How to Fix Reversing Valves in Heat Pumps – Troubleshooting Guide

Reversing valve for heat pumps

Some of the most common yet least known problems in heat pumps occur when the reversing valve stops working. As not many people know how to fix this problem, it often gets replaced. Here we are going to show you how to fix reversing valves in heat pumps or replace it when needed.

Heat pumps are some of the most adaptable machines we can have at home, as they can deliver heating and cooling capacity without problems. However, these processes happen when the device is put in different modes, which can only occur when a component does its work correctly – the reversing valve. 

But as the reversing valve is entrusted with such a significant activity, it often gets damaged and can cause very tough problems with heat pumps. Fortunately, there are ways to fix it and avoid replacing it – but you’ll have to know when and how first. Here we are going to show you everything you need to learn and more.

The Refrigeration Cycle

The whole action of a heat pump is to maintain refrigerant going up and down inside so it can deliver both heating and cooling on different components for more efficient and effective performance. This refrigerant process is called “the refrigeration cycle,” and it is only possible with a reversing valve.

The reversing valve is a regulator that changes the direction of the refrigerant inside the heat pump. It reverses the refrigerant flow to turn the refrigeration cycle from heating to cooling or the other way around. This aids a heat pump to deliver both heating and cooling capacity, with the same equipment and just a slight change on the inside.

It is composed of 3 smaller valves and a solenoid, an electrical component. The valve also has a sliding mechanism which can change the position of the valve to meet its needs according to the type of process it is delivering. When the user presses the “change mode” button on the device, an electrical signal is sent to the solenoid in the valve; this part activates the sliding mechanism, and then it makes sure the refrigerant passes through the valve to the desired place so it can either cool or heat depending on the selected mode.

So, when the reversing valve doesn’t work, very likely the refrigeration won’t happen correctly, creating a few problems easy to spot. The following guide will aid you to troubleshoot the different issues that could arise when the reversing valve of your heat pump is not working correctly.

Troubleshooting Deficient Reversing Valves

Many problems can arise when a reversing valve doesn’t work. However, they often get confused with other issues with the compressor, condenser, or even with fans that don’t work correctly. Sadly, there are no specific ways to know when a problem is directly the fault of the reversing valve. But there are a few that mean the valve can be the reason, such as:

Stuck Valve: Physical Problem

Sometimes, people tend to think that is a device is heating or cooling, it is not the fault of a valve but instead that it is the compressor or condenser that doesn’t want to change of process. Actually, when the device doesn’t change from one method to another, it very likely means that the valve is stuck or that it has a physical issue. 

  • To check if it is a physical problem, the first thing you need to do is to grab a plastic object and tap on the body of the reversing valve. It could be stuck by dirt or dust, which would immediately free the valve at first touch.  If it keeps stuck, you will need to check further.
  • Check the capillaries to make sure they are not blocked or closed, which could mean the device is dirty and cause the valve to get stuck. If it is, try to clean the capillaries. It should immediately start working. If it doesn’t, keep checking. 
  • Look for dents, scratches, holes or fissures on the valve. Anything that could damage the valve, cause a leak or eventually make it lose energy could immediately get stuck. If you can’t spot any physical damage of this kind, then it has something else.
  • Inspect further to check if it has torch marks, burned paint, or heavy oxide. This means the valve was a victim of overheating. This causes plastic and electrical parts of the valve to get damaged, so very likely needs replacement.

If you’ve checked all of these and none appears to be the reason, then you need to check for electrical problems.

Defective Coil: Electrical Problem

When the solenoid is not working correctly, it will not energize the valve, making it get stuck or sometimes overlook the energizing process and eventually turn off mid-operation.

  • To check if it is an electrical problem, you will have to make sure the reversing valve is energized by merely using a voltmeter to review the voltage of the solenoid. If it doesn’t have the right voltage, the coil of the solenoid is very likely broken or defective, which means you need a replacement of it.
  • If it has the right voltage, make sure the solenoid coil is also energized with a magnetic field. Using a screw, you will take the solenoid coil from the stem and put the screwdriver head in the hole it will pull the screwdriver out. If it doesn’t then it means it is not energized.
  • If it turns out to be not energized, it could be that a wire is disconnected. If after checking that the solenoid and the electric part of the valve are connected, and it keeps delivering the same problem, you will have to replace it.

