Why not simply a one-way 110V fridge?

[InterBlog]

Originally Posted by Roadtrek Adventuous RS1

A...[Dometic] 8501 refrigerator... ...

I glanced at the manuals. This one appears as if it might be "next gen" to Dometic's older model number 2351. They've added a crude means of adjusting the temperature, and there's a light that will tell you when the gas runs out, but there is still no visible means of reading the actual temperature inside the fridge.

For somewhere between $5 and $30, you can add your own externally-readable thermometer, and I do recommend this (pic below; we drilled out the face of the Dometic and ran its lead inside). Doing this will tell you everything you need to know. Part of the reason why the reviews are so mixed on this thread is that fridge performance can vary wildly based on whether the fridge is in motion or not. A 3-way fridge jostling around on the road interferes with its ability to circulate. Even when our 3-way was "working", we routinely saw temperatures climb to 45 degrees while we were in motion. When we'd stop for the night, it would dive back down into the low 30's. For this reason, someone who drives, say, 3 hours at a stretch might not notice much degradation. But we drive 10+ hours per day when we are on the road. As a result, we were having food ruined all the time.

There's also the issue of burping, which was covered by another recent thread. Our second Dometic failed completely and we thought it was a goner until we removed it and burped it, mostly for laughs because we thought burping was an urban myth. To our astonishment, it immediately resumed working. It now makes a superb garage refrigerator for us, having had these two needs satisfied: the ability to burp (free-standing - no hard-mounting in a cabinet), and no jostling around.

[Doneworking]

Two cheap helpers for my refrig. I have been using the fan for twenty years and it still works perfectly fine. Three different rigs over those years and it still performs the same.

https://www.amazon.com/Valterra-A10-...frigerator+fan

Get something like this and put the transmitter in the refrig and stick the receiver/inside temp on the dash and see the temp in the refrig while you drive. You can buy smaller and cheaper ones at Walmart (about $10). No drilling and constant monitoring from the flight deck.

https://www.amazon.com/Crosse-Techno...al+thermometer


Paul

[avanti]

I, too, have fridge and freezer temperature displays on the dash. I did it with a pair of thermistors and a little hacker-magic. It is very reassuring. With my NovaKool, the numbers are pretty boring, though.

[kite_rider]

Well, this discussion has veered way off the original question; but I can't help myself and will join in the absorption fridge discussion anyway...

Pro's for the absorption fridge (Standard equipment in a VW Campervan, I had to think hard to come up with the pro's ):

1. Silent operation! Took me a while to get used to the gentle hum of the compressor that cycles on and off on my current fridge when I was trying to fall asleep.
2. No battery drain when boondocking and parking in the shade.
3. Consumed very little propane. Seems to run for ages in the summer with minimal propane draw.
4. Waste heat actually kept the VW slightly warm at night when camping in cooler climates (see Con's on this too! )

Con's: (somewhat specific to the VW installation, which only vented the propane exhaust and not the general waste heat from the system. Note that if you are putting an absorption fridge in your Class B and want it properly vented, you usually end up cutting a big hole in the side of your van!):

1. Only works when parked on level ground! This was a pain in the A$$ to find at crowded trailheads. Even then you really need to install some sort of internal thermometer to see if the fridge is actually working; then you only find out it's not when your food and beer are warm. (not something that I've even needed to worry on my 12V compressor fridge)

2. Seemed to cool relative to the outside temp rather than a thermostat. So if it was hot outside, it would be 30 or 40 degrees cooler in the fridge. However, if it got cold at night things would freeze in the fridge. It always pissed off my wife when her fresh vegetables would freeze in the camper van.

3. The burner needed maintenance to work properly. Many VW Campervan owners were so flummoxed by the finicky fridge that they took it out entirely. The original burner would easily get clogged up with rust and debris and need to be cleaned and it was tricky to get to. (As an aside, a new improved burner made things *much* better; an essential upgrade for that fridge.)

4. The waste heat made the camper almost unbearable on a hot summer day. When parked at a trailhead it was mandatory to open up the side window vent and top vent or the van would be a sauna, even in the shade.

I can say from my experience that I will always own compressor based fridges from here on out. However, I'm NOT convinced that it's worth the extra money to buy a 12V DC fridge as opposed to a 110V AC fridge for a new camper build.

[cruising7388]

Originally Posted by kite_rider

2. No battery drain when boondocking and parking in the shade.

The 3-way can run on propane only with battery support which controls the gas valve, the igniter, the control panel and the circuit board. If you are talking about a conventional RV with a couple of 6 volt AGMs, without some recharging source, you will eventually run out of battery and shut down the reefer long before you run out of propane.

[Roadtrek Adventuous RS1]

Originally Posted by cruising7388

The 3-way can run on propane only with battery support which controls the gas valve, the igniter, the control panel and the circuit board. If you are talking about a conventional RV with a couple of 6 volt AGMs, without some recharging source, you will eventually run out of battery and shut down the reefer long before you run out of propane.

We've got a 160 watt Zamp solar panel on the RS Adventuous.

I think we're OK .. doesn't draw as much power as a DC or AC unit...

Just had the unit checked today. Works fine.
Not doing anything until it's an issue.

[avanti]

If I had a well-working absorption fridge in good condition, I don't think I would replace it either. But, if I ever had to replace it, I wouldn't even THINK about another absorption unit.

[Bud]

Originally Posted by avanti

If I had a well-working absorption fridge in good condition, I don't think I would replace it either. But, if I ever had to replace it, I wouldn't even THINK about another absorption unit.

avanti, Yes You Would,:

If there was 'Not Enough Reliable Electrical Power'.

