Refrigeration Question

[Dockhead]

My boat has two reefer units, one for a front-loading fridge, and the other for a top-loading separate freezer. They are Isotherm SP units with Danfoss BD compressors.



They are 23 years old and have been slowly leaking gas for years. For a long time one shot of R-234a from one of those auto parts store tap cans in the spring was enough to keep it going.


No more. The freezer one is still more or less OK but the fridge one needs topping off once a month already. Time to finally do something about this.


I have a few options on how to deal with this:


1. Try to find the leak and repair the units. Apparently they commonly leak at the condensor through hull.


2. Just replace the condensor through hull. They cost £1000 each (ouch!).


3. Replace the condensor through hulls AND the compressors.


4. Replace the entire reefer units.


These units are 23 years old and other than the leaks they have been absolutely bulletproof. Never had the control board problem common to the Danfoss compressors, or any other fault other than the leaks. It's a shame to get rid of these but I think putting money into 23 year old equipment of this type is probably not a good idea.



My reefer boxes are built into the cabinetry and I really want to avoid replacing those if possible -- that would require major surgery on the cabinetry which would double or triple the cost of this operation.



So my real question is -- is it OK to reuse the the evaporators -- which apparently don't have any faults -- and replace the compressors and condensors?


Anyone with knowledge have any tips?

[pcmm]

A bit more information is needed here. What type of refers do you have? Does it have quick connects for the Refrigerant lines? my Frigoboat system had the o-rings in the quick connects disintegrate, which caused a lot of leaking of gas. I ordered replacements, and the problem went away. But it did take me a bit of messing about to get the refrigerant levels mostly correct afterwards.

[SailingHarmonie]

If your system has the quick connects, then swapping out is easy, if you are comfortable with adjusting the charge as required. Certainly Isotherm units of this age had quick connects in most cases. And as pcmm suggests, if you are opening them up anyway new o-rings would be a good idea.

If it is a hard plumbed system it can be done, but would require someone with more skills than the average cruiser.

[rslifkin]

I wouldn't be too concerned about reusing the evaporators if you're convinced they're not the source of your leaks.

I do agree with the logic that the components are old enough that they're probably not worth putting money into, as you may not be far off from more parts of the system wearing out or failing. And depending on how easily the leak can be found and fixed, a repair may not be all that much cheaper than replacement anyway.

[Dockhead]

Originally Posted by SailingHarmonie

If your system has the quick connects, then swapping out is easy, if you are comfortable with adjusting the charge as required. Certainly Isotherm units of this age had quick connects in most cases. And as pcmm suggests, if you are opening them up anyway new o-rings would be a good idea.

If it is a hard plumbed system it can be done, but would require someone with more skills than the average cruiser.

I believe it has quick connects, but I am definitely hiring a skilled reefer tech to do this. I don't have either the skills nor the equipment to pull the deep vacuum needed before charging and don't want to risk the installation to save just a few bucks on someone's time.


I will probably try to do this in Sweden where Isotherm is made. I've had good luck there finding really good Selden tech guys and I hope the situation with refrigeration will be similar.

[Dockhead]

Originally Posted by rslifkin

I wouldn't be too concerned about reusing the evaporators if you're convinced they're not the source of your leaks.

I do agree with the logic that the components are old enough that they're probably not worth putting money into, as you may not be far off from more parts of the system wearing out or failing. And depending on how easily the leak can be found and fixed, a repair may not be all that much cheaper than replacement anyway.

I hate to scrap the compressors and control systems which have been totally fault free for all these years, one of the very few pieces of equipment on the boat like that. But I can't escape the fact that these like everything have a limited useful life and 23 years is surely near the end of that.


But I'd really like to keep the evaporators since changing them would mean major surgery on the cabinetry, which I really don't want to do.


Thanks for your comment.

[Exile]

I've owned my boat for 17 years at this point and inherited from a PO two SeaFrost systems -- with large, separate frig & freezer boxes -- and they have been one of the few systems which have been largely trouble free. I can think of only 3 instances where I had to have a tech come onboard to do any servicing, and they were all relatively simple and inexpensive fixes.

The first was a small but elusive leak that was eventually uncovered & repaired under some cabinetry. No. 2 was the replacement of the (very old) condenser for the engine drive system. Finally, yet another longstanding leak was resolved by one of the aforementioned o-rings at a connection point.

My point being that, if what you're describing is chronic leaking of refrigerant, it may be worth your while to have a tech give it a go with one of their leak detection devices before replacing expensive components or the entire system. An experienced tech should also be schooled up on the locale of common leaks and be able to pinpoint them in short order. I don't know exactly how much longer than 17 years my systems have been operating, but it could easily match the 23 years cited, and could also be original to the boat (1986) since they were commonly installed OEM by my particular boat builder.

