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Condensate pump not working

Updated: 22 October 2026

Water is on the floor, the pump hums without emptying the tank, or the boiler has locked out and the fault code points at condensate. This condensate pump not working guide gives a safe order of checks: isolate, follow the water, then split float, tube, non-return and motor failures that look alike from the outside. It assumes the pump is already fitted. New installs start on [how to fit a condensate pump](/hub/heating/condensate-pump/sub/condensate-pump-how-to-fit). Replacement shopping waits until the route is verified. Use the [condensate pump comparison](/hub/heating/condensate-pump) only after diagnosis. UK fault notes and installer anecdotes inform the structure. They are not tests of your exact ASIN. A qualifying purchase can earn a commission at no extra cost to you.

Water is on the floor, the pump hums without emptying the tank, or the boiler has locked out and the fault code points at condensate.

Our top picks

Aspen Pumps Aspen FP3349 Max Hi-Flow

Best overall

Aspen Pumps Aspen FP3349 Max Hi-Flow
8.8/10about £85.00
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AirTech-UK AirTech-UK 554405

Rank 2

AirTech-UK AirTech-UK 554405
8.4/10about £82.99
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BAOSHISHAN BAOSHISHAN QS-360L

Best value

BAOSHISHAN BAOSHISHAN QS-360L
6.0/10about £59.99
View offer
On this page
  1. 1.Make it safe before you diagnose
  2. 2.Four faults that look the same
  3. 3.A frozen pipe is not a dead pump
  4. 4.What buyers in this set reported

Make it safe before you diagnose

Turn off the pump at the mains or the switched spur before you lift lids or pull barbs. If the boiler has locked out on high condensate level, do not bypass the safety wire to force heat. Catch drips and protect nearby electrics. A full tank with a silent motor, a motor running on an empty tank, intermittent cycles, or heat from the housing each point somewhere different. If the outdoor tube is iced solid, the indoor pump may be fine. HHIC treats freeze as a route problem, not automatically a dead motor. A gas boiler that will not reset after you clear water still needs Gas Safe. This page does not authorise opening the combustion case.

Four faults that look the same

A stuck float or fouled chamber stops the start or stop signal. Condensatepump.co.uk lists a stuck float among causes of continuous running. A QS-24L reviewer says the pump never stops once started. A QS-24B reviewer reports a stuck float and a dangerously hot motor. Clean the chamber and inlet screen if the manual allows, and keep the assembly level. QS-24B must stay horizontal. A blocked or kinked inlet mimics a dead pump because water never reaches the impeller. Glow-worm’s manual, written for its own pump, lists a pinched hose and a blocked inlet among high-level causes. Trace the tube without pulling live wiring. A failed non-return lets discharged water run back, so the float never sees a falling level. Backflow through a perished non-return is a cheap check before a new ASIN. Hum with no flow, or silence with a full tank, points at a dead motor or a jammed impeller. AirTech’s UK reviews include intermittent pumping after two weeks. Aspen’s file includes a one-day failure in a non-UK text and a stuck float in a Spanish review.
Aspen Pumps Aspen FP3349 Max Hi-Flow

Testsieger

Aspen Pumps Aspen FP3349 Max Hi-Flow
8.8/10about £85.00
View offer

A frozen pipe is not a dead pump

When the outdoor condensate pipe freezes, the boiler may lock out while the indoor pump appears idle because water never reaches it, or the tank overflows back at the appliance. Thawing and insulating the external leg belongs in boiler route work on the boiler condensate pump page, not in buying another pump. A safety switch open on high level can hold the boiler off even when the pump bowl looks dry. Check the high float before you assume the motor is gone. Listings that print a normally closed contact, such as Aspen’s 3.0 A line, are meant to interrupt the appliance when the tank overfills. Bridging that contact for a quiet night removes the protection the circuit is there to provide.

What buyers in this set reported

Reviews here give fault shapes, not probabilities. QS-24L runs continuously when the float does not stop the motor. QS-24B reports include heat, a stuck float, and wiring colours that stopped a UK buyer fitting the unit. AirTech texts describe intermittent pumping. BAOSHISHAN QS-360L has a one-month total failure among five reviews. Grundfos owners mention loud running even when the pump empties. A 4.4 average across 90 Aspen reviews still includes bare wires and noise. When cleaning restores flow, re-test with water in a bucket before a long heating run. If the motor is hot or trips the supply, stop. Call a Gas Safe registered engineer if the gas boiler will not clear its condensate fault once the route is open and the outdoor pipe is not frozen, or if the safety circuit needs testing. Call an electrician for damaged mains, improvised bare flex on Aspen or Ejoyous, or a new fused spur. Call an HVAC technician if the fault ties to refrigerant work on a split. Buy from the best condensate pump page only when lift and duty are known and the old pump is confirmed dead, not when a non-return simply sticks.

Common questions

The pump runs and never stops. Is the motor dying?
Often it is a stuck float, backflow past a weak non-return, or a leak that keeps the tank filled. Continuous run without flow also appears in QS-24L’s UK review.
The tank is full and the pump is silent. What next?
Check supply power, inlet blockage and an impeller jam before you assume replacement.
The boiler is dead but the pump looks dry. Could the safety switch be open?
Yes. High-level trips can hold the boiler off while the bowl is empty if the float or switch failed.
Can I bypass the alarm wire for the night?
No. That removes the overflow protection the safety circuit exists to provide.
The pump is loud but it does empty. Is that a fault?
Grundfos reviewers mention loud running while still pumping. Noise without emptying is different from noise with flow.
When is it a new pump, and when is it a clean?
Clean the inlet, float and non-return first when the motor spins and the listing matches the duty. Replace when the motor is hot, dead or intermittent after basic service. AirTech’s intermittent reports are an example.
When do I stop and call a Gas Safe engineer?
When the gas boiler will not reset, when safety wiring needs alteration, or when condensate work touches the boiler’s certified route beyond simple external tubing you were already shown.

Related pages

Condensate pump buying guide

Condensate pump

Best condensate pump: top pick and who should skip

Boiler condensate pump: gravity, acid and Gas Safe

How to fit a condensate pump: the sequence, then stop

Sources

Public UK and manufacturer sources named below. amazon.co.uk prices, stars and review counts on these twelve listings were taken from the listing files. Page updated October 2026.

  1. Approved Document H, drainage and waste disposal (retrieved 21 October 2026)
  2. HHIC condensate discharge installer guide (retrieved 21 October 2026)
  3. HHIC condensate pipe guidance news (retrieved 21 October 2026)
  4. Gas Safe Register FAQ (retrieved 21 October 2026)
  5. Aspen FP3349 tech sheet (retrieved 21 October 2026)
  6. Grundfos Conlift1 LS data (retrieved 21 October 2026)
  7. CoolEasy condensate pump buyer's guide (retrieved 21 October 2026)
  8. condensatepump.co.uk boiler note (retrieved 21 October 2026)