DX System

pyroracing85

I know a lot of you guys say DX system. Are you talking about the standard refrigeratant system seen in more households?

beenthere

DX.
Direct Expansion.

It refers to the refrigerant as the heat transfer medium for absorbing heat from either air, or ground.

Geos, can be DX or Indirect.
Indirect. A medium such as water.water glycol absorbs heat from the ground, and then is pumped/circulated to another heat exchanger where the refrigerant absorbs that heat.
Direct Expansion goes, have copper tubing/pipes in the ground that the refrigeratn its self is pumped through to DIRECTLY absorb the heat.

A standard residential air to air A/C or heat pump is a DX systems.

pyroracing85

Thanks a lot for that detailed answer. I am just reading as much as I can about HVAC systems. Learning a little. I don't know where to go after this though. Finishing my Mechanical Engineering degree then signing up for trade school and going to try to get a field interning as a HVAC intern.

beenthere

Your courses included fluid heat transfer right?

Your half way there then.

pyroracing85

Of course. Well it's called fluid systems and also Thermodynamics and Thermal Systems are most likely the ones that pertain to HVAC systems.

Half way there huh? I start the trade school in january.

pyroracing85

Also, there is a heat transfer class

beenthere

That is the one you need.

pyroracing85

So your saying heat transfer is the most important?

I still need to learn the service side though.

beenthere

I started out in installation.
I knew it wasn't something I wanted to do for the rest of my life the first year.

Understanding heat transfer. Lead to being able to do more then say.
I'll let the office know that you need a salesman to come out and do a load calc to know for sure if your system is under sized or not.

While it would be great if the average service tech knew how to size and design a system. And then test its true capacity, and delivered performance.

But, in the real world, very few can do that.
They may guess that a hydronic system might work better with a bigger circulatior.
Or check temp rise across a heat exchanger, and say its within spec.

But they can't realy tell how much heat is being delivered to the house.

Or how many GPM the circ needs to move.

In hydronics. A basic formula is:

Q=500*GPM*Delta

Most service techs have no idea what it means.

Enthapy delta*4.5*CFM

Most service techs have no idea what it means, or where or how to get the variables.

So are you sure you can find a company that any of the service techs or installers will know any of that.

pyroracing85

Q is specific heat. Then you have latent heat.

I know about that stuff. Would never hurt to learn more that is for sure.


Well I dont know if I will become a service tech or not. I don't know where I am going to fall. I don't exactly want to sit behind a desk all day.

beenthere

Q is a common reference for BTU.
In a hydronic formula, its sensible BTU.

The heat transfer will help youmore then you think.

Sitting in an offie all day wouldn't be any fun.

Then again. Hoisting up a 5 ton compressor on a roof when you 60 wouldn't be any fun either.

Keep in mind. That refrigerant/DX systems are going to have a limited future.

In the next 20 years, you can expect to see more thermoelectric cooling being used in more applications.
As the EPA tightens up more on refrigerants.

pyroracing85

Thermoelectric huh?

stuperintendent

you should look into interning with an established mechanical engineering firm before you graduate. the best engineers are ones that have practical working knowledge of the systems they design, though.

pyroracing85

I definitely will be. I have a year left of college to finish. A lot of companies are turning away even free workers.

beenthere

Yep. As the technology improves. It will become a realistic method cooling homes. Instead of just electronics, and small coolers like Coleman uses it in.

flashheatingand

Pyro, you sound like a bright guy with a lot of ambition & spirit. Somebody gave this advise to me when I was 30 and it stuck. He said "Whatever field you choose" look at the the older generation of colleagues. If that is where you would like to see yourself great. Otherwise get out!!! Odds are those who chose "desk jobs" are better off financially, or at least had higher pay checks. In addition, several of those likely had more "interesting" work as well.Just because you have a degree doesn't confound you to a desk job.

In looking for internships which is a great idea, check out companies such as Honeywell, Carrier, Goodman,... the list goes on. You might also check out ASHRAE, or one of the lab testing programs. Trade school is good and all, but, it's not all that.

pyroracing85

To be honest I would like to start a business as soon as possible. That is and has been one of my main goals. The only reason I see trade school is learning the service side to start a business. I might be wrong. I am not sure don't know to much about this industry.

pyroracing85

So you say don't waste my money on trade school?

beenthere

What kind of business do you want to start?

Design/Engineer(need 5 years internship with an engineering firm in my state to get your state engineers number).
Consulting.
Installation and service.

flashheatingand

If your primary goal is to start your own gig, it would behoove you to take courses in areas such as book-keeping, microsoft word & excell, sales, time management, web page deveolopment, marketing...etc. Today, you want to get into a hvac field, and it is a fine field. In two years, you may decide there is a lucrative possibilitiy in minature doll houses. Who knows, but the skills that were previously mentioned will be critical no matter what field you choose.

Trade school is great, but it's not the end all for everybody. Quick easy advise: get ojt with an old school hvac guy. You will beconsidered his b--ch, but if (s)he is a square guy, it will pay dividends. Don't get taken advantage of some guys are plain ol cocksuckers.. If you are still into hvac in a year or so, then sign up for school.