We've been on several new home construction inspections recently, and three of them had Multi-Zoned Split System heating and A/C installations with electronic diverter valves installed in the ductwork. While these slick new electronics are (or would be) great at saving energy by regulating and limiting heating and cooling based on the desired setting of "the thermostat in the zone', they have all failed in two major areas.
For two of them (installed by different contractors), they both had four zone-dampers in the ducting, but failed to have four corresponding thermostats. Each zone needs a thermostat and without one, well, guess what, there is NO airflow to that portion of the house where one is not installed. Properly done, there would have been two independently working zones upstairs, and two downstairs (i.e. 4 thermostats).
This new complexity has poped up recently and it took some research to get to the bottom of it as neither HVAC installer would admit that anything was wrong with their installation even though there was no airflow to large portions of the new homes. The answer was "Well the system (i.e. thermostat) is not calling for any cooling". In these cases it was a nice warm summer day and as you may know we inspectors crank down the thermostat(s) to 65 degrees or less to get the A/C systems running while we are in the home (opening and closing doors and windows). According to the Diverter System manufacturer's instructions, each electronic diverter needs it's own thermostat. Missing in these cases. Technically, you could trigger two or more diverters with one thermostat, but in these two homes they apparently were not wired that way, and there was not a whiff of air flow. But putting two diverters on one thermostat defeats the purpose and efficiency value of having the split zones. You might as well have installed mechanical diverters that could be manually adjusted as necessary for proper heating and cooling.
The third house was a bit more interesting as it had the upstairs thermostat (only one) in the master bedroom. This was a 4K square foot home with four large bedrooms and three bathrooms upstairs. Needless to say, if you were to close the master bedroom door for the night, best of luck for any proper heating or cooling for the other three sleepers.
What do we do, and what should you do if you find the issue of no airflow or can't match the thermostats to the systems installed? Write it up as a major defect and throw it back to the owner or builder. I would hate to have someone move into the new home and the first issue they have is a lack of heating or cooling when they are finished for the day and have just sat down to relax.
Here are a couple of pics to reference one of the HVAC installations with electronic diverters. Notice that the installer was courteous enough to put tags on the diverters, but the helper (or vice versa) never came and wrote on two of the tags, which zone each one was controlling.
This new complexity has poped up recently and it took some research to get to the bottom of it as neither HVAC installer would admit that anything was wrong with their installation even though there was no airflow to large portions of the new homes. The answer was "Well the system (i.e. thermostat) is not calling for any cooling". In these cases it was a nice warm summer day and as you may know we inspectors crank down the thermostat(s) to 65 degrees or less to get the A/C systems running while we are in the home (opening and closing doors and windows). According to the Diverter System manufacturer's instructions, each electronic diverter needs it's own thermostat. Missing in these cases. Technically, you could trigger two or more diverters with one thermostat, but in these two homes they apparently were not wired that way, and there was not a whiff of air flow. But putting two diverters on one thermostat defeats the purpose and efficiency value of having the split zones. You might as well have installed mechanical diverters that could be manually adjusted as necessary for proper heating and cooling.
The third house was a bit more interesting as it had the upstairs thermostat (only one) in the master bedroom. This was a 4K square foot home with four large bedrooms and three bathrooms upstairs. Needless to say, if you were to close the master bedroom door for the night, best of luck for any proper heating or cooling for the other three sleepers.
What do we do, and what should you do if you find the issue of no airflow or can't match the thermostats to the systems installed? Write it up as a major defect and throw it back to the owner or builder. I would hate to have someone move into the new home and the first issue they have is a lack of heating or cooling when they are finished for the day and have just sat down to relax.
Here are a couple of pics to reference one of the HVAC installations with electronic diverters. Notice that the installer was courteous enough to put tags on the diverters, but the helper (or vice versa) never came and wrote on two of the tags, which zone each one was controlling.