Refrigerator improvements July 24, 2017, 03:03:31 am Three years ago, there was a discussion on improving the refrigerator's performance.Adding fans to the cooling coils was the beginning, with several members using the following fan.Dometic Refrigerator Deluxe Fan to INCREASE cooling inside with METAL GRILL...I have used fans, inside the refrigerator, for over twenty years, to stabilize the refrigerator's interior temperature.about the same time, our LD's original refrigerator died and and was replaced with a Dometic RM2662. I was not satisfied with its or the original refrigerator's performance in hot temps.So, another project was started, to see it the refrigerator could be made to work better.To monitor the interior temperatures, and variations inside the refrigerator, two wireless temperature sensors were installed in the the refrigerator and two in the freezer.I tried several combinations of interior fans and came to the conclusion that while a fan is necessary but it's location isn't super critical as long as the air is moving, keeping the cold air dropping and the warmer air rising. New refrigerator and shroud | FlickrI ended up keeping the fan in the location it has been in for years. A very quiet computer fan is now used, wired to a interior's light 12-volt supply.Refrigerator fan | FlickrAlso tried an fan in the freezer but it made no difference.Next, computer fans were mounted near the top of refrigerator's roof vent, to promote air flow up and out.It made a small difference but still positive. I wired a pair of small 12-volt computer fans in series and ran the supply wires to the solar panels junction box, on the roof. The output of the panels is a little less the 24-volts, so the fans were happy, and they would shut off at night, when not needed.Even with the fan figured out, I was still unhappy with how warm it ran at times, in hot weather. The installation of the refrigerator was examined and it was determined that the refrigerator compartment was not installed as specified by in the Dometic's owner's manual. The manual showed that the compartment should narrow down to less than a 1/4", between the exterior wall and the exterior cooling fins. Our LD had 1-1/4" of clearance. The purpose of the tight clearance is to force the air flow through the cooling fins. In our LD , much air the air flow was taking the easy, low resistance way around the fins.The owner's manual also indicated that the refrigerator should be insulated all the way around with foam insulation.Our LD's refrigerator was open all the way around, exposing the it's entire exterior to whatever the outside temperature was.So, to start the reinstallation, a stand was built, to set the refrigerator on, when it was pulled out.The refrigerator's compartment was rebuilt, adding a spacer to reduce the cleanrance between the exterior wall and the cooling fins to 1/8". The bottom, top and side of the refrigerator compartment were insulated with polyisocyanurate rigid foam insulation board, before the refrigerator was put back in.Thermasheath Rmax Thermasheath-3 1 in. x 4 ft. x 8 ft. R-6 Polyisocyanurate...After several months of monitor the refrigerator's interior, in some very hot weather, I'm happy with the results.It now keeps the interior temps in the mid 30's, even in 100+ temps with the sun beating on the compartment.. Having the sun shine on the refrigerator's compartment, will stress any refrigerator. Shading it, in hot weather it is suggested.Running the refrigerator on 120-volts, using a Kill-a-watt monitor, it appears to use at least 20% less power to maintain the same temperature. This should also mean less propane usage.Also noted was the fans, mounted in the vent, stopped having a positive effect and have since been removed. Less to go wrong.The only downside noted is the freezer runs a couple degree warmer, at times, since the cooling unit is not operating as much.The freezer warms faster than the refrigerator, being 30+ degrees cooler, it gains heat quicker.Reinstalling refrigerator | FlickrLarry 5 Likes
Re: Refrigerator improvements Reply #1 – July 24, 2017, 09:55:24 am LarryThat insulation looks as if it is a great help, and most likely would benefit most all motor homes and TT ever built. I know almost every installation i have ever seen has more than an inch of space. Thanks for posting and the pictures, your temp stand was a great idea.Would have been a real help the last time I replace a cooling unit.Garry
Re: Refrigerator improvements Reply #2 – July 24, 2017, 10:03:38 am Nice tutorial, thanks! I look at our fridge with a skeptical eye. It is a rebuilt original. I am putting new refrigerator and this insulation mod on my list of improvements. Again, thank you.
Re: Refrigerator improvements Reply #3 – July 24, 2017, 12:15:40 pm Quote from: Garry Foster - July 24, 2017, 09:55:24 am Thanks for posting and the pictures, your temp stand was a great ideaWould have been a real help the last time I replace a cooling unit.The stand was made to be the same height as the installed refrigerator.Once the gas, electric and the mounting screws are removed, it wasn't hard to pull the refrigerator out, sliding it onto the stand.It made it a one person job. Reinstallation was easy too.Only downside was the stand would not fit thought the door or window so it needed to be built, disassembled, and then reassembled, inside the LD. A screw gun made easy work of this.Larry 1 Likes
Re: Refrigerator improvements Reply #4 – July 24, 2017, 12:40:00 pm Quote from: Larry W - July 24, 2017, 12:15:40 pmThe stand was made to be the same height as the installed refrigerator.Once the gas, electric and the mounting screws are removed, it wasn't hard to pull the refrigerator out, sliding it onto the stand.It made it a one person job. Reinstallation was easy too.Only downside was the stand would not fit thought the door or window so it needed to be built, disassembled, and then reassembled, inside the LD. A screw gun made easy work of this.LarryHow long did this project take, Larry? Nice work and thanks for posting.Wouldn't it be great if RV manufacturers built everything right/perfectly from the get-go?Chris
Re: Refrigerator improvements Reply #5 – July 24, 2017, 01:07:47 pm Quote from: Chris Horst - July 24, 2017, 12:40:00 pmHow long did this project take, Larry? Nice work and thanks for posting.Wouldn't it be great if RV manufacturers built everything right/perfectly from the get-go?The actual reinstallation was a long day's project, thinking about and researching it took a lot longer.I have looked at other LDs refrigerator installations and have found similar conditions in most of them.'Can't leave anything alone' Larry 2 Likes
Re: Refrigerator improvements Reply #6 – July 24, 2017, 05:35:26 pm Our 2009 Dometic has always worked very well for us without fans or other changes. We have a standalone thermometer that we use in the freezer and the lower compartment. We often have to decrease the setting to the #3 or #4 setting because it gets too cold. And we've been in some mighty serious summer heat too. So it makes me wonder if LD made some changes to the refrigerator installation in the last 8-10 years? Or perhaps we're just lucky.
