Water Regulating Valve

[uhPrintUs]

Water-regulating valves controlled by refrigerant head pressure are recommended to be installed in the supply water line to a condenser. I've seen several installed many years ago that are in the condenser leaving water line.

What are some reasons for the recommended location as being in the supply line and not in the return line?

[Joe Harper]

They need to be in the outlet, not the inlet. Otherwise the water will just go down the drain.

[Joe Harper]

Let me clarify that thought.

The water is held in the condenser by the reg valve. When the condensing temp rises, the valve opens up and let's fresh water in, by letting water flow out of the coil. If the valve were to be placed on the inlet, it would open up, and the water would simply flow through the coil and out to the drain. The coil temp would never be regulated.

[mk#1in03]

Most water cooled units I see are always on the inlet side of the condenser. The only one that I can think of that regulates on the outlet side is Hoshi ice machines. I believe the said they use a little less water that way but I could be wrong.

[trouble time]

I must agree most I have seen are on the inlet side of the condenser. I have seen them on the outlet but rarely.

[baub]

If the regulating valve is placed on the supply water side, the out let line has to rise above the condenser, in effect, acting as a trap and allowing the condenser to stay full of water.

One positive point to keeping the regulating valve on the inlet is the water pressure in the condenser will be at atmospheric pressure. If you have a rupture in the wall between the refrigerant/water, as the gas leaks out into the water, little or no water will enter the system. Eventually, all the gas will leak out and both the water side and refrigerant side will be at 0 psi.

In the same scenario, with the regulating valve on the outlet side, when the system loses it's refrigerant charge, the coolant water, under line pressure will be forced into the system.

This is not 100% black and white. It would depend on other factors such as, if the compressor is tripped or cycling on a LP control.

Hoshizaki does install their regulating valves on the outlet of the condenser. And I have seen Hoshi machines squirting water out of the service valves.

I would like the hear what others have to say.

[rayr]

Methinks reading the IOM is a good idea. In a ton of years Hosi is the only one I have seen on the outlet.

[Moparmyway]

I have seen 1 or 2 inlet valves allow the water to completely drain from the condenser. This was on larger machines though, and I too have seen water coming from Schraeders on large outlet regulated water cooled condensers that blew a tube.

So long as you stop the water from completely draining from the condenser, the inlet regulated valve setup is the way to go, IMHO

[skpkey9]

You want the regulator on the outlet that way coil stays full water and has less fouling... Unless you like cleaning fouled condensers

Hope this Helps....

[icemeister]

According to Penn/Johnson Controls, the preferred method is to install the valve on the inlet to the condenser but if the condenser must be fully flooded it may be installed on the outlet side. This is an except from their installation instructions sheet:

Flush water lines to clear any foreign matter that may
interfere with valve operation. Mount valves vertically
on the inlet side of the condenser with spring housing
up. If it is necessary to keep the condenser flooded
with coolant, the valve can be mounted on the outlet
side. When mounting the valve in a position other than
vertical, follow the instructions of the equipment in
which the valve will be installed. Make refrigerant head
pressure connection to bellows. If additional capillary
tubing is required, use 1/4 in. O.D. tubing or larger.

It make no difference to the valve operation, and as I see it, if the outlet of the condenser goes to atmospheric pressure, install the valve on the inlet side and simply pipe the outlet so the condenser isn't free-draining. Then, you keep the condenser flooded and at atmospheric pressure during the off-cycle.

http://cgproducts.johnsoncontrols.co...c=284&req=v46*

[skpkey9]

If the water level continues to rise and fall the water will leave deposits causing the condenser to foul, If you wish to prevent this then the regulator is installed on the outlet so you can maintain a flooded coil, as to the excerpt that Icemiester just posted...
I've haven't had any issues and I alway install or move regulating valve to outlet... The ones on the inlet always seem to have issues...

Hope this Helps...

[Russ57]

Mounting on the inlet tends to keep water hammer down. But then I'm using tower water so I have pressure on both lines. Still I generally see them on the inlet side, even on ice machines.

[uhPrintUs]

Thank you.

Your responses have given me some ideas as to reasons for piping one way or the other. I've seen it done both ways, and was curious why some instructions state to install on the inlet with no further explanation.

[DeltaT]

Consideration must be also taken to how the water cooled condenser is piped.

It should be piped with the supply water into the bottom and out the top so that the water will fill all the piping inside the condensor and leave no air traps.

