Author Topic: Archive 34  (Read 2993 times)

Richard

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Archive 34
« on: April 30, 2012, 04:12:17 pm »

Archive 34

The Mons



Joined: 22 Aug 2006
Posts: 3    Posted: Wed Sep 06, 2006 12:27 am    Post subject: Now I am really confused
 

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Richard:

After reading your 12/24 book, I feel that I now have more information that I did before. But with the additional information come increased confusion.

It seems like the way to go is with an expansion valve and receiver/dryer system. Is the Technautics system, the only readily available one with this configuration?

Thanks.

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kollmann
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Joined: 23 Jun 2004
Posts: 332
Location: Fort Lauderdale, Florida    Posted: Thu Sep 07, 2006 2:47 am    Post subject:
 

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When an evaporator itself is to be operated under load at a wide range of temperatures such as in a eutectic holdover plate a thermostatic expansion valve (TXV) is a better expansion device than a capillary tube. Refrigerant capillary tubes must be correctly married to the capacity and desired temperature range of an evaporator. A TXV can be purchased with a very wide capacity range and its automatic nature will maintain a desirable consistent superheat across the evaporator coil.

If a thin plates capillary tube is correctly sized for, condensing unit, evaporator temperature range and evaporator capacity, a system will perform efficiently.

Technautics with their large surface area holding plate and TXV is a good efficient system for the right application. Because of its volume of plate solution the TXV's control will result in a faster temperature pull down than the same size plate with a capillary tube expansion device. I do not know of other companies using the TXV on BD compressor systems. I do recommend receivers and TXVs on do it yourself systems as they will regulate the compressors output to match the heat transfer ability of an evaporator/holding plate.
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sailorbuz



Joined: 05 Sep 2006
Posts: 2    Posted: Tue Sep 05, 2006 8:59 pm    Post subject: Just want a cold drink in mexico
 

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I have a 6 cubic foot ice box ,top loader with 3-6 inches insulation and I want to convert .I bought an AB cu 100 air cooled danfoss bd 50 compressor and a large verticle evap.( hAVE NOT INSTALLED yet) Boat lives at 6000 feet on a lake near Durango Colorado BUT we spend 5 weeks in the Sea of Cortez the end of May and june and 60 lbs. of dirty Block "fish" ice lasts 6 days at most W/O much room for food. Air temp in in the 90s and sea temp is between 68F and 88F depending on our location.I have (2) 100 amp hour batteries and a 75 watt solar panel .Alternator is 30 amp on an atomic 4 ,I am thinking that the AB power plate might be the most efficient way to go as I would love to have a 2cf freezer with a proper divider and not listen to a compressor cycling .Am I dreaming or is this possible .Any advise is welcome Buz Branch S/V DOUBLOON Durango Colorado email <sailorbuz@hotmail.com>

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kollmann
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Joined: 23 Jun 2004
Posts: 332
Location: Fort Lauderdale, Florida    Posted: Tue Sep 05, 2006 10:44 pm    Post subject: Refrigeration Performance
 

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There are a number of boaters that have contacted me about the poor performance of power plates when connected to the output capacity of BD50 compressors. The problem is these plates lack the ability to transfer the amount of heat in a six cubic foot box in a warm climate. Their largest vertical evaporator has twice the capacity of their power plate. When a compressor is asked to overpower the evaporator/power plate as it would be in this case in your application the system would not be energy efficient, nor would it do the work needed.

Your 30 amp alternator is of very little value as within 10 minutes after startup, when it gets warm, it will only put out 15 amps per hour. You will need 60 amp-hrs per day to just support refrigeration, or half that if you only want to replace cooling provided by ice. I recommend 300 watts of solar panels or a high output alternator with smart regulator.
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R.L. Kollmann
Author of DIY Refrigeration & 12-24 Volt Refrigeration

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sailorbuz



Joined: 05 Sep 2006
Posts: 2    Posted: Wed Sep 06, 2006 12:22 am    Post subject:
 

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Thankyou for your prompt reply, What I get is that I should go with the large vertical evaporator but need to increase power . Would a 3rd battery be necessary in addition to increasing charging capability. and, would I have freezer capability with a proper divider as you have described elswhere.. and ..how much cubic feet of freezer can I handle. You are greatly appreciated.Best regards, Buz Branch

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kollmann
Site Admin


Joined: 23 Jun 2004
Posts: 332
Location: Fort Lauderdale, Florida    Posted: Thu Sep 07, 2006 12:53 am    Post subject: Batteries and refrigeration
 

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If you have an AB large Bin evaporator in that large a box, in the tropics, the bin will be the only freezing section you can count on.

