Basic Boat Refrigeration DIY

[accomplice]

If you have an opportunity to evacuate the system, install service valves high and low and replace the filter-drier. Then, pressurize the system with nitrogren.

I recently installed a refrigeration system on my boat. I found leaks at 250psi (of Nitrogen) that were not evident at 35psi.

Once you're satisfied the system holds nitrogen at high pressure (for a while), evacuate and load with refrigerant.

Gauges, pump, nitrogen tank, and regulator are not very expensive to buy, but you may be able to borrow them instead.

[accomplice]

oh, and you can inject a flourescent dye when adding the refrigerant (to an empty system, is harder to do if already under pressure) which shows up under uv/blue lamp.

i haven't done this personally, but have seen it done and it can help to identify source of leaks.

[accomplice]

Originally Posted by Dockhead

Is there a book? Marine refrigeration for idiots?

One that I remember was a good book for troubleshooting was Doolin's Troubleshooters Bible.

[onestepcsy37]

Best refrigeration book for cruisers is by Richard Kollman. Go to his website to order it.

[socaldmax]

They sell freon sniffers. The one I played with was extremely sensitive, it would beep if you breathed near it. Amazon sells a nice one for $47.

My neighbor had a 2.5 ton A/C on his house, way too small. He had it replaced a yr ago with a 4 ton, really close to the right size. Something went wrong with the install or the new unit, after countless calls and their techs unable to find out why it wasn't cooling, they ripped the entire system out - FAU, condenser, all copper piping and started over with a 5 ton unit free of charge, to make up for the aggravation. The new one works.

Sometimes, even the "professionals" get stumped.

We're very fortunate to have Richard's level of knowledge available to us, many professionals never achieve the level of diagnostic skill he possesses, they just burn through your money throwing parts at it until they accidentally "fix" it.

[hellosailor]

Sniffers can be quite tricky to use for small leaks. Among other things, the sniffer's tip can be contaminated, and any air movement in the area (i.e. a fan) makes them useless.

For a small leak, I'd suggest adding UV dye to the refrigerant, letting it run, and then coming back every week or so with a UV inspection light to try finding the dye marking the leak. UV lamps complete with dye injection kits are commonly sold and not terribly expensive. You can buy refrigerant with a dye charge mixed into it, and you can buy bright UV flashlights and a yellow goggle (increases contrast, makes the dye much easier to spot) and do it piecemeal as well.

Given that it is taking years to lose enough to create a problem, and how cheap and easy it is to add R134a (assuming that's what it uses) waiting and watching for a UV dye stain will give you a cheap way to see just what the larger problem is.

There are also whole courses (leading to US-EPA certification to deal in refrigerants) online, to get the bigger picture. But for "serious" repairs you need a good vacuum pump, which isn't cheap. Plus the gauge set, which is used for one type of refrigerant only, plus you still need the leak detection bits, plus....You know, like chess & poker, the rules are very simple, the game is very easy.(G)

A UV kit and some patience will make it easy to find the leak, assuming you can actually SEE into ALL the odd places. If it is in the evaporator coils, etc., it may be quite hard to observe, even with the UV. Which still can mean "if I can't see any leaks, it must be in the piece I can't look into."

[accomplice]

Originally Posted by hellosailor

But for "serious" repairs you need a good vacuum pump, which isn't cheap.

It isn't fast, but I picked up a Robinair 1.5cfm pump for about $85. If you're willing to let it run for a while (hour?). It isn't commercial-duty -- so don't expect to use it every day.

[hellosailor]

Sounds like you got lucky and got a bargain on a used vacuum pump, assuming that one pulls the vacuum down enough for those systems. If Dockhead just wants to go out and BUY what he needs, new and not trolling around for used...It won't be $85, will it?

[Richard Kollmann]

Using fluorescent dye is bad advice if used to test for refrigerant leaks on small BD compressor systems. If you must use this dye it should be limited to only 2 drops and not the 1/4 ounce recommended for automobiles.

Also Bad advice to leak test with 250 psi of nitrogen as it can destroy Roll-bond thin plate aluminum evaporators. One hundred and fifty psi should be maximum test pressure and even then on older evaporators pressures above normal conditions may open weak spot pin holes common on units more than 10 years old.

General advice to add refrigerant is also bad if loss of refrigerant is not confirmed by a non destructive method first, Examples, adding refrigerant to a Frigoboat keel cooler system with a restricted capillary tube may limit Frigoboat’s possible recommended repair fixes or it may cause owner to scrap an EZ Kold complete system with a failed water cooling condenser.

I have practiced and guided technical services from remote locations for almost 60 years. If a person is smart enough to operate a boat they are capable of most DIY pleasure boat refrigeration repairs. NO, you do not need to buy my books as most all guidance is available free on my web site. What you must know first is the possible weak points in the system you have, this information can generally be found on the web.

[accomplice]

Originally Posted by hellosailor

Sounds like you got lucky and got a bargain on a used vacuum pump, assuming that one pulls the vacuum down enough for those systems. If Dockhead just wants to go out and BUY what he needs, new and not trolling around for used...It won't be $85, will it?

Amazon.com: Robinair 15115 VacuMaster 1.5 CFM Single Stage Pump: Automotive

[accomplice]

Also Bad advice to leak test with 250 psi of nitrogen as it can destroy Roll-bond thin plate aluminum evaporators. One hundred and fifty psi should be maximum test pressure and even then on older evaporators pressures above normal conditions may open weak spot pin holes common on units more than 10 years old.

Mine was (is) a holding plate system with R-404a. At 90F is 204psi, at 105F is 253psi. I greatly respect your knowledge and experience, and 250psi might not be the right pressure test in OP's case (R-134a, evaporator plates), but in mine it was.

[jeepbluetj]

I got my cheapie Harbor Freight 2.5cfm pump for something like $59. I've only used it on automotive applications thus far (as the fridge in the boat seems to work just fine)

[Dockhead]

Originally Posted by typhoon

Dockhead, what do you mean by "self-pumping" . Are they water cooled ?

Regards .

Yes, they are passive water cooled -- the condenser is a loop formed inside a special through-hull. The motion of the boat "self pumps" water over the condenser. It seems to work extremely well, although I guess my cruising grounds -- where the water temp is rarely over 20C -- is not the harshest test.

[ColdEH]

Originally Posted by Dockhead

Yes, they are passive water cooled -- the condenser is a loop formed inside a special through-hull. The motion of the boat "self pumps" water over the condenser. It seems to work extremely well, although I guess my cruising grounds -- where the water temp is rarely over 20C -- is not the harshest test.

O yes I remember that set up , I always thought it was a good idea, but i agree, water cooling my be over kill , you are probably just fine in your area with air cooling. I actually intend to air cool even in the tropics , just making sure the fans have a fresh air source .

I know there were issues with any "O" rings in many water cooled systems , do you have them in your setup? Maybe a source for leaks .

Regards