"HvacTech2" wrote in message
...


Hi PrecisionMachinisT, hope you are having a nice day

On 22-Jul-12 At About 14:21:23, PrecisionMachinisT wrote to
PrecisionMachinisT
Subject: Defrosting heat pumps

P From: "PrecisionMachinisT"

P "HvacTech2" wrote in message


P Now back to the original post--I still think he needs to have the
P jumper checked and reset the timer to 30 or 60 minutes if its
P currently set at 90.......this being somethning I do on a routine
P basis when the weather changes to the point where frosting of the
P outdoor unit becomes problematic.

Again, experience comes in. different brands use different defrost
methods.
Trane uses demand defrost and some use pressure or the standard time/temp.
one would have to know what brand/model he has to be able to even start
to form an opinion. even then it is too hard to make a diagnosis over the
net. you really need to be there to check pressures airflows etc...


Just to get to the basics......IF the coil is frosted and the airflow
blocked, then the system isnt able to pick up much at all in the way of
heat--and so it *needs* to be defrosted...the sensing method and most other
system specifics becoming pretty much moot at this juncture.

--

SVL