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PIPES, VALVES & FITTINGS


When the heating comes on, the warranty gaps show


By Arne Glass, specification manager, Brymec, makes a case for whole-system thinking at specification stage to protect installations from future insurance claims


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ccording to the Association of British Insurers (ABI), the average cost of escape of water claims has risen to an estimated £2.5 million


every day. Naturally, this impacts construction and building services more generally. For heating contractors, the liability doesn’t start on site. It starts at specification stage.


A heating system is only as tight as its weakest joint


Low-temperature Hot Water (LTHW) and domestic hot water circuits don’t rest. They heat up, cool down and repeat across every working day of a building’s life. Each cycle places stress on every connection in the system. In a coherently specified installation, that thermal movement is calculated and designed for. In a mixed-manufacture assembly, it rarely is. Escape of water affects 65% of UK construction


projects. When the source is an LTHW joint or a domestic hot water connection, the damage escalates fast. The question of who carries the cost follows close behind.


Where substitutions break the system


Heating system compatibility failures rarely begin on site. They begin in procurement, when a specified component is swapped for an ‘equal or approved’ substitute, usually late and usually driven by price. The substitution gets approved, but the compatibility question doesn’t get asked. In any heating circuit, those material choices


have direct consequences. For example, different varieties and materials of press-fit fittings and tubes may involve different tool requirements and tolerance ranges. Plastic-to-metal connections in LTHW and domestic hot water pipework create a further specific problem. In most cases, plastics expand at a greater rate than metals under thermal movement, placing the joint under stress that grows with every heating cycle. The failure doesn’t announce itself at commissioning. It surfaces during occupation, often two or three heating seasons in, when remediation costs have multiplied. By that point, the contractor has left site. The


mixed-material pipework specification has been rewritten swap by swap, without anyone mapping the system boundary where one manufacturer’s warranty stopped and another’s began. The exposure doesn’t fall on procurement alone. Under the Building Safety Act 2022, an


Left: Arne Glass, specification manager, Brymec


undocumented substitution that changes the design transfers liability to whoever authorised it, not automatically to whoever wrote the original specification. But without a written record of objection, the original specifier’s exposure is harder to close than many assume.


Warranty terms: read the conditions, not just the duration


A 30-year warranty isn’t a promise. It’s a commercial document with conditions written to allow claims to be scrutinised and, where possible, challenged. Brymec’s Stainless Steel Press-fit System carries


a press-fit warranty of up to 30 years. But the terms are specific. The installer must hold a current manufacturer training certificate and use approved tools maintained to manufacturer requirements. They


must install certified 316L stainless steel tube and retain the commissioning paperwork. An ‘equal or approved’ substitution introducing a different tube grade or a non-listed tool makes those conditions impossible to satisfy after the fact. The lesson here is to read the full conditions. Not


the warranty length on the data sheet. Even valid claims reach a ceiling. Standard manufacturer warranties exclude indirect and consequential loss. A mixed-material pipework failure in a live LTHW circuit causing water damage to a building’s fit-out doesn’t produce a proportional recovery. The gap between the component cost and the remediation bill lands with the installer, the main contractor or their insurer. That’s the reality of building services warranty liability in practice.


Three habits at submission stage


None of this requires a structural change to how you work. It requires discipline at submission stage. Read full warranty conditions on every proposed substitution, not just the stated term. Establish which conditions become impossible to satisfy once a material or manufacturer boundary is crossed. For every ‘equal or approved’ swap crossing a


system boundary, request written confirmation from the replacement manufacturer. Confirm the substitution preserves heating system compatibility and maintains the warranty position. Keep the response on file. Where a single supplier isn’t achievable, map


the exact interface where one manufacturer’s coordinated system warranty stops. Name the party carrying that risk before sign-off. Do it in writing before handover, not after. Specify consistently from a single manufacturer


and those interfaces disappear. The warranty position is unified across the full assembly rather than spread across a patchwork of product-level terms. There is one accountable contact and one technical team to call when something needs resolving. That’s the practical case for whole-system thinking at specification stage.


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