Refrigeration -- Replace or Repair?

[Dockhead]

My boat is 22 years old now, 14 of those years in my ownership.


She has Isotherm refrigeration -- a front-loading Isotherm box and top-loading separate freezer, each with its own compressor using an Isotherm SP through-hull as a condensor.


I have been pleased with this system, which allowed me to store enough food to feed 5 people on a 3 month trip to the Arctic with rare reprovisioning. The large separate freezer is especially great.


But both systems have had slow gas leaks for years. This has not troubled me all that much as one refill every spring has kept me going. But one refill became two and now the fridge part is leaking badly and I can't put off any longer doing something about it.


My question is whether it's worth renovating 23 year old Danfoss units or whether it's better just to replace them, as they are not all that expensive.


I like the SP system and would definitely keep that -- it's very efficient in the cold waters I sail in.



I would think that perhaps I could replace the two compressors and the two SP through hulls and all the lines, but leave the boxes and evaporators.


OR -- since they both still run fine -- would it makes sense to try to have them repaired and keep using them for a while?


Advice appreciated.

[rslifkin]

What compressors do they use? If they're BD35 or BD50 units where a new fridge would likely use the same, I'd be inclined to let an HVAC tech look at them and decide if they can be easily repaired or if the cost wouldn't be worth it relative to a new unit.


I see no reason to spend extra money on a new unit unless the old one can't be cheaply repaired or the new unit is a worthwhile upgrade.

[Turtle Blues]

Slow leaks are almost always at the mechanical connections and schrader valves. Disassembling and reseating with a proper sealant may extend the life of the systems.
If replacing go with a complete system, orifice and distribution tube sizing has changed with the newer refrigerants so it is difficult to do a partial refit.

[SailingHarmonie]

Assuming it’s an R143 system, replacing bits certainly is possible, with a caveat. When you buy new components, they all come with the correct charge in each piece. If you swap out existing pieces it the refrigerant is not distributed the “correct” way and the overall charge will probably need to be adjusted, maybe up, maybe down.

[Dockhead]

Originally Posted by rslifkin

What compressors do they use? If they're BD35 or BD50 units where a new fridge would likely use the same, I'd be inclined to let an HVAC tech look at them and decide if they can be easily repaired or if the cost wouldn't be worth it relative to a new unit.

I see no reason to spend extra money on a new unit unless the old one can't be cheaply repaired or the new unit is a worthwhile upgrade.

They are BD35F compressors, running on R134a.


I guess the question is whether at 23 years old they are anyway end of life so not worth spending money on.


Another big question is whether I can keep the evaporator plates. Replacing the boxes and evaporator plates would double or triple or quadruple the size of the job.

[SV THIRD DAY]

Originally Posted by Dockhead

They are BD35F compressors, running on R134a.


I guess the question is whether at 23 years old they are anyway end of life so not worth spending money on.


Another big question is whether I can keep the evaporator plates. Replacing the boxes and evaporator plates would double or triple or quadruple the size of the job.

The compressors have a 20yrs realistic life span....so throwing more money into an end of life compressor doesn't seem like a good use a boat bucks.

[Bowdrie]

First order of business, a through comprehensive leak checking.
Decisions of what to replace (or not,) are useless without knowing where the refrigerant is going.
As has been mentioned, the connections and Schrader valves are high priority.
However, the pressed aluminum evaporators are highly suspect in old systems,
particularly where the copper tubes enter/exit the evaporator(s).
Any paint missing from the evaporators?
If so that's a great spot for minute leaks to develope from corrosion.