We are quite a BIG DEAL in the world of Dupont! You know, Dupont, the miracles of science! Kirk and North Valley Mechanical are featured in the case history attached and on their website!
Kirk Buscho, North Valley Mechanical, in Phoenix, Arizona, was researching R-22 alternatives over the last two years. Recent EPA activity made the search for a viable alternative more urgent. Kirk said, “We looked at a few products, several versions of R-22 replacements. We work closely with our local distributor, American Refrigeration Supplies, so we were informed on all of the options available today. For me, it was a matter of testing the products in the field so we could fully understand the best product in terms of performance similar to R-22.”
When considering options to replace R-22, Kirk indicated there were several factors that were most important to him. He said, “I was looking at refrigerant compatibility in terms of performance and wanted a refrigerant that will perform. I wanted something that is easy–be able to take out the old refrigerant and add in the new refrigerant–without a lot of hassle. Mineral oil compatibility was huge for residential A/C systems. I wanted a refrigerant that was not going to be too picky about how you treat it and that lends itself to be compatible with mineral oil. I was looking for a design and performance parameter that mimics R-22 so my techs don’t get nervous about using an alternative to R-22.”
Residential Retrofit Project Details
Kirk decided to try ISCEON® MO99™ on a retrofit of a residential package heatpump a Goettl 2.5 ton with a leaking indoor coil in May 2012.
Kirk explained, “The system was down and several contractors had attempted to repair the unit, but were unsuccessful. The unit had been charged with R-22 multiple times. Due to the number of attempts to fix the system, it appeared that the system would need to be replaced. The unit had a piston orifice going to the indoor coil and the inside coil was like Swiss cheese. Several previous attempts were made to repair the unit, unfortunately, the repairs did not include replacing the filter dryer and leak detection dye and system sealant had been added to the unit. The oil spill in the drain pan did not look so hot. Even with his home warranty, the customer was looking at an out-of-pocket expense of $2500 to $3000.”
The 2.5 ton Goettl Model HP 305J was a 12 SEER unit and dated back to the early 1990’s and locating parts was going to be difficult.
Kirk devised a plan to try to retrofit the unit to DuPont™ ISCEON® MO99™ refrigerant as a last attempt to salvage the unit. He knew it was going to be difficult since Goettl closed their manufacturing facility and parts are no longer available for the unit. There were not many options available to fix the unit. The coil needed to be replaced, and a new coil was not available. A custom created coil could be purchased, but it was cost prohibitive to do so. Buscho identified another shape of coil that matched the size of the old coil in both volume and tonnage and Robert Forbes, field superintendent, assembled the unit including placing air baffles on each side so that air would flow through the coil. The new coil was equipped with an R-22 TXV versus an orifice.
Kirk evacuated the system to 500 microns, changed the filter dyer, and charged the unit with MO99™ refrigerant to original system specifications. He said, “The internal volume of the replacement coil was approximately the same as the old unit. In cooling we got 21 degrees split with good air flow with the blower working to specification. We got both good air flow and good numbers on the subcooling on the liquid line and superheat on the suction line. Pressure-Temperature (PT) under conditions was matching stride for stride the temp that we should be seeing.”
In a conversion using ISCEON® MO99™, the steps to complete the process include recovering the R-22, replacing the critical seals, charging the refrigerant, restarting and monitoring the system for potential leaks.
On a package or split system you’re only replacing valve cores and the valve caps as they have elastomeric seals. We’ve discovered no need to replace Teflon® or nylon rings.
The day of the retrofit was hot, the ambient temperature was 106° F. Kirk felt this was the ultimate test for MO99™. He explained, “The day of the retrofit was a good indicator, and subsequent days have been over 110°F, as well, no problems with cooling performance. The usage of MO99™ is running about 95% by weight of the original system capacity. We followed up with our customer on a couple occasions, basically going on a fishing expedition to see if there are any issues, and found our customer is extremely happy.”
Kirk said, “The homeowner was very satisfied, with the results of the retrofit. He told us, ‘I’m thrilled because now I have cooling and my kids can sleep comfortably at night.’ Having a happy customer is gratifying for us–it’s what we strive for.”
Kirk explained, “We’ve converted approximately 50 units to MO99™ so far this year. We haven’t had any problems or call backs on any of them.”
Kirk added, I know some people are concerned about MO99™ and look at the capacity of MO99™, thinking about capacity loss especially in Phoenix because of the heat. This is probably the largest hurdle to overcome. Many confuse the capacity of MO99™ with the efficiency of MO99™ vs. R-22. It takes a little longer to move the same amount of heat but needs less power to do so, so I see it as a net break-even. Since a large number of equipment we run into is oversized for the home, a little longer run time is a positive result for the homeowner because it gives a more even comfort level throughout the home.”
Copyright © 2012 DuPont. The DuPont Oval Logo, DuPont™, The miracles of science™, MO99™, Teflon®, and ISCEON® are trademarks or registered trademarks of E.I. du Pont de Nemours and Company or its affiliates. All rights reserved. K-25859 6/12