Heating Help

A Good TIme

@ May 25, 2012 1:07 PM in OESP 59th Annual Convention

It was definitely a great event! A good time was had by all. Great to see everyone.

Doing Great!

@ May 6, 2012 6:26 AM in bad txv?

Semester is winding down, getting ready for a relaxing (more or less) summer. Getting the backyard ready for barbeque season!

Enjoy!

Darts?

@ May 5, 2012 6:56 PM in bad txv?

Did someone say darts? I love that game.

Indeed Don...It is definitely fun to throw them and see how close we get!

How are things down in lovely Virginia?

Agreed

@ May 5, 2012 7:38 AM in bad txv?

As I always say, Don, we need a complete set of readings to narrow the possibilities.
We can definitely speculate about al of the possibiliies, as there are many. I too am curious about the rest of the numbers.
This is a perfect example of why it's important to obtain all pertinent readings to ensure an accurate diagnosis.
I always relate this story to my students:
You go on a "no cooling" call. Let's say it's an older R-22 system with a capillary tube. The outside ambient temperature is 90 degreees and the indoor air temperature is 80 degrees. You gauge up on the system to find the operating pressures lower than desired (196 psig/100 degres on the high side, 55 psig/30 degrees on the low side). You immediately determine that the system is undercharged and proceed to add refrigerant to the unit.
Adding refrigerant causes the gauge readings to change only slightly, if at all, so you add more refrigerant. Still very little change. So you add more refrigerant and the operating pressures rise slightly. So you add more refrigerant. The operating pressures are still way too low, but you determine that the system is cooling a little better than it was and a little cooling is better than no cooling.
You prepare the bill and present it to the customer. She goes to the other room to prepare your check and you decide, while you are waiting, to check the air filter. At the filter, you realize that the homeowner can easily knit a sweater with all of the junk that is on the filter. You pull the filter out and the massive suction falls just short of pulling your hat into the return duct.
The light bulb immediately goes on as you rush out to the condensing unit. After gauging up again, you see that the operating pressures are through the roof. Now you have to remove all of the refrigerant that you put into the system.
A superheat calculation would have, along with the return air temperature and the evaporator saturation temperature, helped to avoid this mistake.
Enjoy!

How bad is the leak?

@ May 4, 2012 8:42 PM in Trane A/C Leak - Repair or Replace

As an environmentally concerned individual, eliminating the leak by whatever means is the way to go. However, please be aware, that you are under no legal obligation to repair it. Is this a leak that requires the addition of a pound or so of refrigerant every year, or is it one of those leaks that allows refrigerant to escape as soon as it is added? If the leak is a small one, you can opt to have the system recharged. The Clean AIr Act of 1990 pertains to systems that contain 50 pounds of refrigerant or more. A typical residential split system holds less (often much less) than 10 pounds.

For the most part, leaks in evaporator coils can be repaired. Locating the leak, however, can be a little more difficult. If your service company has determined that the leak is definitely in the condenser coil, they can introduce an ultraviolet solution into the system to pinpoint the leak with a UV light.

As Techman said, some leaks in aluminum coils are very difficult to repair. But, there are new products on the market that make repairing the coils much easier.

Alternatives to repairing the leak, such as replacing the entire system, are going to be very costly.

Please let us know how you make out.

Not a Bad TXV

@ May 4, 2012 8:26 PM in bad txv?

If the TXV was wide open, your evaporator pressure would be high, but your evaporator superheat would be close to zero.

In order to determine the problem, please provide the following:

Condenser saturation temperature:
Evaporator saturation temperature:
Condenser Outlet (liquid line) temperature:
Evaporator outlet (suction line) temperature:
Outside ambient temperature:
Return air temperature:
Temperature of the four ports (line connections) on the four way reversing valve:

The problem sounds more like a leaking reversing valve than a bad txv. With the above information, we can get to the bottom of the problem.

I would not use it.

@ April 29, 2012 7:45 AM in Leak Sealers?