Isn't it that simple? But maybe I've got it wrong? Please assist.

The variety of reasons for 'Not Enough Reliable Electrical Power' is, a bunch.

Bud

[avanti]

Originally Posted by Bud

avanti, Yes You Would,:

If there was 'Not Enough Reliable Electrical Power'.

Isn't it that simple? But maybe I've got it wrong? Please assist.

The variety of reasons for 'Not Enough Reliable Electrical Power' is, a bunch.

Bud

I would fix my power problem if I had to. Really.

[Bud]

Originally Posted by avanti

I would fix my power problem if I had to. Really.

I believe you, me too with a new or different B.

Bud

[kite_rider]

Originally Posted by cruising7388

The 3-way can run on propane only with battery support which controls the gas valve, the igniter, the control panel and the circuit board. If you are talking about a conventional RV with a couple of 6 volt AGMs, without some recharging source, you will eventually run out of battery and shut down the reefer long before you run out of propane.

Agreed that an absorption fridge does use some DC power when running on propane; but by comparison to a compressor fridge that power is negligible. I use to leave my NorCold fridge in my van on for *months* at a time (on propane) and there were no dual 6V AGMs in the picture, just a single wet cell Group 27 RV/Marine battery. The recharge source was the van's alternator and it worked just fine even if I left it parked for a couple of weeks.

The same battery wouldn't have lasted 2 days with even the most efficient 12V compressor fridge; and a 110V AC fridge was out of the question.

[Roadtrek Adventuous RS1]

Originally Posted by kite_rider

Agreed that an absorption fridge does use some DC power when running on propane; but by comparison to a compressor fridge that power is negligible. I use to leave my NorCold fridge in my van on for *months* at a time (on propane) and there were no dual 6V AGMs in the picture, just a single wet cell Group 27 RV/Marine battery. The recharge source was the van's alternator and it worked just fine even if I left it parked for a couple of weeks.

The same battery wouldn't have lasted 2 days with even the most efficient 12V compressor fridge; and a 110V AC fridge was out of the question.

Which brand is better??? Or more reliable to keep things cold..?

[markopolo]

Originally Posted by cruising7388

The 3-way can run on propane only with battery support which controls the gas valve, the igniter, the control panel and the circuit board. If you are talking about a conventional RV with a couple of 6 volt AGMs, without some recharging source, you will eventually run out of battery and shut down the reefer long before you run out of propane.

Maybe some or all newer absorption fridges require 12V DC electrical power to function but I know for certain that the Dometic unit in my van doesn't need 12V DC to run on propane. The DC wire has never even been connected! I run it off the inverter while driving, 110V at campsites if available or propane when dry camping.

[avanti]

Originally Posted by markopolo

Maybe some or all newer absorption fridges require 12V DC electrical power to function but I know for certain that the Dometic unit in my van doesn't need 12V DC to run on propane. The DC wire has never even been connected! I run it off the inverter while driving, 110V at campsites if available or propane when dry camping.

If it has the "two button" piezo starter (or a pilot light) and/or no lights on the front-panel, it is probably the "no power required" type.

[cruising7388]

Originally Posted by avanti

If it has the "two button" piezo starter (or a pilot light) and/or no lights on the front-panel, it is probably the "no power required" type.

If it's a pilot light I guess the gas valve is controlled by a thermocouple but doesn't a piezo starter require an energy source?

[avanti]

Originally Posted by cruising7388

If it's a pilot light I guess the gas valve is controlled by a thermocouple but doesn't a piezo starter require an energy source?

No. I am talking about the kind where you have to push hard until a strong spring releases. A hammer hits a piezo-electric crystal, which generates a tiny, high-voltage current which then sparks across the ignitor. Same as those cheap propane fire-lighters.

[gregmchugh]

Originally Posted by cruising7388

If it's a pilot light I guess the gas valve is controlled by a thermocouple but doesn't a piezo starter require an energy source?

Nope, no electricity needed...

https://www.amazon.com/Maverick-Bl-0.../dp/B0012RRG8O

[cruising7388]

Originally Posted by markopolo

Maybe some or all newer absorption fridges require 12V DC electrical power to function but I know for certain that the Dometic unit in my van doesn't need 12V DC to run on propane. The DC wire has never even been connected! I run it off the inverter while driving, 110V at campsites if available or propane when dry camping.

IIRC, my Dometic fridge (circa 1990) had two battery inputs and while pulling the heavier DC wire disabled the 12 volt boiler, there was still battery supplied to the fridge control panel and circuit board. Doesn't your fridge have a control panel and a circuit board? If it does, I don't see how it can operate without battery support.

[cruising7388]

Originally Posted by avanti

No. I am talking about the kind where you have to push hard until a strong spring releases. A hammer hits a piezo-electric crystal, which generates a tiny, high-voltage current which then sparks across the ignitor. Same as those cheap propane fire-lighters.

You're certainly correct, it can be done manually. But is this the way it's done in an RV application? To light off the boiler with manual piezo stimulation wouldn't you have to remove the outside ventilation cover of the reefer to do this? Isn't this done conventionally by remotely by pushing an "LP" or "Automatic" button on the fridge control panel and isn't the piezo lighter at the boiler going to require some battery source?

[cruising7388]

Originally Posted by markopolo

Maybe some or all newer absorption fridges require 12V DC electrical power to function but I know for certain that the Dometic unit in my van doesn't need 12V DC to run on propane. The DC wire has never even been connected! I run it off the inverter while driving, 110V at campsites if available or propane when dry camping.

Can you disconnect all your batteries and still get the fridge to work, and if so, in what modes?