Low Ambient Charging Kit for A/C System Commissioning
The best tools for cold weather commissioning of A/C systems.
Talking to Ron - a technician/owner - the other day, he mentioned with all of the cold weather he was not working. Too warm for heating, and simply too cold to start the air conditioners he had installed over the winter. So here he was sitting at home waiting for the weather to break to get back on the road. Ron like most other technicians has had no luck working on systems when temperatures are below 70 degrees and he is really are not even comfortable working there. Why? Because he knows he will simply have to return to check the charge when the weather warms. Like most technicians Ron has either overcharged or under charged most systems he has tried to start in this weather which resulted in additional costs from the refrigerant to simply the trip back to the job site. If there was good news, it was that Ron was at the right place at the right time as TruTech Tools has solutions to get him back on the road.
Working when the weather cold presents a whole new set of challenges from the additional time required to perform the evacuation to the accuracy of the tools we use to measure. If the right tools and process are followed this otherwise almost impossible process can easily be completed in record times with unprecedented accuracy. Use these same techniques in warm weather - and it only gets better!
Rules for low ambient charging
Use tools that are designed for the process, see below
Keep the evaporator coil above freezing, preheat the house if necessary to increase the load on the system
If wet-bulb falls below 50 degrees or the evaporator falls below 32 degrees, weigh in the additional charge
With TXV systems only maintain a 100 minimum PSI drop across the metering device for R22 systems and a 160 PSI drop for R410a (Block the condenser if required)
Do not rush! Things happen slower when the system is cold. Give the system time to respond to changes in charge - especially if the system has an accumulator.
Digital refrigeration gauges like the Testo 550 and the Digi-Cool 1250 with temperature compensated sensors are key to the success in charging any system in cold temperatures. Digital gauges allow the technician to charge with much higher accuracy and directly by superheat or subcooling without the need for temperature pressure charts. By allowing the technician to directly read the saturation temperatures of the refrigerant, the process can be easily monitored to verify the evaporator is above freezing and the pressure drop across the metering device is adequate to avoid stacking refrigerant in the condenser.
Micron Gauges/Vacuum Gauge
Evacuation in "low ambients" presents a host of problems including moisture removal, speed, and accuracy of the vacuum sensor. The BluVac by AccuTools eliminates the latter. Using proprietary technology and temperature compensation, the BluVac allows the technician to accurately measure vacuum in temperatures well below freezing. The meter automatically compensates for accuracy and display refresh rates to make low ambient commissioning a snap. Because of the fast response time of the sensor, moisture problems are quickly and easily identifiable even if sublimation of ice is occurring.
Below, a comparison of the Accutool BluVac at two different ambient temperatures.
Digital scales are not created equal! The AccuTools DS220-R is the ideal scale for low ambient charging. Using strain gauge technology the accuracy and precision of the DS220-R is unparalleled. Beyond accuracy is ease of use. Along with traditional units of measure like lbs, lbs/oz, and kg, the DS220-R allows the user to charge completely in ounces (oz) to make the process easier without the need for conversion when adding refrigerant charge based upon line set length. Coupled with the charging module, the scale can be configured to precisely weigh in the charge without fear of going over. With an audible alarm the technician is aware immediately when the desired charge is reached. The DS220-R is rated at 0.5% accuracy from 32 degrees to 140 degrees F.
Below, accuracy of the AccuTools Digital Refrigeration Scale
Size does matter! A single 1/2' hose can decrease evacuation times by a factor of 10 when compared to a typical 1/4" hose. (1/4" hoses - even vacuum rated types - should be avoided for evacuation. They are simply to small!) When temperature drops so does the evacuation rate. Molecules move slower and the time required to complete the process also slows. Vacuum rated, large diameter hoses designed and constructed by Appion solve these problems. An investment in a high flow evacuation rig with vacuum core tools will return in a few weeks of use. With the MegaFlow kit technicians will reduce evacuation times by a factor of 16. The MegaFlow speed kit contains all of the required hoses, 1/2" and 3/8", vacuum rated core tools and a full 1/2 bore manifold to significantly reduce evacuation times on everything from window units to 2000 ton centrifugal chillers.