mtushmoo
10-09-2005, 11:11 AM
I was changing a condensor fan on an AC unit at a party store yesterday. The owner of the store asked me if I could take a look at his ice maker. I'm an HVAC guy more than anything else, but figured I could look at it and see if I could do something for him.
His complaint was that it seemed to use a lot of water, all the time - even when it wasn't making ice.
I opened the front cover. I didn't get the model number, but it's got a recirculating water curtain, a float valve contraption and a cold plate. The whole unit's 3 1/2 to four feet wide.
The float valve was going full blast, and the water was running right down the siphon tube. I found some instructions on the back of the unit for setting the height of that, and some instructions for setting the float for water level.
The siphon was set too low, and the float too high - so it was running constant. The siphon was about 2/3 plugged with some kind of slimy white sludgy stuff.
So after straightening that out, it seemed to be working in a logical way. It drained the tray after it harvested, didn't run all the time, and had enough water to not be sucking air at the pump while it was recirculating.
So, I figure I did some good there, and picked up my stuff to take it back to the truck. That's when I had a "Shmoo you're an idiot" moment as I walked past teh drain that was still running like crazy - and realized that it had a water cooled condensor - and was *supposed* to have water running almost all the time.
The outlet water from the condensor was blatantly cold, as was the liquid line at the condensor outlet. It seemed reasonable to me that I could throttle back the water flow a little.
I put the guages on it. It was running about 210 pounds on the high side before I started on it. I gave the water flow control valve 1 1/2 turns. That was enough to get the outlet water noticably warm, bring the liquid line up to a sort of ambient feel, and the pressure up to 250.
These seem like reasonable conditions to me, and the water flow was noticably lower.
I'd like to know if there's a scientific method to this, though - and to make sure I didn't cause any harm. I'd hate to have the guy call me next week needing a compressor.
As a secondary question, how would you set the refrigerant charge? It's got an expansion valve - so I know it's going to be a subcooling measurement, but water flow is going to change that, too. I 'spose you'd have to chose what you want the high side pressure to be, and then set the charge to adjust the subcooling.
So how do you decide what those number should be?
I appreciate the help.
Thanks
Eric
His complaint was that it seemed to use a lot of water, all the time - even when it wasn't making ice.
I opened the front cover. I didn't get the model number, but it's got a recirculating water curtain, a float valve contraption and a cold plate. The whole unit's 3 1/2 to four feet wide.
The float valve was going full blast, and the water was running right down the siphon tube. I found some instructions on the back of the unit for setting the height of that, and some instructions for setting the float for water level.
The siphon was set too low, and the float too high - so it was running constant. The siphon was about 2/3 plugged with some kind of slimy white sludgy stuff.
So after straightening that out, it seemed to be working in a logical way. It drained the tray after it harvested, didn't run all the time, and had enough water to not be sucking air at the pump while it was recirculating.
So, I figure I did some good there, and picked up my stuff to take it back to the truck. That's when I had a "Shmoo you're an idiot" moment as I walked past teh drain that was still running like crazy - and realized that it had a water cooled condensor - and was *supposed* to have water running almost all the time.
The outlet water from the condensor was blatantly cold, as was the liquid line at the condensor outlet. It seemed reasonable to me that I could throttle back the water flow a little.
I put the guages on it. It was running about 210 pounds on the high side before I started on it. I gave the water flow control valve 1 1/2 turns. That was enough to get the outlet water noticably warm, bring the liquid line up to a sort of ambient feel, and the pressure up to 250.
These seem like reasonable conditions to me, and the water flow was noticably lower.
I'd like to know if there's a scientific method to this, though - and to make sure I didn't cause any harm. I'd hate to have the guy call me next week needing a compressor.
As a secondary question, how would you set the refrigerant charge? It's got an expansion valve - so I know it's going to be a subcooling measurement, but water flow is going to change that, too. I 'spose you'd have to chose what you want the high side pressure to be, and then set the charge to adjust the subcooling.
So how do you decide what those number should be?
I appreciate the help.
Thanks
Eric