" terminal) was a bit loose (seems like I didn't tighten it enough) so could that have short the fuse?

2) The inter-connected G wire isn't meant to be put into the PEK perhaps. I called Ecobee support again and they said the thermostat should only be connected to the PEK. I can then connect the PEK G wire and the HRV G wire separately into the G terminal. I don't know why there are wires interconnected with the thermostat. Is this normal? I am still not even sure if the two wires connected together with the thermostat and HRV are truly the "G" wire. All I know is they are connected and there was only one G wire prior to installing the Ecobee.

Here is a diagram I tried to put together to make sense:



Side note: Is it okay to have 3 wires connected to the Comm/24V terminal? Currently I have the Ecobee3 PEK  C-wire, my humidifier, and A/C. The PEK C-wire and humidifier are really close to each other in the terminal. This didn't cause the shortage as my humidifier is off and the Ecobee3 was working fine before, but just wanted to check for the winter.

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #1 on: June 29, 2017, 11:32:56 AM »
Use the 3 wire interlock method or you risk back feeding the AC when the HRV turns on.  The Vanee will have NO, NC and C terminals.

Connect HRV NO to R on the furnace board.

Connect HRV C to G on the furnace board. (This should be the only wire on G).

Marette the NC HRV wire to the G wire coming from the PEK.


Offline redkulat

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #2 on: June 29, 2017, 12:15:17 PM »
Use the 3 wire interlock method or you risk back feeding the AC when the HRV turns on.  The Vanee will have NO, NC and C terminals.

Connect HRV NO to R on the furnace board.

Connect HRV C to G on the furnace board. (This should be the only wire on G).

Marette the NC HRV wire to the G wire coming from the PEK.

I've never wired a PEK so I'm not 100% if you should follow the 1st or 2nd drawing I attached.

Wow thank you very much for those drawings they are both helpful. I will try the second drawing later tonight.


I just looked at the manual on page 12 and it is exactly as you described (ALTERNATE FURNACE INTERLOCK WIRING):

http://www.vanee.ca/DATA/DOCUMENT/17_en~v~installation-manuel-60h-series.pdf


1) I'm going to undo the G wire marette with the thermostat and HRV. I took a few pictures from before I installed the PEK.


I took the pictures below  before installing the PEK. Going by colour it looks like HRV wires are:

  • Red = NO / R
  • Green = NC (marette with G from thermostat)
  • White = C?
  • Blue = Empty


So basically the PEK G-wire will be marette with the HRV Green wire (NC), with the White (C) wire connecting to the G terminal





Offline redkulat

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #3 on: June 29, 2017, 12:29:44 PM »
Use the 3 wire interlock method or you risk back feeding the AC when the HRV turns on.  The Vanee will have NO, NC and C terminals.

Connect HRV NO to R on the furnace board.

Connect HRV C to G on the furnace board. (This should be the only wire on G).

Marette the NC HRV wire to the G wire coming from the PEK.

I've never wired a PEK so I'm not 100% if you should follow the 1st or 2nd drawing I attached.

Also just another question, thank you again for all your help.

I have a question about the Comm/24V terminal. I just got the Ecobee3 Lite and there were already two items connected to the Comm/24V terminal.

1) Humidifer
2) A/C

I added the Ecobee3 Lite C-wire (common wire) as well. It was a tight fit, but I made all three fit into one slot. Do you think this is an issue? The humidifier wire and ecobee3 c-wire are slightly touching.

I haven't had the humidifier turned on yet, but do you imagine this to cause an issue or blow the furnace's fuse?

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #4 on: June 29, 2017, 02:40:07 PM »
There's no issue if the 3 wires on C are touching.  You may want to leave one short wire connected to C and then marrette the other wires to it.  Sometimes when you try to put more than 2 wires under the screw they are loose and can be pulled out.  Just make sure none of the other wires on the furnace board are touching wires that are on a different terminal.

I'm thinking it was the way you had the thermostat and HRV wired that caused a low voltage short.

Offline redkulat

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #5 on: July 01, 2017, 10:36:17 AM »
There's no issue if the 3 wires on C are touching.  You may want to leave one short wire connected to C and then marrette the other wires to it.  Sometimes when you try to put more than 2 wires under the screw they are loose and can be pulled out.  Just make sure none of the other wires on the furnace board are touching wires that are on a different terminal.

I'm thinking it was the way you had the thermostat and HRV wired that caused a low volatge short.  You may have double powered G.

I wanted to thank you for the help, you solved my issue. I marette the HRV and the Ecobee PEK G wire together. I tested everything and it I all working perfectly.

Offline jayz79

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #6 on: July 04, 2017, 08:23:54 AM »
Thanks Redkulat for starting this thread and the Admin for the detailed Diagram. This resolved my ecobee3 Lite and HRV wiring issue as well!
- I created this account to Thank you guys!

