Any tips on how to air test the following scenario?  We have a single zone HRV system in a House with Suite (i.e., two zone MURB).  The downstairs suite has an outdoor access (door) and no connection to the main floor house, so the building classifies as a 2 zone MURB requiring a 2 zone test. Considering the HRV is set-up as a single zone serving both zones, any tips on how best to conduct the air tightness test (considering the HRV duct system is connecting the two units)?  

Is there any reason you can not put a door on the main and one on the lower unit and run at the same time?

Rider, there is a 1 blower 2 zone solution detailed in the ERS Technical Procedures section 7.6.5. Basically you conduct the blower door test as you normally would, one test for each zone. The only difference is that in addition to measuring the pressure in the unit you are testing relative to outside, and the flow pressure/cfm, you also have to measure the pressure in the adjacent unit relative to outside. So there are 3 data points per pressure measurement. It involves a long hose going into the other unit, and perhaps a piece of metal tubing so you can run the hose in the corner of a closed door or window. Then you just plug in the hose to the other unit into the 'input' on the house pressure side of the gauge. When you choose this method in H2K a new column and section will appear to enter in this additional data. Hope that helps.