Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 26-01-2015, 11:43   #1
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,735
Refrigeration Problems

I have two separate Isotherm SP systems cooling a fridge and separate freezer.

When I bought the boat 5 1/2 years ago, the fridge was not cooling well, and I had gas added to it, whereupon it performed flawlessly for another 4 1/2 years. Then, last summer, cruising in Sweden on my way to Finland, the fridge just about stopped working, and the compressor became very hot as well. I found a marine refrigeration guy who added gas, and it worked ok again. Then just a few weeks later, the freezer stopped cooling well -- if only I had thought to have that checked at the same time the guy did the fridge .

The problem seems to be a slow leak of refrigerant, and last summer, I thought, if I only have to top it off once every four years, it's really not a problem.

But now the freezer is cooling weakly again, a little over half a year after it was topped off

What is the right thing to do in this case? The Swedish refrigeration guy told me that small leaks like this are almost impossible to track down -- is that true? Are there any likely places to look?

Or should I just buy cans of refrigerant and a hose kit, and just top it off myself as often as it needs it?

Or give up, and replace it all?

Advice gratefully received as always.
__________________

__________________
Dockhead is offline   Reply With Quote
Old 26-01-2015, 11:52   #2
Registered User

Join Date: Jan 2010
Location: Port Ludlow Wa
Boat: Makela,Ingrid38,Idora
Posts: 1,973
Re: Refrigeration Problems

Before you give up, try the soapy water trick. It seems to be getting worse. If both systems are separate you could be reaching the end of life for seals in the compressors.
__________________

__________________
IdoraKeeper is offline   Reply With Quote
Old 26-01-2015, 11:53   #3
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,385
Re: Refrigeration Problems

Get in touch with the guru of refrigeration: Richard Kollmann. He has an excellent website. One of his points has always been than 99% of frdige problems are electrical (unless you're sure it's a leak). Good luck.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Old 26-01-2015, 11:58   #4
Registered User

Join Date: May 2011
Posts: 18
Re: Refrigeration Problems

Hi i service a lot of small marine systems and have found the surest method of leak detection for me is to remove all refrigerant from the system and then pressure the system with approx 125 lbs pressure of dry nitrogen.Then i would also remove hose and cap service valve.Now brush and spray soapy water onto all tubing and parts.
__________________
RONDO is offline   Reply With Quote
Old 27-01-2015, 04:17   #5
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,735
Re: Refrigeration Problems

Thanks for all the good advice!

Now one more question -- is it worth chasing these leaks? Is there a reasonable chance of success?

These units are now 14 years old -- what is their normal useful life? These Danfoss compressors are not all that expensive -- maybe it make sense to just replace them? I can well imagine that some hours of screwing around with the old ones will soon add up to the same money, with no guarantee of a good result, whereas replacing them will give me a new system. What do you guys think?
__________________
Dockhead is offline   Reply With Quote
Old 27-01-2015, 05:57   #6
Don't ask if you can't handle it
 
sailorboy1's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: On the boat somewhere
Boat: Hunter 410
Posts: 12,307
Re: Refrigeration Problems

I would try a pressure test to find the leak since the system works fine otherwise. Otherwise maybe it is time for you to get a recharge kit.
__________________
jobless, houseless, clueless, living on a boat and cruising around somewhere
sailorboy1 is offline   Reply With Quote
Old 27-01-2015, 06:20   #7
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,573
Images: 240
Re: Refrigeration Problems

Quote:
Originally Posted by Dockhead View Post
... These units are now 14 years old -- what is their normal useful life? ...
You're probably approaching the unit's end of life.
The “standard” life expectancy of a domestic household refrigerator typically varies between 10 & 18 years, with 14 years being considered “average”.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 27-01-2015, 06:29   #8
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,735
Re: Refrigeration Problems

Quote:
Originally Posted by GordMay View Post
You're probably approaching the unit's end of life.
The “standard” life expectancy of a domestic household refrigerator typically varies between 10 & 18 years, with 14 years being considered “average”.
Thanks -- does that also apply to marine refrigeration, which is shut down most of the time?