If nothing seems to be happening electrically, then you need to look for further conclusions.

Leaking Valve: Refrigerant Problem

Now that you’ve checked the electrical parts of the valve, you need to make sure if it is the refrigeration system that is malfunctioning.

  • First, make sure the refrigeration system has the proper refrigerant charge, as overcharged or undercharged systems may cause a reversing valve to malfunction. Fix the charge by adding or reducing the charge accordingly. If it is not a charging problem, it could be a leak in the valve or compressor, or in one of the copper tubings around the device causing a lack of pressure.
  • Check for leaks in the heat pump; if you can’t find any, then it could be the compressor or the reversing valve. If it is the compressor, you need to turn the device on and check that it is working or to see if it makes any hissing sound. If it works correctly and doesn’t make any noise, then very likely it is a reversing valve issue.

The problem of many defective reversing valves is that people often confuse them with broken refrigeration processes. The issues are almost identical, when a compressor doesn’t pump to capacity either heating or cooling process is diminished. Similarly, when the reversing valve is leaking, either the cooling or heating capacity is reduced.

However, when the compressor is functioning correctly, it could be delivering refrigerant around the device, but the valve with a leak may be losing this refrigerant making the machine to get stuck or just not provide the desired heating or cooling performance.

A leaking reversing valve will spit the refrigerant from high to low side. This means you need to test the temperature of the valve at specific locations, comparing temperatures according to the heating or cooling process. 

  • In heating mode, the discharge line goes through the reversing valve towards the indoor coil. The suction line goes from outside to the inside. You will have to check the suction line that comes from outside and the suction line of the valve which is in the bottom, making sure temperature differences don’t past the 3ºF. If they do, you will have to change the valve.
  • In cooling mode, the discharge line is the one that goes through the reversing valve to the outdoor coil while the suction line will send refrigerant from the indoor coil to the outside coil. Check both reversing lines the same way as in heating mode, and the difference shouldn’t be higher than 3ºF or else you will need to replace the reversing valve.

If you can’t find a physical, electrical or a leaking problem on the valve, then 100% it is a problem of other parts of the heat pump. Otherwise, if you do find a problem with one of these parts of the reversing valve that demands a replacement, then go to the next section.

How to Replace a Reversing Valve

A reversing valve is usually found close to the compressor or condenser of the heat pump. It is generally soldered to the pipes or copper tubing, which are typically going in and out the device towards the other parts of the heat pump.

This construction of a reversing valve makes it hard to fix and replace. Sometimes they are installed so roughly that only removing the pipes means having to de-solder or even disconnect with heat the entire metal pieces from the device, which is both tough and risky. However, we have the perfect way to do it:

  • Locate fittings or connections near the valve. Then remove the pipe connections and mark each one accordingly to have a reference guide at the moment of installing the new valve.
  • Now add the new reversing valve and braze the old tubes to it. Make sure to follow the referencing guide to avoid installing it incorrectly and damaging it once again.
  • After brazing the tubes, replace the manifold and put the new one, soldering the fittings or connections near the valve to make sure it fits tightly inside.
  • It is important not to overdo the solder on each copper tube. This could cause both the device to lose pressure with the refrigerant or eventually cause a leak due to much soldering iron in the connections.

Need Help with Your Heat Pump Reversing Valve?

Heat pumps have thousands of ways to show when a problem is occurring, whether it is because they get frosted or stop working, or merely because they don’t want to change to the desired mode when you need to. When the latter happens, very likely it is a problem of the reversing valve.

This reversing valve is a very stubborn and secret part of heat pumps, and if you are not familiar with it, you may end up fixing other parts of the device instead of it, which could be the cause of the problem.

But don’t worry. If you follow our previous advice, fixing and replacing a reversing valve will be a piece of cake entirely. Don’t waste more of your time and adjust your heat pump today!

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