Taco Zone Valve Stuck Open [Reasons and Solutions!]

Taco Zone Valves are known for their reliable operation, but even the system can have problems. When a Taco Zone Valve becomes stuck open, it can cause serious issues in the heating and cooling system. 

So, why is your taco zone valve stuck open?

Taco zone valves are stuck because of powerhead issues, manual lever issues, or valve issues. Start diagnosing the stuck valve by checking the power head and manual lever. If these are working well, the problem resides in the valve itself. To solve it, you may need to force close or replace the entire valve assembly. 

This is only the highlight of this article. There is much more to be learned here. So, keep reading the article to the end to know it all.

What does it Mean by Taco Zone Valve Stuck Open?

Taco zone valves can control the temperature of a zone of your house. When the valves are functioning, the valve opens in order to initiate the heating or cooling process.

If the taco zone valves are stuck open, it could indicate issues regarding the valve assembly, powerhead, or manual valve lever. 

As a consequence, your zone valve won’t work properly in large spaces. You might even need to spend some money on a patio and space heaters for the large space.

Why is the Taco Valve stuck open?

Source: doityourself.com

There are a total of 3 terminals in a taco valve zone. For the taco valve to be opened, it requires 24 volts across terminal 1. The 2nd and 3rd terminal is assigned for the closing of the taco valve. These 2 terminals also require 24 volts. 

When the taco valve stuck open, chances are the 1st terminal is getting more than 24 volts. As a result, the valve is forcefully kept open. 

Additionally, it could mean that the 2nd and 3rd terminals aren’t connected well. If these 2 terminals receive less than 24 volts, they cannot close the taco valve. Eventually, your zone will be overheated for the valve to stay open for too long.

A combination of thermostats and transformer poles is responsible for the opening of the taco valve. A similar kind of system is used for the sync between the parallel pipings in a water heater.

Are Zone Valves Normally Open?

In general, the taco zone valves are supposed to be closed. The valves only open when the zone valves are functioning. So, taco zone valves aren’t meant to be stuck open.

How to Tell If a Taco Zone Valve Is Bad?

To truly identify bad valves, you have to know the signs of going bad or damaged. A bad taco zone valve can give out a few symptoms such as-

• Not producing enough heat or uneven heating. Valves are supposed to provide sufficient heating to the zones. 

• Making loud noises. The taco zone valve might create some hammering or banging noises. 
• Constant leaking issues. Water may leak from the valve the same way the water heater leaks while using a washing machine. 

What to Do When Taco Zone Valves Stuck Open?

Source: ebay.com

When your taco zone valve is stuck open, you need to check 3 things. Check the power head, and manual lever, and check if you can forcefully close the valve.

Firstly, if the power head is bad, the zone valve might stay open for an indefinite time. To test it, use a small hammer, and tap the valve lightly. If the cover of the valve closes then most likely you have a bad power head. If that’s the case, replace the power head.

Secondly, if the power head is working, check the manual lever. If the lever moves too freely, it may create problems in the future. The lever control might come loose and decrease over time due to this issue. 

To fix this, you have to tighten/loosen the valve. In the middle of the valve, you should see a small plate with a metal spring attached. 

Keep repositioning the metal plate until the valve closes. After this, if the valve’s freely opening and closing, it means that the lever’s adjusted properly. 

Thirdly, there’s a way to force close the valve. To force close taco zone valves-

• First, disconnect the top wire (marked #1) and wait for 2 minutes. You may look for any taco zone valve wiring diagrams for help.
• Then, disconnect the remaining wires and wait 2 minutes. 
• Next, rotate the power head and remove it. 
• Finally, reconnect all the wires and it should put the zone valves into a forced-closed position.

If any of these methods are not working or seem inefficient, replace the zone valve itself. The chart below shows the product numbers and descriptions of the replacement parts-

Match the chart above to get the right replacement parts and replace your valve! To replace the zone valve, you need to solder a new valve into the place of the old one. 

You can double-check with the manufacturer just to make sure. After replacement, the valve will open and close only when needed.

Frequently Asked Questions (FAQs):

How many volts is a zone valve?

There is about 24V in a zone valve. It is powered by an AC power source. It’s possible to manually increase the voltage.

How much does it cost to replace a zone valve?

Replacing a zone valve can cost from 350 dollars to 850 dollars. If you’re planning to replace a zone valve, thoroughly test them beforehand. Additionally, find out how many zone valves need to be replaced; as it may be expensive!

How long do zone valves last?

Zone valves last around 10 to 15 years and up to 20 years. This life expectancy is based on the cycles the zone valve completes. 

Final Words

Hopefully, now you know what causes the taco zone valve stuck open and how to fix it.

You can consult a mechanic if it all seems confusing for you. In exchange for some labor cost, they can fix it in a jiffy!

Have an awesome day.