My previous boat had an air-cooled reefer which was about 30 years old when I got rid of the boat, and still worked ok. Unlike this system, I never had any leaks and never needed to service it.

I don't know anything about these much more modern Danfoss units, except that they fry their electronic control boards from time to time. Are they mechanically weaker than the old ones? Do they wear out? Does the fact that they are shut down most of the time extend their life, shorten their life (seals drying out?), or doesn't matter?

Could it be that running mine with low gas, which made them run very hot, hurt them last summer?

Is it a good idea to replace them at this age? I'll have another 4 month, 3000 mile cruise this summer, like last summer, sometimes with a lot of people on board, and the refrigeration is pretty important.

Grateful for all advice.
__________________
Dockhead is offline   Reply With Quote
Old 27-01-2015, 06:30   #9
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 17,032
Re: Refrigeration Problems

Quote:
Originally Posted by Dockhead View Post
Thanks for all the good advice!

Now one more question -- is it worth chasing these leaks? Is there a reasonable chance of success?

These units are now 14 years old -- what is their normal useful life? These Danfoss compressors are not all that expensive -- maybe it make sense to just replace them? I can well imagine that some hours of screwing around with the old ones will soon add up to the same money, with no guarantee of a good result, whereas replacing them will give me a new system. What do you guys think?

I think you know the answer, seems you have stated it pretty well to me.
__________________
a64pilot is offline   Reply With Quote
Old 27-01-2015, 06:50   #10
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,735
Re: Refrigeration Problems

Quote:
Originally Posted by a64pilot View Post
I think you know the answer, seems you have stated it pretty well to me.
I'm just speculating based on zero knowledge.

Maybe someone who really understands these systems will say:

"Those compressors are bulletproof and last 30 years. Find the leak and get it properly evacuated and charged and forget about it. But keep a spare control board on hand as those do go out unpredictably."

For example. Or maybe it could be:

"Those compressors are useless once they've been overheated once, so just replace them now."

or:

"They will be near the end of their useful life at that point in any case, so go head and replace them."

I just don't know.
__________________
Dockhead is offline   Reply With Quote
Old 27-01-2015, 08:25   #11
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,573
Images: 240
Re: Refrigeration Problems

Quote:
Originally Posted by Dockhead View Post
Thanks -- does that also apply to marine refrigeration, which is shut down most of the time? ...
Good question(s) for Richard Kollmann.
Cruisers & Sailing Forums - View Profile: Richard Kollmann
Kollmann Marine
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 27-01-2015, 08:40   #12
Marine Service Provider

Join Date: Aug 2004
Location: Ft. Lauderdale
Posts: 784
Re: Refrigeration Problems

Quote:
Originally Posted by Dockhead View Post
Thanks for all the good advice!

Now one more question -- is it worth chasing these leaks? Is there a reasonable chance of success?

These units are now 14 years old -- what is their normal useful life? These Danfoss compressors are not all that expensive -- maybe it make sense to just replace them? I can well imagine that some hours of screwing around with the old ones will soon add up to the same money, with no guarantee of a good result, whereas replacing them will give me a new system. What do you guys think?
Unless you want to take the project on yourself to find leak and correct it, complete replacement now may be your best decision. Air cooled Danfoss BD compressor refrigeration units are generally repairable at 14 years but the same unit water cooled is exposed to much harsher conditions. Tampering with refrigerant can cause interior acid corrosion over time destroying aluminum evaporators. Low voltage discharge from Danfoss compressor into seawater over time will damage condenser coil as well as galvanic corrosion damage from dissimilar metals in saltwater.

What is the present condition of evaporator? If evaporator’s exterior coating has blisters this can be caused by internal micro size refrigerant leaks do to a small moisture content in refrigerant.

