Heat Pumps and Electric Heating - time/temp defrost; 50/70/90 minute?

I asked my HVAC guy if he could set the proposed new HP to 90 min.
He said yes, but it would first reverse much quicker, and the 2nd defrost would be 90. Are they all like this?
Is he correct?
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Is this to melt off snow from an overnite storm?

Thanks!

No. There are two types of defrost. One (like yours) is time/temp defrost. The other is demand defrost.

Both have a temp sensor on the outdoor coil.

In demand defrost when the temp sensor tells the control board the coil is cold enough for a defrost, defrost is started.

You have time/temp defrost. Which means that the control board will check the temp sensor every 50/70/90 minutes of run time. If the sensor is open (meaning cold coil) defrost is started. If the sensor is closed the board says ok, I'll check back in another 50/70/90 minutes.

The thing you have to remember is that the more frost on the outdoor coil, the more cash it cost to heat the home.

90 maybe fine in FL, but keep an eye on the unit (look for excessive frosting on the coil) you may or may not want to drop back to 70.

Now as far as the snow from an overnight storm. My Mom called me from SC after an overnight ice storm. She was concerned about all the ice on the heatpump (as were the neighbors). I told her to turn the a/c on with the tstat set very low for 10 to 15 minutes.

She called back a few hours later, everyone turned on the a/c and no more iced heatpumps.

Thanks! I guess the ruud was defective, as it defrosted after 20-40 minutes. even 70 minutes would be ok as i usually only need 1 hr of heat on a cold morning.
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coil never got more than a light frosting.