The central heating pump is the beating heart of your central heating system. You can find out more about boilers and central heating systems here. But how do you prevent problems from occurring, and how do you deal with them if they do?
Always disconnect the pump from the electricity supply before inspection, carrying out repairs or attempting a replacement.
Pump Not Starting
Is the spindle turning? If not, use the manual handle or a screwdriver inserted in the shaft to start it. Other fixes include increasing the pressure and flushing with water. Do not submerge the pump.
If the central heating system is not calling for the pump to start or a fuse has gone, call a qualified professional to check the wiring.
Humming in the System
The most common cause is vibration from an incorrectly seated pump. Turning the pump down may fix the problem. If not, tighten the bolts. Remember that a correctly running pump will vibrate slightly.
Radiators Heating Unevenly
If the radiators are hot downstairs but not upstairs, your pump could be jammed. This problem commonly occurs when the heating has been turned off for a while – over the summer, for example. You’ll need to locate your pump, which is usually near the boiler.
A gentle tap with a hammer should kick-start it. Otherwise, proceed as for a non-starting pump.
If you’re having work done on your central heating system, then foreign bodies can enter the water supply and jam the propeller. You’ll need to open the pump and thoroughly clean it.
Over the years your system can accumulate grime that can affect the running of the pump. You’ll need to give the entire system a power flush to clean it. Allowing the water to deteriorate and become sludgy can severely compromise the life of your pump.
If air gets trapped in your central heating system during a refill, it can result in no heating. First bleed the radiators with a radiator key, and then locate the bleed screw on your pump.
Slacken the screw, but don’t undo it completely. You’ll hear any trapped air escape, accompanied by a trickle of water. Close the screw and top up the system.
Does My Pump Need Replacing?
There are several instances when your pump cannot be fixed and will need replacing. Internal corrosion will stop your pump’s components working. Corrosion occurs more quickly when a central heating system has not been in use for some time. Make this a priority check when buying an older property.
If the pump is leaking, then it may need to be replaced. This is almost certainly as a result of corrosion which can’t be fixed. If brown liquid is leaking from the start capacitor, or it looks burnt out, you can replace this part only.
If the pump is no longer circulating, the gate valve could be faulty. If this is the case, you will need to replace the pump. If the pump is on but not circulating water around the system and feels hot, the motor may have failed.
How Can I Remove My Old Pump?
If your pump has failed, you will need to remove the faulty pump and replace with a new one. Choose a reputable brand like Grundfos, and make sure it matches the size of the pump you’re replacing. This avoids the need for any adjustments to pipework.
First disconnect from the electricity supply. Then turn off the water supply to the pump by closing any isolation valves. If these are not fitted, make sure you do so for future ease of pump maintenance. Then drain down the pump.
Finally, remove the union nuts, clean the valves and replace the washers.
Fitting a New Pump
Ensure that the direction of the flow markings on your new pump matches the previous fitting before attaching the valves and checking for leaks. Now, with the pump switched off, release any trapped air. Then rewire and switch on the pump.
Throughout this procedure, ensure that everything is dry and there are no leaks.
Your heating pump will give you several years of service if you keep it and your central heating system well maintained. As it’s the heart of your system, consider replacing an older pump with a newer, more energy-efficient model.
Following this simple checklist will enable you to easily solve most common central heating pump problems and keep your system running at maximum efficiency for years to come.