Frigo boat O rings for quick coupling

[Kristian]

Hello Fellow cruisers.

I just want to share a bit of information regarding Frigoboat quick coupling leaks and a few other problems I discovered getting on top of the problems I have had.

I have had a situation where I have had to refill my system once a year with a little R134a gas. I did think that it was not a big deal a 1kg bottle costs about 20Euro and lasts for ever.

Recently I started getting problems with the systems really working substandard and I do believe that this is really from the system not only leaking gas out but most likely also from drawing air in on the suction side , all eventually leading to possible freeze up of capillary tube , diluted charge etc.

I did find many nice posts here on CF helping me to successfully get my fridge and freezer back to perfect working order and one of the things I learned is the changing of the O rings in the quick couplings is essential every about 5 years.

A funny thing is that being on the Island of Sardinia it was not so easy to get the O rings even though the manufacturer Veco is Italian...

In the end I asked in a store in Porto Torres and the owner said that he used to sell and service the Frigoboat systems. He was very well aware of the O ring problem. Being a fantastic man he just told me to jump into his car and we drove to his friend doing service on car A/C systems.
At the store I learned from the service technician that introducing R134a the whole car industry changed from black to green O rings. If I understand it correctly these green O rings will have a much longer service life than the black ones that go hard.
When starting sourcing O rings I first went to a company that is a Frigo boat service agent, of course he did not have the correct o rings on the shelf but had a scrap system so I got 2 quick connectors that he cut of ( you just meet so many fantastic persons sometime). Looking at the construction I realized that there is a definite possibility to add o back up O ring that sits further down on the male coupling and will be compressed on three sides when the coupling is screwed down. ( no need to tight these couplings very hard) It rests basically against the threads on the male connector and the female with its chamfered edge will slide on top of it compressing both downwards and towards the thread.

So what is the correct size , I could not find any internet information so my measurements from the old ones are ( hard to measure O rings but it give you an Idea what to lock for)
ID 11mm and thickness of the cross section of the O ring just above 1.5mm.

If you want to try the back up O ring I mounted , the size for the one I used is :
ID 12mm cross section 2mm.

When changing the O rings I think it is a good idea to get new a new cap for the service port as well, this is a standard 1/4 SAE fitting and it is easy to get new caps since these are used on many A/C fridge installations.

I did really want to get on top of and understanding this problem so I spent 200E on a vacuum pump , hoses and gauges + a 1kg bottle of R134a.

( In the EC and many other countries you are not allowed to use things like this without a certificate so of course I had a friend with a certificate to help me with the work!!!!!)

8 hours of vaccum ( 4 hours on each on fridge and freezer) and careful heating with a heat gun then carefull and slow refilling not to overcharge ,the systems are working better than ever.

Having the possibility now to really work with these things I´m thinking of perhaps making a single water cooled condenser for both the fridge and freezer. I did read about an Aussie guy that did just that for his camper with good results.
He used a low amp circulating pump just circulation his drinking water through the condenser that is basically a bigger copper tube with a smaller inside. Please see:

http://www.zipworld.com.au/~frankp/condenser.pdf

I do have 700 liters of drinking water and it will really not be possible to heat it significally even when the water is getting low in the tanks. It would be nice not having to worry about seawater blockage, corrosion problems or anything like that with the seawater cooled systems that are available for the frigoboat sytems. With the condenser coil placed just outside the tanks and a 0,3 amp circulation pump (4 litres / minute) run by the compressors ( instead of the fans) I think my systems will be more efficient and take less amps.

It might be good to know that you can easily change the rpm on the Danfoss BD 35 or BD 50 just by adding the correct resistor in the thermostat connection. Since I had to study so much I realized that the guys installing my frigoboat systems did not know that the recommendations for the size of evaporators used in my systems requires higher RPM than the basic 2000 that you get without any resistor.

Hope this post might help someone to get cold beer again ( not to mention frozen ice cream)!!!
Kristian

[aaron212]

First off, thanks for sharing a bunch of useful information. I happened upon your post whilst trying to troubleshoot a Frigoboat system on my friend's boat.


I would normally hesitate to reopen an old thread like this, but I think there may be a potential safety issue with your idea of using your water tank to cool the condenser. Namely, I would be concerned about increasing the risk of your water tank becoming a breeding ground for Legionella bacteria, which grows best between 25 C and 45 C. (of course, depending on the climates you are sailing in, it may already be a breeding ground)