How To Fix Adjust And Replace A Boiler Auto Fill Valve Not Working?

Who likes to surrender their winter delight because of a boiler auto fill valve not working appropriately in the residential water heating system? Problems like this may be unforeseen. Yet, if we don’t solve it soon enough, they can snowball. And, the most money and time-saving way to deal with it is to fix the problems by yourself.

Hydronic heating systems are heavy equipment and contain the risk of electricity, flooding, and heating hazards. However, dealing with faulty fill valves is safe if you are well informed about the troubleshooting procedure. And to ready you up for the job, we are here to instruct you on how to figure out and fix the problems.

Boiler Auto Fill Valve Not Working

How to fix boiler auto Fill valve not working

The boiler auto-fill valves or the pressure regulator can malfunction for a few reasons, and their solution varies based on them.

So, let’s figure out which problem you have from the table below to resemble the solution that will work for you.

Reasons For Not WorkingSolutions
Not enough water pressure in the boilerAdjust boiler fill valve
Clogged regulatorAlternating the fast-fill lever
No water passage in the boilerReplacing the Autofill valve

Although the list above will let you point out the problem with your automatic water feed valve, we advise you to go through the entire instruction once. In turn, you will have an insight into the best safekeeping and supervising practices for your boiler system.

Now, let’s get going.

How To Adjust Boiler Fill Valve?

The boiler fill valves soothe the water pressure of the main water supply and safely pass the water into the boiler. Generally, the fill valves are pre-adjusted for supplying 12 psi of water pressure. But, over time, this adjustment screw can loosen or tighten. As a result, it may change the system fill pressure.

So, you need to know the ideal pressure of the system to readjust the boiler fill valve for supplying standard pressure to the system. But, how to determine the correct system pressure? It depends on the amount of water pressure that can deliver modest water flow to the topmost water outlet in the hot water supply line.

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Let’s calculate the necessary system pressure for your boiler system. Later on, we will describe the steps to change the supply pressure in your boiler fill valve.

  • First of all, calculate the height of the water heating system (the distance from the heater to the highest hot water outlet).
  • Now divide the system height by two, and you will get the required pressure in psi for your boiler.
  • For example, a typical two-storied resident has 24 feet system height. The pressure of the boiler for this resident should have 12 psi pressure.

If you see that you are not getting that pressure reading in any gauge of the boiler, then you need to readjust it to the recommended level. So, synchronize your expansion tank pressure with it.

Now, let’s see how to adjust the pressure-reducing valve screw.

  • First of all, loosen the lock-nut on top of your fill valve.
  • Now turn the adjusting screw while you get a reading of the outlet pressure.
  • Turning the screw clockwise will increase the coercion in your system
  • And, turning the screw counter-clockwise will decrease it.
  • Finally, tighten the lock nut when you get the proper pressure on the outlet gauge.

Replacing The Autofill Valve

Autofill valves may last a long time. It depends on the amount of debris and mineral in the incoming water. If the water is not dead and there are some air-pockets in your system, the valve assembly may also corrode. In such cases, it clogs up and shuts off the valve in a fixed position.

To get rid of it, you may try flushing it or cleaning the assembly. But, if the feed valve had been sitting there for a long time, your best bet is to replace it with a new one. You can change it by yourself. Although you will need some tools to safely and deftly complete this task.

So, let’s have a look at the necessary tools:

  • Adjustable wrench
  • Pipe dope
  • Pipe wrench
  • Drain hose
  • Bucket.

Now, let us prepare the hydronic system to extract the old autofill valve securely.

  • Firstly, turn off the electric connection to the heater and other surrounding electric appliances.
  • Then, shut off the hot water supply valve to all other loops to prevent back feeding.
  • Now connect a drain hose to the drainpipe of your boiler system and run the outlet to your washroom or sewer line.
  • Also, shut down the water supply valve to the heater.
  • Finally, turn the drainpipe on and drain the system from water for half an hour or so to get all the water out.

Now, we are ready to move on to the second part of replacing a feed valve. And to remove the old valve, do as we instruct:

  • There is a union connection on the rear side of the feeding valve arrow mark (left to the supply direction). Loosen it up with an adjustable wrench.
  • Then, place a bucket underneath the connection and rotate the nut with your hand to disconnect it. Simultaneously, let the water drip slowly into your bucket.
  • Now, you also have to disconnect the other end from the water supply line. For this, grip and rotate the entire assembly counter-clockwise using a pipe wrench. The fill valve assembly will come off.
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Now, we can finally install the new auto-fill valve. Here’s how you will do it:

  • In the beginning, apply pipe dope on the nipple (male connector) on the front end of the feed valve and fasten it with the supply inlet.
  • Apply dope on the other end of the threaded connector too.
  • Now, attach and rotate the auto-fill valve around the connector. When it looks sturdy, tighten the connection with the pipe wrench by turning it a one-and-a-quarter rotation more.
  • Place the union gasket inside the fastening nut and cover the rear threaded connection of the valve with dope.
  • Then, tighten the nut around the valve joint so that there is no chance of leakage.
  • Finally, check if all the connection is secure and move on to the purging pipe to let out all the air pockets from the system.
  • Relieve the restraining lever of the regulator, open the valve at the purging pipe, reactivate the water supply, keep an eye out for leakage, and close the lever after you are done purging.

See? It’s not that hard to take up boiler pressure-reducing valve troubleshooting when you know the proper plumbing practices and safety measures.

Cleaning The Fill Valve Clog

There is no easy way to take apart the entire pressure-reducing valve assembly. So, cleaning it from the inside can be complicated, if not impossible. However, you can do a simple trick to dislodge debris formation from it. To do this, take preparations similar to the replacement procedure.

Double-check so the boiler power is down and there is no excess force at the pressure relief valve. But, open the water passage to the feeding valve. And, the subsequent steps to clean your boiler Fill Valve and backflow preventer are straightforward.

Go crazy with the fill valve lever. Closing it and opening it in immediate succession will let the sudden flow of water in your fill valve shall wash away the clog after repeating it for some moments. After it, you’ll see that pressure control is restored in your fill valve.

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Frequently Asked Questions (FAQs)

How do you adjust a boiler autofill valve?

To adjust the pressure of your boiler autofill valve, you need to know the allowed and safe pressure in the system. Follow our guide to find out the proper pressure. Then, loosen the adjustment screw locknut and finally rotate the screw to get the proper pressure flow in your system.

How does a boiler autofill valve work?

Boiler fill valves reduce the municipality water pressure to a suitable level for the boiler system to operate and heat the water properly. If the pressure in the system degrades than its ideal pressure, the valve automatically opens, and after coordinating the standard system pressure, it closes automatically.

Why is my boiler not filling with water?

First of all, check if your boiler fill valve open or closed. If it is closed and not pouring water in the boiler, it is possibly clogged or the inner part of it is corroded. To solve this problem by yourself, go through our DIY guide

Final Words

Fixing the hydronic heating system as soon as the problem appears is the wisest decision. And the pressure irregularity in it generally originates from a boiler auto fill valve not working efficiently. And to help you deal with it by yourself, we have compiled this DIY troubleshooting guide.

Finally, with the hope that you enjoyed reading our guide and fixing your boiler pressure regulating valve along with it, we conclude here.

Stay fine and blessed until we come with another guide.

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