you can but not at the same time.

Some zone systems give priority to a single zone. So that priority zone will get the call first, from there any opposing calls will be taken when the priority zone is satisfied. Usually this priority zone is set for the Master Suite.

Because it's a zone system the calls rarely take that much time to complete. If you're calling for both heat & cool this typically illustrates mild temps outdoors so there isn't going to be much of a delay to handle opposing heat / cool calls.

If you're running a crypto farm / server room or something similar it's best to have a dedicated HVAC system for that kind of application.

I service the Katy, Texas area.

"so there isn't going to be much of a delay to handle opposing heat / cool calls." Typically there's a time delay between switching modes from heating to cooling or cooling to heating. This is to protect the compressor. A typical time delay is of the order of 5 minutes, so you won't get a more rapid switch over than that. Depending on the number of zones and the requested mode changes that could challenge both your patience and your comfort.

A typical time delay is of the order of 5 minutes, so you won't get a more rapid switch over than that.

It could be 5 min. / can be as short as 180 seconds / 3 min. --- It greatly depends on the equipment used / knowledge of those doing the work.

There is more to the switch over than just protecting the compressor -- because if you have a call to cool the last thing you want is warm air being blown into a zone you are trying to cool or vice versa -- cool being blown into a zone that is calling for heat.

Depending on the number of zones and the requested mode changes that could challenge both your patience and your comfort.

This comment above is why you use a builder to build and an HVAC pro for HVAC work. That being said.. your mileage will vary for probably in the realm of at least a 1000 different variables.

I service the Katy, Texas area.

Heat pump control systems typically include multiple time delays. The most important time delay function is to protect the compressor. There is typically a time delay of 5 minutes +/- to allow for pressures to equalize when changing modes and prevent damage to the compressor. There is also a time delay to prevent damage to the compressor due to short cycling i.e., restarting the compressor (in the same mode) after it's been off only briefly. There may also be a separate time delay on the air handler blower motor which enables the compressor to start up and run for a period of time prior to blowing air. That's a comfort issue, not an equipment protection issue and that delay is for the blower motor, not the compressor.

Time delays can be as short as 1.8 seconds. Could they be as long as 5 min? yes. They can also be as long as 10 min.

I wouldn't call a builder to ask which delay setting is best.

It doesn't take 5 min. for system pressures to equalize after shutting off. I know this because I actually work on these systems.

click to enlarge.

The time for pressures to equalize in a system will be a function of the particular system design and its operating conditions. Compressor time delays are typically 5 minutes +/- You can go with what the manufacturer recommends or you can substitute the "expertise" of whatever HVAC tech shows up on your job that day. The time delay for an air handler blower motor is typically a few seconds. As previously stated, it's not for equipment protection, but rather for comfort. A 1.8 second time delay on a compressor would not be sufficient to protect it long term. I wouldn't suggest it.

"On a Bosch residential heat pump/furnace can i run A/C on one zone while running heat from the second zone?"

In answer to your original question, no you can't (not unless the two "zones" are two completely separate split systems).

Compressor time delays are typically 5 minutes +/- You can go with what the manufacturer recommends or you can substitute the "expertise" ... [ of a builder who doesn't actually do HVAC, but has sub contractors on speed dial ] sic

typically? sometimes but not always. Most modern day thermostats have a delay of 3 minutes built into them. (modern day: made within the last 10- 20 years or so)

Thermostats didn't always have a delay built into them? yes that's right... why I displayed the picture of the specific control above.

The Bosch IDS 2.0 Heat Pump condenser has a delay built into the control board of the heat pump condenser already. Among many other safeties to protect the compressor.

Aside from safety of the compressor the time delay of 5 minutes or longer was primarily used for AC / heat pump condensers that contained piston compressors as trying to start under load conditions would often trip the OL circuit of the compressor and cause nuisance trouble calls.

The OL circuit trips, the compressor isn't going to run until it cools off. Too many 'nusiance' trips of this circuit repeatedly often times kills the compressor. This was primarily a problem of 20 years ago, not today (2023) because piston compressors (reciprocating) are rarely if ever used today in AC or heat pumps.

The Bosch IDS 2.0 uses 3 phase rotary compressors --- light years ahead of what was used even 8 years ago. (protection of compressor is already built into the machine)

Most modern day AC's and Heatpumps use scroll compressors of which *rarely* ever need any sort of delay at all to start up. The con or problem with repeated starts and stops (short cycle) will cause the compressor to become devoid of crankcase oil as the compressor doesn't run long enough to replenish the oil it is ejecting on start up of the compressor.

Short cycle is a term that is often times confused because enthusiasts let alone builders do not fully grasp the term. (how short is short) -- the function of such is even further confused when considering the "normal" operation of a zone system. What is normal? To someone who doesn't actually do what they pretend to do from a forum board. While that sounds like a hit piece this is the world we live in. Context is provided so you don't walk away from this conversation without realizing that meanings of such phrases mean more than what you really think about this subject of HVAC.

If it's 80 degrees outside and the AC turns on finishes the call in 10 min and shuts off then restarts 5 min later only to repeat the same thing? To someone who doesn't know this could be classic example of a short cycle. But is it REALLY? if the system in question is a zone system?

To summarize: if you are physically manipulating thermostat due to impatience you could theoretically initiate as low as 3 min delay from the thermostat, from that point the signal goes to the zone controller which depending on calls received from other zones could initiate at least 180 second delay, maybe longer. From there the zone controller once delay has subsided and signal sent to Bosch condenser could initiate another delay of 3 min imposed by Bosch control board.

So under *certain circumstances* mentioned above the delay could be upwards of 9 min or longer.

I know this because? I have a Bosch IDS 1.0 + zone system at my house that I installed in Oct 2019 at my house. + I actually do this for a living.

Not an enthusiast: Texas HVAC Licensed and Insured.

I service the Katy, Texas area.

The point, and you seemed to have missed it, Ray, is that a time delay when switching over from one mode to another (and that's usually 5 minutes +/-) can result in uncomfortable conditions in all zones. Priority is normally given to heating mode. For illustration purposes, let's say one or more zones are in air conditioning mode when a zone calls for heat:

Zones in air conditioning mode

One or more zones call for heat (priority)

Air conditioning is suspended

5 minute delay initiated for change from a/c to heat mode

Heating in any zones calling for heat. Heating for, say, 5 minutes to satisfy the thermostat

One or more zones call for air conditioning

5 minute delay for change from heating to a/c mode

System returns to air conditioning mode. Elapsed time is 15 minutes with no air conditioning.

Systems aren't designed for rapid change over of heat to a/c or a/c to heat. Your claim "so there isn't going to be much of a delay to handle opposing heat / cool calls." is, well, a lot of hot air.

I'm a licensed P.E. with 18 years industrial HVACR experience and 24 years collaborating on design of residential HVAC systems. I don't know if that makes me an enthusiast, but I'll admit I don't spend my days uncrating replacement equipment, working in hot attics or breathing Freon.

For illustration purposes, let's say one or more zones are in air conditioning mode when a zone calls for heat:

For illustration purposes let's not think why we have one zone calling for heat when all other zones are calling for cool.

You'd rather argue over such a rare occurance so rare that it doesn't matter. But you want to argue so...

It has to be cold to need a call for heat? If it's cold why then are there other calls for cooling?

Charles is a PE that can't see the forest from the trees. (You don't spend your days thinking ahead either... and that's sad, sad, sad.)

As you said before Charles, it's not rocket science. But for some they probably should require a rocket license. ha~ha.