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  1. #1
    Join Date
    Jan 2013
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    Nest Thermostat - Fantech HRV working?

    Hi Everyone,

    After I read so many cases and facts online and still can't figure out if my setup is properly done, I'd like to post my case here so that you guys (experts) can help me to solve this issue. I am gonna provide as much details as possible, so it will be a bit long. Thank you in advance!!

    I bought a Nest thermostat and paid $119 to a nest concierge installer to install the thermostat for me (I am located in Montreal, Canada, Nest sent a third party installer). Please see below my equipment:

    Single fuel system
    Nest thermostat 2nd generation
    Carrier (FA4CNF030) Heat Pump (Compressor unit on the outside).
    Aux heat as electrical heating element.
    Heat Recovery Ventilation - Fantech HRC-804M

    I had a separate de-humidstat to control the HRV (Heat Recovery Ventilation), since I want to use the Nest to control everything together (heat, cool and HRV), the tech wire everything together for me into Nest, also installed a relay for the 2 wires of the HRV going into the Nest. However, I didn't realize that the nest can't control the HRV until the installation is completed. Current outdoor temperature in Montreal is -21C, I set indoor temperature as 22C, humidity is recorded as 21 to 25%... Here are my questions:

    Q1: How does the HRV work with my hvac system? I know that HRV is suppose to bring in fresh air and warm it up a bit and send into my hvac return thru the "heat recovery core". I tried to open up the cover, I don't see the vent door open, however, there is slightly some air flowing across, not a lot. Isn't it a HRV suppose to run constantly to bring in fresh air? My model doesn't have a on/off switch to turn on/off, it only has what they called a damper to control the opening/closing of door to allow fresh air in, at which it is connected to my de-humidistat upstair (see attached picture).

    Q2: If the HRV is controlled by the de-humidstat, it won't trigger the vent door to open until the humidity goes above the setpoint, that means the HRV is always off if my humidity is low inside of my house?

    Q3: I connected the wire of the de-humidstat into * terminal of my nest, is it going to work? The tech doesn't seem like to know how to set it up, but he did the wiring anyway because the nest is suppose to control humidifier or de-humidifier, but not HRV! I can select the setting in the nest as "Humidifier, de-humi with a/c, de-humi standalone". He also did some wiring when install the relay downstair in my panel.

    Q4: How do I know if the tech wire my thermostat correctly? I called Nest customer service and they told me the tech wire the thing wrong, instead of O/B, he insert the orange wire into W!!!! I had to switch it by myself. I hope right now it is heating thru my heat pump but not my Aux heating as the second stage (electric element). I don't want to end up paying my hydro catching with surprise!

    Q5: Should I just control the HRV separately with the de-humidstat since my nest is not suppose to control the HRV? My concern is if I leave it the way it is right now, will my HRV still function properly with my unit?

    I am really getting frustrated, the tech is suppose to tell me if it will work or not with the HRV using my nest, I paid $119 and now even worse... I called Nest and they told me to call back the installer, called the installer back, they gave me some comments saying I shouldn't use this thermostat because they don't know, well, shouldn't they accept the job when nest asked them? They said they will call me back next week. Really disappointed.... Hopefully you guys can help me to solve this problem ASAP...

    Thank you so much and please see attached pictures for information.

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