This is just a note to confirm that I offer FREE Troubleshooting help for your Marine A/C & Refrigeration issues…But I ONLY do this in the FORUM section…If you can’t take the time to register & ask in the FORUM…I usually won’t respond…(this section is not setup for dialog/discussion…it’s only setup for comments)

My only request in return is that you Consider me when buying replacement parts, or units…And that if local, you also consider my services….But how’s they saying go ?

No Purchase Necessary…That price can’t be beat at half the cost !!!

All you need to do is join & ask in the FORUM section most relative to your issue  http://marine-ac.com/forum/

Post your own title (thread) in the section that applies, and I’ll be happy to respond with my best honest advise…

Thanks Again,

Steve~

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Recently I was on a boating message board and came across a discussion about pumps and some troubles folks had experienced.

The original poster had a March magnetic drive pump that would not pump water, and after the usual back flush & priming sugguestions he could still not get it to pump water…Just before I read the thread he had found that either something had gotten past the strainer (or he didn’t have one) and had lodged between the impeller magnet and the pump housing stopping the impeller from turning, but not the motor from running…

Then the questions & discussion centered around how their systems reacted to loss of water flow and how & when their pump ran…Some of it was info that was a bit misleading for others depending on what type of system & control they have…So I posted these two posts below to try to help out…It’s good info so why not share it here on my own site too ?

• My first post…

I’m glad the Chief Alen sorted out his pump problem but I thought I could add a bit of info to the thread…

If it is a single A/C system installed (not more than one compressor or control) there will be no need for a pump relay.

If it is a older Cruisair 3 knob type cabin control…Yes the pump will run with the fan and not cycle with the compressor unless it has been changed or is a newer digital control.

The thought back in those days was that when wired to the fan circuit…The owner could verify flow over the side before switching the system to run…They have since re-thought, and have changed that practice/wiring…

Yes it can also be wired to the compressor circuit so that it will cycle with the compressor…
It can be a simple change, but first you need to find where the pump wire runs to…Some run to the unit, and others are run to the terminal strip that should be within 3 feet of the cabin control….You then just remove the black pump wire from under the red terminal (Cruisair) and reconnect it along with the purple compressor wire…The pump should then cycle with the t-stat/compressor.

The other thing to watch for with the March Mag drive pumps is if they are run dry for very long…They will heat up enough to melt the plastic on the back side of the impeller around the ceramic shaft, and also the impeller mating surface of the plastic head itself…
The impeller may appear to rotate fine when the cover is removed but it won’t when the pressure of the cover is against the impeller with the cover installed…If this is the case…The housing & impeller can be replaced, or you can also get the complete head without having to replace the whole pump.

Steve~

• Then another gentleman posted…

“I guess I must have the ideal system. If the water flow is disrupted on mine…the breaker trips.”

• My reply…

That is a good thing…But not actually a function of design of the A/C system or control.

I’ll try to explain…

Most Marine A/C units with manual cabin controls have what is called a “Line Voltage” automatic reset high pressure switch (meaning it is actually carrying the compressor current) that trips around 425 psi, but then resets itself at around 325 psi…

Mermaid was one exception…They had/have a Manual reset Hi PS Switch with a push to reset button…Anyway…

Normal system operating high side pressure is somewhere between 200-250 psi depending on water flow & the temp of that seawater…

Also…In a Normal startup (system has been idle for a few minutes) the low & high side pressures will be equal (or very close)
This pressure will depend on ambient air temp but it will not ever be much over 196 psi (that’s assuming a 100 degree cabin)and usually much lower.

The compressor has a fairly easy time getting rolling against that kind of pressure….But at where the pressure switch resets (325 psi) it has a much tougher time and thus draws much more amperage (than normal) in trying to re-start against that High pressure…Therefore tripping the breaker…

Units that didn’t come with a start relay & capacitor have a harder time starting than ones that did come so equipped…

The ones that came equipped usually will start on lower dock power, and also may re-start at that 325 psi if the breaker is not closely matched to the size system it is powering…

Breakers are most often spec’d for wire size & distance to any given piece of equipment (under normal load conditions) for that equipment…The wire is also sized to be able to carry that projected load.

So you might see…There are trade offs…

Tripping that breaker weakens it a bit every time…Yeah I know…It shouldn’t happen that often…And it does protect my A/C & Pump…

But having a unit that did not come with start components can mean the difference of being cool, or not being cool with marginal dock power (Like at a lot of backwoods marinas, and behind many homes) It can also mean a given unit may or may not start on a smaller gen set or inverter with other essentials running…

Tanqueray…I’m not saying your unit does or does not have start components…I’d have to know what you have to know that, but I can also say to everyone that a start kit can be added very easily to most all systems that don’t have a relay & capacitor already installed if your situation warrants it…

The reason most manufacturers didn’t use them was cost…I can also add that up until a few years ago Cruisair had them on all their units.

