MCS installers — why the grant insists, and how to choose well
No MCS certification, no £7,500. Here is what the requirement actually protects you from, how to verify any installer in two minutes, and how to pick a good one from a certified field.
The rule, and the reason for it
Every Boiler Upgrade Scheme installation must be carried out by an installer certified under the Microgeneration Certification Scheme. This is not bureaucratic decoration: the installer is the only party who can apply for your voucher, claim your £7,500 from Ofgem, and register the completed system on the MCS database. Choose a non-certified firm and the grant simply does not exist for you — there is no self-service route around it.
The deeper reason is that heat pump performance is made or broken at design time. A boiler forgives lazy installation by brute force — 70°C water covers many sins. A heat pump running efficiently at 35–45°C forgives nothing: undersized radiators, skipped heat loss calculations, or wrong unit sizing all surface as cold rooms and savage electricity bills, the exact failures our running-costs page quantifies. MCS exists to make the design discipline mandatory — certified firms must follow recognised heat loss methodology, size emitters properly, complete noise assessments for outdoor units, and submit to audit. It is a floor, not a ceiling, but it is a meaningful floor.
Verifying an installer in two minutes
Go to mcscertified.com and search the company name or certification number — the register is live, so lapsed certifications disappear. Confirm the certification scope includes heat pumps, not just solar PV. Then confirm membership of a consumer code (HIES or RECC), which MCS requires and which gives you deposit protection and dispute resolution. Finally, ask for the insurance-backed guarantee details in writing — it is what keeps your workmanship warranty alive if the firm later disappears. Any installer who hesitates at any of these four checks has answered your real question.
Choosing between certified installers
Certification filters out the cowboys; it does not rank the survivors. The differentiators worth paying for: a room-by-room heat loss calculation done from a proper survey, not a floor-area rule of thumb; a proposed design flow temperature of 45°C or lower, with the radiator changes that implies itemised in the quote; a predicted SCOP with its basis shown, so the running-cost promise is checkable; experience with your property type — solid-wall Victorians and modern estates are different trades, which is where a firm rooted in its own patch, like Cornwall installer CCS Heating & Renewables, earns its place on a shortlist; and clarity on who manages the BUS paperwork (the right answer: they do, and the £7,500 comes off the quoted price, as the scheme page describes). Price matters, but the £2,000 spread between quotes matters less than the £400-a-year spread between a SCOP of 2.8 and 3.8 — buy the design, not the discount.
Red flags worth walking away from
Quotes issued without a site visit or data-led survey. "We'll keep your boiler as backup" (hybrids are grant-ineligible, and the suggestion usually signals under-confidence in the design). Pressure to sign before the voucher application. Vagueness about which firm actually holds the MCS certificate — subcontracting chains can leave the certificate holder a stranger to your job. And any request for you to claim the grant money yourself: the scheme does not work that way, and a firm that says otherwise either doesn't know the rules or hopes you don't. The eligibility page and the official guidance at gov.uk describe the legitimate process — anything that deviates from it deserves suspicion.