I have been getting HPF error from my a/c seawater pump in a 2005 Hunter 33.... hard to read but i think the pump is a "Dometic PM?500? max 60 hz"... All of the valves/strainers/hoses seem to be clear, detaching the discharge hose at the pump and letting it drain, then re-attaching it seems to clear the error and it works for 15min to 12 hours or so ... seemngly random, and it manages to cool to middle/high 70s (which feels cool in our 95oF+ NC summer weather!) of course, the pump is always full of water at start. The pump was likely installed in 2005 and I am thinking to replace it with a new one. Does anyone know what the current appropriate model for this pump might be?
Seawater pump for A/C
- Thread starter 4Winds
- Start date
I have a 2005 Hunter 33 and replaced my pump a couple of years ago with
Cal Pump S580T-20 580 GPH Pump with Flow Adjuster, 20-Feet Cord
https://www.amazon.com/gp/product/B002NJII3W/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1
Whew, it was only $212 back then. Quite a price jump in two years.
Directly from my notes, which I vaguely remember:
"original was MS680, Little Giant tech support said S580T is exact same pump".
I am a light user of the a/c, so YMMV.
Does the water seem to be flowing out of the thru-hull at the same rate when you get the error code?
Cal Pump S580T-20 580 GPH Pump with Flow Adjuster, 20-Feet Cord
https://www.amazon.com/gp/product/B002NJII3W/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1
Whew, it was only $212 back then. Quite a price jump in two years.
Directly from my notes, which I vaguely remember:
"original was MS680, Little Giant tech support said S580T is exact same pump".
I am a light user of the a/c, so YMMV.
Does the water seem to be flowing out of the thru-hull at the same rate when you get the error code?
If it's a March pump, it can be rebuilt with easy to install "wet" end. Maybe other pumps as well.
I had similar problems with my 5 year old air conditioner. It started with HPF Error occasionally and the water flow seemed slow. I tried to flush the coil with acid to clear any gunk in the tubing to no effect. Then the breaker started to trip after running for a while. When I went to change the breaker I found one of the terminals was burnt. I cut a new end and reconnected the wire to a new breaker. It worked for a while then started to have the same problems. I inspected the breaker and found the same wire was blackened again. I then looked at the ac wire and it was 14 gauge. The manual recommends a minimum of 12 gauge. I checked the wire with an amp meter and found the air conditioner was running 17-24 amps then tripped the breaker. I replaced the ac wiring with 10 gauge and now the amp draw dropped to 12 amps max with no more problems. I had assumed the installation of the unit was correct and spent a lot of time trouble shooting. This is probably not your problem, but this story may help someone out there.
Thank you for the very important insight. Though I am at least the fourth owner, I realize now I have been assuming most everything on the boat was installed correctly. That's at least 3 opportunities for erroneous adjustments even before it fell into my hands. Thank you.
Where does the pump's power cable tie into the electrical system of the boat? It appears to run under the floor of the cabin in the main salon, under the table ...
I'm going through this on my boat right now. '07 H38. LG pump from 2 years ago failed already! Its the 580 mentioned above. I just purchased a replacement from Defender, was $300 and change.
Now I know about the March pump rebuild kits I think I'd change pump type. The things that matter are the flow ratings, marine/submersible rating, and ofc the right voltage, inlet, and outlet sizes for your application.
The wiring for mine heads off to the starboard side where there is a junction box under the starboard athwart ships settee. If you lie on the cabin sole you s/b able to trace the cable with your fingertips.
I dont want to deny that your pump might be shot BUT.... I used to get the HPF error, but the pump ran meaning it made noise. No water flowing overboard. So I would unhook and giggle the line coming out of the pump and eventually it would start pumping water. So after a lot of some times it works, some times not, with similar symptoms and a clean strainer before the pump, i found a technique that has worked for two years. The sitting lines had sea critters in them and were clogging up with algae, etc.
So now when I shut down the AC, I close the seacock with the pump running. Pitch on pump changes and I casually walk over to the breaker and after about 10 seconds cut off the pump, with units still running.. This clears the lines to the unit, so no more critters. I always leave the seacock closed unless im using AC.
