How do I drain my boiler only?

Asked By: Meridith Mir | Last Updated: 21st February, 2020
Category: home and garden home appliances
4.5/5 (479 Views . 13 Votes)
How to Drain a Radiator
  1. Turn off all power to the boiler. The power switch will be located on the boiler.
  2. Turn off the gas to the boiler system.
  3. Shut off the water intake valve.
  4. Let the system cool down for at least 30 minutes.
  5. Locate the drain valve at the bottom of the boiler.
  6. Open the drain valve by turning it counter-clockwise.

Click to see full answer


Keeping this in consideration, how do you drain a combi boiler?

How to drain and repressurise a combi boiler system

  1. Before you begin. Turn off the boiler and disconnect it from the power supply.
  2. Locate the drainage valve. The drainage point in any system will usually be the lowest point of the lowest radiator in the property.
  3. Open the vents.
  4. Opening the filling loop.
  5. Check for leaks.
  6. Bleed the radiators.

One may also ask, how do you drain a sealed central heating system? Draining a Sealed Central Heating System Start by turning off the boiler and disconnecting it from the mains power supply. You will then need to locate the lowest radiator in the house; you should find the system's drain valve here. Fix a length of hose to the drain valve and make it secure with a jubilee clip.

Beside this, how do you drain a central heating system without a drain valve?

The alternative way to draining the central heating system is, if you have no draining point, fit a draining point to the top of the radiator. When both radiator valves are in the off position. Once the draining point is in place, then attach the hosepipe and open draining valve including both radiator valves.

How often should I drain my boiler?

You should only drain it approximately once every year for maximum efficiency. If you drain it too often, you can introduce minerals that cause scale inside the boiler, as well as oxygen, which can eventually cause corrosion in the boiler.

32 Related Question Answers Found

How do you fill up a combi boiler?

To refill a combi boiler, the drainage valve is closed and the hose removed. The filling loop located underneath or near to the boiler is then opened to allow the system to repressurise to the level recommended in the manual. To get rid of the air trapped in the system, the radiators are then bled, starting downstairs.

How long does it take to drain a boiler?

It almost takes 20-25 minutes to drain out entire water from the heater and executing the whole process. But this duration varies from the size of the heater. Ideally, with the flow rate between 9 GPM to 17 GPM, for a 5—gallon tank, if the water flows out in the full swing, the tank gets emptied within 6-7 minutes.

How do you flush out a boiler?

To flush the system, open the blow-off valve and let the water run off into a bucket until it runs clear. If the water still looks rusty after the system has been flushed, call a professional service person. Turn off power to boiler, and let water cool until it's just warm.

Can you run a combi boiler with water turned off?

If you have a combi boiler then the hot water is supplied direct, so by closing the mains stop valve it will shut off the water. However, if you have a hot water cylinder this will be an indirect supply and there will be a valve on the pipe from the cold water storage cistern to the hot water cylinder.

How do you fill up a boiler?


Open both valves to allow cold water to enter the system, keeping an eye on the pressure gauge. Close both valves when the pressure gauge reaches 1.5 bar. Remove the filling loop if it isn't a built-in one. Turn the boiler back on and recheck the pressure.

How do you bleed a radiator on a combi boiler?

At the top of each of your radiators will be a bleed valve. Depending on the type of bleed valve, you may need a radiator bleed key or a flat head screwdriver to undo it. The next thing to do is switch your heating system off completely so that no problems are created by bleeding the air out while it's still running.

Will my boiler work if the water is off?

Will turning my water off affect my boiler? People often worry that turning off their water supply will adversely affect their boiler. The worry is usually caused by a fear of overheating, like boiling a kettle with no water in it, but in reality, it's unlikely to cause any damage or risk.

Do I need to drain the system to change a radiator valve?

Locate the drain off
You'll need a hose at this point which will connect to the drain off and then you'll want the other end of the hose to be outside, ideally where the water can run off into either soil or an outside drain. Open the drain cock and when it's empty you're ready to change the radiator valve.

Do you need to drain the system to change a radiator?

The answer to this is yes and no -- but it's all good news – yes you don't have to drain the whole central heating system but no you don't even have to connect the two pipes together. By closing the valves at both ends you can drain the water out of the radiator then take it away.

Are radiator bleed keys universal?


Universal key
Universal radiator keys are usually used on valve tails, blanking plugs and bleed plugs, but may have profiles (shapes) to fit other parts as well.

How do you drain and refill a heating system?

How to refill a central heating system efficiently
  1. Drain out the water. The first thing to do is to drain all the water out of your system.
  2. Close all bleed & drain valves. At this point, you will be ready to refill your central heating system.
  3. Bleed out the air from your rads.
  4. Switch on the boiler & check for leaks.

How do you flush a home radiator system?

How to Flush a Radiator
  1. Turn Off Your Heating.
  2. Spread Your Sheet Everywhere.
  3. Turn Off the Valves.
  4. Open the Bleed Valve, Drain the Radiator, Close the Bleed Valve.
  5. Remove the Radiator and Hose it.
  6. Follow the previous steps to disconnect your radiator in reverse order.

Can you fit isolation valves on central heating?

Remove the isolation valves. They should not be used on a heating system. In time they will only leak anyway.

How do you drain an old boiler expansion tank?

Drain the Expansion Tank
Hold a bucket under the water drain valve on the expansion tank; or attach a garden hose to the threaded fitting and extend the other end of the hose to a bucket or floor drain. Open the drain valve and allow all water to drain out of the expansion tank.

How do you flush a pressurized central heating system?


Before the flush
  1. Go around the system and record:
  2. Take a sample of the system water for reference.
  3. Establish whether the system being powerflushed is open or sealed.
  4. Turn off all electrical controls and electrically isolate the system and then isolate the cold water supply to the central heating system.

How do you drain water from home?

To drain the plumbing system, proceed as follows:
  1. Shut off the main water valve at the water meter.
  2. Starting at the top floor, open all the sink faucets.
  3. Go to the basement or the lowest level in your home, then open the faucet in your laundry tub or lowest sink, and let all the water from the above floors drain out.

How do you fill a sealed central heating system?

Before you begin to fill the central heating system, make sure all the radiator bleed valves and drain cocks are closed. Open the valve on the filling loop, when the pressure reaches 1.5bar close the valve on the filling loop. As the radiators fill with water, air will become trapped at the top of the radiators.