Offline rwodar

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #7 on: October 09, 2017, 06:07:56 PM »
Use the 3 wire interlock method or you risk back feeding the AC when the HRV turns on.  The Vanee will have NO, NC and C terminals.

Connect HRV NO to R on the furnace board.

Connect HRV C to G on the furnace board. (This should be the only wire on G).

Marette the NC HRV wire to the G wire coming from the PEK.

I used this wiring diagram and blew my 5A fuse on furnace board. I followed everything and double checked wiring. I have the exact same HRV unit.

What could be wrong? Ecobee support told me to remove the G wire marrette and effectively removing the fan interlock with furnace.
I am using the PEK because I have no C wire at the Ecobee3.

Not sure what to do next.



Offline hepkat

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #8 on: January 02, 2018, 03:46:17 PM »
Thanks to Admin! I was doing the exact same thing that redkulat did (including blowing the fuse). Your solution works like a charm!

Sticky this! I've spent all day on this.

Offline Temp223

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #9 on: January 06, 2018, 06:53:56 AM »
Use the 3 wire interlock method or you risk back feeding the AC when the HRV turns on.  The Vanee will have NO, NC and C terminals.

Connect HRV NO to R on the furnace board.

Connect HRV C to G on the furnace board. (This should be the only wire on G).

Marette the NC HRV wire to the G wire coming from the PEK.

Great answer. Thank you. IS there any chance you can explain how that NC/NO/C area works? At first I thought it meant G thermostat ->C hrv-> G furnace, controlled by Something, and if the controller did engage NO (R thermostat) was connected to C hrv and therefore G furnace. But I don’t understand which condition would result (or need) NO-C, or how this switch would turn on the fan when the HRV is on. So I’m thinking it’s a little more complicated.

Thanks!

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #10 on: January 06, 2018, 08:07:45 AM »
You really only need NO and C to engage the furnace fan when the HRV starts, but on some furnaces that can back feed Y and start the air conditioner.  Using the 3rd wire on NC will prevent this from happening.

Offline Temp223

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #11 on: January 06, 2018, 08:25:06 AM »
I think my question is more low level. I’m just wondering what is controlling NC and NO? I apologize if that’s really stupid haha

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #12 on: January 06, 2018, 08:35:44 AM »
The NO, NC and C terminals on the HRV are just a relay.  The NO terminal on the HRV gets its 24V from the furnace R terminal.  When the HRV starts the C terminal on the HRV sends 24V to the furnace G terminal and starts the furnace fan.  The NC terminal gets 24V from the thermostat G terminal, if the thermostat fan is set to on, and then engages the G terminal on the furnace and starts the furnace fan.  This acts like an isolation relay to prevent it from back feeding the air conditioner through the Y wire.

Offline Temp223

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #13 on: January 06, 2018, 08:47:03 AM »
I get it. I think part of the reason I was confused is because I mistook R for heat call. Sorted out now

Thanks!

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #14 on: January 06, 2018, 09:14:28 AM »
Yes, it’s the same R that powers the thermostat.  On a call for heat it sends 24V down the W wire.

Offline redkulat

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #15 on: January 08, 2018, 12:55:01 PM »
Glad to see this post is helping others, thanks to the Admin!

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #16 on: January 08, 2018, 01:44:31 PM »
Yes, we should sell our revised HRV / PEK wiring diagram to Ecobee LOL

Offline Cylac

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #17 on: March 19, 2018, 08:07:47 PM »
Here is a diagram I tried to put together to make sense:


Is this the final diagram of your setup?
I have my hrv interlocked to my furnace and I'd like to free up my C wire by installing the PEK. (I want to use the extra wire to control my HRV using the Ecobee ACC+/- ports.. still not sure it'll work yet!)

Thanks

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #18 on: March 19, 2018, 08:28:42 PM »
Try this one.

Offline Cylac

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #19 on: March 19, 2018, 09:33:48 PM »
Thanks! I couldn't see any attachments as I didn't realize I wasn't logged in at the time! lol

Your diagram is what I was going to try next! ;)

Once I make that switch I'm gonna attempt to hook up my HRV to the ACC+/- ports of my ecobee.

I only have 1 spare wire (the old C) available from the furnace. My HRC control panel (dehumidistat) is right next to my ecobee so I can add additional wires between to the 2 if need be.

I've attached a diagram I put together. I was thinking of adding a wire from the HRV control panel R port (power?) to one of the ecobee ACC ports too.


Would you have some suggestions? recommendations?

Thanks!

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #20 on: March 20, 2018, 07:05:00 PM »
I didn't realize guests could not view attachments.  I changed that setting now.

