Power Plate AND Evaporator

[Aprilsailor]

The refrigeration system on my boat has a 5 cu ft freezer and a 7 cu ft refer compartment. It currently has both an AB Power Plate coupled with a AB Cold Machine and a Frigoboat 160F evaporator coupled with a Frigoboat Capri 50F, installed in the freezer. Both of these units are controlled by a single AB digital controller. There is a spill over fan between the boxes, with a separate AB digital controller, to cool the refrigeration box.
The system has been working more or less OK, but I thought there was too little cycling off time. My solar panels were keeping up most of the time (West Coast Florida), but I’ve not liked the battery draw over night.
Today I’ve found that the ColdMachine has actually expired…. I don’t know it’s age, but suspect well over 10 years. So my first task is to replace that unit.
My question is about sensibility of having a power plate installed in the same box with a thin plate evaporator. Can they be expected to work nicely together? How does a single controller operate condenser unit driving these two different type of units?
My gut tells me to take out the power plate now that I’m taking out the ColdMachine, and install another Capri 50F with another thin plate evaporator. But I do want to be smart about what I remove.
I’d appreciate input on how the power plate and thin plate evaporator really work together (or not) with a single controller, fed with only a temperature input against a set point temperature.

[Richard Kollmann]

Originally Posted by Aprilsailor

The refrigeration system on my boat has a 5 cu ft freezer and a 7 cu ft refer compartment. It currently has both an AB Power Plate coupled with a AB Cold Machine and a Frigoboat 160F evaporator coupled with a Frigoboat Capri 50F, installed in the freezer. Both of these units are controlled by a single AB digital controller. There is a spill over fan between the boxes, with a separate AB digital controller, to cool the refrigeration box.
The system has been working more or less OK, but I thought there was too little cycling off time. My solar panels were keeping up most of the time (West Coast Florida), but I’ve not liked the battery draw over night.
Today I’ve found that the ColdMachine has actually expired…. I don’t know it’s age, but suspect well over 10 years. So my first task is to replace that unit.
My question is about sensibility of having a power plate installed in the same box with a thin plate evaporator. Can they be expected to work nicely together? How does a single controller operate condenser unit driving these two different type of units?
My gut tells me to take out the power plate now that I’m taking out the ColdMachine, and install another Capri 50F with another thin plate evaporator. But I do want to be smart about what I remove.
I’d appreciate input on how the power plate and thin plate evaporator really work together (or not) with a single controller, fed with only a temperature input against a set point temperature.

You have already made the decision to remove the AB and its Eutectic power plate. These power plates were not intended to be used in a large box or in tropical climates. The Capri 50F condensing unit with the large aluminum thin plate evaporator is your best option. Each of these Capri systems must have its own thermostats for two reasons; one being compressor speed control and so they both will not attempt a start up at the same exact time. The control temperature for thermostats must be taken off evaporator temperature do not use box temperatures to operate thermostats.
The performance will be better because you replaced the power plate with a more efficient thin plate evaporator but the daily energy consumed may still be greater than you would like. Satisfaction with solar or any other alternative power source is only when keeping house battery bank always above 70% charge.

[Bowdrie]

Originally Posted by Aprilsailor

The refrigeration system on my boat has a 5 cu ft freezer and a 7 cu ft refer compartment.

Twelve cu ft in total is a large amount, may I ask what kind of boat it is, and is the box stock or a custom rebuild?

[Aprilsailor]

Thank you for your insight and advice. I had a follow up question or two, but first I went to your website and read Tip#6, which covers thermostats. Got my answers. Using separate thermostats for each evaporator/condenser set makes sense to me. I’m going to be looking for thermostats with wide range of temperature. I like the idea of using a freezer when you need a freezer, but using the box as a refer when you don’t really need a freezer. I’m sure that will have an impact on my dc electrical load. So I’ll try to find thermostats which allow me to use freezer box as freezer, but also as 2nd refer. I’ll probably keep my digital readout and sensor, just for quick check on freezer box temperature - just disconnect wires providing signal to compressor. Thank you for sharing your knowledge and experience. BTW… I checked my calculations on box volume and I used wrong box length. My freezer is no more than 4 cu ft, and the refer is about 5 cu ft.

[Aprilsailor]

Bowdrie; you can see in my previous post that I mucked up the volume calculation, overstating the internal volume of freezer and refer. I need to refine my measurements and get more confidence on volume. But to answer your question, the boat is an Island Packet 420, which is relatively new to me. A couple of other owners before me, so I don’t know it’s full history. Based on IP drawings, I THINK the freezer and refer boxes are “stock.”

[Bowdrie]

Originally Posted by Aprilsailor

Bowdrie; you can see in my previous post that I mucked up the volume calculation, overstating the internal volume of freezer and refer. I need to refine my measurements and get more confidence on volume. But to answer your question, the boat is an Island Packet 420, which is relatively new to me. A couple of other owners before me, so I don’t know it’s full history. Based on IP drawings, I THINK the freezer and refer boxes are “stock.”

I only asked as I thought "Jeepers, that's a big box, must be a really big boat".
In your original post you indicated that run times were more than you thought they should be.
As the box is probably stock, I was wondering about the amount of insulation that had been used.
Lack of insulation, (and well sealing lids,) are one of the leading causes of reduced performance in factory boxes.
Thank you.