Re: Refrigerator improvements Reply #7 – July 24, 2017, 06:14:32 pm I did some of the same work on mine when tracing out the solar panel wiring on my TK. I should have read the manual as I need more insulation on the back. I hope I kept the stand material in one piece and don't have to make it again.
Re: Refrigerator improvements Reply #8 – July 24, 2017, 06:46:45 pm "The only downside noted is the freezer runs a couple degrees warmer, at times, since the cooling unit is not operating as much."Bummer! The whole purpose was to freeze the ice cream!
Re: Refrigerator improvements Reply #9 – July 24, 2017, 07:36:12 pm Traxless said"So it makes me wonder if LD made some changes to the refrigerator installation in the last 8-10 years? "In 2008 they went from fiberglass to 'styrofoam 'insulation . Perhaps that made the difference.Different material, different installation techniques?
Re: Refrigerator improvements Reply #10 – July 25, 2017, 12:43:45 am Larry,how did you determine the pedestal platform dimensions... Im most concerned about depth. Was that by manual? How heavy is a fridge anyway?Nice job Larry. Its most important to have the coldest beer in the fridge. You sure have had one heck of an LD year.Now the beer will be cold enough too.I think I may want to tackle this project. thanks for posting on it.Lyd
Re: Refrigerator improvements Reply #11 – July 25, 2017, 01:38:49 am Quote from: Traxless - July 24, 2017, 05:35:26 pmOur 2009 Dometic has always worked very well for us without fans or other changes. And we've been in some mighty serious summer heat too. So it makes me wonder if LD made some changes to the refrigerator installation in the last 8-10 years? Or perhaps we're just lucky.I have not examined a wide range of LDs, just a few, most of them being older, early to mid 2000s.Some that have looked are better insulated than ours but none had the restriction or venturi in the vent, at the rear cooling fins.Larry
Re: Refrigerator improvements Reply #12 – July 25, 2017, 01:52:48 am Quote from: Ed D. - July 24, 2017, 07:36:12 pmIn 2008 they went from fiberglass to 'styrofoam 'insulation . Perhaps that made the difference.Different material, different installation techniques?Our 2003's refrigerator compartment walls were insulated with styrofoam. There was a big gap between the insulation and the sides of the refrigerator. The styrofoam's adhesive had failed and were falling off both walls, exposing two, 1/8" thick, interior walls to the exterior temperature. A side effect of replacing and upgrading the insulation was a little better interior temperature regulation.Larry
Re: Refrigerator improvements Reply #13 – July 25, 2017, 02:29:15 am Quote from: Lydia Drake - July 25, 2017, 12:43:45 amhow did you determine the pedestal platform dimensions... Im most concerned about depth. Was that by manual? How heavy is a fridge anyway?Measure the distance from the bottom of the refrigerator's compartment to the floor. You may need to pull the refrigerator out a bit to see the edge.Build a stand the same height. You want to slide the refrigerator out onto the the stand, without lifting it.Set the stand on a sheet of cardboard so it can pulled away from the refrigerator opening, to provide access space.The idea of the stand is to allow doing the project without having to lift the refrigerator.The top of the stand measured 2' on each side, sized to the refrigerator.It was made from three cheap 8' X 2" X 4"s. With a power mitter saw and impact driver, it was a half hour project.It took as long to design it as to make it, nothing high precision here. It isn't furniture grade.I still have the stand, disassembled, if you want to borrow it. The refrigerator isn't as heavy you would think, much of it is plastic and foam, with a bare minimum of metal.Every generation of Dometics gets cheaper and lighter than the previous gen.Old school Dometics were heavy, made from real steel. They lasted longer too.Larry
Re: Refrigerator improvements Reply #14 – July 25, 2017, 11:06:42 am Quote from: Larry W - July 24, 2017, 03:03:31 amThe installation of the refrigerator was examined and it was determined that the refrigerator compartment was not installed as specified by in the Dometic's owner's manual. ....Also noted was the fans, mounted in the vent, stopped having a positive effect and have since been removed. I'm using a fan module on the fins inside the fridge, and it's a definite improvement, well worth the $17 they cost.I just went through this exercise with the Norcold refrigerator on my SOB. It had the proper baffling at the top and fiberglass insulation on the sides. The bottom rear baffle was missing (rear clearance of 1.25" instead of less than 1"), so I easily added that.I tested the effect of 4" computer fan mounted on the lower outside vent, much like bumper did on his LD. The roof vent exit temperatures were at least 10 deg F lower than without the fan (and I have the temperature logger charts to prove it). I now have two fans mounted on the lower intake vent, like bumper, based on how well one worked in my test, and his reports of excellent fridge functioning with two fans.My guesses: the two fans Larry used in the top vent were too small physically, and could not pull air through the compartment without some ducting; putting fans on the bottom vent does a better job of pushing air into and through the compartment.I like Larry's connection of the fans in series to the solar panels. I'll try that, as it's easier than my plan to use a thermostat and 12 volts from the batteries.
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