It looks like the Ecobee 3 PEK is wired differently than the Ecobee 3 Lite and Ecobee 4.  The Ecobee 3 Lite and Ecobee 4 have a PEK terminal and you connect the G wire to the C terminal on the Ecobee and connect the Y wire to the PEK terminal on the Ecobee, the R wire to RC and the W wire to W1.  With the older Ecobee 3 we connect W to W1, R to RC, G to G and Y to Y1.

The interlock wiring in your diagram looks good, but there’s something wrong with how you wired Y I think.  I would wire the PEK Y wire to the furnace Y/Y2 terminal.  That is where the AC is wired to.  Your diagram shows it connected to the furnace Y1 terminal.

You will need to fish 2 wires from your existing HRV control over to the Ecobee 4.  Connect one wire to ACC+ and the other to ACC-.

The Ecobee will act as a set of dry contacts to control the HRV.  There's a setting in the Ecobee to tell the ACC terminals to act as a set of dry contacts and control an HRV.  Keep in mind the Ecobee will only be able to control one HRV fan speed, high speed or low speed.  I recommend using the high fan speed.

You need to cut a piece of thermostat wire and strip both ends and install it on the HRV between the ON 2 and RED 3 terminals.  I attached a picture of a Lifebreath HRV wiring.  There are no bathroom controls connected in this picture.  In this picture a Honeywell Prestige thermostat is setup to control the high speed HRV using dry contacts.

Connect one ACC wire to the HRV ON 2 terminal and the other to the HRV HI 6 terminal.  It doesn't matter which terminal you connect to the ACC+ or ACC- wires.

Your bathroom controls can still connect to the HRV terminals RED 3, YEL 4 and GRN 5.

Offline Cylac

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #21 on: March 21, 2018, 09:46:15 AM »
Thanks Admin for the reply!

The Y wire was correctly hooked up at the furnace panel. I made a mistake on my diagram.  ;D

Before attempting to install the PEK I tried using 2 wires directly from the HRV control panel to the Ecobee. My timers would stop working and flash like crazy until they died completely. I had bridged HRV RED(3) and HRV ON(2).

If I install the PEK, I was thinking of using the spare wire I have (old C wire prior to installing the PEK) and linking it from Ecobee ACC+ to HRV HI(6). Then fish a wire between the HRV control panel (R) and Ecobee ACC-. I'm not sure if that'll prevent the timers from going crazy. I believe the R wire is just power.

I've attached a revised version.

Thanks again

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #22 on: March 21, 2018, 03:22:15 PM »
It's worth a try but I think you will need to use a dedicated 2 wire to connect the ACC+ and ACC- directly to the HRV, ON 2 and HI 6 terminals.  Something tells me you can't connect the Ecobee through the existing HRV control.

Offline tetris

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #23 on: April 02, 2018, 05:28:06 PM »
Can I add a C wire for my new ecobee without changing my current wiring as described in #10 post diagram for Alternate furnace interlock wiring?

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #24 on: April 02, 2018, 05:53:13 PM »
Are you adding a new wire between the furnace and Ecobee and connecting it to C or are you using the PEK power extender?

The interlock wiring is seperate and runs between the HRV and furnace and does not connect to the Ecobee.  The Ecobee wiring would run between the furnace and Ecobee and would not affect the HRV interlock wiring.

If you add the PEK you may have to marret the G wire from the PEK to the HRV NC wire.  What version of Ecobee are you using?

Offline tetris

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #25 on: April 02, 2018, 05:59:16 PM »
I have the option to connect the ecobee3 C directly to furnace C 24V terminal without using the PEK. My current wiring as shown in Alternate furnace interlock wiring diagram. I believe just adding a direct C wire connecting ecobee3 to furnace do nt need to change my current wiring configuration as have no issues with my VanEE HVR and central Air. I am replacing a Honeywell 7-day programable stat that doesn’t have C wire and runs on 2 AA batteries.
Is it safe to add C wire for ecobee3?
Thanks admin for the quick response.

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #26 on: April 02, 2018, 07:37:01 PM »
Yes, that’s correct.  There’s no problem connecting a wire beween the furnace C and Ecobee C terminals.

You may also have an AC or humidifier wire connected to the C terminal in the furnace.

