How to drain a boiler – 3 working methods

A dependable boiler system is often necessary to keep your house warm and cozy during the winter. To maintain optimal performance, even the most energy-efficient boilers need to be maintained. Draining the boiler is an essential part of boiler maintenance that helps to ensure optimal performance by removing sediment buildup. In order to help you maintain a comfortable and effective home heating system, we’ll look at three practical ways for emptying your boiler in this article.

Although draining your boiler can seem like a difficult task, it can actually be quite simple if you have the right information and methodology. Draining your boiler on a regular basis aids in the removal of accumulated sediment, which can reduce system efficiency and possibly result in expensive repairs later on. You can increase the boiler’s lifespan and have reliable heating throughout your house by adding this maintenance task to your schedule.

Using the boiler’s drain valve is one way to empty your boiler. You can safely release water from the system by using the drain valve, which is located close to the bottom of the unit. It is imperative that the boiler be turned off and given time to cool down before starting the draining procedure. After it has cooled, connect a hose to the drain valve and point the other end of the hose to an appropriate drainage spot, like an outside area or floor drain. To release the water, slowly open the valve while keeping an eye on the flow to prevent spills or splashing.

In the event that your boiler lacks a dedicated drain valve or that accessing it is difficult, you may use a pump to make the draining process easier. A pump is the best option for larger systems or those with restricted accessibility because it makes it possible to remove water from the boiler more effectively. You must connect a pump to the boiler’s water outlet and direct the water discharged to an appropriate drainage point in order to use the pump for draining. To ensure the safe and efficient operation of the pump, make sure you adhere to the manufacturer’s instructions.

Using a chemical cleaner is an additional method of draining your boiler in addition to manual methods. These cleaners are designed especially to dissolve and get rid of sediment buildup in the boiler, which helps to increase performance and efficiency. When using a chemical cleaner, you should carefully follow the manufacturer’s instructions, which usually call for adding the cleaner to the boiler and letting it run for a predetermined amount of time. The loosened sediment can then be removed by draining the boiler, which will make your system cleaner and more effective.

Why you can"t drain the water through the faucet

The faucet will only release a maximum of one to one and a half liters of water if the home water supply is turned off and the "hot" valve is fully opened; the tank will stay full. In order to ascertain the causes of the situation and then appropriately empty the water from the heating tank, take a moment to become acquainted with its mechanism and working principle:

1. The heated water intake is provided from the upper zone of the tank – that"s where the end of the tube is located. The water supply is organized in the lower part of the boiler.
2. At the inlet of the cold water supply pipe (CWS), a check valve of the disc type is installed, preventing the water from flowing back into the main line. It also discharges the excess pressure arising from heating and expansion of the liquid.
3. When you use the storage heater (turn on the DHW tap of the mixer), the water is drained out of the tank under the influence of the pressure of the main DHW pipe.
4. Without pressure from the main line, the system does not work – the water itself does not flow from the tank. Only a small part of the liquid that was above the intake pipe can be discharged through the faucet tap.

Note: The horizontal and vertical models are arranged in the same manner; the tank’s orientation in space is irrelevant. The DHW extraction pipe is at the top of the tank, and the supply is at the bottom.

Preliminary judgment. Since the "cold" spigot is near the bottom of the tank, there is no other way to empty the boiler except through it. The heater’s plumbing system determines the draining technique; in certain situations, this may require slightly disassembling the pipe connections.

Discharge through a safety check valve

It is advised to use this method with all well-known water heating tank manufacturers, such as Ariston, Thermex, Gorenje, Electrolux, and so forth. As indicated by the instruction manual’s diagram (above), the appliance is linked to the water supply network.

• A safety group for boilers is installed on the inlet pipe;
• A stopcock is placed in front of the group;
• No fittings are provided on the outlet pipe or a ball valve is installed.

Justification. The safety group is a three-in-one automatic element that has a plastic lever-operated check valve, safety valve, and drain cock.

How to use the valve to drain the water:

1. Shut off the water main at the water inlet to the apartment, disconnect the heater from the power grid.
2. Empty 1-2 liters through the nearest faucet by opening the DHW valve all the way. Leave the sanitary appliance in the open position so that air can fill the void in the tank.
3. Put a bucket under the valve spout, turn the lever and slowly empty the tank.

The heater does not need to be disassembled, and emptying it before the water cools down is not required. Drawbacks with the approach:

• due to the small cross-section of the spout (5…8 mm) water runs off too slowly, a boiler for 80-100 liters will empty in about 2 hours;
• The valve is often clogged and does not allow liquid to pass through;
• Sometimes the safety group gets sour and the drain doesn"t work at all.

Small water heaters with 25 to 50 liters can use this method as long as the valve is operating normally. Large volumes will take too long to drain.

Quick emptying through the DHW connection

You will need a pipe (gas) or adjustable wrench in order to drain the water from the boiler connected in accordance with the manufacturer’s instructions. If we don’t disconnect the pipes, there won’t be any other option. Method:

1. Wait for the full tank to cool down, or turn off and maximize the use of heated water.
2. Close the domestic hot water supply to the house, let some water out of the faucet, leave the faucet open. Again, disconnect the power supply to the water heater.
3. Unscrew both connections to the boiler with a gas wrench. It is worth to put a bucket to avoid flooding the floors and other objects under the hot water heater.
4. Use a wrench to grasp the edges of the valve and unscrew it slowly. Close the opening of the "hot" pipe with your finger, otherwise air will freely pass into the tank, water will rush in a stream.
5. Finally twist the safety band, place a bucket at the bottom and release the finger. If it is necessary to stop the flow, plug the DHW connection of the boiler again.
6. Before assembling and filling the tank, clean the pressure relief valve well (preferably blow it out).

