Write the same brief for every installer
Begin with a short, factual brief so quotations answer the same problem. List the rooms, dimensions, ceiling heights, occupancy, glazing, orientation, insulation clues, hot periods and whether you need cooling only or reversible heating and cooling. Add ownership or leasehold status, preferred indoor and outdoor locations, access limits and any known electrical work. The CoolCompare BTU calculator and Multi-Room Split Designer can help organise questions, but their estimates do not replace a room-by-room survey or a heat-loss calculation where heating performance is being designed.
Tell each contractor which outcomes matter: bedroom noise, several independently controlled rooms, winter heat, appearance, maintenance access or a firm budget boundary. Do not lead with a preferred capacity copied from a retailer page. Ask the installer to explain the load and system arrangement they recommend, then record what was excluded. A consistent brief makes price, scope and risk comparable and reduces the chance that the cheapest quotation simply omits drainage, electrics, access equipment, planning evidence or making good.
Expect a site survey with visible design reasoning
A useful survey looks beyond floor area. It should consider solar gain, roof or loft exposure, occupancy and equipment heat, door-opening patterns, ventilation and the temperature goal. For heating, ask how the designer has addressed winter conditions and room heat loss. For cooling, ask why each unit's sensible capacity and airflow suit the room. A confident answer is not the same as documented design; request the assumptions and keep a copy so a later change of model can be checked rather than accepted as an equivalent by name alone.
The physical route should be equally specific: exact indoor and outdoor positions, pipe length and concealment, condensate fall or pump, electrical isolation, core drilling, structural supports, vibration control, safe access and fire-stopping where relevant. Ask where water will discharge in cooling and defrost operation and how equipment can be serviced without entering another property. A video call may screen a straightforward job, but it cannot reveal every concealed service or building constraint. Treat any quotation issued without adequate site evidence as provisional until those risks are inspected.
Verify legal credentials and scheme claims independently
Ask which named people and company will perform work on the refrigerant circuit. GOV.UK says stationary air-conditioning and heat-pump installation, service, leak checking and refrigerant recovery require the relevant F-gas qualifications. Check the evidence with the issuing or certification body rather than accepting a logo on a van or website. Confirm public-liability cover and, where design advice is material, ask what professional cover applies. Certification does not prove that every proposed design is good, so credentials are a gateway to due diligence rather than a substitute for it.
MCS has a different role from an F-gas qualification. GOV.UK directs households seeking government heat-pump funding to an MCS-certified installer, and MCS installation requirements or a consumer-code membership may apply to particular funded routes. A conventional cooling project does not automatically become MCS-certified, and a company being MCS-certified for one technology does not prove scope for another. Verify the current entry, technology and trading identity. Grant and scheme rules can change; check the dated CoolCompare Grant Tracker and official scheme material before relying on eligibility or an amount.
Compare exact equipment and honest performance boundaries
Require the manufacturer, full indoor and outdoor model numbers, quantity of each unit, rated capacities and the published test context. Clarify whether heat mode is a reversible heat pump, resistive heater or unverified claim, and whether hot water is outside the system's scope. Compare published indoor and outdoor sound values only when the measurement type and operating point are clear. CoolCompare's product and noise pages can organise verified fields, but manufacturer-specific tests are not transformed into independent laboratory results or guarantees for your room.
Ask how controls work, which functions depend on Wi-Fi or a cloud service, what happens when the internet is unavailable and whether every room can be controlled independently. Check low-temperature heating output if winter use matters, not only a seasonal headline. For multi-split proposals, ask how simultaneous room demand affects available capacity and whether one outdoor-unit fault stops all connected rooms. A substituted model should trigger a fresh comparison of capacity, efficiency, dimensions, sound, warranty and planning evidence before you consent to the change.
Make the quotation show the real contract price
An itemised quotation should separate equipment, labour, VAT, electrical work, condensate pumps, access equipment, core drilling, supports, pipe covers, making good, commissioning, waste removal and optional maintenance. It should state who obtains planning, freeholder or building-control consent and who pays if extra work is uncovered. Record deposit, stage-payment and final-payment terms, the planned dates, cancellation rights and the process for variations. Citizens Advice recommends checking traders and agreeing the work in writing before home improvements begin.
If a grant is involved, use the CoolCompare Grant-to-Quote Checker to separate the project price before grant, the grant amount and the customer balance. A public grant should not be disguised as the installer's private discount, and eligibility should not be promised before the required checks. Compare at least two or three genuinely equivalent scopes; a lower total may be rational, but only after omissions and provisional sums are visible. Avoid paying outside the agreed method or accepting a pressured same-day decision merely to preserve a claimed offer.
Define installation, commissioning and handover evidence
Before work starts, agree protection of floors and furnishings, working hours, access, dust control, shutdowns and responsibility for permissions. Ask what happens if the planned pipe or drain route proves impossible. Refrigerant work is not a DIY handover item: the qualified installer should complete the circuit work, test and commission in line with the equipment and applicable requirements. Electrical work, penetrations and fire-stopping must be carried out and evidenced by people competent for that scope rather than assumed to be covered by an air-conditioning badge.
The handover should identify every installed model and serial number, final pipe and cable route, isolators, drains and maintenance access. Request commissioning records, certificates that apply to the job, warranty registration, operating instructions and a practical demonstration of modes, filters, timers and fault indicators. Ask what to do if water leaks, a breaker trips or an error code appears. For a reversible system, confirm which settings provide heat and which are cooling or drying. Do not sign a completion statement until agreed defects and missing documents are recorded.
Check warranty, aftercare and dispute routes before choosing
Separate the manufacturer's equipment warranty from the installer's workmanship promise. Record their duration, exclusions, servicing conditions, response route and who pays for diagnosis, access equipment or replacement labour. Ask whether another authorised contractor can preserve cover if the original business closes. For heat-pump work, Energy Saving Trust's best-practice guide links technical design with consumer protection; RECC publishes a consumer code for member businesses. Membership can provide a framework, but it is not an invented performance rating or a guarantee that no dispute will occur.
Make a final scorecard covering design evidence, verified scope credentials, exact equipment, total contract price, permission responsibility, noise and drainage plan, commissioning documents, warranty and aftercare. Keep screenshots or dated register checks with the quotation because membership status can change. CoolCompare only calls an installer verified after the stated evidence has been reviewed; a directory listing, referral fee or retailer relationship must never substitute for that process. This checklist is general consumer information, not legal, engineering or financial advice, and project-specific uncertainty should be resolved by the relevant authority or competent professional.
