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Tech Tips:

Something to Watch For When Replacing a Thermostat

Sometimes, you may have to replace a fancy thermostat with a simple one. It may be because the customer got fed up with all the options, or maybe the basic stat is the only thing on your truck. No matter the reason, you need to make sure the new thermostat can do the old one's […]

Coil SHR, Ventilation, and Bypass Factor – Advanced Psychrometrics Part 2

This is the second article in a three-part series where we explore advanced psychrometrics. The source material for each of the articles in this series is ACCA Manual P Sections 3, 4, and 5. This article is based on information found in Section 4. If you followed the previous advanced psychrometrics article, you now know […]

What Willis Understood

I've been reading a book called Cool: How Air Conditioning Changed Everything, and it got me interested once again in the history of air conditioning and refrigeration. Like many things, the people who are credited with “inventing” are the ones dogged enough to make an idea commercially successful, not the idealists forever tucked away in the […]

EcoBee Thermostats and Dehumidification

Dehumidification features have been common on residential systems ever since the introduction of variable speed blower motors. The system is set up so that the blower can produce less CFM per ton when the latent load (humidity) in the space is higher than the setpoint relative humidity. Slowing the blower increases moisture removal by […]

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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 podcast episode, Bryan talks about non-bleed TXVs and whether they need hard starts.

A non-bleed (hard shutoff) TXV is a metering device that shuts off during the off cycle; it closes shut when there is no superheat. This strategy prevents refrigerant migration, especially in cases where we have long line sets. Liquid refrigerant stays in the condenser and is kept out of the evaporator, suction line, and compressor crankcase.

When we have a non-bleed TXV, the compressor may have a hard time starting under the conditions created by the hard shutoff TXV (high head pressure, low suction pressure). Reciprocating compressors are more likely to have this problem than a scroll or rotary compressor. If you have a short line set, 230+ voltage, and a scroll compressor, you probably won’t need a hard start kit. You may need a hard start kit if you have a reciprocating compressor, a longer line set, or 208V power.

The OEM will recommend a hard start kit that is suitable for the equipment. Aftermarket hard start kits are okay if a compressor is old and struggling, but they’re not the preferred option and should be as close to the OEM’s recommendation as possible. Hard start kits typically consist of a start capacitor and a potential relay. Positive-temperature coefficient resistors (PTCRs) also exist, and these have a resistor that heats up and eventually takes them out of the circuit. Hard start kits should not be added to inverter-driven equipment and are not meant to compensate for voltage drop issues; they can cause more harm than good if they’re used when they’re not necessary or not used correctly.

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Search Episodes

Non-bleed TXVs and Hard Starts – Short #257

09/16/2025

Bryan Orr

Scroll Compressors & New Refrigerants w/ Copeland

09/11/2025

Bryan Orr