How to Pressure Test Cast Iron Baseboards

Cast iron baseboards or radiators heat homes by using hot water to create steam that flows through the metal. This creates heat, which radiates from the device into the ambient air of the room. In addition, cool air drifts into the bottom of the sheet metal enclosure of the baseboard, is heated by the cast iron and flows out the top of the sheet metal covering as warm air. If your baseboard is not heating the room, but the boiler is functioning, this may be a sign of an air buildup preventing the hot water from flowing through the baseboard system properly. If so, you may need to pressure-test the system, forcing water through the piping, to resolve the problem. This pressure test also will reveal any leaks that may be present in the baseboard system.

Garden hose

Instructions

- 1
  Locate and open the air bleeder valve if the baseboard system has one. Exercise care and open the valve very slightly. This may allow a release of enough air to prevent the need to pressure test. If air is expelled, the system may be air-bound. If water is expelled, the system does not have an excess of air.
- 2
  Use the pressure method if the baseboard system does not have an air bleeder valve. Begin by connecting one end of a garden hose to the baseboard system's boiler drain valve and placing the other end either outside the house or near a drain.
- 3
  Open the bypass to any automatic pressure-reducer installed in the baseboard system. This is often a lever than can be lifted to force hot water into the system. By opening the bypass, you force hot water into the baseboard at higher-than-normal pressure, and this should force out any air blocking the system from working.
- 4
  Observe if any leaks occur in the baseboard pipes or heat radiators, if you suspect there may be a problem. Signs of leaks can include rust or damage to the pipes or nearby walls or carpeting.
- 5
  Close the bypass, then close the boiler drain valve. This will restore the system to its normal pressure and should re-establish proper working conditions.

Pressure Drops in Radiant Floors

What Are Input BTU & Output BTU?

Heating & Cooling Repair