Note: The digital controls of Cruisair/Marine Air handle Hi/Ps much differently than manual controls….But that’s another post…

Steve~

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We have touched on seawater cooling and lack of…Now what about if you have a intermittent problem, or the pump won’t start at all ?

In boats with multiple systems running on one seawater pump there is most likely a Pump Relay to receive a signal from each system to tell the pump it needs to run…That is unless it has been bypassed and the pump runs 24/7 from the breaker ( I see this done fairly often)

Lets start with the breaker in the main panel…Most are labeled A/C pump or similar…Some boats may have the pump breaker tied in with one of the A/C system breakers (Ocean Yachts for one used to connect the pump to the Main Salon A/C Breaker) but most should have a stand alone breaker…

The breaker feeds the pump relay and carries the load of the pump only…this power can be either 115 or 230 volts depending on the pump installed…

The individual systems aboard will then have their own breaker that powers/protects each A/C system & it’s wiring…These can also be 115 or 230v supplied…The reason I describe this is that some boats have a mixture of system voltages…Hatteras for example, always supplied one of the smaller systems as 115v and the rest as 230v…They would then install a 115v pump so that if all that is available on the dock is 115v, you can still have at least one cabin of A/C for crew/kids while the owners/parents go to the resort for the night without starting the generator (Well this has always been my assumption and nowadays most docks will have 230v anyway)

There have been many types of pump relays over the years…Some with mechanical relays (in previous times) but most for many years have been “ignition protected” solid state designs…Here are the most current & popular versions that I see, and a few of the most common failures…

Some were for built for only 2 systems and could not be expanded for more…Marine Air still makes a 2 unit relay (2PRP) but they also offer one that can handle up to 6 systems (6PRP) on one pump…you don’t have to utilise all if you have say 3 or 4 systems, and it actually gives you spare circuits to re-connect a system to if the one it’s connected to were to fail (that is if you have the 6PRP)…These relays are just a metal box with a single circuit board and all needed components on that board…Other than complete board replacement, there are no repair parts available/needed.

Cruisair went about it a bit differently…Years ago they offered one pump relay that could handle up to 8 systems on one pump (PR8X) and it came with individualised components, all of which could be replaced…The “Circuit Board” & separate” Triac” (solid state relay that switches & carries the pump current) came with the box…You could then add “Triggers” for as many units as needed, and you could also select trigger voltage (115 or 230) to match the system voltage feeding it….These triggers of course were/are replaceable with two screws & two plug on wires in the event of failure…

The only problem with this Pump Relay was the box was a bit large for smaller areas in boats that may only need 2 or three triggers…So they built a smaller box that can house all the same basic components (circuit board & triac) but only has room for up to 3 triggers…It can also be purchased with the triggers pre-installed for either 2 or 3 systems (PR3X-?) The question mark would be the number of triggers pre-installed (either 2 or 3)…They still offer the PR8X, and it can also now be purchased with triggers pre-installed but either box is not hard to add/install trigger/s in…

The main purpose of these relays is to run the pump when a system is calling for it…That means any system that is running a compressor (Some with just fan, IE: older Three knob cabin control-ed systems)…But if a trigger circuit in either type box fails (Marine Air, Cruisair, or any manufacturer) the pump may run for one or more systems…But not for the one that has the failed trigger circuit…

This sometimes causes confusion because if any one of the good triggers starts the pump…All systems that are connected to that pump will get seawater, and thus run normally….

However if the system/s with the good trigger/s cycle off, and the one with the bad trigger either continues to run, or starts up with the others off…It may/should shut down randomly with a fault code on the cabin display.

The easiest thing to do to verify if you have a problem is to test run each system” individually” to verify if you are pumping water with just that system running…If you find a system that won’t start the pump, the trigger circuit (in the pump relay) for that system has likely failed.

Also if the pump won’t run at all…These Pump Relays all have fuses installed either inside the box (Newer automotive type pull out fuse) or in a typical twist type fuse holder mounted thru the box ( It’s how Ocean Yachts gets away with running the pump on the salon breaker)…This should be one of the first things to check….If the fuse is blown, and then blows again after replacement, it’s time to look at the pump & associated wiring for shorts or bad/wet connections.

These Pumps & Relays are pretty easy to troubleshoot with a volt meter and a bit of common sense, but going into that here would be a bit long for all models…If you want help with your individual installation, I’ll be more that happy to answer in the forum troubleshooting section http://marine-ac.com/forum/troubleshooting/

Just let me know what you have and we can solve it there together…If you have another brand of equipment or model of pump relay, it’s likely that I have seen a few…We can figure those out together too…

Steve~