Fridge Maintainance Reminder

[Lin]

My Norcold has not been working right.  Although the freezer was measured at zero or below, the frig was 45 degrees.  I spent some time thinking about how I would remove it from its cave and turn it upside down for a while, what I would get if that didn't fix it, and even spoke to an expert this morning who told me it was probably the circuit board.  I was resigned to that since it is far better than it being the cooling unit.

We are dry camping so have been running the frig on gas.  Although we do run the generator several hours a day for other things, I have not bothered to switch the frig to AC during those times.  This morning I did just that to see if it made any difference.  Guess what!  The frig cooling fins began to get cooler.  Oh yeah, it's been two years since I cleaned out the gas orifice.  I have now invested the 20 minutes needed for that job, and the frig temp is dropping.  The cooling fins have gone from 32 down to 23 in an hour or so.

The point being-- well, I guess it's obvious.

[Lin]

In spite of having a better flame and improved cooling, I still thought something may be wrong.  I did a little internet research and came across something interesting.  Apparently, Norcold recommends not using gas above 5500 feet and suggests that you use AC.  How do you do that when dry camping at 6000+ feet as we are?  Anyway, we will find out if that really makes a difference in out case after Sunday.

[TomC]

This is why I use a 12vdc/120vac compressor type refrigerator.  Good Luck, TomC

[thomasinnv]

Are the cooling fins in the refrigerator compartment free of excessive ice build up? When the ice gets thick enough that the air space between the fins starts to disappear the compartment will not cool as well. The more ice there is present, the less cooling you are going to have. I know it seems kinda backward, but the air moving over and through the fins is what cools the compartment, not the ice. In this case, ice is NOT your friend.

[TomC]

With any refrigerator, more then a 1/4" build up of ice on the cooling coils will actually act as an insulator not allowing the super cold air to circulate.

At least on my refrigerator (Norcold A/C, D/C compressor type) to defrost it, I simply turn the refrigerator off then put a towel inside under the cooling coils and covering the entire interior.  Then the ice melts into the towel and not onto the food inside.  Typically takes 4-6 hours to do.  Safest way to do it-not using a hair dryer or scraping the ice off the coils possibly damaging the coils. During hot humid summers, sometimes have to defrost every week.  Good Luck, TomC

[Lin]

Derrick, there was ice, but not all that much.  I should clean out the back and make sure there are no blockages in air flow.  I'll get the ladder out and check that today.

As I understand it, the higher altitude causes a less efficient burn, but it looks to me that the heat would still be more than the electric coil.  That's merely a guess though.  Of more interest is that the CO alarm went off early this morning, and the frig is the only combustion source running.  I can't readily see how the gas would get inside, but I turned it off and the reading went down from 70ppm to 35ppm in about 20 minutes and to zero later . A less efficient burn would be consistant with CO production.  There may be a high altitude kit that can be installed or a change in the flame adjustment if one was to need it.  Anyway, Norcold's recommendation may be in part out of a CO concern, but since the combustion is outside, they may not feel it necessary to go into that detail.  It is worth being aware of the issue though.

Tom, do you feel that your system will be adequate for dry camping?  How large a battery bank would you need, and how much daily generator time?  I feel a little bad for my neighbors since mine is the only generator I hear.  

[gus]

Anything burning at high altitude will be too rich because of less Oxygen, including your DD, and will make smoke.

Smoke in the frige = carbon buildup in the burner.

Water will also boil at much lower temps, including in the DD cooling system!!

[Lin]

Gus, The real surprise for me was the production of CO.  Of course, it makes sense, but I just didn't think of it.  Apparently there is some penetration of the living area.  When the CO alarm went off, I almost thought to ignore it, but then did remember that the frig was running on gas.  It seems that the cabinet above the frig and to the left are not sealed well.  I certainly owe Kidde some thanks.

