Adding a new DC Fridge during a LA Heatwave

[themexicandoctor]

Glenn,

Don't be depressed.

Solar isn't supposed to be the Magic Bullet & maybe mine needs more fine tuning but here is a image that is depressing to the naive;

A whopping 1.1kwatts & I didnt even reach Absorption.

However i did set my Solar MTTP to 6 hours Absorption because I believe it has the sense to move into Float when the value's are right.

Those other days I was running the Generator so the Solar didn't have to strive as hard.

Maybe my MTTP settings are wrong.That is a problem for next week

[yvairguy]

I was commenting in the other thread and was thinking that you needed a thread for just the Refer and here it is...

I don't understand why people want to re-engineer what is sent from the factory. This is a three phase compressor and it uses an inverter board to drive the compressor. The fan that is attached to the back of the unit has nothing to do with maintaining air flow anywhere except to try and find "cool" air to run across the inverter board and then the compressor. It's a piss poor design. If it was mine I would be tempted to redesign the condenser.

In the other thread you talk about how you have a "large cavity" behind and around the cooler. If this area is anything warmer than the outside ambient temperature on a hot day you need a fan to pull the hot air from this area and exhaust it out of this area. If it is anything above ambient temperature you kind of have a proofing cabinet for dough.

Think of the radiator in the car, how well would it cool the engine if you dumped all the heat from the radiator into a box around the radiator? I guess you could cut some little holes in the side of that box(like the vents you have now) and it might help as long as you were at idle or maybe 10 mph, what if you wanted to do 80? What if you were in the middle of a heat wave with record temperatures?

ask the manufacturer what the design ambient temperature is for the condenser on this unit.

[themexicandoctor]

Originally Posted by yvairguy

I was commenting in the other thread and was thinking that you needed a thread for just the Refer and here it is...

I don't understand why people want to re-engineer what is sent from the factory. This is a three phase compressor and it uses an inverter board to drive the compressor. The fan that is attached to the back of the unit has nothing to do with maintaining air flow anywhere except to try and find "cool" air to run across the inverter board and then the compressor. It's a piss poor design. If it was mine I would be tempted to redesign the condenser.

In the other thread you talk about how you have a "large cavity" behind and around the cooler. If this area is anything warmer than the outside ambient temperature on a hot day you need a fan to pull the hot air from this area and exhaust it out of this area. If it is anything above ambient temperature you kind of have a proofing cabinet for dough.

Think of the radiator in the car, how well would it cool the engine if you dumped all the heat from the radiator into a box around the radiator? I guess you could cut some little holes in the side of that box(like the vents you have now) and it might help as long as you were at idle or maybe 10 mph, what if you wanted to do 80? What if you were in the middle of a heat wave with record temperatures?

ask the manufacturer what the design ambient temperature is for the condenser on this unit.

I am NOT changing anything but in the last week I have followed the instructions of the Novakool Head Engineer, Mariam.

Today was the last straw, my batteries have been full from a lot more driving yesterday & today & yet overnight, the refrigerator woukd NOT average below 40°.

Then at around noon it just got hotter & hotter even though I took the vent cover off as I drove 30 minutes. Then it got to 45, 46, 47 & 48°F.

I then pulled out a personal 12 volt fan & blew it across the condenser coils for 10 minutes, zero change. Then for 25 minutes against the compressor (which is now hot to touch), & the vent as per the photos.

Finally it is coming down slowly but I am pissed off, ir was as high as 48.8 & now after over an hour of the fan on full its at 48.2°, its taken 60 minutes to fall 0.6°.

A couple of times today I did what the Engineer asked me to do, turn the knob down slowly until it clicks, which I did - it clicks around 2.75 on the 1-7 dial (is this all it is capable of)

I included your question in my last email to the Engineer about the design ambient temperature & will follow up tomorrow.

So far this is completely unacceptable.

Tomorrow I am adding new batteries & taking them from outside to the inside of the rig, under the bed - another $1500 in order to babysit a $1200 refrigerator investment. The RV Guy who is doing the work is an expert in fridges, he will check it tomorrow.