What is present condition of through hull condenser's sacrificial zinc anode? And when was it last changed? Electrolysis here even with copper nickel alloy will cause very small leaks in the beginning and progress over time to faster leaks.

If you decide to find the leak yourself let me know and I will send you a step by step test procedure where all you will need is a small can or 134a a tap a can injector and two days of free time.
__________________
Richard Kollmann is offline   Reply With Quote
Old 27-01-2015, 09:01   #13
Senior Cruiser
 
skipmac's Avatar

Cruisers Forum Supporter

Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 12,373
Re: Refrigeration Problems

If timing isn't good to buy/install a new one and you want to give it a try I do believe a good refrigerant leak detector can locate even tiny, slow leaks.

At least might help isolate the problem area and keep you in operation until you pick up a new system.
__________________
The water is always bluer on the other side of the ocean.
skipmac is offline   Reply With Quote
Old 27-01-2015, 15:00   #14
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Cowes (Winter), Baltic (Summer) (the boat!); somewhere in the air (me!)
Boat: Cutter-Rigged Moody 54
Posts: 19,735
Re: Refrigeration Problems

Quote:
Originally Posted by Richard Kollmann View Post
Unless you want to take the project on yourself to find leak and correct it, complete replacement now may be your best decision. Air cooled Danfoss BD compressor refrigeration units are generally repairable at 14 years but the same unit water cooled is exposed to much harsher conditions. Tampering with refrigerant can cause interior acid corrosion over time destroying aluminum evaporators. Low voltage discharge from Danfoss compressor into seawater over time will damage condenser coil as well as galvanic corrosion damage from dissimilar metals in saltwater.

What is the present condition of evaporator? If evaporator’s exterior coating has blisters this can be caused by internal micro size refrigerant leaks do to a small moisture content in refrigerant.


What is present condition of through hull condenser's sacrificial zinc anode? And when was it last changed? Electrolysis here even with copper nickel alloy will cause very small leaks in the beginning and progress over time to faster leaks.

If you decide to find the leak yourself let me know and I will send you a step by step test procedure where all you will need is a small can or 134a a tap a can injector and two days of free time.

Thank you!! Very useful advice.

I can't really evaluate the evaporators -- they are behind the stainless steel walls of the Isotherm-made boxes.

The through-hull condensors seem fine. I inspect and clean them every time I lift out (every 3 or 4 months), but they are never really dirty, and the anodes don't wear. I wire brush them to expose fresh zinc.

It sounds like you are recommending replacing everything, the entire system, and not just the compressor. That is far more serious than what I was thinking, but what you say makes a lot of sense. How stupid would it be to replace the compressor if the through hull unit has pinhole leaks.

So maybe there's no easy way out just replacing something -- maybe I'd better start tracking those leaks. So, I'd be grateful for your procedure.

Thanks again.
__________________
Dockhead is offline   Reply With Quote
Old 27-01-2015, 15:23   #15
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Re: Refrigeration Problems

Isotherm sells everything in parts, don't they? You seem to have probable reason to believe that your problem is a leak.

If you think the most probable leak is the evaporator or lines to it (my guess), then replace that.

If the leak continues, replace the condenser, although I think if this is bad, you would have contamination showing far worse issues.

It is probably less likely that the compressor itself is bad if it is running fine now.

I'm assuming you have already done an easy leak check of the schrader valves, cap o-rings and exposed tubing.

Mark
__________________

__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Reply

Tags
refrigeration

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
And More Refrigeration Problems Dockhead Plumbing Systems and Fixtures 3 29-05-2014 09:13
How About A/C & Refrigeration wjflier Boat Ownership & Making a Living 8 14-04-2010 07:23
Refrigeration help ... GordMay The Library 5 21-07-2004 13:07
Refrigeration CaptJason Electrical: Batteries, Generators & Solar 0 26-05-2003 12:41



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 16:38.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.