#wrench

Tech Tips:

I’ve got a confession to make. I'm “that guy.” Call it OCD, call it being anal-retentive, but I'm always making an effort to be as technically correct as possible. One aspect of that effort has been the use of torque indicating or torque limiting tools when tightening fasteners. It started after I put new valve […]

Making a Ductless Flare That Won’t Leak

In this video Jesse and Bryan demonstrate the creation of a 3/8″ and 1/4″ flare on a ductless unit including – Reaming and Deburring Using a small amount of lubricant Making the flare, though we would suggest using a high quality orbital flare like THIS ONE Using a torque wrench to tighten to specs

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How to Evacuate an AC system, Full Vacuum Procedure

Our latest Podcast

HVAC School – For Techs, By Techs

Real training for HVAC ( Heating, Ventilation, Air Conditioning and Refrigeration) Technicians. Including recorded tech training, interviews, diagnostics and general conversations about the trade.

In this short Q&A podcast episode, Bryan answers a listener-submitted question about superheat, including what it is and how we measure it.

Superheat is the number of degrees a refrigerant is above its saturation point. The saturation point is where you will have a liquid-vapor mix, so superheat only exists when a substance is a vapor. Saturated refrigerant should only exist in the evaporator and condenser, during which it is being boiled or condensed.

We usually measure superheat at the evaporator coil outlet and compressor inlet. The superheat at the evaporator outlet is usually around 5-14 degrees Fahrenheit, and it’s often between 10 and 20 degrees at the compressor inlet (compressor superheat). However, many systems try to get lower superheat values, and some manufacturers may require higher superheat values at the compressor inlet to prevent liquid refrigerant from getting into the compressor. Accumulators can help keep liquid refrigerant out of the system as well. We may also measure superheat coming out of the compressor on the discharge line (discharge superheat); this superheat may exceed 100 degrees Fahrenheit. Discharge superheat can let you know if the compressor is overheating the oil and causing breakdown or carbonization.

We use superheat to set the charge for fixed-orifice metering devices (as opposed to subcooling for TXVs), as superheat is a measure of how well we’re feeding our evaporator coil. When the system is off, the superheat will be 0. A system will equalize, and the refrigerant will be at saturation when that happens.

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