Head Pressure for any given Refrigerant

[jakb21599]

Hello friends, is thier a chart that tells you about what the head pressure should be on different refrigerants? Is their a rule of thumb when it comes to checking ? I know that several factors will affect the head pressure, but assuming every thing is good with the system, what kind of head pressure are you looking for when you hook your guages up? these are the most commonly used refrigerants that i am using. R22, R404A, R408A, R410A, R134A, R401A. All have different pressures as you are already aware of, so i was wondering if thier was a rule of thumb as to what the head pressure should be on refrigerants assuming system is fine ?

[Tayters]

As far as I know rule of thumb for an air cooled condenser - saturated high side pressure 15-20K above ambient.

Cheers,
Andy.

[Magoo]

Plan on a condensing temp of +35'C for what ever refrigerant.Maximum +40'C.

[jakb21599]

ok. thanks

[Tesla]

Hi jakb
You may like to search this forum as there was the same question posted a month or so ago with some slightly different values and opinions for rules of thumb.

[jakb21599]

Hi jakb
You may like to search this forum as there was the same question posted a month or so ago with some slightly different values and opinions for rules of thumb.

Hi Telsa, i looked but did not see. Do you happen to remember the name ?

[mad fridgie]

I am going sound like a smart arse, not my intention, but you should not even consider rules of thumb, this may just cause you heartache. In modern times energy efficiency is becoming very important, one of the best ways to reduce power is reduce your condensing pressure "saturated condensing temperature" "SCT", so depending upon the application and the design engineer, you may find TDs from 5 to 20C, then bring in cond pressure control further increasing the range.
When look at refrig system should focus on the system as whole and not just the individual parts of the process

[jakb21599]

I am going sound like a smart arse, not my intention, but you should not even consider rules of thumb, this may just cause you heartache. In modern times energy efficiency is becoming very important, one of the best ways to reduce power is reduce your condensing pressure "saturated condensing temperature" "SCT", so depending upon the application and the design engineer, you may find TDs from 5 to 20C, then bring in cond pressure control further increasing the range.
When look at refrig system should focus on the system as whole and not just the individual parts of the process

I understand where your coming from and didnt take it as being a smart arse. I am just looking for a base line on the different refrigerants head pressures and what they should be under normal running conditions. Example being with R22 and R410A. The head pressures are a night and day difference when the system is running fine and no trouble with them.

[Tesla]

Hi Telsa, i looked but did not see. Do you happen to remember the name ?
http://www.refrigeration-engineer.com/forums/showthread.php?30072-compressor-discharge-temps&highlight=rule+of+thumb is where you will find what I had mentioned.

[Gary]

You will be ahead of the game when you start thinking in terms of saturated temperatures instead of pressures.

If you put two identical systems side by side, containing two different refrigerants, the saturated temperatures (SST and SCT) will be nearly identical, regardless of refrigerant.

If you know what the saturated temperatures should be, then it doesn't matter what refrigerant is in the system.

I used to tell people to ignore the pressure scales on the guages and look only at the temperature scales for whatever refrigerant is in the system, but these days you need a pressure/temperature chart.