Author Topic: Archive 16  (Read 4759 times)


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Archive 16
« on: May 03, 2012, 09:50:27 am »

Your books    Archive  16
I am unable to select the second book from the website. I would like both books. Can this be arranged? Tks, Ken

Sea Frost also has the BD unit with the BD50F comp. just don't order the BDX the "X" is apparently thier biggest (as in BD80) 12 volt. I think the double "cold plate" bin is a great idea. It gives more room for freezing than the thin plate bins available. It has a valve instead of a cappilary tube. It is stainless steel instead of aluminum. The comp,/cond. unit is boxed with possitive air flow. It all sounds good to me.

The frost is down stream from the insulation Bob

Norcold SCQT-6407
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

Frost on the Line inside of the box
Richard, bought the Sea Frost with the BDX80 compressor and 2 evaporator plates and installed them in my box. Evaporator plates works great but I noticed that one of the lines inside of the box has about a 1/2" of frost on it. The box is sealed tight and I just finished putting additional insulation in the box. Added 3" of insulation along with what was already on the outside. Tops and doors are sealed tight( you can't pull a dollar out from any spot). My question is this ok? Freezer is 18 degs. and the frig is 32 deg. with a spillover divider. Any comments? Thanks Manofsteel s/v Magic Moments

As long as the refrigeration unit uses the recommended line sizes six to eight feet elevation difference does not seem to matter. The extra tubing is normally stores in an 8 to 12 inch coil near condensing unit, vertical or horizontally coiled.

Two Book order
Sorry, I recieve two to three double book orders a week so try again, if this does not work place both orders separately.

Poor performance
The actual length of ice or frost on return line is important along with the amperage required when box temperature is warm. If there is too much frost or amperage is high, there is either too much refrigerant or the refrigerant is contaminated.

Envirosafe or Glacier Cold refrigerant
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 for the efficiency claim. I'm just wondering if anyone has used this stuff and can confirm the compatibility and/or efficiency claims.

Refrigerator/Freezer Delta T
Frost on refrigerant lines inside the refrigerated area is normal. Your Spillover system is not allowing freezer to get cold enough, it is spilling too much. There needs to be a temperature differance of at least 20 degrees between boxes. A good freezer temp of +5 degrees with refrigerater temp of 35 is what a home refrigerator is designed for.

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.

Refrigerant Advice
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.

Refrigeration Performance
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.

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 much cubic feet of freezer can I handle. You are greatly appreciated.Best regards, Buz Branch

Now I am really confused
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.

Batteries and refrigeration
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.

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.