Come on rocket, you said the primary system would maintain the
temperature even though it could not handle the setback, so this means
it is then sized for the heating load and by your own admission, can
not handle the setback, so you have a booster.

Now the problem is that something sized for the heating load, which
then can deliver a significant amount of heat from a low temperature
source, is going to have much more capacity than needed for cooling
unless of course you live in Bermuda.

I thought when you were pitching 3 systems you realized this problem.
At least you sort of had all your bases covered then, one sized for the
cooling load, another sized to make up the difference needed for the
one sized for cooling's heat output vs the required heat output, then a
third system system to finally prove you could accomplish set back and
then recover in time.

Nothing viable in the above.

So try to increase your batting average then, you finally got a hit
when you realized that in the warmest time of the day you would have
the maximum heat output from a heat pump.

Maybe you could just summarize one of these viable systems that covers
all the bases. Come on bottom of the ninth two out and if you hit a
grand slam, you got a chance of losing with dignity.