While zoning a HVAC system there are few things that should be firmly kept in mind.
The building that has to be zoned should be highly insulated. Each level of the zone should have identical zoning design. And the zoning should be done in such a way that in case modification or repair is needed at a later stage, it can be easily carried out. Also it should be done in the most cost effective manner. A zoning having less number of zones and fewer thermostats is considered an effective design.
Let’s take the same diagram that we took in the first article and try to understand the basic design considerations before we go further. For this we will just take only one factor i.e. solar gain under effect.
Here, when the sun is in the east. NE and SE are under sun’s direct heat and thus require more of cooling. SW and NW zones are not affected by solar gain and thus don’t require additional cooling. So as the condition of an effective design says, NE and SE should be taken as one zone, including E, i.e. NE,SE and E should be provided with one thermostat and in the similar way SW and NW zones should be considered as one zone, including S and also should be provided with a common thermostat.
A normal design would have made each zone as separate zones with their own individual thermostat. But this will have been an expensive zoning with 6 zones and 6 thermostats. An expert designer will keep these things in mind and reduce the zones to increase cost effectiveness.
Therefore, the above system will be an effective system with two zones and two thermostats.