DX coil distributor issue

[Lc_shi]

Hi sirs,
Usually we order the DX coil directly from manufacturer. It happened we weld the distributor this time by ourselves. There's much unbalance between different circuit(we checked each circuit temp).It looks like an easy thing but we changed several distributor and can't fix it completely. Who has the experience with the distributor tech:-)

rgds
LC

[US Iceman]

Hi LC,

The distributors are usually based on a specific number of coil circuits which are determined by the coil manufacturer. The coil circuiting is based on several items.

First is the coil for air conditioning and does it have a requirement to operate at reduced load? The manufacturers have several different ways to circuit a coil for this. The coil for this may circuited so that the entire face area of the coil is active at part load. This is normally for a large coil with 2 distributors.

A single distributor coil normally has this taken into account.

There are names for the circuiting methods: row split, face split, or interlaced. This has to do with how the coil manufacturer designed the coil circuits for the application.

The distributor tubes have to be equal length, otherwise the pressure drop through each tube will create different flow rates through the coil circuits.

(The coil circuits also have to be equal length. If the coil circuits are not equal length; This creates unbalanced loading of the coil circuits and works the same as unequal distributor tubes)

The distributors are sized for a total pressure drop of 25-40 psi depending on the refrigerant. This pressure loss is for the distributor, distributor nozzle, and distributor tubes.

I like to install the distributors vertically to help distribute the liquid and flash gas.

See the following for additional information.
http://www.sporlan.com/20-10.htm (Distributors)

http://www.sporlan.com/10-9.htm (TXV selection info)

When brazing the tubes into the distributor you have to be very careful to prevent excess solder from sealing off a distributor tube. These can be difficult to solder until the person has some experience doing so.

If you have different circuit temperatures, it appears you have unequal refrigerant distribution in the coil.

Hope this helps.

Regards,
US Iceman

[US Iceman]

LC,

Here is a link that describes the various methods for splitting coils.

http://www.usacoil.com/newsletters/apr.pdf

This is a quick review of the differences.