Any HVAC techs on here?

If so I need some advice please


Ok so I have a 2 ton water cooled AC from comfortaire it is model WPC-24.

My water valve was faulty (when the compressor shut off water still flowed through the unit) so I changed it out.

In order to adjust the water flow, I need to hook up a manifold gauge and set the water flow rate so that the high side pressure reads 230psi.

from the instructions:
WATER VALVE
The Water Regulating Valve is adjustable (by
means of stem on top of valve) to control
refrigerant system head pressure. Counter
clockwise rotation of the handle increases
head pressure and clockwise rotation
decreases the head pressure.
It will be necessary to field adjust the valve
because of variance in water pressure, flow
rates and temperature encountered.
Fasten a service head pressure gauge to the
service fitting on the compressor discharge
line to determine the head pressure. The
optimum condition is 230 p.s.i.a.


Also as I installed the high pressure line to the water valve some R-22 was lost. Of course I'm not sure how much and I'd like to check if I have sufficient freon in there now. The unit SEEMS to run fine, and in the meantime I set the water flow rate so that it seems like the rate/temp of the water coming out is the same as it was before (with the old faulty water valve).

The air coming out of the unit is 50 degrees f
So my question's are :


1. How do I determine whether I lost enough Freon that I need to add some?

2. How do I know how much freon to add without adding too much? (I have access to a tank). The yellow sticker where all the values are supposed to be inside the panel is blank...no numbers


3. The attached images are of my red hose terminal on the manifold. Is this a low-loss fitting (I think it's not). I understand that without a LL fitting I'll lose a bunch more freon if I attach and unattach the high side hose. If I need to I will get a ball valve or other Low Loss fitting before I attempt any of this so I can dump the high side pressure into the low side before removing the manifold.

4. Is there any sort of pressure gauge that can be permanently installed on the high side? I'm just thinking that as the seasons change and my entering water temp changes my ideal water flow rate will change as well. This would give me at a glance ability to maintain correct water flow through the unit.

Any help much appreciated. And if you take the time to answer please let me know whether or not you're trained in HVAC.

I'd post this on an HVAC forum but they'll all just tell me to hire a pro...

Happy Happy

I'm not a HVAC technician, but I've done lots of work in automotive related a/c, which is R-134, which is just a different flavour, really. The pressure/temperature relationship is the main difference between the them.

1. How do I determine whether I lost enough Freon that I need to add some?

In the systems I work with, you can't. In order to ensure a proper charge is achieved, you need to recover the refrigerant, and then charge the system to the proper amount. This is accomplished using a machine, and a scale to weigh the refrigerant tank before and after. Simple math, and voila, you now know the amount you put into the system.

2. How do I know how much freon to add without adding too much? (I have access to a tank). The yellow sticker where all the values are supposed to be inside the panel is blank...no numbers

Weigh the supply tank, before and after. Good luck metering it as it flows in though, that will be tough. Don't overcharge it, liquid refrigerant in the compressor is worse than being undercharged.


3. The attached images are of my red hose terminal on the manifold. Is this a low-loss fitting (I think it's not). I understand that without a LL fitting I'll lose a bunch more freon if I attach and unattach the high side hose. If I need to I will get a ball valve or other Low Loss fitting before I attempt any of this so I can dump the high side pressure into the low side before removing the manifold.

A low loss line will prevent freon from escaping to the atmosphere, it doesn't affect what is in the system. When you attach your gauge set to the service port, you are removing refrigerant from the system, by filling the gauge set lines. The rule of thumb is 2 oz of refrigerant is contained per foot of line. Or maybe that is per line. I've smoked too much since I last checked and I can't remember, so google it.

4. Is there any sort of pressure gauge that can be permanently installed on the high side? I'm just thinking that as the seasons change and my entering water temp changes my ideal water flow rate will change as well. This would give me at a glance ability to maintain correct water flow through the unit.

I don't see the problem with leaving the gauges permanently attached, they shouldn't leak. Check it by spraying with a soap and water mixture around the fittings and look for bubbles. In your case, I'd just leave it connected.

A small loss from attaching lines is probably insignificant, I never worried about getting it 100% perfect and have never had problems from losing an oz or two or three or who knows from attaching and removing the gauges. Check the capacity of the system, it's not two-tonnes of refrigerant in there. It'll likely be a couple of pounds. The average vehicle holds 1-2 lbs, and plus or minus a few ounces won't hurt it either way. Too much refrigerant is dangerous, the system won't be able to boil enough of the refrigerant and you may end up with liquid going to the compressor. Too little, and you'll end up with poor cooling, and risk compressor damage because of lack of lubrication. The oil in automotive systems is carried around by the refrigerant. In a household refrigerator, it isn't. The oil is in the motor case and stays there. In your case, I don't know.

Hope this helps!

Edit: A low loss fitting holds the refrigerant in the gauge set line, rather than allowing it to escape to the atmosphere. It won't go back into the system, unless you have a pump to force it there. The same amount of refrigerant will be removed from the system when you attach the lines. If you connect and disconnect the same gauge set over and over, you'll lose a lot of refrigerant without a low loss fitting. If you use one, the same refrigerant will be trapped in the lines, so you will lose far, far less refrigerant when you connect and disconnect the line. However, over time this refrigerant will escape from the lines.

lifeinabox said:

A low loss line will prevent freon from escaping to the atmosphere, it doesn't affect what is in the system. When you attach your gauge set to the service port, you are removing refrigerant from the system, by filling the gauge set lines. The rule of thumb is 2 oz of refrigerant is contained per foot of line. Or maybe that is per line. I've smoked too much since I last checked and I can't remember, so google it.

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Click to expand...

My understanding is (and correct me if I'm wrong), that a low loss fitting will trap the liquid freon in the high pressure hose, and by then opening both valves on the manifold gauge, most of the high pressure liquid r-22 will force its way (because of the pressure differential) into the low side thereby losing less freon than I would without a low loss fitting.

That sounds possible, but I'm not sure. They way I would do it was with a machine that recovers the freon in the lines and gauges after the system has been charged the proper amount. If the compressor is running, with the low side hooked up, in an automotive system it will pull down to about 20-30 psi on the low side, which will recover some of the freon in the gauge set, but not all. You may be able to get more out of the line this way, because the static pressure (compressor off) is anywhere from 70-100 psi. The regulations are *very* strict on not venting refrigerant to the atmosphere, so the gauges I use aren't designed to do what you mentioned, but it may be possible, although you will end up losing some.