The product information states that the solution remains a liquid until it leaks from the system and, after reacting with the moisture in the air, creates a seal. From this, I can only assume that the humidity of the air surrounding the unit will have a direct effect on the performance of the product. In addition, if the solution crystalizes once it leaves the system, then it is only sealing the outside of the leak, no the entire leak. When we braze a fitting, we should be completely filling the fitting with filler material, not just the outside. Since high side pressures are, well, high, I am not certain that I would trust a "surface" repair.

If the manufacturer of this product is reading this post, I would definitely welcome you to provide us with your take on the situation, as we all like to learn!

Thanks and have a great summer!

No Incline Needed!

@ April 29, 2012 7:32 AM in Return Air Duct: Incline Necessary?

Feel free to level as you wish.

My vote would be no.

@ April 28, 2012 5:51 AM in one mini split for entire floor....

In order for the cooler, conditioned air to "reach" the rooms, there needs to be a difference in pressure. If the indoor unit will be located in the hallway, the lowest (air) pressure will be at the unit's return (in the hallway), while the highest pressure will be at the supply (also in the hallway). With bedroom doors closed, the desired airflow path will be from the supply, right back to the return.

Even with the doors open, the airflow will likely be insufficient to actually cool the rooms without overcooling the hallway.

If it were my house, I would steer clear.

Please let us know what you decide..

I'll Try to Warm Them Up for you!

@ April 7, 2012 6:21 PM in Heating Alert! - OESP

It'll be great to see you all at the conference!

They definitely did save the best for last!

Got a good price on the equipment?

@ April 6, 2012 5:30 PM in Vac pump oil

Got a good price on the equipment, I presume!

Hope all is well and have a great summer!

Yes indeed

@ April 6, 2012 11:11 AM in Vac pump oil

You can use whatever oil is recommended by the vacuum pump manufacturer. Just keep in mind that manufacturers often recommend replacing the vacuum pump oil before (and after) each use.

By replacing the oil after each use, you are reducing the amount of moisture stored in the pump between jobs. If you are doing a ton of air conditioning work and the pump is in constant use, replacing the oil before use is fine (at least in my opinion).

Have fun!

Capacitor Voltage

@ March 29, 2012 6:31 PM in Capacitors

The voltage rating on the capacitor is not the voltage that will be discharged by the device, but the maximum voltage that the capacitor should be exposed to. So, back in the day, I would stock my trucks with 440V capacitors instead of 370V devices. This way, there was never a problem with a technician installing a capacitor rated at 370V when the original was rated at 440V.

Just for the record, capacitors wired in parallel with each other will result in a total capacitance that is equal to the sum of the two capacitances. So, two 20uFd capacitors in parallel will give you the equivalent of 40uFd. From the good old days of basic electricity, capacitors in parallel add up as resistors in series do, and capacitors in series add up as resistors in parallel do.

Have fun!

I would assume....

@ March 25, 2012 10:12 PM in Chiller

Based on what you have posted, I am willing to wager that there was indeed a previous water flow problem (probably as the strainer clogged up) that caused an earlier technician to remove the screen in the first place. Strainers are rated for a clean-screen flow rate, which will obviously be well above the actual flow rate once the screen starts doing its job.

I would agree with your decision to put in a larger (6") strainer, as this will have no negative effect on the system, will clog much slower than the 4", and not provide a significant restriction to water flow.

With the 4" strainer intact, there was very likely cavitation and noise, but the most common problem was likely that of high pressure issues.

Keep us posted!

Direct Burial?

@ March 22, 2012 12:45 PM in Question for Eugene and others

If you are planning on playing with a direct burial system, bring the compressor inside, along with the accumulator and the reversing valve. Just be sure to insuate the refrigerant lines well to reduce losses.
Sounds like a bunch of fun...
Keep us posted.

Absolutely Amazing

@ March 22, 2012 12:37 PM in brazing alternitive

I love it and recommend it to everyone. The burst pressure on these joints is super high and you can see immediately if there is a leak. It's self-sealing and can be used directly over soft-solder without having to re-clean and re-prep!

