Evaporative condenser drain traps

[Superfridge]

Hi all
Is it necessary to to trap evaporative condenser drain lines under all situations? The reason I ask is I have seen a couple of installations recently with no trap. I thought they all need a trap and long dropper legs to overcome the large evap/con pressure drop and to ensure a liquid seal.

One being a single evap/con draining into a hp receiver, this system had no receiver to discharge ballance line either. The condenser has a single outlet drain line so if it was trapped it may not drain well???

The second system is also a single evap/con draining into a hp leg with a high side float and a balance line from the leg to discharge. The evap/con has two outlets with dropers of about 500mm and then T together. This system also has a thermosyphon oil cooler connected to the hp leg.

[Segei]

Idea of liquid trap to prevent condenser flooding.
Example 1. No balance line. Pressure in receiver will be slightly lower and liquid will drain fine. However, liquid can flood condenser if condensing pressure drop suddenly.
Example 2. This condenser can be partly flooded, because it has ballance line and no traps.

[Superfridge]

Thanks Sergei, i'm glad someone replyed.
So it would appear a trap is necessary in most situations and the main reason for the trap is to allow free draining of the liquid from the condenser.

If no trap is installed the condenser drain line would have to be sized for sewer flow and a ballance line should be installed when the HP receiver is located where the abient temperature change is substancial?

[Mark Selby]

As long as your just running 1 cond you can get away without a trap but all your piping needs to be done correctly. As for my company we add traps to all drain legs or reverse traps to headers

[Josip]

Hi, Superfridge

Hi all
Is it necessary to to trap evaporative condenser drain lines under all situations? The reason I ask is I have seen a couple of installations recently with no trap. I thought they all need a trap and long dropper legs to overcome the large evap/con pressure drop and to ensure a liquid seal.

One being a single evap/con draining into a hp receiver, this system had no receiver to discharge ballance line either. The condenser has a single outlet drain line so if it was trapped it may not drain well???

The second system is also a single evap/con draining into a hp leg with a high side float and a balance line from the leg to discharge. The evap/con has two outlets with dropers of about 500mm and then T together. This system also has a thermosyphon oil cooler connected to the hp leg.

Generally, when we have one condenser with single coil we do not need to make a trap, but one condenser with two or more coils in parallel or two or more condensers in parallel it is necessary to make a traps to balance coils, otherwise one or more coils/condensers can be out of duty ....

.... that is very similar to home central heating system where we use balance valves at radiator outlets to balance complete system i.e. to achieve warm water circulation through each radiator ... with traps on condenser outlet drain pipes we do the same ...


Best regards, Josip

[Superfridge]

Thanks for the reply Josip. You explained it well!