Offline tetris

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #27 on: April 02, 2018, 07:55:33 PM »
That’s correct, AC wire s already connected to C and Y, and I don’t have to remove AC wire from terminal C.
I am still reading if its have any advantage to operate HRV from ecobee3. I guess I will lose fan 3 speed control in this case.
Thanks

Offline rjpotter

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #28 on: May 29, 2018, 01:03:02 PM »
Hoping for some help, I have a similar issue.  Just got a free ecobee 3 lite installed from the GreenON program and the 3amp fuse blows on the furnace board whenever I turn on the upstairs bathroom fan.  I apologize if I don't know the terminology, I'm not an HVAC pro, but I believe the bathroom fan is interlocked with the furnace so that whenever the main bath fan switch is thrown, it also turns on the furnace blower.   There is also a switch on the main floor by the thermostat which also activates the upper bathroom fan & furnace blower - The townhouse was built in 2008, I'm assuming this wiring configuration is building code, and therefore common?
There wire to the thermostat had only 4 wires, so the installer installed the PEK.
Now, the as the wires make there way from the furnace to the thermostat, there are 2 wires spliced into the red & green wires which are then wired into the interlock relay, which is connected to that above mentioned switch that turns on the bath fan & furnace.
The installer has no idea how to fix, and suggests just removing the 2 wires that connect the interlock relay to the furnace - he's never seen this wiring configuration before.    Could the problem be that the interlock wires splice in after the PEK, should they be fed directly from the board instead?   
Any help would be appreciated - let me know if I can clarify anything.

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #29 on: May 29, 2018, 04:04:41 PM »
The switch in the bathroom and on the main floor are 3 way switches and do the same thing, turn on/off the bathroom fan and furnace fan.  This is a ventilation requirement in the Building Code when no HRV is installed.

It's hard for me to see the relay, but I think the white 24V wire is on terminal #1 and the black 24V wire is on terminal #3.  Terminal #1 is a common contact and should connect to the G terminal in the furnace.  Terminal #3 is a normally open contact and should connect to the R terminal in the furnace.

Are you sure he didn't touch the wires maretted together above the plumbing pipe?  It looks like the white common wire is creating a direct short to R.  I would turn off the furnace power and switch the white and black wires above the plumbing.  The black wire should be connected to the red wires, and the white wire should be connected to the green wires.

If that works, turn the thermostat system to OFF and turn the thermostat fan switch to AUTO.  Now turn either the main floor ventilation switch or bathroom switch and start the bathroom fan.  The furnace fan should start running.  Turn the switch and the fans should stop.  Now turn the thermostat fan to ON and do the same thing.  During each test make sure to check that the AC outside has not started when the fans are running.  They really should have ran 3 wires from the relay to the furnace to avoid back feeding Y and starting the AC when the furnace fan starts.  This would be easy to fix if that relay was in the same unfinished room as the furnace.  You would run a normally closed wire from terminal #2 and connect it directly to the wire coming from the thermostat G terminal.  Then Terminal #1 wire would connect directly to the furnace G terminal, and Terminal #3 wire would connect directly to the furnace R terminal.

Offline rjpotter

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #30 on: May 29, 2018, 09:39:58 PM »
Wow! Thanks admin, for the very detailed response.  You are correct about the white wire on relay terminal 1 and black on terminal 3.   Is this mixed up wiring what's causing my fuse to blow?
That relay and the thermostat wiring are quite accessable, so maybe I should have a pro come a rewire everything.  Maybe a dumb question but do I need an HVAC technician or an electrician?
Also, is it normal for that relay to make a loud pop sound whenever the bathroom fan is switched on?

Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #31 on: May 30, 2018, 04:16:00 AM »
Yes, I believe you have the common connected to R which creates a short.  Hire an HVAC pro to do the low voltage wiring.  The popping sound is normal when the relay closes.

Offline Garce

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #32 on: June 19, 2018, 10:30:37 PM »
Sorry for the innocent question
I have:
1. ecobee 3 lite
2. Furnace
3. AC
4. HRV Vanee

I assume that this instructions are to have ecobee controlling Furnace and AC only (while there is an HRV in the mix but not controlled by ecobee but by the HRV control panel)
Correct?
To my dissapointment, ecobee 3 lite doesn't control HRV according to their site


Offline Admin

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #33 on: May 10, 2019, 11:13:00 PM »
Yes, the Ecobee 3 Lite doesn't have ACC terminals.  They need an Ecobee 5 that will actually control an HRV and humidifier, not just one or the other.  This is why I use the Honeywell Prestige 2.0 at home, as it controls both.

I also have an Ecobee 4 I've played around with and to be honest I don't like how it controls the HRV.  You can never seem to turn it off.  The APP never let's you reduce the run time below 20 minutes.  Instead of running 20 minutes an hour it just runs for 4 min then turns off, then will run another 2 minutes and turn off until it finally reaches 20 minutes of run time.  The APP also doesn't let you change a lot of settings available on the thermostat itself.  It does a much better job at controlling a humidifier with it's window frost protection.

Offline Sergroum

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Re: Ecobee3 Lite + HRV wiring blew furnace fuse
« Reply #34 on: May 29, 2019, 12:27:56 AM »
I wonder if there's any other stats out there aside ecobee that have remote sensors. That's really their biggest advantage.