It Depends

@ March 16, 2012 11:24 PM in brazing alternitive

You need to check the local codes in your area. Some jurisdictions do not allow filler materials with low melting temperatures (below 842 degrees) to be used on air conditioning equipment. For example, it is frowned upon in New York City.

Word on the street says that, in the event of a fire, the potential for firefighter injuries can result if excessive heat from a fire causes low temperature joints to rupture.

I personally do not recommend the use of low temperature filler materials on refrigerant lines, even on the low pressure side.

Can't remember the name

@ March 16, 2012 6:26 AM in brazing alternitive

I can't remember the name either, but here was my experience with it.

I was given a sample of the product at at trade show and brought it back to my students to "play with". We decided to do our own field testing...

They created joints on a small piping project using the product (which was not as easy as described by the rep, but that's another story) and then tested the fitting and all held quite well.

As you are all well aware, air conditioning and refrigeration piping is subject to vibration, so the students used the product on a live system. Well, this product and vibration do not play very well together. The joint cracked and leaked.

I sent an e-mail to the company, based in College Point, New York, and posted our results here on The Wall. I invited the owner of the company to respond to our results, as maybe we were doing something wrong. We never heard back from the company.

I am not a fan of cutting corners or taking shortcuts so, personally, I would not use it on equipment that I am getting paid to install, service and warrantee.

Cannot Be Stressed Enough

@ March 13, 2012 10:26 PM in converting to 410a

Now that we are on the topic, as mentioned, it is very important to push nitrogen through the lines when brazing. This is especially important when dealing with R-410A systems. The ester-based lubricant has a relatively strong scrubbing effect on the interior surfaces of the piping materials. This scrubbing effect can free any oxidation that might have formed on the interior piping surfaces during brazing.

By passing nitrogen through the lines during the brazing process, we are removing the oxygen from the pipes and, therefore, the ability to oxidize.

Uniweld has a really neat flow indicator that let's you know that nitrogen flow is present, especially at very low pressures.

http://www.uniweld.com/index.php/productlisting/details/798/361/nitrogen-and-co2-kits/nitrogen-flow-indicator

Have fun!

Based on what you say...

@ March 4, 2012 8:44 PM in oil logged evaporator or bad txv?

Based on the information you provided, it looks like there is a problem with the TXV.
The thermostatic expansion valve has a one-line job description, which is to maintain constant evaporator superheat. If the superheat is high and the refrigerant charge is correct, it means that the valve is not feeding the correct amount of refrigerant to the evaporator coil.

While you are taking your subcooling readings, take a temperature reading at both the outlet of the condenser coil and the inlet of the TXV. SInce this is a self-contained unit, the temperature difference between these two points should be very low.

Now... There is another possibility that will be addressed when you get your subcooling reading. If there is physical blockage in the condenser coil, the TXV will not be able to feed the proper amount of refrigerant into the evaporator coil, even if it is fully open.

Is there a receiver on this unit, or is the bottom of the condenser coil serving the purpose?

Have fun!

A couple of more readings...

@ March 4, 2012 5:51 AM in oil logged evaporator or bad txv?

A couple of more readings would be helpful. What is the temperature of the liquid line at the outlet of the condenser coil? What is the temperature of the suction line at the outlet of the evaporator?
These two temperatures, teamed with your operating pressures will help determine if there is a refrigerant flow problem or a charge problem.
Also, please let us know exactly where the pressure readings were taken (for example, on the discharge line or the suction line)
If the system is so equipped, high side and low side readings at multiple points in the system (discharge line and liquid line) are often useful to help detect internal blockages in the system.
Please keep us posted.

That'e the way they are

@ February 26, 2012 9:56 AM in locking caps

That's the way they work.

Although we would like to think that our service valves do not leak, the truth of the matter is that they do. The "backup seal" in the service port cap is not intended to be a major pressure holdback point in the system since major injuries could result if a technician were to remove the cap and have it shoot into his eye.

Enjoy!