Two 100 amp batteries is never enough capacity for a boat with refrigeration. Battery capacity on a cruising boat should exceed four times the total amount of current used per day and still have power left for engine starting. One important factor to remember is a batterys capacity rating decreases with age and use and each day of discharging it will never return to the previous days new rated capacity.
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Nick



Joined: 17 Jul 2006
Posts: 3    Posted: Tue Aug 29, 2006 4:51 am    Post subject: Envirosafe or Glacier Cold refrigerant
 

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Has anyone used one of these hydrocarbon refrigerants? They claim to be compatible with r134 systems without replacing the oil or any other system components but supposedly require 30% less compressor horsepower.

See http://glacier-gold-refrigerants.com/ for the efficiency claim. I'm just wondering if anyone has used this stuff and can confirm the compatibility and/or efficiency claims.

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kollmann
Site Admin


Joined: 23 Jun 2004
Posts: 332
Location: Fort Lauderdale, Florida    Posted: Thu Aug 31, 2006 12:11 am    Post subject: Refrigerant Advice
 

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There are a number of claims about the many new refrigerants but before you destroy your compressor see if the compressor manufacturer has it on their approved refrigerant list.
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R.L. Kollmann



Morris Covin



Joined: 09 May 2006
Posts: 3    Posted: Mon Aug 28, 2006 9:43 pm    Post subject: Norcold SCQT-6407
 

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I have the SCQT 6407 installed in my sailboat icebox and it was working fine for the two years that I have owned the boat. (I'm not sure how old the Norcold unit is) Then one day it just quit cooling. I can feel the unit running (humming) but the plate in the icebox is ambient temp. I am guessing that the compressor is running as I can feel the unit emitting a small vibration. I read in another post where you stated

"I assume when you say the compressor has died You mean it trips either the circuit breaker, or thermo disc if so equipped, before any rotation starts. Things to check before replacing compressor; Start run relay, Start capacitor, Circuit breaker, and thermo overload disc. To check relay, thermo disc and capacitor on one of these small compressors a serviceman will plug in a solid state Three In One Relay Overload Start Capacitor. This unit sells for about $15 and is easy to install as a single unit replacement for all three"

Does this apply to this type of unit? Should I have a tech put this "Three in one relay on my unit? Also, can this unit be switched over to R-409 or 134? I thought about pulling the entire unit out in order to take it home and tinker with it or take it to a A/C service center to see if they could figure out what the problem is.

At first I figured the unit had just given out and the whole thing needed replacing. But, since the unit is running, maybe it is something simple.

HELP!

Thank you

Morris Covin
s/v Early Start
Houston TX
SailingHouTX001@sbcglobal.net


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kollmann
Site Admin


Joined: 23 Jun 2004
Posts: 332
Location: Fort Lauderdale, Florida    Posted: Wed Aug 30, 2006 9:24 pm    Post subject: Norcold
 

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The compressor used by Norcold is a not a conventional compressor it has a bouncing magnet instead of a rotating motor. A 22 or 26 volt alternating or pulsating current causes the pump to pull the compressor piston down then a spring will force piston up when current reverses. When the unit performs the same on AC and DC and compressor is vibrating the problem is almost always a refrigerant leak. Even if a servicing gauge could be connected and the compressor is bad there is no quick fix. Your best course of action is to replace the complete system.
If the refrigerant is low most of these units do not have a servicing port. If it needs refrigerant I would only add R12. I have seen people spend from $300 to $500 hiring someone to try to repair them.
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R.L. Kollmann