Venmar A130H65RT HRV synchronization with furnace troubleshooting

[thegoodlife]

Hi,
Has anyone set up a Venmar A130H65RT with the following (or similar) equipment to operate in the syncronization control?

Thermostat: Ecobee3 Lite (no accessory contacts).
Furnace: Lennox G32Q3/4-100-3 (model year 2002).
HRV: Venmar A130H65RT

Following the wiring diagram provided by Venmar for interlocking the HRV with the furnace fan, and also interconnecting the W conductor for syncronization with the furnace's heating cycle only results in the furnace fan operating when the HRV is operated, and not the desired control logic of the furnace/T-stat calling for the HRV to run when the T-stat calls for heat. I currently have the HRV in 'Standby' mode, which I assume to be the mode for the syncronization to function, but the manual is not very clear on the complete setup.

I've attached pics of the wiring, as well as the relevant section of the Venmar manual on the wiring interconnections and syncronization setup. The pic of the furnace control board contacts shows the 7-conductor coming in from the T-stat on the right, and the 5-conductor (with orange Gf coming back from the HRV) coming in from the bottom of the pic.

This Venmar unit has the relay built in, and this home does not have A/C, if those are relevant factors in the possible solutions.

Any suggestions would be greatly appreciated. Thank you!

[Admin]

It doesn't look like you have a control wired. If you're using the HRV to switch from STB to MIN or MAX you are bypassing any synchronization.

You likely have to upgrade the Ecobee and use the ACC+/- terminals.  Once wired the HRV should give you AUTO or SMART mode option.  The manual is unclear how the HRV only runs with either heating or cooling using the W or Y terminals.  Maybe you need to use one of their main controls for those options but on page 15 it looks like you can access those options on the HRV LCD screen.

See page 13 of the attached manual and the Wiring for Dry Contact Connection diagram and use the V terminal on the HRV.  It only mentions not being able to use W or Y under the Alternate Wiring for Dry Contact diagram.

[thegoodlife]

Thank you for the fast and detailed response! Your ideas seem sound to me, and I think the manual isn't very clear on what the built in relay actually does, but maybe what I'm trying to achieve isn't typical. After running the HRV over the weekend on continuous low speed, independant of the furnace and Ecobee, it may be better to keep the controls simple until I better understand how the HRV needs to operate to achieve our objectives (lowering RH and generally improved air circulation/exchange). I should have bought the Ecobee5, but a lesson learnt on not future proofing around technology.

Thanks again for taking the time and effort to share your knowledge, it is greatly appreciated!

Jason 

[Admin]

No prob.

I believe the relay is for interlocking the HRV to the furnace so the furnace fan starts when the HRV starts.

If you had the Ecobee with ACC terminals there is no need to install the interlock wiring as the thermostat will start the furnace fan.

I installed an Ecobee and used 20 min ventilation every hour and I noticed when the Ecobee controls the HRV it runs many times during the hour for short 2 or 3 minute periods.

I have never used the equipment synchronization and the W or Y terminals so I'm curious how that works.

They have great Tech Support if you needed some answers. 

1 (800) 567-3855

[thegoodlife]

Thank you for the additional insight and the tech support suggestion as I'd like to understand the intent of the syncronization function as the manual makes it sound like the furnace should be calling for the HRV to start upon the furnace fan starting with a heating/cooling cycle, but I'm not sure their relay could actually do that reverse control logic. I will give them a call and let you know the outcome.

BTW, I've found the Ecobee default's settings (especially the Heat Differential Temp. threshold) to be very inefficient considering their marketing focus on energy efficiency. Even though I run the 2-stage furnace using a single stage thermostat configuration I have the Ecobee staging set to Manual to be enable selection of the Heat Differential Temp. threshold to a more reasonable deviation to prevent many short runs of the furnace. This is all explained on Ecobee's support website, however the average user isn't going to dig that deep into the manual controls and I definitely don't see the need to have a 0.3oC (0.5F) differential to make the home feel comfortable. I ended up loosening up the control to 1.1oC and the number of furnace starts per day is considerably less with a neglible change in comfort (at least for me) and hopefully more efficient use of energy over the long term. Ecobee actually recommends a 1.1oC heat diff. temp. threshold for a heat pump, so why would they not suggest the same for a furnace, as many short runs on any piece of mech. equipment doesn't make much sense.

Sorry for the rant. Thanks again for the assistance and interest!
Jason