The Newsletter!!

[RoBoTeq]

Norm...one word; "poetic license".

Now, back to the cap tubes. If the pressures entering the cap tubes are three times the rate of expansion exiting the cap tubes then the newsletter needs to be printed in color format.

[MechAcc]

The Critical Nature Of Cap Tubes

http://www.achrnews.com/CDA/ArticleI...143073,00.html

Coping With Capillary Tube Blockage

http://www.achrnews.com/CDA/ArticleI...,23482,00.html


[Edited by MechAcc on 09-18-2005 at 12:10 PM]

[condenseddave]

Originally posted by NormChris


Dave, look at the tabs at the top of any HVAC window. There is a newsletter tab.

What's an HVAC window?

[gruvn]

Originally posted by NormChris


gruvn, you have yet to provide a single clear agruement for your belief that the evaporator capacity on a cap tube system increases with an increase in heat load.

You of course can't because it does not.

OK Norm, heres what I was thinking. You write many articles and books on these types of topics, you have your own spot on several high profile websites for several manufacturers of HVAC related equipment and tools, you are a well respected senior training officer for a high profile brand of commercial and residential equipment. It is a very respectable resume and I do respect it, on several occasions I have referred friends of mine to take a look at Norm's Corner. I myself have it bookmarked and I have read most of your articles.With that being said , I would like to give you this proposition,

Correct me if I am wrong , but your position is that

"a capillary tube metering device cannot modulate refrigerant flow to the load demand."

Below are your words

No, the total pressure differential across the cap tube decreases. The suction pressure rises at a higher ratio than the head pressure. The total evaporator superheat increases greatly. The evaporator capacity decreases.


What I would like to see you do Norm is, write an article on capillary tubes and state clearly that a cap tube cannnot modulate to the heat load on the evaporator, don't say it out of context but say it as it is and let it stand on its own. The reason that I ask you to do this is because I know that you won't. You won't be able to write that article because you know it will not be recieved very well, by people that know better. And it will cause you some embarrassment that will require a lot of back pedaling to rectify.


By the way do you have any previously written articles on cap tubes , if so please tell me where I can find them.

With that being said I will close this arguement , let me know when it goes to print Norm,

Oh, and I have showed you an article that states my arguement, please find an article or reference that supports yours.

[condenseddave]

Originally posted by outside rep
I would guess a window that heats and cools you house by some magical way with a invisable thermostat

Where can I purchase one of these mystical devices, and can I install it myself????

[gruvn]

oh well I suppose he misplaced all of those articles , that explained how the cap tube had no ability to modulate refrigerant flow. Hey no problem I'm sure you will find them some day.

[NormChris]

Originally posted by gruvn
oh well I suppose he misplaced all of those articles , that explained how the cap tube had no ability to modulate refrigerant flow. Hey no problem I'm sure you will find them some day.

You sir disappoint me. I was expecting you to directly support your position in hopes that we could all learn something from the discussion.

I have absolutely no concerns about stating my position which is well understood by many of us in the industry. It is really very basic and in fact fundamental to a solid understanding of the refrigerant cycle.

I have a number of writing assignments currently under way as well as a heavy speaking schedule. Some day I will write such an article. Meanwhile, I am giving you the opportunity to "correct" me so I avoid making a fool of myself when I do write the article. You see, if I am incorrect, I am quite willing to admit so and do so in public such as right here at this forum.

So, the topic is this; What happens to the superheat in the evaporator when the heat load on the evaporator increases and what happens to the capacity of the evaporator under those same conditions?

But, I don't need to take votes, I want a clear, direct and complete explaination of the process and the factors involved.

So, go for it. Don't tell me to read the SAM manual, I have the SAM manual. Don't tell me what YOU THINK other sources say. Explain it to us yourself.

If I am incorrect I want to be corrected. I am ready to learn, are you?

[gruvn]

Originally posted by NormChris


As the heat load increases the suction pressure increases and the superheat increases. The increase in suction pressure causes the pressure differential across the cap tube to decrease. This in turn causes LESS refrigerant to enter the evaporator.

The evaporator starves for liquid refrigerant.

ok my position is that the cap tube will modulate refrigerant flow to the evaporator according to the load. It is a simple and true statement, you are trying to complicate it. In other words .A cap tube is a modulating refrigerant control, thats it. Thats my position, is yours the opposite still ?

[RoBoTeq]

Just goes to show; "A fat turd by any other name, still smells the same."

[gruvn]

Don't know what you mean,

[NormChris]

The questions are and always have been

1) What happens to the superheat on a cap tube fed evaporator when the heat load is increased?

2) What happens to the evaporator capacity on a cap tube system when the heat load is increased?

There is nothing complicated about these two questions.

However, I want a clearly stated set of explainations for the answers to these two questions.

[gruvn]

Originally posted by NormChris


The questions are and always have been

1) What happens to the superheat on a cap tube fed evaporator when the heat load is increased?

2) What happens to the evaporator capacity on a cap tube system when the heat load is increased?

There is nothing complicated about these two questions.

However, I want a clearly stated set of explainations for the answers to these two questions.

1) What happens to the superheat on a cap tube fed evaporator when the heat load is increased?

Answer = Superheat will first increase, same as a TXV


2) What happens to the evaporator capacity on a cap tube system when the heat load is increased?

Answer = Eficeincy will go down at first, same as a TXV

Agree ?

[NormChris]

BTW, I am well aware of bubble point and cap tube operation. Perhaps you should write an article and have it published.