How to Drain a Heating System
Heating systems that run on water typically use a boiler to heat the water that is used to provide heat for the house. You may need to drain your water-heating system to perform maintenance, such as cleaning mineral deposits or residue that can prevent water flow. Once the heating system has been drained, you can perform repairs or routine maintenance and then refill the boiler. Does this Spark an idea?
Instructions
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Drain the System
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1
Turn off the gas supply for the burner or turn off the electric circuit to the unit from the circuit box.
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2
Close the inlet or water supply valve on the boiler. This will prevent any water from coming into the boiler while it is being drained.
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3
Wait between one to two hours for the water in the boiler to cool.
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4
Place a bucket under the drain valve for the boiler.
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5
Open the drain valve until the bucket is full and then close the drain valve.
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6
Dump the bucket of water and repeat the previous step.
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7
Stop draining water from the boiler when the water appears clear.
Refill the Boiler
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8
Close the drain valve.
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9
Open the supply valve to begin filling the boiler.
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10
Turn on the gas supply or turn on the circuit for the boiler on the circuit box.
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11
Wait for the boiler to fill with water.
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1
References
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Comments
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zymer
Jan 30, 2011
(cont.) When refilling the system it's advisable to add boiler rust inhibitor (available at heating suppliers). The relief valve must be temporarily removed in order to provide an opening in the boiler with which to pour the boiler water treatment. Before refilling the system, open every vent valve on every radiator. Otherwise, a laborious trapped air removal procedure is guaranteed. You must react quickly and have a sufficient number of 1-liter vessels (cut-off soda bottles) to catch a small amount of bleed water from each radiator until you've closed each vent. Always vent the radiators in sequence from lower to upper level. -
zymer
Jan 30, 2011
This article is terrible. The water will not drain until the system is thoroughly vented. After closing the water supply valve to the boiler (step-2 of above) you should next open a vent valve located on just ONE of any of the radiators located at the highest level of the building. A bucket has nowhere near enough capacity for above step-4, as there will be at least 50 gals to drain. Better to connect a garden hose to the boiler drain and route it to the laundry tub-sink. After the water stops flowing, open another vent valve on any ONE of the radiators located on the lowest level. When the water again stops flowing there will still be a height of water in the system equal in level to the height of the laundry tub-sink. So next the hose must be redirected into a low bucket for removing the final amount of water; roughly the amount contained only in the boiler itself. When...
