Calorifier Blowdown
Purpose
To flush out dirt and sediment from the bottom of hot water cylinders where bacteria can grow.
Required Equipment
Hose for safe discharge, bucket, thermometer
Required PPE
Heat-resistant gloves, safety goggles, gloves, overalls, safety boots
Required Tools
Spanners, hose, bucket, thermometer
Step-by-Step Method
- Find the drain/blowdown valve at the bottom of the cylinder.
- Attach a hose and route it to a safe place. The water will be very hot (over 60 degrees C).
- Make sure the discharge point can handle hot water.
- Open the valve fully.
- Let the water run until it comes out clear (usually 30-60 seconds).
- Close the valve.
- Check the temperature goes back to 60 degrees C or above.
- Check for leaks after closing.
- Write down what you did - date, time, how long, what the water looked like.
Pass Criteria
Water runs clear. No leaks from the valve after closing. Temperature goes back to 60 degrees C or above.
Fail Criteria
Water stays dirty after a long blowdown (may need inside cleaning). Valve leaks after closing (replace the seal). Temperature does not go back to 60 degrees C (check the heating system).
Common Problems & Corrections
Valve will not open - It may be stuck. Use gentle force or replace the valve. Valve leaks after closing - Replace the packing or valve. Water stays dirty - Need inside inspection and cleaning. Think about descaling. Temperature does not recover - Check thermostat, heating element, boiler, and circulation.
Warnings
Blowdown water is extremely hot (over 60 degrees C) and will scald badly. Make sure it goes to a safe place away from people. Wear heat-resistant PPE. Do not force stuck valves.
Relevant Legislation
ACOP L8 (4th Edition), HSG274 Part 2, Pressure Systems Safety Regulations 2000 (if applicable)