Re: A54 fridge circulation pump


ngtnewington Newington
 

Hi Scott, Mohammad et al,

I puchased Amelia in the West indies and sailed her to Greece. So have both tropical and temperate climate experience regarding the fridge system.

We have the same three fridge unit set up and the cooling pump lasts us quite well, probably along the 5000 hours estimate. I have noticed a few things;

1.The whole sea water cooling circuit is prone to shell growth.  This may originate in the main raw water strainer; so we now regularly clean it. The plastic basket that pulls out cleans up nicely by putting it in an acid bath. 

2. Due to that shell growth I have found fragments of shell within the valves on the fridge system circulating pump. These fragments are not good for the pump. 

3. I have found that the whole fridge sea water circuit, is also prone to shell growth. About once a season I take off the hose from the circuit and connect it to a hose pipe from the shore and blast fresh water through the whole thing. On one occasion I found that the copper manifold near the exit skin fitting was gunked up so the water could not flow. This required poking it out with a piece of wire. It was muddy crud!

4. When I bought the boat there were 4 spare fridge pumps aboard, the Amel set up installed two pumps so that it is quick to swap over. This all tells us that the system is prone to the pumps failing by design, and that the previous owner had issues with this.

5. When a pump fails, I swap to the spare and then strip down the failed one. To date the brushes have been good, bar one. Generally the problem has been shell fragments in the valves. So I clean it and put it back as the spare.

6. When swapping pumps I notice that the sea water flows as the pump is changed. In other words the pump is below the water line, so might not a non self priming pump work? 

Of course in the long term it would be great to improve the insulation for the fridge units, alas it is a big task, but frankly in this day and age polyurethane foam is not the best. Vacuum panels are the way to go. The fact that the units are running 80% of the time in the tropics tells me that the insulation is the real problem.

All the best,

Nick

Amelia AML 54-019
Kilada Greece




On 13 Jan 2020, at 19:28, Mohammad Shirloo <mshirloo@...> wrote:

Hi Scott;
 
We’re currently in the Med, so we’re on board full time for about 5 months every year. The fridges are obviously on all the time. We typically run two of the fridges and do not typically have a freezer on. I agree that the system will be working harder in the Caribbean and tropical conditions and are working closer to their design limits.
 
One of the reasons we selected an Amel, was because it had been tested over decades in conditions we expected to experience. I cannot comment based on personal experience about tropical conditions, since we have not experienced it with our Amel. I would look into the experience of all other Amel owners who have experienced the same conditions and if a significant percentage were experiencing what you and Arno have experienced, then I would conclude that there may be some design issues with the system. Otherwise I would suspect some other issue that may be unique to us. I typically suspect the design and component issues as a last resource, after I have eliminated all other possibilities.
 
Sorry that I cannot be of much more specific help, just another point of view.
 
Happy Sailing;
 
 
Mohammad and Aty
B&B Kokomo
AMEL 54 #099
 
From: main@AmelYachtOwners.groups.io <main@AmelYachtOwners.groups.io> On Behalf Of Scott SV Tengah via Groups.Io
Sent: Sunday, January 12, 2020 3:18 PM
To: main@AmelYachtOwners.groups.io
Subject: Re: [AmelYachtOwners] A54 fridge circulation pump
 
Mohammad,

Do you live aboard full-time? Arno and I do and our experiences are similar. In tropical heat and 2 fridges and a freezer running, at any given time, it's very likely one of the compressors is running which means the pump is running. 

I would guess my pump runs 80+ % duty cycle. The Frigoboat pump interface really should have the ability to coordinate the compressor operation "schedule".

My understanding, confirmed by long discussions with pump engineers at Marco, is that brushes on any DC electric motor last 2500 hours on average and in the best circumstances 5000 hours. With the near continuous duty, the Flojet pumps get quite warm, which accelerates brush wear. If you take my experience with 6 month motor life and multiply it out: 180days * 24 hours a day * .8 duty cycle = 3456 hours, which is right within spec.

If your pump lasts 11 years in the same use case as Arno and myself, that would mean it's lasted over 75,000 hours!

Even March pumps, which are brushless, are only rated for 50,000 hours. But sadly for my setup, the March rep told me it wouldn't work since their pumps won't self-prime, confirmed by Arno's testing. I would really love to retain the self-priming capability of the Flojet pump but get a brushless motor on it, like Oliver has done.

-- 
Scott 
2007 A54 #69
SV Tengah
http://www.svtengah.com


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