Holding plate freezer 12v recommendations

[Typhoon]

Originally Posted by OzePete

Hi John, did you fit both of those BD35 systems to that 7CF freezer? That is getting closer to the performance the OP required.

Cheers Pete

Hi Pete

Both boxes in this boat were 7 cubic feet. Client wanted one bd35 in each box . I judged the r value to be around R20 . Of course this is a very big freezer for a Bd35. With the existing insulation the freezer side obtained -12 c at mid compressor speed during a very hot week up here with the boat on the hard. Amp hr usage over 24 hrs was approximately 72ah/12v . He has plans to add a set of vacuum panels to the the box this year . This should bring the amp hrs down significantly .
The fridge section is perfectly adequate and really does not need the addition of insulation . The boxes share one wall , this really helps .

Regards John

[OzePete]

Hi John, I assumed (wrongly!) that you had installed the two systems in one freezer box and that this might have been the answer for TJ who is looking for more grunt. You are spot-on regards the 7CF freezer being too big for a BD35 and hope your client follows your advice and improves the insulation greatly. I entered the cabinet and equipment factors into our 'Heat load and Duty Cycle estimator' and at 7CF (190 Litres) and with R20 rated insulation, this freezer has a heat load of 50.52 watts per hour to achieve -18C in a 40C environment. This relates to a 137% duty cycle for a BD35 to achieve an evaporator at -25C. With a then COP of 1.19 the BD35 simply will not hold -18C with such a poor cabinet R factor. Increasing the cabinet's R factor as you suggested should see the duty cycle decrease to 78%, and such a run % is acceptable in such extreme conditions quoted. Like you John, we also know that INSULATION is the key to a successful refrigeration outcomes where power supply is limited.

Cheers, Pete Ozefridge | 12 Volt Refrigeration Systems