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Post by Damen af Kungsholmen on Sept 29, 2022 13:36:21 GMT
Hi The fridge working by taking “cool” air to the condenser and make it warmer. Today are the air coming from the dustbin compartment by a small fan mounted on the compressor unit. I measured a difference of 4,5 degree at the dustbin compared under the ply. By getting cooler air will the efficiency be better. OK I am living latitude north 59, I have none experience how I will be on latitude north 35 at the Mediterranean Sea. Cooler air to the condenser will lower the consumption of amp hour. It’s simple as that. My modification toke me two hour to make and I am sure it will help. Otherwise, I have lost two hour and 25€ Intention are that I could leave the fridge on for several weeks sourced by 540Ah LiFe charge by two times 110 Watts solar cells with individual MPPT charger. After two weeks I had 84% left on the battery. OK I forgot to turn off the router and minor current thief. I just want to share this improvement. Cool regards Dan
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Post by zaphod on Sept 29, 2022 14:43:52 GMT
Nice job on the duct. Did you add a 2nd fan, or are you just relying on the condenser fan to draw the air? If you added an extra fan then you have to factor in the amp draw of the fan to your overall efficiency and noise.
It is a good idea if you have really high cabin temperatures, but the temperatures you are measuring are relatively cool, and the unit will have no trouble maintaining design pressures with either temp.
Did you take amp draw readings before and after your mod? Was there a significant change in amps?
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Post by ohana on Sept 29, 2022 16:53:02 GMT
Thanks for the photos, I did something similar on my 439 where the original fridge air circulation arrangement by Jeanneau is exactly the same as yours, where the warm cabin air is drawn in to the fridge compressor and then the warmer air exits out into the void behind the galley counter unit. I looked at turning the compressor unit round 180 degrees but this would not have been practical. So I fitted a 90 degree 100mm pipe bend on the intake side so the compressor now draws air from the bilge area rather than the cabin. I didn’t do any before and after temp measurements but an un-scientific observation shows the fridge compressor seems to be running less often since doing this mod.
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Post by Damen af Kungsholmen on Sept 29, 2022 21:00:26 GMT
Nice job on the duct. Did you add a 2nd fan, or are you just relying on the condenser fan to draw the air? If you added an extra fan then you have to factor in the amp draw of the fan to your overall efficiency and noise. It is a good idea if you have really high cabin temperatures, but the temperatures you are measuring are relatively cool, and the unit will have no trouble maintaining design pressures with either temp. Did you take amp draw readings before and after your mod? Was there a significant change in amps? Thnx No extra fan. Its just a passive modification. The factory have placed the fan directly to the dustbin cabinet. Every degree lower temp I can bring to the condenser will help the power consumption. The amp current will not change at all what ever I do. But the time the compressor are working will be less as lower temp I can bring to the condenser. Its not that easy to measure how many amp hour I will save. I should measure the time the compressor are working before and after the modification.
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Post by Damen af Kungsholmen on Sept 29, 2022 21:10:54 GMT
Thanks for the photos, I did something similar on my 439 where the original fridge air circulation arrangement by Jeanneau is exactly the same as yours, where the warm cabin air is drawn in to the fridge compressor and then the warmer air exits out into the void behind the galley counter unit. I looked at turning the compressor unit round 180 degrees but this would not have been practical. So I fitted a 90 degree 100mm pipe bend on the intake side so the compressor now draws air from the bilge area rather than the cabin. I didn’t do any before and after temp measurements but an scientific observation shows the fridge compressor seems to be running less often since doing this mod. My pleasure. A photo are always telling more then words. I was first thinking of making hole at rear of the cabin to suck air under the coach but the warm water heater are located their so that was not a good idea. Would be easy to measure the time the compressor are running. But that will be done when I have time over or never.
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OhWell
Full Member
Posts: 33
Jeanneau Model: 43DS
Home Port: Ft. Lauderdale
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Post by OhWell on Sept 30, 2022 11:53:52 GMT
Add a Victron Smart Shunt to your system to get a graph of exactly when your refer is running on your phone! Great fun after decades of wondering.
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Post by Mistroma on Oct 1, 2022 5:09:35 GMT
Tidy job. I suggested a similar thing to my wife but she keeps a load of stuff in that locker. I've been meaning to add a vent under the door and this might prompt me to finally get around to that job. We currently unblock the bin lid and tie the door open when anchored and this does improve airflow.
Following tips might be worth considering.
1) Cover the fridge top. We made 2 covers from foam covered with vinyl and metal foil inside on top and bottom. Large one over the door and smaller one in the corner. We made them slightly short to leave a gap at cooker end. It is a great help in summer and the top of these often get VERY hot in sunlight.
2) Insulate not water tank locker There's a large hole leading from the two and straight to the compressor. I pulled foil backed insulating sheet over the gap. The locker gets very warm when full of hot water and not pipes run close to the compressor.
3) Check and clean fan area I remove the grill a couple of times each year to look at the system. I usually use a vacuum cleaner to remove a load of fluff from the heat exchanger and fan.
I have also wondered about improving vent to bilge area instead. Air temp. in the saloon is often 38C in summer but water temp. only 32C. Cabin temp would be 4C higher without my side window and deck covers in place.
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Post by ohana on Oct 3, 2022 19:48:01 GMT
Add a Victron Smart Shunt to your system to get a graph of exactly when your refer is running on your phone! Great fun after decades of wondering. Hi - spotted typo in my last post, my analysis was unscientific! ( now corrected the post) I have a master volt Battery Monitor system with current measurement, but this is for all house systems, so hard to tell what’s only fridge draw.
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Post by Damen af Kungsholmen on Oct 4, 2022 10:02:55 GMT
Add a Victron Smart Shunt to your system to get a graph of exactly when your refer is running on your phone! Great fun after decades of wondering. Add a Victron Smart Shunt. Smart idea. I was not thinking of that. I have already one in the system with BT. Next summer I will make a test to let the fridge run with the old air inlet and the new for some period. Also measuring the different of temperature.
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Post by zaphod on Oct 4, 2022 17:18:20 GMT
Certainly it can't hurt to draw air from a cooler area of the boat, particularly if the cabin gets very hot, but I think you are over estimating the overall effect of that mod. It could have a small effect on the amp draw of the compressor because the compressor may run with a lower head pressure, but it will not reduce the cycle time of the compressor unless the stock configuration was so bad that it was unable to fully condense the refrigerant, which is unlikely. The compressor has a fixed refrigerating capacity.
Cycle times are a factor of box insulation and the contents of the box more than anything else. If your cabin is very hot the fridge will cycle more due to heat gain through the box insulation. The greater the temperature difference between the box and the ambient air the more frequently it will cycle. Also, a box full of fruits and veggies will cycle more than a box full of beer because organics are constantly producing heat as they ripen, (Heat of Respiration)
Don't get me wrong, I like the mod you did, just don't expect radical results from it in terms of cycle times. For that you will deed to make improvements to the box itself.
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