If not piped that way air traps on the top of the tubing will form and create hot spots which will eventually lead to a bad condensor and/or high head pressure.

The condensor should also be piped with a "reverse flow" meaning that the discharge from the compressor is piped so it meets the coldest of the supply water.

Once those two ingredients are in place, then the water regulating valve should be mounted at the highest spot of the water cooled condenser at the exit of that condensor.

That way all the water will not only fill all the tubing but the supply pressure from the pump/water supply will keep the water pressing up against the tubing.

[uhPrintUs]

Our water cooled condensing units are connected to a closed loop cooling tower. All of the condensers are at a level lower than both the return and supply mains, so the condensers remain full of water whether the water reg valves are installed on the inlet or the outlet of the condensers.

[DeltaT]

Our water cooled condensing units are connected to a closed loop cooling tower. All of the condensers are at a level lower than both the return and supply mains, so the condensers remain full of water whether the water reg valves are installed on the inlet or the outlet of the condensers.

Well maybe, maybe not. Here's a point I'm sure will bring a discussion. It still depends on how your water cooled condensors are piped. If the water supply comes in the top and circulates down to the exit through the bottom there still exists the great possibilites that all of the water in the tube is not making a solid contact against the entire tube, especially the top of the tube, thereby making the unit less efficient as there is less heat transfer and causing an unnecessay higher head pressure.

That would even be more the case if the water regulating valve would be on the inlet side of the water cooled condensor as the water would be subject to the return side of the pump and not to the high side pressure of the pump.

[Russ57]

Seems to me this is getting silly. If we are talking top and bottom then we have a shell and tube heat exchanger. Those that are designed for tower water ideally will have a three pipe connection for tower water. Inlet water is bottom and top, the outlet is the middle. The difference between supply and return pressure is low, typically only a few psi. Regulator goes on inlet side and is controlled by cap tube connected to the head of the compressor. The heat exchange will always be totally full of water and any time the compressor runs the regulator will be open to some degree. It should close completly when the compressor cycles off and high pressure falls low enough. The return water piping has a positive pressure and isn't running a vacuum so it isn't going to drain the condenser when the regulator valve shuts off. The water should be treated and the compressor should run often enough that no fouling takes place. Delta T on the water side should be fairly low and water discharge temp shouldn't be more than 100 degrees under any condition.

The hot gas discharge line has to enter the top of the condenser shell and the liquid line has to be taken off the bottom of the shell. Unless the shell is totally flooded you simply can't get liquid of the top of the shell. Rather it is an air handler coil or a water cooled condenser you want the coldest air meeting the coldest water or the coldest freon meeting the coldest water. After all the hot gas is going to be upwards of 200 degrees. If you allow your inlet water to see that you might not have any water left that is cold enough to get your liquid freon down to 105 SCT and subcooled.

[skpkey9]

This argument is going nowhere fast... No matter how you look at it... each side is right and not gonna waver... I know i'm not gonna give on my position and neither is anybody else....

There now I said it.. And we can now move on to the next issue whatever it may be...

[hvacpope]

Consideration must be also taken to how the water cooled condenser is piped.

The condensor should also be piped with a "reverse flow" meaning that the discharge from the compressor is piped so it meets the coldest of the supply water.

I thought "counterflow" means; when the entering coldest water meets the leaving subcooled liquid first and the warmest water desuperheats the discharge from the compressor.

[DeltaT]

Note the last paragraph fo the tube/tube type condenser & the associated piping pictures as some examples.


Water-Cooled Condenser
Many large commercial refrigerating units use a water-cooled condenser. This condenser is built in three styles:
Shell and tube.
Shell and coil.
Tube-within-a-tube.
In the first type, the refrigerant vapor goes directly from the compressor into a tank or shell. At the same time, water travels through the tank or shell in straight tubes. The second type also uses a shell. However, the water travels through the shell in coils of tubing.
The third type uses two pipes or tubes—one inside the other. The refrigerant passes one way through the outer pipe. The condenser water flows in the opposite direction through the inner tube. Water velocity should be 7-10 fps (2.13-3.04 m/s). If flow is too fast, water may remove the oxide coating, causing pitting. If the water velocity drops to 3 fps (0.3 m/s), scaling will occur.

Also see the piping pictures on:
http://www.hvactroubleshootingguides...ondensers.html