What Pipe Do I Use for Boiler Blowdown?

Boiler Blowdown

• A home boiler heating system includes a water tank, a fuel combustion chamber and a series of pipes that run throughout the home. Heated water flows through the piping to deliver heat within a home’s living spaces. The constant flow of water through home boiler heating tanks requires periodic cleaning of leftover residue and solids from ongoing use. If left unattended, the accumulated debris can cause scaling and corrosion problems along boiler tank surfaces. To remedy this situation, boiler systems include a blowdown component that’s designed to clear out built-up tank residue.

Blowdown Systems

• The type of boiler blowdown system used determines which areas of the blower tank are flushed out. Some systems target residue and debris at the bottom of a boiler tank while others flush out the entire tank from top to bottom. Systems equipped with a continuous blowdown function flush out the entire tank. Some systems also include an automated function that uses sensors to determine when a boiler tank requires flushing. Systems equipped with a manual blowdown function only flush out debris from the bottom portions of the boiler tank.

Function

• A boiler blowdown pipe attaches to a separate blowdown tank. The pipe includes a valve that remains in the open position so residue can flush through the pipe. The blowdown tank connects to the underside of the boiler tank, since residue and debris tend to settle on the bottom surfaces of the boiler. As the water coming out of the blowdown pipe carries the same temperature and pressure properties as the water in the boiler tank, blowdown pipe designs must be strong enough to withstand the flushing of high pressure water supplies. In effect, blowdown pipes provide a controlled passage for water to flow through.

Pipe Components

• Blowdown pipe consists of strong materials designed to minimize the effects of any abrasive solids contained in the water. Materials used to make blowdown pipes include brass, copper, stainless steel and cast iron. The outlet portion of the pipe has a “Venturi tube” shape that looks like a narrow, tube-like passage. The outlet shape helps to increase water flow rates while reducing the pressure or force of the flow. Since different boiler sizes and types operate at different capacities, the size of a blowdown pipe must correspond with a boiler’s capacity.