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Central Heating Pumps

This web page describes central heating pumps:

  • What they are.
  • What they do.
  • Common problems & symptoms.
  • Common fixes.

What They Are – Central Heating Pumps

Central heating pumps are water pumps that pump water round a central heating system.

 

Central heating pumps are about 15cm (6 inches) in size.

 

See below for an image of a central heating pump.

 

Central heating pump

 

The image on the above shows a central heating pump.

 

The central heating pump in your heating system may not look exactly like the pump on the left, the water may flow in a different direction or may not have a ‘pump pressure adjust’ dial.

 

An arrow on the pump shows the direction of water flow.

 

What They Do – Central Heating Pumps

Central heating pumps are water pumps that pump water round a central heating system.

 

The pump pumps hot water, from the boiler, round the radiators and back to the boiler.

 

Water coming out of the boiler is hot, as the water goes round the radiators it loses heat; the heat goes from the hot water into the atmosphere (heats the room).

 

As water heats the atmosphere (the room) it becomes cooler. The cool water goes back into the central heating boiler. The boiler heats the water and the boiler circulates the water again.

 

Common Problems & Symptoms – Central Heating Pumps

See ‘Common Fixes – Central Heating Pumps’ below.


Pump housing hot – a good sign the pump needs replacing – pumps should be warm(ish).


Pump rattles or produces a humming noise – is the pump loose? Check the mounting (securing) screws, are they loose?


Pump noisy; grating or knocking – a good sign that something is wrong inside the pump; replace the pump.


Pump only heats some of the radiators, for instance upstairs only – turn the pump pressure up. Pump may be ‘on the way out’, not enough power to pump water round the central heating system.

 

Hot Radiators Upstairs But Not Downstairs (Or Vice Versa).


Noises from the central heating – air in the pump; bleed the pump.

 

Central Heating Noises


Boiler heating the hot water but not the central heating – a common problem after not using the central heating for some time. Give the central heating pump and pump valve a ‘love tap’ – a gentle tap. A ‘love tap’ sometimes ‘frees’ a sticking pump or valve.


Boiler heating the central heating but not the hot water – a common problem after not using the central heating for some time. Give the central heating pump and pump valve a ‘love tap’ – a gentle tap. A ‘love tap’ sometimes ‘frees’ a sticking pump or valve.


Pump not making ANY noise – seems dead – has the RCD tripped? Is the pump turned on? Is there a fuse near the pump? Has the fuse blown?

 

What RCDs Are

 

Electrical RCD – Find, Reset, Investigate A Constantly Tripping RCD


Pump constantly switches on and off – is the room thermostat broken?


Pump keeps breaking – is the pump ‘clogged’ with debris? Clean the pump out. See ‘Common Fixes’ below


Common Fixes – Central Heating Pumps

Turn the central heating off before doing ANY repairs.

 

Turn the pump electrical supply off before doing any electrical checks or repairs.

 

Turn the pump electrical supply off before removing any covers or inserting anything into the pump.

 

The image below shows basic information. Read the basic information before doing any repairs.

 

Central heating pump

 

See ‘Common Problems & Symptoms – Central Heating Pumps’, above, for when to try each fix.


List of common fixes:

Always check the pump is turned on – may have been turned off by mistake.

  • Give the central heating pump and pump valve a ‘love tap’ – a gentle tap.
    • Fixes many problems seen after the central heating has been off for some time.
  • Bleed the air out of the pump – prepare for a small amount of water leakage. Turn the central heating on, loosen the pump bleed screw by about half a turn let the air out.
  • Pump housing hot:
    • Prepare for a small amount of water leakage.
    • Remove the pump bleed screw, remove any debris from inside the pump.
    • Remove the pump bleed screw, try to turn the motor spindle with a screwdriver.
      • Is the spindle stuck?
      • Can you free the spindle?
      • Turn the spindle a few times to free (loosen) the spindle.
    • Check the pump fuse.
    • Turn the pump pressure up.
    • Pump rattling.
      • Is the pump secure?
      • Is the electrical connections cover and pump housing cover secure?
    • Pump causes RCD to trip.
    • Check the supply to the pump.
      • Turn the electrical supply to the pump off.
      • Remove the electrical connections cover.
      • Turn the electrical supply to the pump off.
      • Use a voltmeter to check the supply to the pump.
    • Clean the pump.
      • Prepare for a small amount of water leakage.
      • Remove the pump bleed screw, remove any debris from inside the pump.

 

Judge Electrical Limited
15 Mulberry Court, Huntington, York, YO32 9TU
Telephone 01904 764845 (Landline), 07919 033113 Mobile)
Email info@judgeelectrical.co.uk
VAT No. 852917405. Company Number 6359328