I think I understand from various posts that there are 2 basic kinds of controls for 2 stage heatpumps; I'm calling them - time-delay and  - setpoint delta.  I suppose there are more industry standard terms so please let me know what they are.

Anyway my question is which is more effective and efficient?

My own system uses time-delay controls whereby the 1st stage comes on when the temp falls sufficiently below the setpoint, then if after 15 minutes the setpoint isn't satisfied the 2nd stage comes on, then if after another 15 minutes its still not satisfied the auxillary kicks in.  These delays can be adjusted from 5 minutes to 20 minutes each.  As well, the auxillary can be disabled by a given outside temp greater than 'x'.

I understand that other control systems use a temp difference between the actual and themostat setpoint to manage whether or when 2nd stage & auxillary come on?

Which is best?  Why?

Thanks

For comfort time delay is best because it will usually maintain temp ( minimal swing )

differential staging would be more efficient because 2nd stage wouldn't come on until 1st was unable to keep up and temp actually falls a few degrees ( except if you adjust the temp )

Im working on my company installing a third option as standard because I view these two options on a $40k system unacceptable

My plan is to have outdoor temp sensors control all staging in combo with a 5-10 time delay on second and up , It would require a control and sensor for each stage and its only draw back it time it takes to increase temp the closer you get to each stages balance point
ie. 25 and up 2nd disabled
5 and up aux disabled
obviously increasing the balance point setting by 5 degree's is needed to account for wind , and to allow temp movement
P.S go Giants

Geo fan! are you from New York? are you currently watching it against Philadephia? lol

ct yeah its a good one

Hope they make it to the Superbowl again huh? that was so sweet!

sorry to sidetrack the forum!

I think having both time-delay and setpoint delta options available is the best for a user. Why? Because one can pick and choose as pleased.

Regards, Masoud