Getting Ready for the Cooling Rush

Eugene Silberstein 3

Eugene Silberstein 3

What are you guys doing?

What are you guys doing to prepare for the upcoming cooling season? It should be interesting when units start craping out and need to be replaced. Are you confident that you will be able to obtain 13 SEER equipment in a satisactory time frame? Are you starting to keep your own inventory of equipment? What's your plan of attack going to be if faced with a replacement situation and you can't get hold of replacement equipment?

Empire_2

In a few days

All trucks will have an inventory done and any heating parts that are not commonly used will be pulled and stocked for next year. All Vac pumps will have oil changed and be vac tested to 300 microns. Also,..TIME TO CLEAN THE TRUCKS......Everyone loves that request. As far as the new equipment, I do have a plan of attack and that is to Attack each plan as it comes across my desk. I really do not know what to expect this year...

Mike T

Eugene Silberstein 3

Don't Change the Vacuum Pump Oil!

Vacuum pump oil should be changed immediately BEFORE use. Vacuum pump oil absorbs moisture at an amazingly high rate, so changing the vacuum pump oil now, before the need arises to use it will greatly increase the amount of time needed to evacuate the system and may also prevent the pump from reaching the required system vacuum level during evacuation.

I like the idea of testing the vacuum pumps though. Are you planning on replacing the oil for the sake of the test?

Empire_2

You got it right on the money.

Although we usually change oil after each use, I know it should be done before, but for the test, Yes we will change it. Also, when we use our pumps we monitor with micron guage which every truck has. (by the way I'm not impressed with the digital ones) I have never had a problem with time of evacuation. Most trucks have the standard 5cfm pumps and we have 2 7 cfm. I personally cannot tell the difference. We are really big on leak checks. We use 3 methods,...Halogen, ultra sound, and the standard bubbles to pinpoint. Never missed a leak yet.

Thanks Eugene.

Mike T Empire Mechanical

John Mills_5

Your thoughts

Eugene, what are your thoughts on techs going out in 40-50 degree weather and trying, by way of many methods, to check the charge on residential air conditoners?

BTW, got your heat pump book, great job!

Eugene Silberstein 3

Thanks!

First of all, thanks for the kudos on the heat pump book... Glad you are enjoying it. I had a blast writing it.

Secondly, I have absolutely no problem starting up an air conditioning system during cold weather, providing that the technicians that are doing the work have been properly trained to do so.

Here are a few things to keep in mind.

Design conditions are 95 degree outside air temperature, 75 degree indoor air temperature at a relative humidity of 50%.

If we are able to simulate these conditions as closely as possible, the chances of our startup being worth more than 2 cents is greatly increased.

It's relatively easy to simulate these conditions, if only for a relatively short period of time. First, crank up the heating system to put some load on the house. People have expressed their concerns about this as taking to long to do in the course of a routine startup, but here'st he trick. Give your customers a call about an hour before you get there and ask them to turn their thermostats up to 77 degrees. By the time you get there, there will sufficient heat load on the air conditining equipment when you arrive.

Have your technicians take a reading of the relative humidity in the home using a sling psychrometer to read the dry bulb and wet bulb temperatrures in the space. An RH close to 50% is great, but don't freak out if it's not.

An Rh below 50% means that our delta-t across the evaporator coil will be greater than the typical 17 - 20 degrees, while an RH above 50% means that our delta-t across the evaporator coil will be lower than the typical 17 - 20 degrees.

Now to the outdoor unit.

Blocking a portion of the condenser coil is not a bad thing. Many have said that this is not an effective mean by which systems can be started up in the cooler months. Such is not the case. Fan cycling, shutters, condenser folloding all operate on the concept that reducing the effective surface area of the heat transfer surface (condenser coil, in this case) will increase the sondenser saturation temperature and pressure in an attempt to maintain the condenser saturation temperature and pressure at the desired level. So, block away but do so carefully.

If the system is operating with a fixed bore metering device, the refrigerant charge can be evaluated by a combination of the evaporator superheat, condenser subcooling, and the delta-t across the evaporator coil.

THE NUMBER ONE TIP FOR STARTING UP ANY AIR CONDITIONING SYSTEM IS TO VERIFY AIRFLOW BEOFRE DOING ANYTHING TO THE SYSTEM.

During the winter months, homeowners may close off some suply registers to avoid overheating during the winter or may not have cleaned the air filter. Improper airflow acrosst he evaporator coil can cause the technician to inaccurately conclude that there is a system malfunction that requires expensive repairs.

More to come.

Hope this helps.

don_181

Ahh yes

my favorite time of year...Summer.

My first priorty is to get a list of hvac contractor together so we can take the Professor class in the Tidewater area of Virginia in May.

Then I'm going to make sure I have plenty of freon and invoices.LOl.

Actually we are already sending out the news letter with the reminder notice not to wait till the last minute.

The truck will acourse will be stock with a box of different size capacitor of the 440 volt kind because, they seem to hold up better then the 370 volts.
Why is that professor?

Lots of coil cleaner and plenty of charge batteries for all
them coil cabinets that going to need to be remove just so we can split the coils and clean them properly.

Oh yes I'm seeing if I rush maybe I can get five system done and a day.

And yes five is enough for me.

don_181

Ahh yes

my favorite time of year...Summer.

My first priorty is to get a list of hvac contractor together so we can take the Professor class in the Tidewater area of Virginia in May.

Then I'm going to make sure I have plenty of freon and invoices.LOl.

Actually we are already sending out the news letter with the reminder notice not to wait till the last minute.

The truck will acourse will be stock with a box of different size capacitor of the 440 volt kind because, they seem to hold up better then the 370 volts.
Why is that Professor?

Lots of coil cleaner and plenty of charge batteries for all
them coil cabinets that going to need to be remove just so we can split the coils and clean them properly.

Oh yes I'm seeing if I rush maybe I can get five system done and a day.

And yes five is enough for me.

Eugene Silberstein 3

Awesome Don

Number 1

Let's start a list and see how many guys we can get for a PRESSURE ENTHALPY WITHOUT TEARS SEMINAR in the Tidewater VA area for May.

Number 2

Let's see how many guys we can get for our existing PRESSURE ENTHALPY WITHOUT TEARS SEMINAR in College Park Georgia on April 10.

Number 3

The voltage rating on capacitors is the breakdown voltage of the dielectric.

Number 4

Capacitors rated at 370 volts will hold up well when used on 115 volt motors.

Number 5

440 volt capacitors are the device of choice when working on motors rated above 220 volts.

Number 6

When the motor turns, a voltage is induced across the start winding. When you are dealing with a PSC (permanent split capacitor) motor, the voltage that is realized at the capacitor is greater than the line voltage suplied to the circuit. So, the 440 volt capacitors hold up better.

Number 7

Let's start a list and see how many guys we can get for a PRESSURE ENTHALPY WITHOUT TEARS SEMINAR in the Tidewater VA area for May.

Number 8

Let's see how many guys we can get for our existing PRESSURE ENTHALPY WITHOUT TEARS SEMINAR in College Park Georgia on April 10.