Does anyone have a similar experience with an HRV, and if so, how did you resolve it?
Your absolutely correct. A line filter at your radio won't fix it. You need to kill it at. The source.
First, you need to figure out exactly where the noise is coming from. RF sniffers really help here
It usually is sourced through a power lead or faulty grounding of the equipment. If the device is in a metal cage, sometime just grounding the case , cleaning off rust and paint, can lead to significant reductions .
Next Toroids, Toroids, Toroids. I find that big 2-1/2" clamp on Toroids ($12) can fix most issues or a least tell you if you are on the right track
The HRV is a model SS 3.12 DD (TP). Power is 120 VAC @ 1.5A single phase.
The unit is constructed in a large metal box with 4 ports for air on the top. The unit plugs into a standard three conductor socket. It also has a remote control cable that goes to the two bathrooms for increasing the air flow. The unit was installed this last summer and is on warranty, so I do not wish to open it up. I suspect the noise is generated by a fan motor. I knew I had a serious noise problem some months ago, but didn't track it down until I was able to sniff around with a handheld receiver (Icom IC-R20). I have placed four 31 material snap-on ferrite cores on both the power cable and the control cable with little detectable reduction.
Looking at the Imperial SS 3.12 there are several observations.
It is a metal case but the door is a large service panel that, normal for HRV, is a lift off. That offers no EMI protection.
Often these HRV boxes use foil insulated ducts. I see the adapter is plastic - Check if the foil is insulated from the box. It could be a major antenna.
It has two variable, medium power fans. That means there is a small VFD supplying power to those fans, and VFD (Variable Frequency Drives) are known for EMI (A switching supply on steroids without any noise suppression.)
Since it is under warranty and you have a great spectrum display: Take a screen shot of the noise, write a brief description, and contact your service department. Request they install an EMI filter INSIDE the case with at least 60db suppression in the broadcast band and above. If you can record a noise sample in the BCB showing the interference it will help. Head Office design people are often more sensitive to BCB interference than exotic ham interference.
I was "lucky" with my VFD as it wiped out the local airport landing beacon.
Perhaps asking the company to swap out to a unit that has a fixed speed (or 2-speed) would be the simplest solution. VFD's are always a problem around radio equipment. Sure, you can work on filtering it, but that is a big hassle. HVAC companies are usually not equipped to understand and fix such technical issues and I'm guessing, you'll end up on your own if you want it done correctly. That's the cynic in me talking.
If you can't get the company to fix it for you... If it won't hurt anything to do so, just shut off the recovery system while operating. Is the amount of heat you are losing during operation of your shack a big deal? I'm guessing not.
I don't know what your call sign is (as you didn't publish it here), but where do you live in terms of geography? A HRV system is something that has little real payback unless you live pretty far north if you have a modern HVAC system.