I know that I dont* want to go to the next size up, the R4500 which is .7cubic feet bigger & the compressor goes from a BD35 to a BD50.

Both fit perfectly, the only difference is that the R4500 is 3 inches deeper, 1 1/2 less than the nightmare Dometic 3Way I am replacing.

*my current unit is rated at 2.2amps which 52.8amps per day & it is running continuously - at this rate, unless I am driving for 60-90 minutes a day & my batteries were at 100%, the Solar alome cannot keep up.

Either I have a Bad Unit or the compressor cannot keep up. I do know that the R4500 is rated at 4.4amps per day which is 105.6ahs per day if the larger compressor is running 24 hours per day. I do not necessarily need a larger fridge.

THIS UNIT WAS SOLD TO ME AS 2.2amp hours for 12 hours of each 24 hour period, that the run times would be half of the 24 hour cycle. I expected more with the heatwave but this is ridiculous.

Any other questions that the engineer would understand based on the Novel above?

THANK YOU GENTLEMEN!

[themexicandoctor]

Here are some photos, love these Sensorpush Bluetooth units, real evidence, instant data forever without opening a door;

[themexicandoctor]

Fan in two positions - I am now at 48.4 & its rising again or 0.3°F after 90 minutes of running the fan directly over the condenser coils & compressor

[themexicandoctor]

Here is the latest photo of tge 48.4°F.

[themexicandoctor]

I may have found part of the issue

At midnight last night I was driving & hit a Third World LA Pothole.

Just a few mimutes ago I opened the fridge to take a photo of the Control Knob position & noticed that the Sensorpush Bluetooth device was no longer attached by velcro to the back wall but instead had fallen behind some plastic shelving.

It is now reattached.

I still have the fan running onto the back of the compressor & condenser.

And the sensor now reads 68.4°F but that because it was in the cab being velcroed a second time.

Please give me 15 minutes before I check on the right temperature.

[GeorgeRa]

The thermostat clicking test demonstrated that it is working correctly. Your cooling of the condenser is not perfect but it should be good enough.

Your tests with fan indicate that the problem is with your fridge, either cooling system is not extracting enough heat or insufficient insulation is not preventing to keep heat out, in both cases it is Nova Kool issues. Ask them about return for another unit or funds.

[themexicandoctor]

Thank you George.

I was reluctant until today, when its 105 out I was trying to give them the benefit if the doubt so far they have been responsive with giving me access to thier Head Engineer & his ideas.

Still waiting for my Sensorpush to cool down to the interior temperature of the fridge

[yvairguy]

Originally Posted by themexicandoctor

Any other questions that the engineer would understand based on the Novel above?

I would ask if it was a from scratch install what kind of ventilation they recommend.

this has a static air condenser. I would replace the bottom vent, open the top vent, put the fan over the screen and pull the air from the top vent, across the condenser, and out the bottom through the screen.

I've been a refrigeration contractor working in the heat of the desert for over 35 years. The guy in the field fixes the crap the engineers can't.

[GallenH]

Originally Posted by yvairguy

this has a static air condenser. I would replace the bottom vent, open the top vent, put the fan over the screen and pull the air from the top vent, across the condenser, and out the bottom through the screen.

I hear you. Some installs call for pulling the air from the inside of the RV where the air is presumably cooler than outside given the tendency to cool the RV with the chassis AC unit.

So many older RVs that have an absorption fridge have an outside vent at the bottom and the top. Purpose to draw in the outside air past the fridge from the bottom and vent it out the top. You seem to be suggesting that in a retrofit you would exhaust it out the bottom? Or the top?

[themexicandoctor]

Originally Posted by yvairguy

I would ask if it was a from scratch install what kind of ventilation they recommend.

this has a static air condenser. I would replace the bottom vent, open the top vent, put the fan over the screen and pull the air from the top vent, across the condenser, and out the bottom through the screen.

I've been a refrigeration contractor working in the heat of the desert for over 35 years. The guy in the field fixes the crap the engineers can't.

