- 1). Turn off the heating system boiler (or shut off the gas line running to it) and wait an hour or two for the water inside it to cool.
- 2). Shut off the incoming water line to prevent the boiler from refilling while you work.
- 3). Place a bucket beneath the boiler's drain valve. This will be marked and located at the bottom of the boiler tank.
- 4). Open the drain valve and let the water drain out until it flows clear. If you want to fully drain the heating system, bring several extra buckets and keep the valve open until no more water flows out.
- 5). Find the expansion tank. This is a secondary tank recognizable by its two valves -- one connected to the furnace or boiler and one for draining. Some newer heating systems have a sealed diaphragm tank that doesn't require draining, but old ones should be drained annually.
- 6). Close the shut-off valve leading to the expansion tank.
- 7). Position a bucket beneath the drain valve and open it to drain the water. If no water flows, you may need to open a vacuum-breaker plug on the drain valve. This can be done by loosening the plug with an adjustable wrench.
- 8). Bleed the radiators. To do this, place a bucket beneath the radiator's bleed valve and open it. You will need either a screwdriver or a radiator key to open the valve, both of which are available at plumbing supply or hardware stores. Air will come out the valve first. You may close the valve when water starts to emerge instead of air, since it is air in the system that causes radiator problems. If you wish to drain all water from the system, you can leave the valve open, but this isn't necessary for regular maintenance.
- 9). Reopen the boiler's water supply valve and the supply valve to the expansion tank and close all the drain valves and bleed valves.
- 10
Reopen any closed gas lines and turn the boiler back on. The system will take a few hours to heat up again.
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