A condensate pump moves collected water to a suitable discharge point when a reliable gravity drain is not practical. Mini pumps are useful where space is restricted, tank pumps collect water before pumping it away, and high-lift models are intended for applications needing greater pumping head.
Choose by assessing the appliance, condensate characteristics, expected flow, vertical lift, total pipe run, pipe arrangement and acceptable noise. Check the proposed duty against the appliance and pump manufacturers’ current instructions.
When is a condensate pump needed?
Air-conditioning equipment removes moisture from the air, while a condensing boiler produces acidic condensate during operation. In either case, the liquid needs a correctly planned route to an appropriate discharge point.
A continuous gravity fall is usually the simplest arrangement. A pump becomes relevant when the proposed drain is higher than the collection point, obstacles prevent a suitable fall, or the discharge route cannot be achieved by gravity alone.
Do not treat a pump as a remedy for an unsuitable or obstructed drain. Before selecting one, establish where the condensate originates, where it may be discharged, and how the route will be inspected and maintained.
Follow the boiler manufacturer’s condensate instructions and check whether BS 6798 applies to the boiler installation concerned. Check the current edition and any manufacturer updates rather than relying on a remembered detail.
Building Regulations Approved Documents provide guidance for England. Wales publishes its own editions, while Scotland and Northern Ireland have their own building standards, so use the guidance that applies in the relevant nation.
Mini, tank and high-lift pumps
Mini pumps
A mini condensate pump is intended for installations where there is limited room around air-conditioning equipment. Its small format can make positioning easier, but the installation still needs access for cleaning, inspection and replacement.
Small dimensions do not determine whether a pump can handle a particular route. Check the manufacturer’s flow and lift information at the actual operating point, along with permitted pipe sizes and routing limits.
Tank pumps
A tank pump receives condensate in a reservoir and starts when the water reaches its operating level. This arrangement separates collection from discharge and is common where condensate arrives intermittently.
The reservoir needs to remain level, supported and accessible. Account for any overflow or alarm arrangements specified by the manufacturer, because a failed or blocked pump can otherwise allow water to escape.
High-lift pumps
High-lift models are intended for applications needing greater pumping head. Check the model’s performance at the required flow and head.
The words high lift are not a substitute for assessing the route. Vertical rise, resistance along the pipe and fittings all affect the duty, while delivered flow generally reduces as pumping head increases.
How to choose the right pump
Start with the equipment manufacturer’s instructions. Confirm whether pumped drainage is permitted, what condensate is produced and whether the proposed pump materials and arrangement are appropriate.
Then record the expected condensate flow, required vertical lift and complete discharge route. Include horizontal runs, changes of direction, pipe diameter, termination point and any section exposed to low temperatures.
- Application: establish whether the source is air-conditioning equipment, a boiler or another condensate-producing appliance.
- Duty: compare the required flow and lift with the pump manufacturer’s performance data.
- Reservoir: allow enough space for the stated tank or collection arrangement and future access.
- Noise: consider where vibration or pump operation could be heard, particularly near occupied rooms.
- Controls: check whether the design requires an alarm, high-level switch or equipment shut-down connection.
- Discharge: verify the destination and termination against the appliance instructions and applicable guidance.
Confirm voltage, electrical protection and connection requirements from the current pump instructions. Use a competent electrician for mains connections. Ask the installer to check the applicable national electrical requirements and manufacturer instructions.
Fitting a condensate pump or its trunking is distinct from working on an air-conditioning refrigerant circuit. For stationary refrigeration, air-conditioning and heat-pump equipment containing F gas, GOV.UK says individuals need appropriate qualifications to install, service or maintain systems, check for leaks, recover gas, or decommission systems. Use a refrigeration engineer competent for the refrigerant and the work, with the appropriate F-gas qualification where the refrigerant and activity require it.
Planning the pipe route
A good route is short, supported and accessible, with no unnecessary bends or points where debris can collect. Follow the pump manufacturer’s limits for tube size, vertical rise, horizontal run and permitted discharge arrangement.
Prevent the tube from being crushed or kinked, and secure it without restricting its bore. Where the instructions require measures against backflow or siphoning, use the specified arrangement.
External boiler condensate pipework can be vulnerable to freezing. Follow the boiler manufacturer’s instructions and check whether BS 6798 applies to the installation concerned before using its routing and protection guidance. BHL’s guide to a frozen condensate pipe covers safe thawing and ways to help prevent recurrence.
The discharge point also matters. Do not direct condensate somewhere that could damage building fabric, create a slip hazard or return liquid towards the appliance.
Examples from the range
The Aspen Mini Tank Pump, MPN FP1056/2, is a mini tank condensate removal pump for air-conditioning and HVAC applications.
The Aspen Hi Lift Pump, MPN FP2071/2, is a 2L tank condensate removal pump for air-conditioning, HVAC and boiler condensate applications.
The Sauermann Delta Pack is a condensate pump kit for air-conditioning and HVAC applications.
These examples represent different formats, not interchangeable choices. Confirm all details against the manufacturer’s current data before ordering or installation.
Commissioning and maintenance
After installation, test the complete system using the procedure specified by the pump and appliance manufacturers. Check that condensate enters the collection point, the pump starts and stops correctly, and the discharge reaches its intended destination without leaks or backflow.
Keep the reservoir, inlet and discharge path accessible for inspection. Sludge, dust and biological deposits can restrict condensate systems, so maintenance should follow the manufacturer’s stated intervals and cleaning method.
Investigate repeated alarms, unusual noise, cycling or overflow rather than repeatedly resetting the unit. Possible causes include a restricted inlet, blocked discharge tube, poor pipe routing, a contaminated level sensor or a pump operating outside its intended duty.
Isolate electrical power safely before maintenance and follow the manufacturer’s instructions. Use a competent electrician for mains electrical work and a suitably Gas Safe registered engineer for work on a gas appliance. For boilers using another fuel, use an engineer competent for that fuel and appliance. If maintenance involves the refrigerant circuit, use a refrigeration engineer competent for the refrigerant and the work, with the appropriate F-gas qualification where the equipment contains F gas and the activity requires it.
Frequently asked questions
Can one condensate pump be used for either a boiler or air conditioning?
Not automatically. Check that the pump, materials, controls and discharge arrangement are approved for the particular application in the appliance and pump manufacturers’ current instructions.
Is a high-lift pump always more suitable?
No. It is useful only where its performance matches the required route and flow. Additional pumping head does not correct poor pipework, an unsuitable discharge point or inadequate maintenance access.
Can condensate be pumped outside?
Only use a termination permitted by the appliance instructions and applicable guidance. External boiler condensate routes need particular attention to freezing risk, so follow the current manufacturer guidance and check whether BS 6798 applies to the installation concerned.
What should be checked if a condensate pump keeps running?
Check for continuing condensate inflow, a restricted discharge, backflow, contamination around the level control and incorrect routing, following the manufacturer’s fault-finding instructions. Isolate the unit and use a competent electrician if mains electrical investigation is needed.
Parts and products at BHL
BHL lists a wider selection in the condensate pumps collection, alongside the Aspen Pumps range and broader air conditioning and ventilation products. We recommend comparing the current manufacturer data with the planned flow, lift, route, controls and maintenance access before choosing a product.