Talking About Air Filtration Systems

Talking About Air Filtration Systems

Spring Forward By Checking Your Heat Pump's Reversing Valve

Tammy Terry

With warmer weather on the way, now is a good time to make sure your home's heat pump is up to the task of keeping your home cool and comfortable. It's usually a good idea to check your heat pump's reversing valve prior to transitioning your heat pump to cooling duty. The following offers an in-depth guide for diagnosing and correcting potential reversing valve issues.

Reasons Behind Reversing Valve Failure

The reversing valve plays a critical role in helping your heat pump switch from heating to cooling mode. As the name implies, it reverses the flow of refrigerant so that it carries heat into your living spaces instead of carrying it outdoors. There are a couple of common ways for a reversing valve to suddenly fail:

  • The main slide within the reversing valve can become stuck due to an accumulation of debris within the valve or a failure of the solenoid-operated pilot valve. This can leave the heat pump locked in its heating mode until the valve is repaired or replaced.
  • The reversing valve can leak internally, robbing the heat pump of its overall performance. These leaks often have the same symptoms as a failing compressor, including high suction and low head pressure.

Dealing With Stuck Valves and Solenoid Failures

If you switch your heat pump to cooling mode only to receive warm air, first make sure the thermostat is actually set to "cool" instead of "heat." You shouldn't rule out wiring issues, although such issues are unlikely unless you've recently installed your own thermostat.

After making sure your thermostat is wired correctly, place the unit in cooling mode and locate the reversing valve on the heat pump. Use a multimeter to check for 24-volt power at the pilot valve solenoid. Next, grab an unmagnetized screwdriver and place the blade near the solenoid. A properly powered solenoid should magnetize and pull the screwdriver blade towards it.

If you don't feel any magnetic pull from the solenoid, turn off the unit and disconnect the solenoid wiring from the actual part. Use your multimeter to measure for 10 to 60 ohms of electrical resistance. If there's no resistance, have your HVAC technician replace the solenoid.

Physically stuck slides can be broken loose with a couple of taps from a rubber-lined screwdriver handle. However, the debris that's causing it to stick will remain in the refrigerant system unless the system is properly purged. If the slide constantly freezes up, then you may need to have a new reversing valve installed.

Dealing With Valve Leaks

Since leaky reversing valves share many of the same symptoms as failing compressors, it can be somewhat difficult to figure out which component is actually causing these problems. You or your HVAC contractor can use these steps to rule out compressor failure in favor of a leaking valve:

  • Turn the unit on, but make sure the condenser motor is disabled. This will cause the head pressure to increase. Allow it to increase until it reaches 475 pounds on your refrigeration gauges.
  • Turn the unit off once the head pressure builds up 475 pounds. Next, listen carefully for hissing noises coming from the reversing valve, as this is the sound of hot gases escaping through the leak.
  • While the unit is in operation, place one hand on the compressor dome and place the other on the suction line leaving the reversing valve. In the event of a reversing valve failure, the valve should heat up much faster than the compressor.

A Replacement May Be Necessary

In some cases, the entire reversing valve must be replaced before the unit can operate normally. It's one of those jobs that are better left to your HVAC technician due to the steps usually required for removal and installation. Not only must the heat pump's existing refrigerant be removed, but the copper pipe connections for the reversing valve must be brazed during assembly. Heat shielding gel can be used to protect the actual reversing valve from heat damage during the installation process.

For more information, contact a company like R & B Heating & Air Conditioning


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About Me
Talking About Air Filtration Systems

Hey everyone, I am Mort Nicholas. Since I have allergies to pollen, dust and chemicals, I must filter the air blowing through my home day and night. The air filtration systems hook straight to the furnace and air conditioner to provide my home with fresh air at all times. The filters used for these systems capture the tiniest of particles to keep them out of my airways. As a result, I often wake up feeling healthy and refreshed. I hope to share the benefits of having filtered air flowing through your home. I will discuss symptoms caused by contaminated air. In addition, I will share information about air filtration maintenance services provided by HVAC contractors.

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