AC/Heat Water Pump on an old Cruisair System

[DBG8492]

This is a new (to us) boat. During the interior survey - conducted after the haul-out - the AC/heat (self-contained units - see pic) worked, and the pump (in the engine room) moved water. There are three breakers - one for the pump and one for each unit. Also, the units have Off/Fan/Run switches.

I wasn't there at the point in the survey when the system was turned on, so I didn't see the process.

I know where the pump is. I know the seacock is open. But when I turn on the breaker for the pump, nothing happens - it doesn't make a sound, and it doesn't pump. The admiral refuses to let me turn a unit on to see if it will kick on and push water when it is ready to start making heat.

My understanding of the way these things work is that there's a relay that switches the pump on when the compressor kicks in and that if the compressor isn't running, the pump won't run either, so I want to turn on a system and turn the heat all the way up to get the heat to turn on and see if it works.

What say you?

 

[tiltrider1]

The pump won’t come on until one of the units completes the circuit. You need to turn on at least one unit and the circulation pump will only come on when you start making heat or AC

 

[DBG8492]

So how long does it take to start making heat or AC? I turned on both the forward AC breaker and the pump breaker, then I put the unit switches to 100% "WARM" with the fan speed in the middle and the Off/Fan/Run switch on "Run," and I let it run for about 30 seconds.

Is that long enough or are we talking minutes here?

 

[tiltrider1]

If the compressor is running there should be cooling water. Lack of cooling water won’t damage the compressor but it won’t make heat or AC.

Was it on long enough for the compressor to kick on?

 

[DBG8492]

I waited maybe probably a minute, maybe a minute thirty.

if the lack of water won't hurt anything in the short term (short term being 30 mins), I'll just let it run for a half an hour tomorrow and see what happens.

 

[Delta Riverat]

The pump should run when the unit (heat or chill) runs, not "fan only"

If the compressor is running then the pump should run. I wouldn't let it run for 30 minutes to see what happens. I would turn it on to check voltage at the pump.

 

[Iggy]

I would turn the temp up to 90 or better and have it set to heat. Sea cock open. Wait about 2 mins, you should have water flow from the though hull. Oh, check the sea strainer first before doing anything. Is it clean?

 

[Grupet]

I have a similar Cruisair system on my 1979 GB, though my top knob is labeled on/start/run.

In the "start" position (same location as your "fan", the fans turn on and the water circulating pump turns on. It runs continuously when the switch is in start or run, whether the compressor is running or not.

 

[Grupet]

Edit. Top knob is labeled off/start/run

 

[ranger58sb]

And if the pump doesn't actually move water when it kicks on -- after the compressor starts -- you might need to bleed air from the system. Some AC pumps don't self-prime.

The Oberdorfer pump for our interior ACs has a bleed screw. The March pump for our bridge AC doesn't, so I just have to wait (as in after a haul-out or whatever) until pressure moves seawater closer to the pump so it can begin moving water.

-Chris

 

[O C Diver]

There are several different scenarios for AC pumps. Some come on and run continuously when the AC power switch is turned on. Some only run with the compressor (usually turning on around 10 seconds before the compressor).

With multiple systems, there is often a control box for the water pump. This box senses power from any of the AC units that are fed by the water pump. Often they can be controlled by 3 to 5 AC units. Whats important to understand is that since none of the AC units will necessarily be on, there is often a separate power supply to the control box, that in turn, powers the pump. You may have a 120 volt breaker that could say "Air Conditioning Pump". If you have a pump feeding multiple systems, I would trace the wire from the pump back to the control box or look for a labeled breaker.

Ted

 

[Bmarler]

I’m not highly educated in these systems, but don’t some older self contained units use heating coils on the heat side instead of being reverse cycle? In that instance, the pump only runs when cooling.

 

[CaptTom]

The units I've seen start the pump a few seconds before the compressor, so you don't get a simultaneous surge from both.

If the pump does run and doesn't move water, the first thing I'd do is bleed the intake line to the pump, as mentioned above. Usually the pumps are below the waterline, so all you need to do is pop the hose off the pump outlet and wait for water to start coming out.

Yeah, and make sure it's a reverse cycle system, not electric heat.

 

[O C Diver]

I’m not highly educated in these systems, but don’t some older self contained units use heating coils on the heat side instead of being reverse cycle? In that instance, the pump only runs when cooling.

Yes, this is correct. In addition, some units also offer both reverse cycle heating and electric strip (coil) heat.

Ted

 

[DBG8492]

LOL - some things have a way of making you feel (and look) like a complete moron.

It is a reverse-cycle system, but the pump is wired to the aft unit only. If you want to run either unit, the fan for the aft unit has to be on.

We were only using the forward system...

Thanks to everyone who responded. The system works - it was an ID10T error.

 

[ABfish]

I wouldn't take the blame for that one. That's just something you learn along with the systems on your boat.

I try to put a label (note) on any system that's not wired as you would expect. For others benefit and in recognition of my mental failings.

 

[tiltrider1]

Not your fault some one took a short cut when installing the system. Probably not the last of the idiosyncrasies.

 

[CaptTom]

Yeah, I wouldn't have been looking for that, either. Seems like a pretty stupid way to install a pump. Good job finding the problem!

 

[duanegeib]

This is a new (to us) boat. During the interior survey - conducted after the haul-out - the AC/heat (self-contained units - see pic) worked, and the pump (in the engine room) moved water. There are three breakers - one for the pump and one for each unit. Also, the units have Off/Fan/Run switches.

I wasn't there at the point in the survey when the system was turned on, so I didn't see the process.

I know where the pump is. I know the seacock is open. But when I turn on the breaker for the pump, nothing happens - it doesn't make a sound, and it doesn't pump. The admiral refuses to let me turn a unit on to see if it will kick on and push water when it is ready to start making heat.

My understanding of the way these things work is that there's a relay that switches the pump on when the compressor kicks in and that if the compressor isn't running, the pump won't run either, so I want to turn on a system and turn the heat all the way up to get the heat to turn on and see if it works.

What say you?

 

[duanegeib]

This should be the manual for your Cruise Air. I am looking for the others.

 

[DBG8492]

This should be the manual for your Cruise Air. I am looking for the others.

Thank you!

 

[duanegeib]

Another larger file

 

[ronobrien]

The pump should run when the unit (heat or chill) runs, not "fan only"

If the compressor is running then the pump should run. I wouldn't let it run for 30 minutes to see what happens. I would turn it on to check voltage at the pump.

Be sure that the thermostat is calling for the compressor to come on. You may have a fan running without a call from the thermostat. The compressor should come on almost instantaneously while there is a call from the thermostat. A "soft start" system may take longer, but I am not very familiar with them. Either way I wouldn't think more than a couple seconds.

 

[DBG8492]

Be sure that the thermostat is calling for the compressor to come on. You may have a fan running without a call from the thermostat. The compressor should come on almost instantaneously while there is a call from the thermostat. A "soft start" system may take longer, but I am not very familiar with them. Either way I wouldn't think more than a couple seconds.

This has been fixed - it was because the boat was wired so that the aft unit has to have the fan on for the pump to run for both units.

I will fix it eventually, but right now, I'm just happy it's working.