Ugh! Yet another air conditioner ?

I have two air conditioners on board, forward and aft. Forward is a Marine Aire and aft is a cruise aire. BOTH are 16,000 btu's. The Marine Aire's sea water pump is no longer viable. It was 1000 gallons per hour. The cruise Aire's pump is 500 gallons per hour.

Ok, here is the question. May I replace the Marine Aire's 1000 gallon per hour pump with a 500 gallon per hour pump? If so, what is the difference? Everything I have researched says 500 gallon per hour is good for a 16,000 btu. Thoughts? Suggestions?

Donna said:

If so, what is the difference?

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500 gallons per hour?

Yeah I am feeling like a genius, but really it was a tough mathematical challenge!

Check with the manufacturer but we run 2-16K units on one ~1000 gph pump so maybe yes?

On a side note I've been told that too much flow can decrease the life of the unit.

Larry M said:

Check with the manufacturer but we run 2-16K units on one ~1000 gph pump so maybe yes?

On a side note I've been told that too much flow can decrease the life of the unit.

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Hey Larry please don't try to hijack this mathematical challenge with some misleading information, I won!
Ok ok I am out

it actually *is* a hard math problem, delta T and surface area of coils and so on. That being said, even 8GPM can carry a **BOATLOAD** of BTU's away.

I have 2 Marine Airr units a 16,000 & a 12,000, they both operate perfectly well with one 1000 gah March pump.

Donna,
There's more to the math than meets the eye. A 500 GPH pump doesn't reflect head (easy wifey B ) or frictional line loss. Simply, pushing water up and through plumbing creates resistance and reduces flow (GPH). So, a pump rated for 500 GPH that lifts the water 5' above sea level and through 50' of plumbing and the AC condenser might only be delivering 300 GPH. If you want to know what is required, you might start by running the other AC water pump, put a 5 gallon bucket under the outlet, measure how many seconds it takes to fill the bucket, and then do the math to figure out GPH. In general higher volume centerfucial pumps feeding multiple AC units lose less volume as a result of head or frictional line loss.

My guess is that you will find a measured output of 250 GPH (4 GPM) will be enough.

Ted

500 gph pump should be fine on a 16000 btu air conditioner. I recommend a March LC-3CP-MD. Marine Aire sells it as their P500.
I think my old company has a pretty good price on it.
March LC-3CP-MD Magnetic Drive Pump

Then what does GPH and GPM stand for?

Hours/Minutes..

Thank you OC Diver for the explanation. I'm doing my best here.

RT Firefly said:

Hours/Minutes..

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Donna said:

Thank you OC Diver for the explanation. I'm doing my best here.

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Sorry I think our fellow OC diver is trying to get credit by throwing numbers and confusing explanations to a challenge that as already been solved.
I gave you numbers and our famous Mr RT gave units, you should be able to resolve the equation by yourself

Lou_tribal said:

Sorry I think our fellow OC diver is trying to get credit by throwing numbers and confusing explanations to a challenge that as already been solved.
I gave you numbers and our famous Mr RT gave units, you should be able to resolve the equation by yourself

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You are right, I should have been. It has been a bad couple of weeks. Working way more than usual, Mother broke her hip, daughter got engaged, had to figure out what was going on with a/c, needed new tires on the car, so life got in the way. Sorry for the stupid question.

WHAT? Daughter got engaged without my blessing??? PFFF
Sorry for mother hip and being a fool
Everything else than mother and daughter is just detail, you don't need ac, just think that I have 7 feet of snow in front of my house and you will feel better
And for new tires... Who need tires when living aboard!!!

Lou_tribal said:

Sorry I think our fellow OC diver is trying to get credit by throwing numbers and confusing explanations to a challenge that as already been solved.
I gave you numbers and our famous Mr RT gave units, you should be able to resolve the equation by yourself

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Some may want to understand why a 500 GPH rated pump doesn't produce that volume going through an AC system. The same pump and AC unit that works in one installation may not work in another because of head pressure and frictional line loss. Sorry if you missed that point or don't understand that people who design these installations, plan around these parameters.

Ted

O C Diver said:

Some may want to understand why a 500 GPH rated pump doesn't produce that volume going through an AC system. The same pump and AC unit that works in one installation may not work in another because of head pressure and frictional line loss. Sorry if you missed that point or don't understand that people who design these installations, plan around these parameters.

Ted

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Some may want to understand (maybe you) that I was just jocking

Lou_tribal said:

Some may want to understand (maybe you) that I was just jocking

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Sorry, I didn't realize you were joking regarding my explanation.

Ted

The pump in Hopcar's link will do just fine with a 16k.

Also, pumps are generally fix-able, depending on model and what might be wrong with it.

O C Diver said:

So, a pump rated for 500 GPH that lifts the water 5' above sea level
Ted

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Most of the boats I have seen don't have their overboard discharge 5' off the waterline

kev_rm said:

Most of the boats I have seen don't have their overboard discharge 5' off the waterline

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This is true, but you will see applications such as my boat, where the waste water discharge includes the gallery sink , ACs units, condensate drains, and other water source discharges, exit through one or two above water through hulls. Essentially, I have two 2" through hulls that handle bilge pumps, washing machine, galley sink, 2 AC units, the shower sump pump, and 2 deck drains. Two of my AC units discharge into common drain pipes 3 to 4' above sea level.

Ted

Donna said:

Then what does GPH and GPM stand for?

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Gallons Per Hour and Gallons Per Minute are ways that you measure water flow rate through the pump.
Example: 10 GPM times 60 minutes equals 600 GPH.
If 600 GPH is good enough for the aft cabin 16000 BTU AC unit , it should be good enough for the forward 16000 BTU AC unit, assuming the plumbing is reasonably the same.

Ski in NC said:

The pump in Hopcar's link will do just fine with a 16k.

Also, pumps are generally fix-able, depending on model and what might be wrong with it.

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Yes I agree, and that is part of the fun of it for me. However, it is time to let this one go. Just not enough hours in the day for this one.