Aside from resealing all around, I may have to consider taking the frig out to make sure nothing is clogged.  Right now, I just turned the frig ball valve back a bit to lower the flame and see if that lowers the CO production while, hopefully, keeping the box cool enough.

[thomasinnv]

I had an issue with CO getting in last year. It was only happening when the genny was running, drove me nuts cause I couldn't figure out where it was getting in. Last summer I pulled the fridge out and spray foamed every nook and cranny and crack in the cabinet (the previous winter I had noticed cold air coming in around the fridge when we had a lot of wind), then put the fridge back in. Seems the CO was coming in through the fridge compartment. It was fully insulated, but evidently not airtight. Ever since I foamed it up the CO detector has not gone off once, been about a year and a half now.

[Lin]

I think this is some useful information.  We did not have the problem before I cleaned the orifice, so my guess is that the lower gas volume allowed it to burn more fully in this high altitude.  Cleaning the orifice increased the gas flow and that casued production of CO.  That production of CO set off the alarm, which now has told us that the frig compartment is not airtight.  That is something I will take care of when we get home after tomorrow.  In the meantime, I turned the frig ball valve back about halfway.  There is no more CO, and for some reason, it is still cooling fine.  It may be that the weather is a bit cooler, or that the flame is less ragged.  When we get home, which is at about 3000ft, I will check to see if there is CO being produced with the valve completely open.

[TomC]

The A/C-D/C compressor type refer uses 5.5 amps @ 12vdc.  It runs about 50% of the time, so using 3 amp/hours would be accurate.  I have 2-8D AGM batteries that are 255 amp/hour each.  Figuring you want to only discharge the batteries to 50%, that leaves 255 amp/hours of useful current.  With just the refer running, that works out to be 85 hours of running.  But-I also have the lights, TV, inverter loads, etc.  When dry camping, I run the genset for 2 hours in the morning and 2 hours at night.  Seems to work that way-key is to have a quiet genset.  Good Luck, TomC

[Lin]

Tom, that seems like a workable approach, but from my experience unless you are running the air conditioning, your generator needs like heating water are done in about a half hour.  That would mean that the generator is running 1- 1.5 hours just to charge the batteries.  That's a pretty big battery charger!  Of course, the charge rate starts out high but tampers off as the batteries come up, so in order to completely top the batteries off, you'd have to run the generator for a period of time when it is just charging at a couple of amps.  Also, my generator is noisier than I like.  It is not terrible, but silence is really what one wants in the park campgrounds. 

On this trip, I monitored the charge rate and cut the generator off when the rate had gone below 20 percent.  I don't know if that is a good choice since it is only random.  I do have an issue with the frig though.  I tested it upon getting home, and at full flame, it is still putting out CO.  Maybe I damaged the orifice when cleaning it or it had been damaged through use.  A needle went through it easily.  I thought that I remembered the orifice as being smaller than that.

[TomC]

Doing a partial recharge of the batteries is OK as long as you do a top off (in my opinion) once a week.  A deep recharge to zero is always what you want.  In my truck, I'll accomplish this by doing the main charging with the genset and inverter/charger.  Then once it is down to only charging around 10 amps, will turn everything off and have the solar panels top off the batteries.  I know that solar panels are expensive, but are worth it if you're going to full time or spend more then a month a year in the coach.  I already have the junction box ready on the roof-just have to find the panels and mount them.  I think I have enough room for four. Good Luck, TomC

[Lin]

I think your right about the solar.  I have been watching Craigslist and want to put up about 15 to 20 amps worth.  My hope is that even though I would not want to be parked in direct sun, they will be able to put out enough power over the day to finish the charge.  I have also considered getting a small, quite 1000w generator just to do the batteries.

[thomasinnv]

My hope is that even thought I would not want to be parked in direct sun, they will be able to put out enough power over the day to finish the charge.

you might want to rethink this approach. Solar panels will not put out any appreciable level of power in the shade. They really need direct sunlight.