Original message
| teeks
 |  "AC problems"
, posted Fri 31 Oct 18:56  
HELP!
I am chief engineer aboard a large Motor Yacht and I am having problems with the air conditioning aboard the vessel and would like some guidance in troubleshooting this system. The basic equipment list is as follows – provided by Florida Heat Pump but installed by outside contractors:
Compressors – EMO-18&24. Air handlers are various models such as AHX-XRS, AHX-XLS, AVX-XRT & others. The controllers are SC 2001. I have tried these controllers with varying temp differentials from 1-3 degrees but notice no difference in performance. I have set all controllers at 70F and fans are “on” not “auto”
Gas is R22 and with all comps low pressures range from 60-70psi and H.P. from 180-200
Despite high heat demand I am experiencing very poor performance and little cooling. I am satisfied that I have adequate raw water cooling as no units are tripping on H.P shut down. The raw water side was de-scaled about 6 weeks ago and yes I will consider doing this again to try and improve performance. Strainers on Raw Water side are clean.
Here’s my observations:
-we are in the tropics and water temp inlet side of the condenser cooling pump is 89-90F
-little heat exchange from the inlet and outlet sides of raw water cooling at the condensers. This varies from 1-6or7F …. Comps not cycling??? – at this point I have not checked line amps. This condenser heat exchange is despite most cabin spaces being at least 10F above set point on the controllers and in some cases as high as 17-19. The yacht is warm to say the least!!
-this system was working OK before and now work has been performed on the system. HOWEVER it may? Be significant that these troubles may have begun after steaming through rough seas. We sucked air into raw water side and had most units go out on HP because of low raw water flow. I cleared the trapped air and units began cycling again – none of them are out on HP. I risk sending you on the wrong path here with the air entrapment BUT these troubles have happened before and it is POSSIBLE though not certain it was after air entrapment in the raw water side?
-I find it hard to believe that I have failure at 10 or more expansion valves ditto with driers however that’s why I am writing to you ….. I have sound understanding of the working principles of the system but am not the expert – you guys are so ANY help and suggestions would be greatly appreciated.
In closing I would add that there are many points of the installation that I consider to be poor workmanship and practice especially with the ducting side of the cooled air. HOWEVER the system works adequately, at least it has in the past and perhaps we have a higher heat demand than in the past as the ambient temp has increased but not radically so since previous acceptable performance.
Where can you point me from here? I am at sea and have 6 more days steaming before reaching Palau where I suspect little tech support will be available.
Thanks in advance for your help here.
Teeks
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Replies:
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| Jojo98
| "Re(1):AC problems" , posted Sat 1 Nov 14:20
Make certain that water strainers are clean, condensers are not fouled, air filters are clean.
Refrigerant pressures seem good. Maybe a little on the low side for 90 deg water. What is needed is superheat temp's and delta T on the air side of the evap's. Are you certain that the units are properly charged?
1 to 7 degree delta at the condenser is probably too low. Is there a way to slow down water flow through the condensers, like a circuit setter or globe valve on the condenser water return line. If there is, choke it off aa little,until you see a differential of 12 deg across the condenser.
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| | teeks
| "Re(2):AC problems" , posted Mon 3 Nov 18:57
Thx Jojo
I will for sure get back to you probably in a few days once I am alongside and can do some real annalysis on the system -you've given me a start point
Teeks
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