Anyone having issues with water being too hot for your A/C to run?

[MarinAirNoWorky]

What a kick in the ass. With their 300 gph pump it now wont work at 88, where it used to be FINE up to 90 (on the chart plotter)...

SIGH. I hate being right about things but having to listen to "professionals" and then they end up making the situation WORSE.

This winter that 1200 gph pump is going right back in.

[MarinAirNoWorky]

Originally Posted by sailorboy1

The thing about that far as high head pressure goes is it going to matter what the air temp is. A 95 degree water may work with a 3 degree air temp differential, but not a 10 degree one.

With that said have you tried to get the system operating with a cooler air temp at start to reduce the heat transfer load on the system?

No, No real way to do that.

However I now have a portable ac that seems to be doing okay, so far. It at least makes it bearable.

[MarinAirNoWorky]

So by the logic that their 300 GPH pump is performing worse, I guess that means if I get a pump that is FASTER than 1200gph, maybe it'll work above 90.. hmmm

[sailorboy1]

Originally Posted by MarinAirNoWorky

So by the logic that their 300 GPH pump is performing worse, I guess that means if I get a pump that is FASTER than 1200gph, maybe it'll work above 90.. hmmm

Well yes a higher flow should reduce the ccompressor pressure by removing more heat. Heat transfer is a function of flow rate and differential temp.

But just because a pump CAN do twice the flow does not mean it will do twice the flow through the system. Twice the flow would also require in 4 times the system pressure needed to do it because of the friction losses. Twice the flow would also need 8 times the power.

It may make a difference to use larger hoses. Even though the size of the heat exchanger would not change the total flow through the system will increase some. You are right at the edge it seems of the system being able to handle it. So maybe the larger hoses plus the bigger pump your started with will do it,

[Captain Bill]

Stop letting the refrigerant out. The pressure is determined by the temperature, not how much refrigerant is in the system. There are charts for what the pressure should be for a given temperature. This of course varies by the refrigerant type used in your system. The refrigerant will vaporize/condense at a given temperature and pressure combination. This depends on the temperature of the condenser hence in your case the temperature of the water absorbing the heat from the compressed gas coming out of the compressor. Releasing the refrigerant will not change this critical temperature unless you let out enough so that the compressor cannot reach the required pressure in which case you won't be cooling very well if at all. You have done as much as you can with this unit given the temperature of the water in the keys these days. As was suggested you might be able to bypass the high pressure sensor at the risk of destroying the unit. a modern computer controlled system might not work at all if the signal from the sensor is not in the expected range or absent altogether.



I was thinking about taking my boat to the keys this month but decided against it when I heard about the water temps. I keep my boat in a canal behind my house in Punta Gorda and run the AC in in dehumidify mode and had a couple of shut downs due to pressure this summer. I know on one day the water temperature was 94.5 when it shut down.

[MarinAirNoWorky]

Yeah, I havent done that anymore at all.

One other thing, it seems to be working okay today with 87 showing on the chart plotter (I think the chart plotter temp is about 2 degrees off, I should figure that out)...

BUT I completely can feel the difference in cool air. Usually it's ice cold with the 1200 gph pump... now it has lost it's icy feel to it.

[Chotu]

Originally Posted by MarinAirNoWorky

Yeah, I havent done that anymore at all.

One other thing, it seems to be working okay today with 87 showing on the chart plotter (I think the chart plotter temp is about 2 degrees off, I should figure that out)...

BUT I completely can feel the difference in cool air. Usually it's ice cold with the 1200 gph pump... now it has lost it's icy feel to it.

If you let out any refrigerant at all, that’s why it’s not working well anymore. That’s why it lost the icy feel. Not the right approach. That just lowers its efficiency.

[Turtle Blues]

Welcome to the Outer Limits of Refrigerant Application Theory.
You are at the extreme end of the temperature zone for heat transfer as the unit was designed.
No amount of modification will help until the water temp drops a few degrees.
Dumping refrigerant without measurement is a really bad idea. It is a temporary solution to an extreme situation and is going to degrade performance overall unless you plan to recharge it when the weather cools. If you are going to alter refrigerant levels put on gauges and record your ambient air, water in & out, and air in & out temperatures to understand the correlation to what you are doing.

Regarding the pump and coolant flow MORE is NOT BETTER.
The manufacturer told you that and GM posted a clear explanation of the basics of heat transfer in the system. If you blast enough water through it you can get the delta t to zero. That means zero heat transfer as in no heat transfer from the cooling coil. Measure the in and out temperatures to make sure that you are picking up a couple of degrees, indicating proper heat transfer.
I'm sure if you poke around the internet enough you can find a classroom demonstration video of this. It's a hands on lesson in Refrigeration 101.
Sorry you can't extract performance beyond the laws of physics. In another month this will be over for this season.

[Spindrift NH]

Do you have free dock water at your marina? If so, as a temporary solution, plumb your ac inlet to a water tank then just keep your water tank full with dock water. I noticed. guy on my dock doing it recently.

[Turtle Blues]

Might want to ask the marina office how they feel about that.
Thousands of gallons a day.

[Bowdrie]

Originally Posted by Bowdrie

where no matter the increase in the pressure/flow of the water there just isn't enough surface area in the condenser to take advantage of the pressure/flow.

We could have another score of pages of responses but none will improve anything if the condenser is just too d**n small for the operating parameters.

Re-posting what I posted ~a score of posts ago.

[barnab]

With everything you have tried...and me not being an a/c specialist...Did you try restricting airflow either on the in- or out-side? Not sure how that would help, but seems like the only thing you didn't try yet. Will make the fan work harder, but if you want to get rid of the unit anyways...


Regarding the not-icy-feeling, did you change anything after changing the pump? As I understood, you didn't release any refrigerant after changing the pump? So I would assume the icy feeling should come back if you revert to the bigger pump?


Edit: if you can control fan speed, you might as well set it to the lowest level...

[Montanan]

To summarize the issue:
Wait for the water to cool then your A/C should return to working well.

The heat sink is too hot.

The system will not work properly outside of its design and construction parameters.

In the meantime, enjoy the warmth.

[Turtle Blues]

Sorry #87 bad idea #1 Blocking airflow reduces heat transfer and can result in a frozen coil. It has absolutely no benefits.
bad idea #2 increasing cooling water beyond design velocity results in decreased performance. Physics 101 you do not make cold, you transfer heat. If the water moves too fast it does not pickup heat, you have zero transfer. That's why you measure in & out temperatures, to verify heat transfer.

bad idea #3 dumping freon. It has done nothing but degrade performance.
It's not the units fault why destroy it ?

Post #88 sums it up. if the unit survives it will need proper measured charging.