Insulating the pipework on an air source heat pump installation is not an optional finishing touch — it is a fundamental part of a correctly specified system. Uninsulated or poorly insulated refrigerant lines, flow and return pipes, and external fittings allow heat to escape or enter the pipework at the wrong point, reducing the efficiency of the system, increasing running costs, and in some cases causing condensation that damages the surrounding structure. For a technology where every fraction of a degree matters to COP (coefficient of performance), cutting corners on insulation is a false economy.
All pipework exposed to external conditions — and any internal pipework running through unheated spaces such as lofts, garages, or underfloor voids — should be insulated as part of every heat pump installation.
What Pipework Needs Insulating on a Heat Pump System?
A heat pump installation typically involves several categories of pipework, each with its own insulation requirement. The refrigerant lines connecting the outdoor unit to the indoor heat exchanger or hydro box carry refrigerant at varying temperatures and must be insulated to prevent heat gain in cooling mode and heat loss in heating mode, as well as to prevent condensation forming on the cold suction line. The flow and return pipes carrying heated water from the heat pump to the heating distribution system — radiators, underfloor heating, or a buffer tank — must also be insulated wherever they pass through unheated spaces to prevent standing losses. Any external pipework fittings, valve housings, and connection points at the outdoor unit are equally important and are a common oversight on poorly executed installations.
Primary Pro — Specified for Heat Pump Installations
Primary Pro produce a comprehensive range of pre-formed and flexible pipe insulation products engineered for the specific demands of heat pump and refrigeration applications. Their products are designed to handle the wide temperature ranges involved — from the cold suction line on the refrigerant circuit through to the heated flow and return on the water side — and are manufactured to the wall thicknesses required to meet current building regulations and MCS installation standards.
The Primary Pro range includes flexible closed-cell foam insulation in a variety of internal diameters and wall thicknesses to suit standard copper and plastic pipe sizes commonly used in heat pump installations, as well as pre-formed insulation for bends, tees, and valves to ensure a continuous insulation envelope with no cold bridges. Their products are UV-resistant where required for external applications, and vapour-sealed to prevent moisture ingress on low-temperature pipework where condensation risk is highest.
Why Wall Thickness Matters
Not all pipe insulation is equivalent — the thickness of the insulation wall determines how much heat loss or gain occurs across a given length of pipe, and thicker insulation is required on pipes carrying lower temperatures (where condensation risk is higher) and on longer pipe runs exposed to external conditions. For heat pump installations, MCS guidelines and building regulations generally require greater insulation thickness than a standard heating installation, particularly on refrigerant suction lines and any pipework in external or unheated locations. Always check the required wall thickness against the pipe diameter and ambient conditions before ordering.
A Note on Compliance
MCS-certified heat pump installations must meet specific standards for pipework insulation as part of the overall system specification. Underinsulated pipework can result in a system failing to perform to its rated efficiency, which can affect eligibility for schemes such as the Boiler Upgrade Scheme (BUS) and any associated warranty claims. Specifying the correct insulation from the outset is a straightforward way to ensure your installation meets the required standard first time.
Browse our full range of heat pump pipe insulation below, or contact our team for help selecting the right product for your pipe sizes and installation conditions.