Food for thought'
Cheers
So now when I shut down the AC, I close the seacock with the pump running. Pitch on pump changes and I casually walk over to the breaker and after about 10 seconds cut off the pump, with units still running.. This clears the lines to the unit, so no more critters. I always leave the seacock closed unless im using AC.
Food for thought'
Cheers
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That is useful ... my pump seems to work well most of the time, but it usually gives me HPF error after several hours. I currently run the pump, it blows for a random period of time, gives up the HPF error, so I shut it down at the panel, wait at least 10 seconds, then turn it on again and it works fro another random 5-12 hours ... Another question ... what is the strategy to get it to blow more cold? I have noticed that on a 90oF+ day, it can never really cool the boat down below 83 or so...
I dont really have any data for the heat except that although the temps on the west coast dont get that high, the humidity can be a real pill. I have two units on my 420 so they do pretty well. Could just be the square footage of your salon and the size of the unit. One test I would try would be to shoot your register(s) with a temp gun. See what is coming out.
After it set off the HPF error I opened the locker under the eat in the salon where the a/c is located ... there was LOTS of heat in there ... I fanned away the heat with a file folder and within a minute the a/c cleared the error and re-started itself. I checked that the ejected seawater is indeed warm ... is there anything that can be done to absorb more of that heat? It seems that in the current 95-105oF temps we are having it just cannot keep pace ... How often does the freon have to be changed? I am sure no service has been done on thisfor at least 6 years.. Yes, as long as the a/c is running , humidity is ok. otherwise it is a roman sauna.
Yep its getting warm from trying to produce cold air. And I would think leaving the seat open may be a limiter by adding its heat, BUT would probably try that. Freon? Hmmm, i am not an HVAC guy bit my units are circa 2004 and have never been formally serviced. Warm water is tough. Hopefully someone else will chime in. Our intake water is only about 75 this time of year.
AC never cools down a boat like a Landlubber home.
We have one 16k BTU and one 8k BTU and it is comfortable at night.
We have local fans [120VAC] that move cooler low Humidity air around the entire boat.
In fact, about 1 AM, it gets too cold and we need a thin blanket.
About that time our AC units begin to cycle and control about about 78F.
Remember it takes time to cool down the contents of your cabin, if you have not had AC on during sailing.
We start our Main AC about 30 minutes before we anchor for the evening Sundown and Adult Beverages.
Jim...
We have one 16k BTU and one 8k BTU and it is comfortable at night.
We have local fans [120VAC] that move cooler low Humidity air around the entire boat.
In fact, about 1 AM, it gets too cold and we need a thin blanket.
About that time our AC units begin to cycle and control about about 78F.
Remember it takes time to cool down the contents of your cabin, if you have not had AC on during sailing.
We start our Main AC about 30 minutes before we anchor for the evening Sundown and Adult Beverages.
Jim...
Hmm, that's about what I have ... 78oF is the coolest it gets now at night in Wilmington,
NC where temps this month are 90-105oF during the day, water is 80-85oF ...so I'm wondering whether I can find a way to vent the excess hot air ... and check the freon. Maybe the a/c is not working so badly after all ...
If you pump more water you may be able to remove more heat, after all that's where the heat is going. The HPF error is likely a high pressure error caused by high temps. Could easily be caused by low water flow. You might measure the volume of water coming out the side of the boat with a stopwatch and a bucket. See if it matches or exceeds the requirement of your AC unit, also post the data here.
Very good idea ... I'll measure the output and see how many gallons I get per minute .... I will definitely report back once installed. thank you!
Current Dometic PM?500? 12V 60hz pump is ejecting 2.1GPM per stopwatch; not sure what it is rated for as label is mostly gone. I have a new March pump 12V 50-60Hz rated for 8.5 GPM. I think I will try switching them out today to see if that makes a difference.
If I remember correctly 16k BTU need a minimum of 4 GPM, that might have been for 12k. Surely 2.1 isn't enough unless the water is cold.
If I can ask ... where does the power from the seawater pump lead ? It looks like it goes under the white subfloor, in the Hunter 33 right underneath the table in the middle of the salon ... if I open up the subfloor (I would need to remove all the teek colored flooring ,the table and find a way to remove all the stripped screws holding down the white subfloor ... what would I see? Will I find the place where that power cable ties into the 12v system?