[drgkjd]

as posted last month, i had 2 new american standard systems installed. these are simple, single-stage units...one 2 ton, the other 3.

while having some electrical work done, the main power was turned off while one of the units was running...and was turned on about 3 minutes later.

so nothing happened, but the question is do the compressors have any built-in start-delay? i know the thermostat has a 5 min delay between cycles.

of course i don't want to try it but what happens if the power has a few-second hit?

ps...looking at the units manual and data, there is not ref to protection or cautions of about starting

 

[supers05]

Most econo / mid level unit's don't. Units with defrost boards sometimes do, as well as some of of premium level. Most mini-splits/ vrf stuff have delays built in.

I like to use the ICM102 (or 105) or similar to add this to any compressor that needs a delay.

Cheers!

 

[user_12345a]

-----of course i don't want to try it but what happens if the power has a few-second hit?-----

The older scrolls could start backwards with a power blip and i know lennox used to put 5 second delay on make timers in their early scroll units to prevent it. (late 80s, early 90s) Running backwards = very noisy, no cooling, can't be great for the scroll mechanism.

then they started putting check valves on the scrolls,

also, starting is hard on the compressor when the pressures don't have time to equalize.

scrolls aren't as affected by that as the recip compressors; scrolls start up almost unloaded due to the lack of valves.

 

[drgkjd]

Most econo / mid level unit's don't. Units with defrost boards sometimes do, as well as some of of premium level. Most mini-splits/ vrf stuff have delays built in.

I like to use the ICM102 (or 105) or similar to add this to any compressor that needs a delay.

Cheers!

thanks..will look into this option.

the system i have in near the econ level (though not the bottom)...looking at the wiring diagram, i don't see any delay mechanism...or any ref to a delay contactor

 

[beenthere]

With the advent of time delays being built into modern thermostat. Straight A/C units generally don't have factory time delays in them.

 

[yuri]

Yep. pretty much redundant.

I would like to see low pressure controls mandatory. Would prevent a lot of burnouts and damaged compressors.