We saved a lot of money, and got a bigger, frost free refrigerator by installing a “home” refrigerator in Pearl Lee.
When our tired old Norcold refrigerator needed repairs we found out parts were no longer available. Not surprising, since it was more than 15 years old. New “marine” refrigerators to fit in the same space started at $1300 and went up from there, so it was a good time to get creative.
After some careful measuring we discovered that we could replace our 7 cubic foot Norcold with a home refrigerator of about 10 cubic feet, for about $300. Since we had been forced to run our Norcold on AC power through an inverter for months, this seemed like a viable option, but more research was needed.
We discovered there are a few differences between “marine” and “home” refrigerators. The marine variety include a mounting flange and hardware, have positive door latches, run on DC in addition to AC power… and that’s about it. The same compressors (the heart of the refrigerator) are often used. The price difference can be attributed to making thousands vs millions and the usual marine markup boaters are all too familiar with.
While marine refrigerators typically give their energy consumption while running, you don’t know how often they will typically run. Home refrigerators have become pretty efficient, and more actual information is available for their power consumption if you know how to use it.
Every home refrigerator in the US has a yellow Energy Guide card like this one for our refrigerator. It tells you the estimated power consumption over a year, so the on/off time, and defrost cycles are factored in. Remember, this is in a home environment, so take it with a grain of salt. To get daily consumption simply divide the annual number by 365 (329,000/365=901) to get daily wattage. Since boaters like to think in terms of amp hours, we can convert watts to amp hours by dividing them by voltage (901/12=75). In reality, you’ll lose some power to your inverter, but not a lot. You’ll also use a few less amp hours when your batteries are putting out more than 12 volts. Most inverters are in the 95% range of efficiency, so that 12 volt calculation works out pretty close. Add a few amps for the time the inverter is idle, so let’s call it 80 amp hours. That’s about what the old Norcold was using! Incidently, this is not an Energy Star model, but in this size range I didn’t feel the extra money for was justifiable.
It’s possible to maximize efficiency by using a dedicated inverter exclusive to refrigerator use. You can get the running wattage from the back of most units, but keep in mind there is a momentary draw on startup of about double the running power. Ours consumes about 88 watts while running. It easily runs on a 200 watt inverter, but we opted to run a 1500 watt inverter. The larger inverter gives us extra power for other tasks and tools. We don’t lose much efficiency with the larger inverter, it might last longer, and it’s convenient when we need to plug something else in.
Once you decide if this project is electrically feasible it’s time to look at the physical aspects. Making sure the new unit fits in the space is obvious. Measure twice, cut once. Since I was cutting 35 year old teak, I measured about a dozen times. Before purchase, or cutting, make sure the new refrigerator can be maneuvered into position. Hatches, doors, counters, ladders all must be considered. A plan on how to actually do it helps too. We used our boom as a crane to lift and lower the beast. Make sure you adequate room to swing the new door as well. Another important space consideration is ventilation. Most modern home refrigerators no longer have evaporator coils on the back, and now use the sides of the box as a heat sink, so make sure you have air flow where you need it. This also makes adding extra insulation to the sides a no no.
The actual installation was pretty straight forward, though not as simple as a marine replacement would have been. We built a small platform to roll the refrigerator back on. This is mostly an installation aid, since the refrigerator is held in place by the mounting flange and lots of screws. For our flange we used angle aluminum and lots of sheet metal screws. I’m pretty sure this step voided our warranty, so we made sure the unit we had actually worked first. Simple hook and eye door latches make sure the doors don’t open when they shouldn’t.
It’s been about a year now, and we’re still pretty happy with our new refrigerator. In that time we have not used anything but solar/battery power to run it, and power consumption is about what we expected. At anchor we only latch the refrigerator door if the harbor gets bouncy. Of course we latch it when under way.
The only problem is, we noticed the freezer door burped out a bit of cold air when we closed the refrigerator door. That was fixed by keeping the freezer latched. This is a refrigerator issue, not a boat issue.
Once again a little ingenuity got us out of the “marine” store and saved us a lot of money. It also gave us a bigger refrigerator with the convenience of not having to defrost periodically.