So far I like your responses - as for AC, I rarely if ever use it - I hsve been recently only as a side benefit of running the Generator to catch up with the Amp draw of the unit.

I dont know if top to bottom will work,The Guru of Marine Refrigeration Rod Lambda thinks the Novakool bottom of the unit mechanicals are ideally suited to top venting.

Here are the vents in a 2005 Roadtrek Versatile 190

[themexicandoctor]

One of those photos shows the Sensorpush temp unit where it had fallen from the back wall of fridge, the velcro above it is where it is supposed to be along with an inside outside view.

The refrigerator sits 6-7 inches away from the outside vents, NO eating to the inside of the truck.

As well as being 6-7 deep, the space is 21 inches wide & 37 inches deep.

[themexicandoctor]

The Sensorpush now reads 42.1° & its starting rise again.

When I put my fingers close to the compressor at 47° I could feel it working.

People have mentioned better venting via baffling, a Potentiometer, Resistors, etc.

[themexicandoctor]

Originally Posted by GallenH

I hear you. Some installs call for pulling the air from the inside of the RV where the air is presumably cooler than outside given the tendency to cool the RV with the chassis AC unit.

So many older RVs that have an absorption fridge have an outside vent at the bottom and the top. Purpose to draw in the outside air past the fridge from the bottom and vent it out the top. You seem to be suggesting that in a retrofit you would exhaust it out the bottom? Or the top?

Yes, while its sometimes a few degrees cooler inside the van, inside to outside venting won't work, i have two Carado Yacht vans I have been using plus the fantastic van & they are challenged keeping the Rear Area below 90 in the heat & the front cab 10 feet away 110

[GallenH]

There seem to be mixed views of venting. I believe than some who advocated drawing air from the inside of the RV and venting it back into the inside via a fan above the fridge venting into the microwave compartment did not have exterior vents and had no desire to add one. Others commented that if you did have them, a venting scheme where you drew air in from the outside through a lower vent and exhausted it through the upper one was a definite benefit at night where the outside air was cooler than inside the RV.

Bottom line is that I don't know which is best. One seems better during the heat of the day (if you are using AC inside the RV be it from the chassis AC or the cabin AC) and the other better at night.

It looks like you also have a vent beneath the fridge compartment? I noticed the wire grid in one of your photos.

[themexicandoctor]

That is a wire mesh that is for the old Dometic to leak condensate & also where the gas line travels to both the water heater & the stove.

For Arvie who just removed his Dometic he found Rodents had accessed the fridge where they were living through this ventrd opening, another guy on the latest same thread said he didn't have any such venting, drainage & his rig was leaking wayer into the rig - my thought was the previous owner had sealed this off.

It literally leaks onto the top of the outside storage cabinet & presumably onto the road.

[themexicandoctor]

It reads VD 12025 LB
12 volt DC - are there better, more powerful fans?

And how viable are they when its 105 out, probably 115 on the black top, & they are bringing hot air in

Again I was sold this unit as a slide in, turn on, get in with your life type unit, with a low 25amp hours draw over 24 hours.

[themexicandoctor]

Originally Posted by themexicandoctor

It reads VD 12025 LB
12 volt DC - are there better, more powerful fans?

And how viable are they when its 105 out, probably 115 on the black top, & they are bringing hot air in

Again I was sold this unit as a slide in, turn on, get in with your life type unit, with a low 25amp hours draw over 24 hours.

Just turned the unit up to #4 on the knob, half a turn from where it was, its presently at 42.0°F but its cooler outside.

I temporarily turned off the personal fan & it seems to be used 1/2 an amp. Lets see what happens.

That personal fan is still blowing away, mostly in an upward fashion against the condenser coils.

Maybe at 3.5 where the thermostat was at was too warm, lets see what happens.

[themexicandoctor]

Okay my fridge is now down to a very respectable 36.6°F without any cooling.

It was probably the Sensorpush falling off its velcro mount at midnight as I was driving & then falling onto a warm ledge (?) and or maybe by clicking it off the way down to 2.75 on the 1-7 knob & having it reset the compressor.

I certainly have no external fans blowing on it now.