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How to compare commercial HVAC quotes

Updated 23 October 2026 · SEO Dons Editorial

Why do commercial HVAC quotes differ so much?

Mostly because the bidders are pricing different jobs. Two contractors can look at the same building and arrive at different design loads, system types, refrigerants, commissioning depth and exclusions, and each total can be reasonable on its own terms. The physical price drivers, such as access, craneage, electrical capacity and builder's work, are set out in the commercial HVAC cost guide. This page covers the other half: what a quote has to say before its total can be compared with another.

An item missing from one quote has not gone away. It has moved to the client, to another trade, or to a variation after the order.

What must a complete HVAC quote itemise?

Use this as a checklist. Mark each row for each bid as stated, partly stated or not stated.

ItemWhat the quote should state
Design basisThe design heat load per zone, how it was calculated, the occupancy and equipment assumptions, and any diversity applied
EquipmentManufacturer, model and capacity of every indoor and outdoor unit, with the declared seasonal efficiency
RefrigerantThe refrigerant, the system charge and the F-gas threshold the system falls into
RoutesWhere pipe, duct and condensate runs go, and whether the route was surveyed or assumed
ElectricalSupply capacity checked, new circuits, isolators and containment, and who tests and certifies them
Builder's workCore drilling, fire stopping, supports, making good and decoration, each shown as included, excluded or by others
Access and craneagePlant lift, access equipment, permits, and the working hours assumed
ControlsController types, any central control or building management interface, and who configures them
CommissioningThe procedure followed, the measured records handed over, and who gives any commissioning notice
F-gas paperworkThe contractor's company certificate number, engineer categories, and the refrigerant record at handover
WarrantyDuration, what it covers, and any conditions about servicing or maintenance
MaintenanceThe visits needed to keep the warranty and the leak checks due, and whether they are priced

Words such as "provisional sum", "allowance", "subject to survey" and "by others" are the usual places a gap hides. Ask what each one covers and what it would cost if the assumption is wrong.

How should heat load and seasonal efficiency be compared?

Start with the design. HSE's CDM guidance says a design includes drawings, design details, specifications, bills of quantity and design calculations, and that specialist contractors can count as designers if they take part in the design work. A bidder that sizes the plant is therefore taking on design responsibility, so the quote should say who holds it and show the load calculation or a summary. Two bids built on different design loads are different products, and their totals say little about which is better value.

Seasonal efficiency comes next. The ecodesign regulation for cooling products, Commission Regulation (EU) 2016/2281 as it applies in Great Britain, defines the seasonal energy efficiency ratio (SEER) as the overall efficiency ratio of the air conditioner or comfort chiller, representative of the cooling season, calculated as the reference annual cooling demand divided by the annual energy consumption for cooling. It is a standardised figure for a unit. It does not show whether the unit suits the building, so read it alongside the design load. The guide to SEER explains how to use the figure.

For multi-split air conditioners within that regulation's scope, the technical documentation must include a list of recommended combinations of indoor units for each outdoor model, and the list must be available before purchase. Ask which combination a quoted efficiency figure is based on. The same regulation covers cooling products up to a rated capacity of 2 MW, and smaller air conditioners are covered by a separate regulation.

What should the commissioning line say?

It should name the procedure, the records and the person responsible. In England, regulation 44 of the Building Regulations 2010 requires the person carrying out the work to give the building control authority a notice confirming that the fixed building services have been commissioned in accordance with a procedure approved by the Secretary of State. It applies to work that engages the ventilation requirement F1(2) or the fixed building services energy efficiency requirement L1(b), and not where testing and adjustment is not possible. Wales has a separate version, so a quote should say which applies and who gives the notice.

CIBSE publishes commissioning codes by system type, including Code R for refrigerating systems, Code A for air distribution, Code C for automatic controls and Code M for commissioning management. CIBSE describes Code R as a standard with which the refrigeration manufacturer and installer is expected to comply. A quote that names the code it commissions to, and lists the measured results it will hand over, is easier to hold to account. The guide to commissioning and handover covers what the pack should contain.

What F-gas paperwork and warranty terms should a quote cover?

For equipment holding F gas equivalent to 5 tonnes of carbon dioxide or more, GOV.UK says the operator must keep records for 5 years, including the quantity and type of gas when installed, and the name, address and certificate number of each company used to install, service or decommission the equipment. The quote should say who produces the installation record and in what form. Checking the certificate itself is covered in the guide to checking an F-gas certificate.

Refrigerant and charge also set the recurring workload. GOV.UK says how often equipment must be checked for leaks depends on the amount of F gas and its global warming potential. Two bids with different refrigerants or charges therefore carry different maintenance obligations. BS EN 378 is the safety and environmental standard for refrigerating systems and heat pumps, and part 1 covers classification and selection criteria, so a quote that says which refrigerant classification the design assumes is easier to test.

Ask for warranty terms in writing before ordering: duration, parts and labour, exclusions, and any condition about who services the equipment or what records must be kept. If the warranty is conditional on planned maintenance, that maintenance belongs in the comparison. The maintenance contract checklist covers what that contract should say.

How do you put bids on a like-for-like basis?

  1. Give every bidder the same brief. For projects under the CDM Regulations, HSE says a commercial client must provide pre-construction information to every designer and contractor bidding for the work.
  2. Fill in the checklist for each bid and mark every cell that is not stated.
  3. Ask each bidder to confirm the gaps in writing and to price them as separate lines.
  4. Adjust the totals for excluded items on the same assumptions, or ask for revised bids.
  5. Compare beyond the install price: declared efficiency, leak-check and maintenance workload, and warranty conditions.
  6. Check the bidders as well as the bids. The wider checks are in the guide to choosing a commercial HVAC contractor.

Readers who want quotes to compare can send an enquiry through the site's form, and the cost guide shows what moves a price once the scope is level.

Sources

Common questions

Should every bidder price from the same brief?

Yes. HSE says a commercial client under CDM 2015 must provide pre-construction information to every designer and contractor bidding for the work. Giving all bidders the same information is also what makes their scopes comparable.

Is a lower seasonal efficiency figure a reason to reject a bid?

Not by itself. The regulation defines SEER as a standardised ratio for the unit, not a measure of fit to the building. Compare it for the exact model and combination quoted, and read it alongside the design load.

Who gives the commissioning notice to building control?

In England, regulation 44 of the Building Regulations 2010 puts the duty on the person carrying out the work, where the regulation applies. The quote should say who that is, because the answer depends on the contract.

What if a bidder will not show the load calculation?

HSE counts design calculations as part of a design, and a contractor that sizes the plant is acting as a designer. A bidder that cannot show the basis for the size has given the buyer little to check, which is a fair reason to ask again or to compare another bid.

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