Advice: It’s easier to manipulate when there’s a tap on the outlet connection. To modify the air/water flow rate, search ahead of time for a ½" (female) threaded valve that you can screw on in place of the pipe that was removed.

This method’s speedy emptying is its advantage; it will take no more than 30 minutes to complete. Drawbacks:

• disassembly is required – at least the DHW pipe must be removed;
• the water heater must be cooled down, otherwise you will burn yourself;
• the pressure from the connection is difficult to control, the vacuum does not work immediately.

Water flow can be reduced; however, the DHW pipe should remain connected to the boiler. Air enters the faucet more slowly and flows sporadically. Watch the video to learn how to empty the 80-liter Atlantic water heater.

Using a strapping with a drain cock

The technique greatly simplifies the process of emptying the water heater. One requirement must be met: as seen in the image below, a drain valve must be positioned on the tee following the discharge valve in the piping scheme. The next issue is one of technique:

1. Cut off the HTW pipeline with a valve, disconnect the power supply, open the hot water at the faucet.
2. Connect a hose of the required length to the drain cock connection, prepare a bucket.
3. Open the valve, drain the contents in portions.

The flow can be simply stopped with a faucet, so there’s no need to disconnect the pipes if needed. Because of the mixer’s restriction of the air flow into the tank, the hose does not spray. It takes 10 to 15 minutes to empty a 50-liter water heater.

Important point. The producers of water heating appliances are not in favor of this piping choice. Reason: There is a tee with pipe fittings between the boiler and the safety group that is not permitted by the rules.

As demonstrated by experience, installing a second valve is safe as long as the user remembers to empty the sanitary water while the heater is running. When the tank’s level drops, the water heating element may "pop out," overheat in the atmosphere, and burn out rapidly.

The second requirement is that the drain valve’s path cannot be obstructed if the tee is clogged. When heated, the expanding liquid will burst either the vessel or the DHW pipe.

Our article "How to Drain a Boiler – 3 Working Methods" will walk you through all the necessary procedures to drain your boiler in a safe and efficient manner. Draining your boiler is an essential skill whether you’re planning repairs or performing regular maintenance. We’ll go over three tried-and-true approaches, each with pros and cons of their own. With our easy-to-follow instructions, you can safely empty your boiler and guarantee its longevity and best performance.

Draining an indirect floor standing boiler

We are referring to water heaters that are installed on the floor and have spigots at the top. Certain models come with a specific drain fitting and can be easily emptied.

Crucial! The right piping layout is key to a floor standing heater’s effective drainage. In order to activate the law of communicating vessels, the end of the drain pipe and the shut-off valve must be lower than the body of the appliance.

How to empty the indirect boiler’s water tank using the connections located higher up:

1. First of all, cool the tank to an acceptable temperature of 25…40 °C.
2. Close the heating and domestic hot water lines, open the water intake valve.
3. Make sure the drainage channel is full of water – open the drain valve slightly ajar.
4. If the channel is empty, turn on the HTW supply, wait for the water to flow from the drainage pipe. Shut off the water supply again. Further, the "indirect" will start emptying due to the law of communicating vessels – the drain will pull all the water out of the tank.
5. When the drainage pipe is full, draining the tank is even easier – open the valve all the way and watch the liquid flow out of the tank.

The process can take anywhere from 30 minutes to 2 hours because indirect water heaters have a capacity of 100–500 liters. ACV, the company that makes these boilers, will send a representative to reiterate the process:

Whether it is necessary to drain the water and when to do it

Sometimes it makes no sense to empty a household appliance’s tank. For instance, if an automation unit—such as a thermostat or sensor—breaks, the replacement can be completed without completely disassembling the unit and without draining the water. Which circumstances call for emptying?

• For winter in an unheated building – summer house, bathhouse, etc. д.;
• before cleaning the heating element, rinsing the inside of the tank;
• when it is necessary to change the magnesium anode;
• in case of relocation of the boiler to another place or complete replacement of the water-heating device.

Advice: All that is needed to eliminate standing water and bacteria (especially legionella) is to "fry" the appliance for an hour at +75 °C on maximum setting. After that, the tank’s contents can be changed.

Remember the correct way to adjust the temperature on your water heater. Open the "hot" faucet and the HTW gate valve, then wait. When the tank is full, water enters the DHW system through the intake pipe and flows out of the faucet.

To ensure the longevity and proper maintenance of your boiler, make sure it is adequately drained. These three techniques will help you drain your boiler efficiently and maintain its optimal operation.

The first approach is simple and widely used; it involves using the boiler’s drain valve. All you need to do is find the drain valve, which is often found close to the boiler’s bottom, and attach a hose. Carefully open the valve to let the water out. To prevent any mishap, always remember to turn off the boiler and allow it to cool down before attempting this method.

In the event that your boiler lacks a drain valve or is arduous to reach, the second, pump-based method may be more appropriate. You can remove water from the boiler by using a small pump and either the pressure relief valve or another access point. Although this approach might need some extra tools, there are some circumstances where it might be more effective.

It may be necessary to use the third method, which involves a power flush, for more extensive draining and maintenance. Power flushing is the process of physically clearing the boiler system of any sludge or debris buildup using specialized equipment. The effectiveness and lifespan of your boiler can be significantly increased with this method, even though it might be more expensive and time-consuming.

Whichever approach you decide on, routine boiler maintenance and draining are necessary for best results. Ignoring this chore can result in decreased effectiveness, higher energy expenses, and possibly expensive future repairs. You can make sure that your boiler keeps supplying dependable heating for many years to come by taking the time to empty it out completely.

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