Re: insulation, and fwiw, I also did not relish the thought and expense of tearing up my two boxes so went with the 1/4" tin foil looking insulation discussed elsewhere. Yes, you lose a bit of capacity and any remote wireless temp sensors will no longer work, but it made a surprisingly big difference in how long I can go before my holding plates (no evap plates) need recharging.

Hope this helps and best of luck with it.

[Dockhead]

Originally Posted by Exile

I've owned my boat for 17 years at this point and inherited from a PO two SeaFrost systems -- with large, separate frig & freezer boxes -- and they have been one of the few systems which have been largely trouble free. I can think of only 3 instances where I had to have a tech come onboard to do any servicing, and they were all relatively simple and inexpensive fixes.

The first was a small but elusive leak that was eventually uncovered & repaired under some cabinetry. No. 2 was the replacement of the (very old) condenser for the engine drive system. Finally, yet another longstanding leak was resolved by one of the aforementioned o-rings at a connection point.

My point being that, if what you're describing is chronic leaking of refrigerant, it may be worth your while to have a tech give it a go with one of their leak detection devices before replacing expensive components or the entire system. An experienced tech should also be schooled up on the locale of common leaks and be able to pinpoint them in short order. I don't know exactly how much longer than 17 years my systems have been operating, but it could easily match the 23 years cited, and could also be original to the boat (1986) since they were commonly installed OEM by my particular boat builder.

Re: insulation, and fwiw, I also did not relish the thought and expense of tearing up my two boxes so went with the 1/4" tin foil looking insulation discussed elsewhere. Yes, you lose a bit of capacity and any remote wireless temp sensors will no longer work, but it made a surprisingly big difference in how long I can go before my holding plates (no evap plates) need recharging.

Hope this helps and best of luck with it.

Well, you make a good point, and a valuable different perspective.



In any case I'm going to need a tech on board so maybe really worth starting with this.

[TeddyDiver]

Originally Posted by Dockhead

snip..

2. Just replace the condensor through hull. They cost £1000 each (ouch!).

..snip

Ouch indeed.. it would be cheaper to fly in an old timer fridge repair man from Cuba as they keep the 90yrs old US style fridges stil running.

[senormechanico]

It might be a good idea to see if you could positively identify the location of the leak.
Ebay has them in many flavors.



https://www.ebay.com/sch/i.html?kw=r...r&toolid=20004

[Cpt Mark]

I had a similar situation except mine used r-12. Only refer tech in my area told me it wasn't worth fixing and suggested I replace it with a stand alone ice chest refer/freezer thing. Worst advice I've ever gotten. I tossed the system and bought the stand alone chest unit which required surgery to fit into the compartments. Hated that and 3 months later, took it out. Rebuilt the entire fridge/freezer compartments again. They were originally 2 separate compartments and then installed the Nova Kool thin plate system. They were $900 USD for the everything per side. I was told that using 1 unit as a spillover system would work fine. I opted to spend double the money because I have redundancy. I love the new system and added more insulation without losing any space in the original boxes by getting rid of the holding plates. While I'm happy with my current system which after rebuilding the torn up boxes was very easy I'd have preferred to keep my original system that had been working fine until it lost it's charge.

[Exile]

Originally Posted by senormechanico

It might be a good idea to see if you could positively identify the location of the leak.
Ebay has them in many flavors.



https://www.ebay.com/sch/i.html?kw=r...r&toolid=20004

Not a bad idea to have one of these onboard. Pretty dramatic diff in cost! Wonder if it's a "get-what-you-pay-for" deal or the cheapos are okay given the once in awhile use.

[Madehn]

call Charlie at Cruise RO and discuss with him-- very knowledgeable and willing to help-- i rebuilt both of my systems using their components but kept my old cold plates- worked out well.

[Bowdrie]

Originally Posted by Dockhead

So my real question is -- is it OK to reuse the evaporators -- which apparently don't have any faults

Key word, "apparently".
Over long periods of time tiny leaks developing where the copper tubing enters/exits the aluminum evaporators are more common than one might think.
The fact that the units hold so little refrigerant and take so long to leak-down points to a very small leak.
Also, some of the older units did not use quick-connects that have O-rings, they used a "knife-edge" metal-to-metal seal.
A tech can carefully pressurize the system and then have the patience of Job to track down the leak.

[Dockhead]

Originally Posted by Bowdrie

. . . A tech can carefully pressurize the system and then have the patience of Job to track down the leak.

Job wasn't paid by the hour, I think


The problem with this, of course, is that you can quickly rack up a bill which is similar to the cost of a whole new system.