- Furnace: U96VA (2-stage, communicating)
Condenser: UA17 (2-stage, communicating)
Zone Control: EWC Ultrazone
Zone Dampers: EWC Rectangular ND with MA-ND5 actuator
Thermostats: Econet UETST700SYS (Main Control/Downstairs Zone 1) & RECTL700ZON (Upstairs Zone 2)
When there is a call for low stage heat in Zone 1, I can see from the control tstat than BOTH zone 1 & zone 2 are open. Airflow is approximately 55% to Zone 1 & 45% to Zone2.
If there is a call for high stage heat in Zone 1, then Zone 1 gets 100% of the airflow and Zone 2 is closed.
The same airflows occur, but reversed, when there is a call for heat from Zone 2, i.e., when there is a call for high heat in Zone 2, all airflow goes to Zone 2, but Zone 1 is closed.
Static pressure shown on the control tstat is approximately 0.50 when there is a call for low heat by either zone (both zones open). When there is a call for high heat from either zone, static pressure shown is approximately 0.83 (only 1 zone open).
I do not understand why both zones are open when there is a low heat call from only 1 zone. My assumption, which may be totally wrong, is that if only one zone is calling for heat, it would receive all of the airflow unless the static pressure was too high in which case the other zone would open partially to alleviate some of the static pressure. But as I mentioned above, static pressure as shown on the control tstat does not seem high and there are no alarms being thrown (at least nothing appearing on the tstat).
Is this normal/correct behavior?
The system was installed last spring, so this is first full heating season. I did not check behavior closely in late November/early December when heating season began, but pretty sure if there was a call for heat in upstairs zone2, then there was some airflow in zone1 downstairs.
My thanks for any insights.
