Refrigerator Run Time to Become 'Cold?'

[sailorboy1]

I don't really run my frig much as I am normally am only on the boat on the weekends and don't have solar/wind power to keep battery charged if I did. But when I do it seems that it takes forever to get cold. Yesterday I motored for 3 hours so ran the frig and the it couldn't freeze the ice trays in a box that was cold already with ice in it. Before I blame the system (charge level I think); how long does your system take to freeze the freezer and ice trays?

[Bash]

Don, do you have holding plates or evaporator plates?

[gs41escapade]

If you have evaporator plates, they should frost up to about 3/4 the way up. If not, then suspect low freon charge.

[joshea]

We have a holding plate which we feel is reasonably efficient it takes the better part of 24 hrs.


Jim
sv Kismet

[svHyLyte]

The size of the evaporator plates seem to be somewhat less importnat than the size of the heat exchanger and the temperature of the ambient air (if air cooled) or water (if water cooled). We have a cold box of about 6 cubic feet that a relatively small 23 year old original equipment air cooled FrigoBoat keeps cold enough to freeze drinks if we turn it down low enough (in Southwest Florida in the summer) so long as the air temperature in the boat is reasonably comfortable. For us, the trick seems to be to give the box a boost when we start out. To that end, my [much] better half freezes a half dozen bottles of spring water and an equal number of bottles of GatorAid that go in the bottom of the box when we start out. These suck up so much heat as they thaw that the box is kept very cold by our system from then on. One trick is to add a thermal blanket to the top of the box so that you are only cooling as much of the box as necessary for the contents. With this, the system uses much less energy. We made a thermal blanket out of two layers of Reflectix--aluminized bubble-wrap--and it made a major difference to both our energy use and the temperature of the box.

FWIW...

s/v HyLyte

[sailorboy1]

I have evaporative plate system. So how long does it take for your plate to frost/freeze up in acold bax once you turn it on?

[Richard Kollmann]

A thin layer of frost will form on 95% of evaporator’s surface after 30 minutes of running regardless of refrigerator box temperature. The thickness of frost will vary based on moisture present in air. If there is even thin frost that can be picked up on your fingernail all over the surface there is enough refrigerant in system. If frosted area is less than 75% the system has a refrigerant leak. If frost check is good poor performance may be a result of dirt restricting airflow on intake side of condenser coil.

[motion30]

I have a under counter frige, it is 110 volt it is 4 months old, Can I change to a 12 volt compressor or should I just scrap the whole unit and replace with a marine unit? I do like the layout of this box

[svHyLyte]

I have evaporative plate system. So how long does it take for your plate to frost/freeze up in acold bax once you turn it on?

Don--

If the foregoing question is directed at us, we get the beginnings of frost on our cold plates within a few minutes of starting our refer and the plates are entirely covered with frost within 20-30 minutes--top, bottoms, sides, etc. We seem to have a very slow leak in our system somewhere (tho even with floresent dye we haven't been able to find it) such that we need a modest recharge (< 1oz) about every 18 months. We can tell when the system starts to get low as the amount of frost on the plates decreases. Our technician, John Bosserman of AAA Marine Services in Tampa, advised us that the extent of frosting indicates the charge level of the system--and also agrees that a small recharge from time-to-time is more cost effective than replacing the system. We've owned this boat since January 2002 and in that time period the recharge costs do not even approach the cost of a replacement system.

Note that when we get a sizable build-up of frost we de-frost the system by rinsing the plates with cold water as the frost itself is a good insulator that can prevent efficient cooling. (That also ensures the box is clean tho' the freezing cold water is tough on the fingers!)

We also have a second, Sea-Frost system, with much larger cold plates, for a freezer of about the same size as the refrigerator. On that the evaporator plates also completely frost up within 15-20 minutes and within 3 hours, room temperature water bottles begin to freeze. That box will keep a gallon tub of ice-cream solid as a rock and, accordingly, while cruising our boat would become the "ice cream boat" for the kids my daughter brought "home" (we carried lots of small cones!)

FWIW...

[sailorboy1]

Thanks! My system is 21 years old. I did see it frost over and fully freeze the ice trays back in May when I motored all day, so ran the unit at same time. But the other day I ran it for about 3 hours and didn't have frost on it (did start to freeze the ice cube trays). So it sounds that my system probably needs to be charged and it seems worth the cost to find out if this is the problem.

[witzgall]

Or the ambient temperature on the two days was very different? VOlume of stuff to draw down or keep frozen has a bearing as well on the times.

Chris

Originally Posted by Don Lucas

Thanks! My system is 21 years old. I did see it frost over and fully freeze the ice trays back in May when I motored all day, so ran the unit at same time. But the other day I ran it for about 3 hours and didn't have frost on it (did start to freeze the ice cube trays). So it sounds that my system probably needs to be charged and it seems worth the cost to find out if this is the problem.

[Strygaldwir]

2 hrs to freeze a tray of ice.

[sailorboy1]

Temp was pretty different the 2 days I memtioned. But, since the first day I have added 2" of insulation. So now there is better insulation and less volume.

[sailorboy1]

Well I figured out my problem and it may be common enough for others to Be aware of sometime.

Our unit is installed under a sette, which has a vent opening on the side. There are 2 fans, one on each side of the condenser. Turns out the fans were running in opposite directions so there wasn't much air flow across the unit at all. Back in May when I first used the unit I found that one of the fans was not hooked up and when I did it was noisy so I just unhooked it, but had plugged it back in sometime later. So this weekend I was motor sailing a couple of hours and was running the unit. I had added 20 pounds of ice the day before and there was lots left in the box when I tuned it on. Couple hours later there was less ice and just a little forst on the evapator. That is when I checked the fans (both were plugged in) and found the problem. Un-plugged the one that hadn't been plugged in when I got the boat back in May and the unit froze the ice up in about 1.5 hours (probably still needs a charge). So there you go, check your air flow to the condenser before going too nuts.