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Old 31-07-2016, 03:46   #106
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Re: Refigeration Amp Hour usage survey

PPS Lagoon owners. Did you realise that your internal fridges were held in place by 4 screws through the soft plastic base of the fridge and readily rip out? Very easy solution is jam door stops on the top to secure it down:
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Old 31-07-2016, 05:29   #107
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Re: Refigeration Amp Hour usage survey

I just bought some . Main source for this stuff is eBay . Aspen aerogell . I have yet to do my doors but should have time soon to work with this stuff . R10 per inch ! Great !

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Old 31-07-2016, 06:34   #108
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Re: Refigeration Amp Hour usage survey

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I just bought some . Main source for this stuff is eBay . Aspen aerogel . I have yet to do my doors but should have time soon to work with this stuff . R10 per inch ! Great !
This would likely make a good separate thread.

I built my own box from 2 and 4 inch 4x8 blocks of extruded polystyrene (styrofoam and other names), hydrophobic and rigid, but I encapsulated it in epoxy, anyway, for more vapor barrier than moisture, and stairstepped the joints for air migration mitigation.

This stuff looks very interesting, but I wonder how one would fabricate an actual box using it. My box was essentially (variations but not significant) plywood, and I applied the insulation inward, using epoxy to adhere to the doorskin furring strips over the shiny-side-out aluminum foil, and then epoxied the interior before beefing up with fiberglass.

And, I wonder if this has any issues like the vacuum panels do, which is that the vacuum eventually dies, and you're left with no insulation (extruded polystyrene does, too, but at a somewhat lesser rate, but a great deal more bulk).

If you were starting from a bare exterior, how would you build your box so that it could have shelves, a freezer/reefer divider/spillover, and doors, using Aerogel only as the insulating medium?

I'll start a separate thread, too...

L8R

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Old 31-07-2016, 06:54   #109
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Re: Refigeration Amp Hour usage survey

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You can't over cool a condenser.
Yes you can.
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Old 31-07-2016, 10:13   #110
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Re: Refigeration Amp Hour usage survey

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Nice. That's a major improvement.

I assume original box. Any idea how much or what kind of insulation?
Yes, we're doing pretty good now. At least the draw is manageable with our charging system, and it's cycling so not working itself to death. I now have hopes that with a more thorough cleaning, and some rewiring, I can keep this old reefer running for a few more years.

The box (two actually, main "freezer" with cooling unit and then a spill-over "fridge" area) itself is like the rest of the boat: old. Insulation is around 6" of blow-in stuff where I can measure it. Hard to know what's in the lids and back though, and unfortunately it does kinda border our engine room on one side, so that doesn't help. We have added a layer of foil insulation inside the boxes. Perhaps try some of this fancy stuff you guys are talking about.

At this point, the beer is staying cold, and the batteries are staying charged, so life is good .
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Old 31-07-2016, 10:57   #111
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Re: Refigeration Amp Hour usage survey

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Yes you can.
I'll bite, without something silly like using ice water, how?
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Old 31-07-2016, 10:58   #112
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Re: Refigeration Amp Hour usage survey

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I can keep this old reefer running for a few more years.
I think you have a very good shot at it, the compressor life seems to be VERY long.
The 1980's vintage Cold machine that I took out of my boat as it was just way too small, is in a friends and working fine.
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Old 02-08-2016, 10:21   #113
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Re: Refigeration Amp Hour usage survey

On the CAL 35 I sailed out to Kwajalein and back I got the number in the tropics down to about 30ah/day if the fridge was not being opened at all. I used an amp hour meter dedicated to monitoring the fridge/freezer circuit and would watch it for weeks at a time while working in the Marshall Islands. The boat was on a mooring with only a wind generator on the stern (Air Marine) and so I would run the boat all weekend and the batteries would be down about 50% at the end of the weekend, then during the week the batteries would be charged in the tradewinds while keeping the fridge cold (I would load the fridge up at the end of the weekend with the next weekends food and drinks)


From memory the total space was about 1.5 to 2.0 cubic feet due to the reduction in space using 6 inches of foam all the way around replacing 2 inches of foam in the original huge box.


Note that this is an air cooled unit which is in the large open aft area of the boat under the cockpit.


Below is the quote from my website Propane Control


---Humm, must be a quirk of that webpage on the boat's site, this is actually the fridge page but this site appears to have looked into the tags of the site and pulled up "Propane Control"

The original ice box was about 9 cubic feet and barely insulated, I first installed the cold machine and found it to work well even if using a considerable amount of electricity. Later I cut out the old box from the inside, found that the insulation was mostly wet and ineffective. The rebuilt box has 6 inches of urethane foam insulation on all sides and a 1" thick vacuum panel in the lid which is roughly equivalent. The inside of the box is constructed of 1/2" marine plywood covered with Formica. The result is a very well insulated fridge which consumes about 30Ah/Day when in the tropics. If I place a 1" piece of foam between the evaporator and the rest of the box I have a freezer which runs at about 3 degrees F and the fridge is about 33 degrees F.
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Old 05-08-2016, 06:59   #114
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Re: Refigeration Amp Hour usage survey

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On the CAL 35 I sailed out to Kwajalein and back I got the number in the tropics down to about 30ah/day if the fridge was not being opened at all. I used an amp hour meter dedicated to monitoring the fridge/freezer circuit and would watch it for weeks at a time while working in the Marshall Islands. The boat was on a mooring with only a wind generator on the stern (Air Marine) and so I would run the boat all weekend and the batteries would be down about 50% at the end of the weekend, then during the week the batteries would be charged in the tradewinds while keeping the fridge cold (I would load the fridge up at the end of the weekend with the next weekends food and drinks)


From memory the total space was about 1.5 to 2.0 cubic feet due to the reduction in space using 6 inches of foam all the way around replacing 2 inches of foam in the original huge box.


