Step 1: Turn off all the components electrically. This means the boiler, pump and any zone valves.
Step 2: Shut the pump valves situated above and below the pump. Most valves turn clockwise to close.
Step 3: Get a small bucket the open the screw on the end of the pump or one of the nuts holding the pump to the valve. If water keeps leaking out for more than a few minutes then the pump valves are not holding and you will need to follow steps 4 to 7. If not, proceed to step 8.
Step 4: Turn off the water supply. This could be at the main or in your loft.
Step 5: Identify any zone valves and set them to manually open (usually an arm or on the side of the valve body).
Step 6: Find the lowest drain point in the heating system and then, using a hose, drain the system of water.
Step 7: Repeat step 3.
Step 8: Once you have no water coming out, test the electrical connections and make sure they are dead. Remove the electrical connections making a note not live, neutral and earth.
Step 9: Unwind the nuts that connect the pump to the valves and remove the pump. Check that the old seals have come off the valves - most new pumps are supplied with new seals.
Step 10: If you have drained the system completely of water because the pump valves won't hold, replace those valves.
Step 11: Fit the new pump, making sure than the pump seals supplied are in place and that the connecting valves are tight.
Step 12: Open the pump valves. Shut the drain point and re-fill the system.
Step 13: Test for leaks. If there are any leaks you may need to tighten up one of the joints or use some jointing paste.
Step 14: If you have no leaks, drain the system again and re-fill with a suitable inhibitor (Sentinel x100 or Fernox).
Step 15: Only now do you reattach the electrical connections in the right place and fit the cover back on the pump. Turn on the electrics and run a test operation of the new pump.
Tip: Sometimes after draining down a heating system you can get air locks. Even if the pump is running fine you might not get a full flow to all radiators. The best thing to do in this situation is to turn the pump on and off. This moves the water and air suddenly. You should be able to hear air gurgle its way around and eventually to the air vents.
- Mark Lewis
We hope that this short guide has helped you in being able to carry out this task quickly and effectively. However the best way to find out more about plumbing is to take one of Access Training's intensive plumbing courses. These are available to both those looking to improve their DIY skills, and those wanting a change of career, gain valuable qualifications and become a plumber. For more information call us today on 0800 345 7492.