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Gary
28-02-2008, 07:29 PM
If I could teach only one thing to service techs everywhere, it would be this:

On every service call, no matter what type of system, regardless of the customer complaint, always start with a visual inspection of the system, in particular looking for airflow (or water flow as the case may be) problems.

Why? Because airflow problems will alter the pressures, but the pressures will not alter the airflow. Logically, airflow is the place to start.

Once you have determined that you have adequate airflow through both evaporator and condenser coils, you have narrowed your search down to refrigerant flow problems and trouble shooting becomes MUCH easier.

paul_h
29-02-2008, 01:46 AM
Yeah, it's second nature to me since I had the misfortune to work on domestics for so long. So many of them don't even have gauge ports, those that do often only have suction ports anway.

So most of the time I check airflows and pipe temps first on any system I am checking due to habits.
The gauges only go on when I suspect low refrigerant or HP trip.

Samarjit Sen
29-02-2008, 04:00 AM
Hello Gary,

I have been studying your posts and find that not only interesting but knowledgable.

You are absolutely correct about the airflow. I am mostly into refrigeration and I find that wether it be a maintenence or designing a plant, airflow plays the most important part.

For a proper airflow , I am trying to know more about fan technology. In case some one has some information on the same, like velocity, SP etc, please share.

eggs
01-03-2008, 01:55 AM
Gary, i follow the TECH method by some guy over the pond;)

First i check that the system is calling for cooling or heating.
The fella who wrote the book;);), insists that this is where to start. Then the Evap, then the Cond......

Cheers

eggs

coolments
01-03-2008, 04:02 AM
Hi gary I totally agree with what you say, i also find most new up coming engineers also depend to much on manuals and fault codes and diagnose on what they say with out getting to the route of the problem resulting in several visits to complete a fault.
I always try to teach the them that most problems can be narrowed down by look, touch and feel around the system before diving to the manuals, its so tough these days as most aprentices only know flare nut to flare nut for pipe size and 123 wiring, if it fails its books or manufacturer tech support. sad though it seems most people will agree in the uk with a serious skill shortage in our trade most small medium sized companies bounce of a few key engineers they have for any thing technical and the rest just work on plant with no issues ay present, those key engineers are paid well so as not to want to leave.
luckily enough the company i work for is big on training being a member of investors in people but for most its learn them the basics and send them out to make a fast buck on install and poor maintenance techniques. I assume its the same on your side of the pond.

iceburg
01-03-2008, 04:26 AM
Why? Because airflow problems will alter the pressures, but the pressures will not alter the airflow. Logically, airflow is the place to start.

I couldn't agree more, I have been doing supermarket startups and spent the better part of an hour today showing stock people how not to block my airflow. I was getting high temps on my cases and when I went down to the main floor what a mess.

I enjoy your posts thanks for all the tips.

Iceburg

Gary
01-03-2008, 06:31 AM
Gary, i follow the TECH method by some guy over the pond;)

First i check that the system is calling for cooling or heating.
The fella who wrote the book;);), insists that this is where to start. Then the Evap, then the Cond......


There are a lot of people around here with my books. I was wondering if someone would catch this... LOL

Okay, ya got me. Nothing happens if it isn't turned on, so...

Make sure it is calling for cooling first, then check the airflow.

Back when I was laying out the fundamental strategy for the TECH Method, I was writing a column for the ACH&R News. I kinda half-jokingly toyed with the idea of calling it the Airflow/Subcooling/Superheat Method. The editors over at the news didn't see the humor in this.

Abby Normal
01-03-2008, 06:47 AM
if you want to condition the air you have to be able to first move the air :)

Samarjit Sen
01-03-2008, 01:58 PM
In refrigeration it is just not the air flow, but the quality. I mean the velocity, static pressure and the throw.