Ac circulation pump

[Ayesore]

Hi. I new to this forum. I have a 1988 Carver Montego 3257. My sea water circulation pump for my air conditioner burnt up last season. There is absolutely no data saying the gpm,, model or serial #. Anybody have any ideas on how I can get a replacement? Thank you.

[km1125]

They are pretty generic and the sizing really just depends on how many units they feed and what size they are. If you have a single 12K BTU unit, you could go with anything above 250 GPH, if you're running three units you'd need at least 500GPH and three large units you could use 1000GPH

Are you sure the unit is no good? Did you clean the impeller section and make sure the impeller spins freely?

[Ayesore]

Thanks for responding. Yes I did check the impeller. I plugged the pump into a 120v outlet and nothing happens. I'm not sure the btu of the only ac unit.( still in winter storage). Thank you for the input.

[km1125]

You're in a northern climate too, so the pump doesn't have to flow as much as if you were in the Gulf. With a single AC unit, any pump 250-300GPH would be fine. You might want to verify the hose sizes (so the new one matches) just to make the swap-out more convenient.

[JohnS]

I just installed a March 510 GPH pump last weekend to run both ac units. Works much quieter and no issues so far.

My ac units:
1 - 16000 btu Marinaire
2 - 9000 btu Marinaire
they both were on this weekend here in DFW, temp was about 102 and inside the boat was 71 during the day and got to 68 at night with both units running.

[bud37]

Let me start by saying I am no Air /heat expert but I do understand pumps and cooling system flow dynamics a bit to be dangerous....

FYI.....just to get on the same page....the cooling water pump specs are generally, unless otherwise stated, the flow in GPH at the pump outlet that is open to atmosphere. (The same applies for bilge pumps by the way). If the air/heat unit requires lets say 300 GPH for proper operation then it means that minimum flow is at the unit itself not at the pump discharge/ the pump rating. There are considerable flow losses in different styles of tubing and fittings which need to be taken into consideration along with the ambient air temp and the average cooling water temp in your boating area along with the height the cooling water has to travel going thru a system.

I guess what I am saying is don't just size to the spec or minimum because your circumstances can change each day as your boat moves around.

JohnS....I am not commenting on your install choice, thanks for posting your solution with the boat model, I just want it to be clear to all about all the factors and why sometimes the pump specs seem overly large but after a specific boat model fitting they may be found to be just enough....hope some of this helps as this is a fairly complicated topic even for the original designers.