Charging methods

Eugene Silberstein 3

Definitely a good piece of reference material.

Darin(in Michigan)

Charging methods

I worked for a Carrier dealer for about six years. During that time I used the recommended superheat method for charging cap tube systems and subcool for charging TXVs. Now I work for a Lennox dealer and their instructions say nothing about superheat charging, charge using subcool for cap tube systems and use what they call "approach method" for charging TXV's. The Philco units we use advise charging based on what I gather as being normal running conditions i.e. if the oda is X then HP= and SP= . Where's the allowance for latent heat based on load?!! If I continue to use SH and SC methods will I be happy with the results. I like consistancy and simplicity.

Eugene Silberstein 3

The approach method...

The approach method is the subcooling method.... in disguise.

Take this example for instance. You have a standard efficiency system that the manufacturer wants to operate at a condenser saturation temperature that is 35 degrees higher than the outside ambient and withe a subcooling of 20 degrees.

If the outside ambient is 85 degrees, the desired condenser saturation temperature will be 120 degrees (85 + 35). With 20 degrees of subcooling, you will have a condenser outlet temperature of 100 degrees.

Now, the "approach" temperature for this system would be 15 degrees (100 - 85). This is the difference between the condenser outlet (liquid line) temperature and the outside ambient temperature. Now if your temperature is lower than the "approach" temperature, you have to remove refrigerant. If your temperature is higher than the desikgn "approach" temperature you will need to add refrigerant to the system.

So, in reality, the manufacturer simply eliminated the extra addition and subtraction steps for you... How nice of them, don't you think?

Empire_2

Lennox Condensers

Don't forget they give you that nice charging scale on the inside cover on the condensing unit. I actually like the well they provide which accomendate a standard pocket temp gauge. Fill with oil and calculate your sub cooling as per the charging chart.

Mike T.

Techman

A Good Idea

Mike T. Thanks for sharing,and I bought a copy of "UGLYS" which now has a dirty fingerprint on a couple of pages!

Empire_2

T-Man

What are the books going for now? I think I paid 20-30 bucks a few years ago. Was just curious. Thanks

Mike T

Techman

UGLY'S

Hay Mike.I'mn not sure what you mean by "books",my copy of "UGLYS" is 4"x6"and 156 pages and it is only $9.95.Are there more books to this?Thanks again!

Empire_2

I'm sorry Techman

I meant book;-) And yes,...you have the same thing as I do. 4"x6".... Nice isn't it? Turn to page 38-39 and check out the conversion table. Ya gotta love it. I think everyone should have this book in the truck;-)

Mike T.

Paul Fredricks_3

What is this book?

Empire_2

Hi Paul

It's a book that gives you all electrical references you can imagine, plus more. Titled, UGLY'S Electrical References. Can be found at most electrical wholesalers counter.

Mike T.