In short
When a commercial pump fails, heat or water stops moving through the building. Typical signs are loss of heating to circuits, low water pressure, pump trips, alarms, abnormal noise or vibration. Check which pumps are running and record any alarms without opening electrical panels, then call a commercial pump engineer to diagnose the pump, motor, controls and system.
Is it urgent?
Call now if
- Both duty and standby pumps have failed or will not change over
- Heating or water pressure has been lost across the building
- A pump is leaking, smoking, smells of burning or has seized
- Boilers are locking out because water is not circulating
Usually suitable for scheduled work
- The standby pump has taken over automatically and is running normally
- Slight noise or vibration with no loss of performance
- Planned pump replacement or seal changes
Commercial pump failure symptoms
| Symptom | What it may indicate |
|---|---|
| Heating circuit cold, boilers overheating | Circulation pump stopped, airlocked or not changed over |
| Low water pressure at upper floors | Booster pump or booster set failure |
| Pump trip alarm | Motor overload, electrical fault, seized pump |
| Grinding, rattling or vibration | Bearing wear, cavitation, impeller damage, air |
| Water around the pump | Mechanical seal failure, gasket or connection leak |
| Pumps constantly swapping duty | Recurring fault on one or both pumps, or a control fault |
Heating circulation pump faults
Circulation pumps move heated water from boilers to radiators, fan coils and air handling units. When they stop, boilers can overheat and lock out, so a pump fault often looks like a boiler fault. See commercial heating repairs.
Booster pump failures
Booster sets raise cold water pressure for upper floors and outlets. Failure can leave taps, toilets and process equipment without water. See water pressure failures.
Duty and standby systems
A duty and standby pair is only as resilient as its changeover. Check the BMS or pump controller to see which pump should be running. If both show faults, or the standby has not started, circulation has stopped.
Low flow, noise, vibration and trips
Low flow can come from a failing pump, a partly closed valve, a blocked strainer or air in the system. Noise and vibration usually mean mechanical wear. Trips point to electrical or mechanical overload.
Motor failures and controls
Motors fail through bearing wear, overheating and insulation breakdown. Variable speed drives, contactors, overloads, pressure switches and BMS outputs can all stop a healthy pump from running.
Professional fault diagnosis
An engineer checks electrical supply and protection, motor condition, pump mechanics, differential pressure and flow, valves and strainers, and the control signals. They will restore circulation where possible, for example by running the standby pump, while a repair or replacement is arranged.
Electrical and pressure hazards. Pump control panels contain live parts and pump casings are under system pressure. Do not open panels or loosen pump fittings.
Repair versus replacement
Lead times for larger pumps vary. Where a like-for-like pump is not immediately available, a temporary solution may be agreed. The engineer should explain the options and costs before work proceeds.
Maintenance and resilience
Regularly alternate duty and standby pumps, test changeover, check seals and bearings, and keep strainers clean. A pump that has never been run may not work when it is needed.
Commercial Pump Repairs: frequently asked questions
What are the warning signs of a commercial circulation pump failure?
Warning signs include heating circuits going cold while boilers run or overheat, pump trip or fault alarms on the BMS, unusual noise or vibration, water leaking from the pump seal, a motor that is hot or smells of burning, and frequent changeovers between duty and standby pumps.
What is a duty and standby pump arrangement?
Two pumps are installed so that one (the duty pump) runs while the other is ready to take over if it fails. Controls should change over automatically and raise an alarm. If the changeover fails, or both pumps are faulty, circulation stops.
Should we repair or replace a failed commercial pump?
Small circulators are usually replaced. Larger pumps may be repairable with new seals, bearings or motors. The decision depends on the pump's age, parts availability, lead times and whether a like-for-like replacement can be fitted quickly.
Why does a commercial pump keep tripping?
Repeated trips can come from motor overload, a seized or obstructed impeller, failing bearings, electrical faults, dry running from low pressure or air, or control faults. Record when it trips and leave it off if it trips again after one reset.
Do booster pumps and heating pumps need different engineers?
Both are mechanical pump sets, but booster sets serve the building's water supply and come with water hygiene requirements. Tell us which system is affected when you call so the right skills are arranged.
UK guidance and references
Primary and industry sources relevant to this subject. Always check the current edition and how it applies to your building.
- Electrical safety at work Health and Safety Executive
- Legionnaires' disease (ACOP L8) Health and Safety Executive
- Water Supply (Water Fittings) Regulations 1999 legislation.gov.uk