View Full Version : water chillers

03-07-2006, 11:41 PM
Hi There,

I was wondering if anyone out there could tell me if it matters which direction the water flows through tube type evap heat exchangers, or should it always go in at the liquid end and come out at the suction end or vice versa.


Alex B

US Iceman
04-07-2006, 12:09 AM
Hi Alex,

In most cases it does not matter. The shell & tube exchangers are usually multiple pass meaning the water or refrigerant flows from one end to the opposite end and back multiple times.

On most exchangers with an even number of passes, the liquid and suction are normally on one end for DX purposes.

If the liquid is on one end and the suction is on the other, then I would suppose you have an exchanger with an odd number of passes: 1,3, etc.

You can only confirm this by manufacturers technical data or by taking the head off, which of course requires new gaskets.

Might I ask why you inquired about this?

04-07-2006, 12:33 AM
Hay Iceman,

The reason I ask this is I am currenly working on a carrier 30gf system that was recently re piped and it keeps showing fualt code low chiller flow, i was wondering if the piped the water in the wrong direction and the water temp sensors are picking this up.


US Iceman
04-07-2006, 02:04 AM
Hey Alex,

Is the low flow fault being caused by a flow switch or flow sensing device? It might be a simple as the "flow switch" is not bi-directional.

Or, the flow switch is opening on increase in flow, which would mean the switch is wired incorrectly.

Or, as you say, the temp. sensors may be simply be sensing the temperatures in reverse, which could generate a fault.

If either of these is true, then I guess you could say the chiller is pipe backwards.

Has anyone checked the pumps to ensure they are running the correct direction and pumping full flow?

US Iceman
04-07-2006, 02:23 AM

I found some information on a series 30HZ. Hopefully it is similar to yours.

On page 6 the diagram shows the chiller water connections. Page 7 shows the symbol listing detailing the inlet & outlet.

Product Data

Operation & Installation Manual

Wiring Diagrams

Controls Manual

Some of the files are under 1MB, while one is almost 2MB.

I hope these are close enough to help you.

04-07-2006, 11:52 AM
Many manufacturers like us do not use flow switches, but differential pressure switches. That sort of pressure switch does only operate on positive pressure, that is if the pump is reversed, the chiller will stop.
And yes, the evaporator, whether s&t or phe, does have a preferred water flow, that is counterflow to coldest refrigerant. Water condensers are 2 or 4 passes, but evaporators are very frequently single pass, so the direction of flow is fundamental.

05-07-2006, 10:22 AM
I just talk about the direction of water flow:

Normally,the inlet of chilled water is near the refrigerant suction inlet of DX evaperator to increase the SUCTION super heat degree.otherside,the inlet of cooling water is near the outlet of condenser to increase liquid sub-cool degree.

Chris Burton
22-07-2006, 02:18 PM
Carrier 30GF flotronic 1 trips on flow problems if it senses the entering water temperature is dropping lower than the leaving temperature:D