Note that this is an air cooled unit which is in the large open aft area of the boat under the cockpit.


Below is the quote from my website Propane Control


---Humm, must be a quirk of that webpage on the boat's site, this is actually the fridge page but this site appears to have looked into the tags of the site and pulled up "Propane Control"

The original ice box was about 9 cubic feet and barely insulated, I first installed the cold machine and found it to work well even if using a considerable amount of electricity. Later I cut out the old box from the inside, found that the insulation was mostly wet and ineffective. The rebuilt box has 6 inches of urethane foam insulation on all sides and a 1" thick vacuum panel in the lid which is roughly equivalent. The inside of the box is constructed of 1/2" marine plywood covered with Formica. The result is a very well insulated fridge which consumes about 30Ah/Day when in the tropics. If I place a 1" piece of foam between the evaporator and the rest of the box I have a freezer which runs at about 3 degrees F and the fridge is about 33 degrees F.
After the reno , how much of a box did you have left (cubic feet) . 30 AH is great !

2 cubic feet ? seems like a huge reduction in space for 6
" of foam

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Old 05-08-2016, 15:26   #115
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Re: Refigeration Amp Hour usage survey

I agree, it would seem so, however, (cuberoot (9)-1)^3=1.2 so a 9 cubic foot box with no insulation and add 0.5 foot of insulation on either side gives just over 1 foot of space remaining in each dimension.

Now, there was probably 2 inches of foam before so only had to add an additional 4 inches to each side or 8 inches, about 0.7 feet additional foam or 2.6 cubic feet.

However the extra plywood and the like resulted in an inner dimension of 12w x 18L x 14h

Which is 1.75 cubic feet.

Insulation eats up alot of space, however the fridge worked really well for passage making




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Old 06-08-2016, 15:49   #116
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Re: Refigeration Amp Hour usage survey

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how?
Quote:
Originally Posted by Richard Kollmann View Post
reasonable control over condenser cooling mediumís temperature range.
Read the post again.
Thanks to Richard.
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Old 06-08-2016, 18:04   #117
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Re: Refigeration Amp Hour usage survey

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Read the post again.

Thanks to Richard.

I don't know which post, but I'll go out on a limb and bet he is talking about adequate cooling, not worrying about having too much cooling.



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Old 07-08-2016, 07:41   #118
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Re: Refigeration Amp Hour usage survey

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I'll bite, without something silly like using ice water, how?
I think that he means that by blowing too much air (i.e. to fast), the air doesn't have enough time to get saturated with heat.

Much like sightly closing your cowl vent will cause your CHT to go down.
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Old 07-08-2016, 15:46   #119
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Refigeration Amp Hour usage survey

Sort of back to the original issue, an old, as in maybe 30 yr old system that has had a very dirty condenser.
As air condensers get old, they do loose cooling efficiency, due of nothing else to oxidation on the coils, seeing as how small 12V fans pull about .25 amps and cost maybe less than $10, what's to lose by trying to see if an additional fan doesn't help, if it doesn't your out $10.

I've never seen lower CHT's from closing cowl flaps, but just cause I haven't seen it doesn't mean it doesn't happen, I'd assume it may have to do with airflow more than velocity? Open flaps may change the airflow around the engine?


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Old 07-08-2016, 16:54   #120
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Re: Refigeration Amp Hour usage survey

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Sort of back to the original issue, an old, as in maybe 30 yr old system that has had a very dirty condenser.
As air condensers get old, they do loose cooling efficiency, due of nothing else to oxidation on the coils, seeing as how small 12V fans pull about .25 amps and cost maybe less than $10, what's to lose by trying to see if an additional fan doesn't help, if it doesn't your out $10.

I've never seen lower CHT's from closing cowl flaps, but just cause I haven't seen it doesn't mean it doesn't happen, I'd assume it may have to do with airflow more than velocity? Open flaps may change the airflow around the engine?


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You are very correct on dirt and debris degrading the efficiency of any heat exchanger. The OP and others should always clean the heat exchanger before moving on.

But I find that most systems have a very piss poor, if any fan shroud/ducting system.
Most seem to have just a "pan cake" fan, ty-wrapped to the condenser. And at best, only 60%~70% of the condenser is seeing any air flow.

Just by moving the fan back an inch or so and constructing a shroud out of card board, generally does wonders.

But short of this, getting a fan that is the same size as the condenser, would be an improvement.


--MAJOR THREAD DRIFT--

I have changed out many jugs due to heat related failures.
True, quite a bit of them have been due to loose, worn or even missing baffles <sp?>, but there have been those that failed because of pilot error due to improper cowl settings.
I was always told and taught, that the cowls were closed to reduce temp by slowing the air flow.
The Piper Tomahawk that I got my licenses in and the Aero Commanders, that were my bread and butter for many years, all were operated with the cowl vents partially closed after TO.

Locally we have a airline historical society that has what I think is the last AW (Air Worthy) "Connie". THey burnt up the first engine due to high CHT. The replacement engine was Zero'd timed, and it failed shortly after installation. Same thing, high CHT.

The official explanation was the cowl linkage was messed up.....But common knowledge among the A&P's was that the Chief Pilot had a standing rule that after climb out, all cowl flaps were to be 100% open. Okay for the other three, tired engines. With worn superchargers and turbo's. It was all they could do make TO power.
But the remaining engine, with it's new supercharger and the replacement engine with all new parts, had no problem making TO power. So cooling was much more critical.

I've been told that now, this engine's cowl vents now get moved to 75% after takeoff.
But, beings I have not personally worked on this plane, it is all secondhand info..
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