Condenser Fan Speed

[kizza231188]

Hey

I am new to RE.

Is there anything bad from running a multi speed condenser fan at full speed all the time?

As in, can the liquid line temp be too cool?

[icemakerman]

Kizza
with the extreme ambients operated under in australia during the summer high fan speed on condensor fans is quiet normal. some manufacturers recommend medium speed up to 38 degrees c ambients, so maybe best to consult with manufacturer.

[nicolacozma]

Hi and welcome,

Using the condenser fan all the time at full speed, will have as a consequence, reduction of the cooling capacity of the system, especially at low ambient temperature. Another consequence could be reduced EER of the system.

[glenn1340]

Another thing to be aware of is if the equipment is fitted with a hot gas valve, if so running the fan constantly can pull down the LP with the result that the hot gas valve will inject hot gas into the LP in an attempt to keep the LP up. Ok in theory but it can result in the compressor overheating and eventually burning out.

[Brian_UK]

What is the full question that you have to provide an answer too?

[kizza231188]

What is the full question that you have to provide an answer too?

Well at the place that I work, there is a dual stage system that is used to cool the kitchen inside. 1st stage has an old copeland recip compressor ( I think ) and at some stage the condensor fan motor seized, and was replaced. When they replaced it, they also installed a condensor fan speed controller, which uses the hp side to control the fan speed. When I saw what they had installed, I noticed that the fan was running fairly slow, and the air that it was blowing was fairly hot. The next day when I came in the 1st stage had locked out on HP/compressor overload. I reset it and it tripped again within a few hours. I opened up the speed controller and changed the pressure settings, allthough I must have changed it too much because ever since then the fan runs full speed all the time. So what I was getting at, is should I adjust it so that its at a moderate speed for say, 22 degree ambient, and then check that its running full speed when it gets hotter outside? Rather than just having the fan running full speed.

Sorry for the long post! Just some info, I'm a student studying electical engineering and I have taken an interest in Aircon/refrigeration, which is why I'm asking these questions! Thanks for all the help.

[Brian_UK]

The fan speed controller should be set for the correct condensing temperature for the refrigerant being used.

Are you able to tell us which fan speed controller is fitted?

[icemakerman]

the first queation i am asking myself is why are you changing settings and not calling the company that installed the controller and getting them to adjust the controller correctly...if you damage the compressor you will have no comeback on the company that installed the controller, the next thing is, is the condenser coil clean, given the extreme ambient temperatures recently i would expect high fan operation at times of extreme load.without fitting guages to the system and knowing what the discharge pressure is i would hesitate to comment on the settings of the fan controller. A little bit of knowlege is a dangerouse thing!!!

[icemakerman]

So what I was getting at, is should I adjust it so that its at a moderate speed for say, 22 degree ambient, and then check that its running full speed when it gets hotter outside?


NO

as Brian stated the controller should be set to the condensing temperature of the refrigerant but it should be set by qualified technician