HRV interlocking with Furnace

[joshimh]

I need help with interlocking HRV to furnace so that when HRV runs, furnace blower should run. I have done the wiring as HRV manufacturers say on page # 18 of the attached link, but no luck so far. I have an issue with two installations that we have done in past 2 days. Contacted manufacturer, they advice that HRV board may be faulty but since we have an issue with 2 units, I do not think that HRV board is an issue.

HRV : Nu-Air ES100
HRV Controller : ES-M2
Thermostat : Honeywell Pro3000
Furnace : Keeprite N9MP1 Hi Eff

http://service.clearservice.com/nuair/campaignimages/1/website/pdf/es_man37.pdf
http://www.nu-airventilation.com/products/hrv_residential/

As per the Nu-Air instruction, I have connected:
-   G from furnace board to i2 on HRV
-   I1 from HRV to G on Thermostat
-   C from furnace board to C on HRV
-   I have changed the jumper on HRV so that any speed HRV runs it should interlock with furnace

Help will be appreciated,
Thanks,
Josh

[Admin]

The manual states the jumper is factory set to run the furnace fan regardless of HRV fan speed, so if you changed a jumper it could be causing the problem.  See the first note on page 23.  Maybe you set the jumper so the furnace fan runs only when HRV is on high speed.  The ES-M2 control will only energize the HRV in low speed.  See Section 4.2.3.  Install a jumper wire on the HRV control to energize the high speed fan in the HRV, and see if your furnace fan starts.  Read Pg.12 and cross reference the serial number for the proper wiring to energize high speed.  There are 2 methods.  This HRV has quite the balancing procedure...

With the ES-M2 control you can balance the HRV in low speed only.  I would make sure the jumper is set to Pin #5 (Interlock On If Any Fans).  The ES-M2 control should start the HRV in low speed and the furnace fan should start.

Before you interlocked the HRV did you test to see if fan on at the termostat would start the furnace fan?

Also does the furnace fan start when the thermostat is switched to fan on, with the interlock wiring installed?

Your wiring is correct.  Thermostat G to i1(B).  Furnace G to i2(G).  Furnace C to HRV C.

[joshimh]

As always thanks for the quick reply,

1. I have tried jumper on 5 and 6 pin
2. I tried jumper on HRV for HI speed but furnace blower did not come on
3. yes before and after installation of HRV, furnace fan runs if t-stat is set to fan ON
4. yes with interlock wiring installed furnace fan start from t-stat with fan ON

I got another email from manufacturer, they asked me to jump HRV R1 to HI which turns on HRV fan to hi speed, and check voltage between C and i2 on HRV (should be between 24-29). If no voltage means HRV board is defective. Well I have given new HRV to customer as he was not happy but same problem furnace blower does not interlock. So it does not make sense that both unit board is defective. Still can not figure out what is wrong.

Thanks once again,
Josh

[Admin]

Well that proves your wiring is correct.  Something in the HRV is preventing 24V from powering G.

Are you sure you're waiting long enough?  Maybe the HRV is running in defrost mode.

I agree it's unlikely you have 2 bad HRV's. 

[michaelk]

Hi josh,

I have exactly same issue, my configuration is almost the same ( different version of thermostat). Did you resolve your issue?  any information  will be really appreciated.

Thank you,
Michael