Cold Air

Inspected a brand new home, the house had dual zoning one thermostat in the family room and one in the upper hallway… I turned up the downstairs thermostat and only cold air came out, shortly thereafter I made my way upstairs and turned up that thermo, then hot air started coming out downstairs…
Any HVAC gurus got any explanation?
Bad Damper?

What control switches are present, and where are they located?

There was only two thermostat controls for dual zoning…

Digital controller issue.
Way outside of what we can even guess from here.
How “shortly thereafter” did you make your way upstairs.?
When you turned up the second-floor thermostat, was the thermostat set to anything other than heat?
What type of unit was this? Gas, electric, heat pump?
You cannot run one thermostat in heat and one thermostat in cooling or off.
If you want to figure out what’s going on, you need to physically verify if the furnace is on or off when you make adjustments to the thermostat. If you turn the upstairs thermostat down and the first floor thermostat on heat and up, the furnace should not turn off.
There is an end switch on the damper actuator that will not call for heat if the damper is not fully open or the actuator switch is defective.

[QUOTE]
How “shortly thereafter” did you make your way upstairs.?
When you turned up the second-floor thermostat, was the thermostat set to anything other than heat?
What type of unit was this? Gas, electric, heat pump?
You cannot run one thermostat in heat and one thermostat in cooling or off.

About 15 to 20 minutes after…
Thermostat upstairs was off…
Natural gas forced air unit…
So if the upstairs thermostat is off I cant run heat in the downstairs of the house?? That doesnt make sense to me…
Two thermostats are supposed to give you that luxury, correct me if Im wrong…

Tim

Hopefully I can simplfy ??

You are probably looking at a single furnace designed to heat both floors with the help of a modulating damper allowing airflow to shift from the lower area to the upper area, based on the thermostat(s) calling for heated or cooled air. Basically the primary T’stat (probably upstairs hallway) controls the complete system operation and the lower T’stat controls the modulating damper operation for temp. control of the lower zone only.

It’s not the best design to split zones with a single system, even when using a Residential grade VAV damper. The best design is two (2) systems, one for each zone, but this is more cost effective and is certainly better than a single system for both floors/zones as use be standard, years ago.

I’m not sure I really helped much, but I would always call for clarification from a expert in the field of concern or continue to ask for help here, like you have done.
There is no shortage of quality knowledge or people willing to help, when they can.

Tim

One system two stats can be complicated you just almost have to be in the installing contractors head as to how things were wired and what components are in the system.

Very rarely is that type of system used here but if I was inspecting I would turn one stat to the off position and operate one stat and observe what activated from the stat. Did the furnace ignite and you would have to locate the damper motor and observe its position and determine which duct feeds up stairs and what feeds downstairs then reverse the process with the stats. There will also be a situation when both stats can or will be calling at the same time you should note the position of the damper in this situation. This can all be accomplished by operating the controls as described by our SOP