Anybody know what the factory raw water a/c cooling pump flow rating is? I have a shipyard telling me that the current units are undersized and that I should increase the flow rate. I have a 1988 67’ CPMY. Thank you
Welcome to the Hatteras Owners Forum & Gallery. Sign Up or Login
+ Reply to Thread
Results 1 to 10 of 17
Thread: A/C Raw water pump size
-
04-22-2024 01:49 AM #1Registered Member
- Join Date
- May 2021
- Posts
- 46
A/C Raw water pump size
Slainte
1988 - 67' CPMY
Houston, Texas
-
Re: A/C Raw water pump size
-
04-22-2024 08:00 AM #3Senior Member
- Join Date
- May 2018
- Posts
- 108
Re: A/C Raw water pump size
I have same boat same year. I have run for 6 years in South Florida with AC going continuously all seasons with March AC-5C-MD pumps, nominally 1,000 gallons per hour. Keep the strainers clean and barnacle bust the condensers when needed. Two things made a big improvement. First, I replaced the hose run from the strainers to the pumps to the manifolds in the generator room - what came out was in rough shape and impaired flow. Second, after having some challenges on the electric motor side of the march pump, I found that the start capacitors were failing (2-3 over one year) but that the motors we actually fine (based on taking it to a motor rebuild shop each time). I now leave the hatch cover off the small bilge area where the pumps sit so they get better air flow and no more capacitor issues...just have to make sure not to break an ankle walking in the port engine room. If the water temp there is much higher than south fla or if you have tons of silt, you might need more velocity/flow rate.
-
04-22-2024 09:09 AM #4Registered Member
- Join Date
- May 2021
- Posts
- 46
Re: A/C Raw water pump size
I have the 17.2 gpm(1032 gph) rated pump. Pm-1000-115, I have already replaced the suction (input) side hoses and strainers. I actually rotated the strainer so that the cap is pointing vertically up instead of horizontal to the side. I am in the process of replacing the discharge (output) hose between pump and manifold. Hopefully that clears thins up.
Slainte
1988 - 67' CPMY
Houston, Texas
-
Re: A/C Raw water pump size
Basic formula is 180 gph per ton/12k BTU
Note that pumps with bronze body and impellers (cruise air / oberdorfer or Scott) suffer from erosion with time and will loose flow
I monitor the coil temperatures to spot trends and avoid high pressure shut downs. Most of the time when temps start going up it s not the pump but restrictions on the system due to growth and shells. Shells have become a big problem in summer is sofl. I have rigged my chillers with fresh water back flush which help reduce the frequency of barnacle busting sessionsLast edited by Pascal; 04-22-2024 at 02:34 PM.
Pascal
Miami, FL
1970 53 MY #325 Cummins 6CTAs
2014 26' gaff rigged sloop
2007 Sandbarhopper 13
12' Westphal Cat boat
-
04-22-2024 09:20 AM #6Registered Member
- Join Date
- May 2021
- Posts
- 46
-
04-22-2024 11:05 AM #7Registered Member
- Join Date
- May 2021
- Posts
- 46
Re: A/C Raw water pump size
Slainte
1988 - 67' CPMY
Houston, Texas
-
Re: A/C Raw water pump size
It all depends on how your air cons are setup.
I added a Tee and two valves on the discharge side of each units so I can hook up a water hose from the ER faucet. When I need to back flush, I shut off that chiller, shut off the valve at the manifold, disconnect the hose at the manifold and put it in a bucket. Then switch the valves on the discharge side and hook up the hose. Whatever shells are trapped in the system get flushed in the bucket
I use the same setup when I need to descale.
I set up a similar system on the 116 I run with 3 chillers except that I was able to hard plumb into the fresh water system. No garden hose. I also have valves and tees on the other end to collect the debris
Every boat is different but the key is to set it up to back flush so anything trapped at the coil intakes gets flushed outPascal
Miami, FL
1970 53 MY #325 Cummins 6CTAs
2014 26' gaff rigged sloop
2007 Sandbarhopper 13
12' Westphal Cat boat
-
04-22-2024 12:27 PM #9
Re: A/C Raw water pump size
I had same pumps in Pau Hana and when I had the OOTB problem with the second MarineAire unit I installed, they told me it was too high a flow rate with that pump. We were in Ft Myers, FL and after I got that unit repaired from the factory-installed problems, I had 3 single-piece units running off 2 pumps. I had pumps on continuous run, and weekly I flushed the lines from the strainer with dock water pressure. They cooled beautifully. I doubt the pumps are the issue, try replacing the hose from the intakes and strainers.
"A smooth sea never made a skillful sailor"
Rob Waldrop
M/V Pau Hana
Ft Myers FL
-
04-22-2024 12:33 PM #10Senior Member
- Join Date
- May 2018
- Posts
- 108