Installation Plan · Berkhamsted, HP4

Air-to-Air Heat Pump System

10 zones · 3 floors · ~27 kW · 2× multi-split outdoor units (SW side) · 0% VAT

At a glance

Property

6-bed detached, ~324 sqm across 3 floors
Berkhamsted, Hertfordshire · ~10 years old · EPC B91
Rear garden faces NW — afternoon/evening summer sun on NW rooms

Goal

Year-round heating + cooling with fully concealed units throughout — no visible indoor unit bodies anywhere. Room-by-room zoned control. Premium aesthetic on every floor.

Unit strategy

Zones 1–3, 5–9 Concealed ducted + linear grilles in ceiling void

Zone 4 Floor console (Study — slim, floor-mounted)

Zone 10 Concealed ducted behind purpose-built soffit (Cinema/Office)

Outdoor units

2× multi-split, SW side of house, adjacent to Family Room wall. Not on the NW rear garden wall.

ODU 1 (~14 kW) → GF zones 1–4
ODU 2 (~16 kW) → upper floors zones 5–10

System spec

Brand: Mitsubishi Electric or Daikin — residential range only
Refrigerant: R32 mandatory
Controls: MELCloud or Daikin Onecta
Gas boiler retained · no BUS grant

Budget

£34,000 – £58,000 total project
Realistic fully concealed: £36,000–44,000
VAT: 0% · Annual service: ~£300–500/yr

Key risks & critical items

Critical sequencing: AC pipe installation must happen while floorboards are lifted during the flooring project — before new wooden floors go down. Book the AC installer on-site during the floor-lifting phase. This is the single most important scheduling decision in the project.
Cinema/Office pipe run: Zone 10 is NE corner of 2nd floor; outdoor units are SW. Estimated 24–30 m — at or near manufacturer limits. Installer must measure and confirm. Options if exceeded: pipe extension kit or separate outdoor unit on NE side.
GF ceiling void depth: Must be ≥250mm for concealed ducted. Lift a spotlight fitting in the Kitchen/Dining and measure before any installer visits. This single measurement determines the ground floor approach.

Ground floor zones

ZoneRoomUnitCap.Notes
Z1 Kitchen / Dining
33.2 sqm		 Concealed ducted 5.0 kW Largest GF zone. NW bifold doors — high afternoon/evening solar gain. Check void ≥250mm. Stepped bulkhead ceiling present — fallback available.
Z2 Lounge
25.1 sqm		 Concealed ducted 3.5 kW NW patio doors — afternoon/evening sun. Check void ≥250mm.
Z3 Family Room
17.6 sqm		 Concealed ducted 2.5 kW SW-facing side garden — afternoon western sun. Closest zone to outdoor units.
Z4 Study
6.3 sqm · wife's office		 Floor console 1.5 kW Small room — full ducted disproportionate. Slim floor console below window, nearly invisible. Daily use.

First floor zones

ZoneRoomUnitCap.Notes
Z5 Bedroom 1 / Master
19.0 sqm + en-suite		 Concealed ducted 2.5 kW SE windows — morning sun. Suspended timber → generous ceiling void, no feasibility concerns.
Z6 Bedroom 2
17.6 sqm		 Concealed ducted 2.5 kW SE + S walls — morning and midday sun.
Z7 Bedroom 3 — kids
13.8 sqm		 Concealed ducted 2.0 kW NW rear + S wall. Afternoon/evening sun.
Z8 Bedroom 4 — kids
12.7 sqm + en-suite		 Concealed ducted 2.0 kW NW rear. Afternoon/evening sun.
Z9 Bedroom 5
10.6 sqm · currently unused		 Concealed ducted 1.5 kW NW rear. Add now at install time — cheap incremental cost on a multi-split.

Second floor zones

ZoneRoomUnitCap.Notes
Z10 Cinema / Office
19.2 sqm · daily use		 Ducted + soffit 3.5 kW Trussed rafter roof space — limited ceiling void. Solution: purpose-built dropped soffit (~80–100mm) along one wall; ducted unit inside, linear grilles facing room. Pipe run 24–30m — confirm with installer. High all-day load: office + evening AV.

Capacity summary

FloorZonesCombinedOutdoor unit
GroundZ1–Z412.5 kWODU 1 (~14 kW)
First + SecondZ5–Z1014.5 kWODU 2 (~16 kW)
Total~27 kW—

Architecture

Outdoor Unit 1 — Ground Floor

~14 kW multi-split
Serves: Z1 Kitchen/Dining, Z2 Lounge, Z3 Family Room, Z4 Study
Indoor units: 4

Outdoor Unit 2 — Upper Floors

~16 kW multi-split
Serves: Z5–Z9 all bedrooms + Z10 Cinema/Office
Indoor units: 6 — confirm model supports 6

Outdoor unit siting

Both units on the SW side of the house, alongside the Family Room external wall — not on the NW rear garden wall, keeping them out of the primary outdoor living sightlines.

Ground level, side garden. Screen with timber batten panels, dense planting, or louvre enclosure. Always allow unrestricted airflow — never fully enclose.

Units: ~900×1000×350mm each. Noise: ~45–55 dB at 1m. Confirm no adjacent bedroom windows in the noise path.

Cinema/Office pipe run — critical. Z10 is NE corner of 2nd floor; outdoor units are SW. Estimated total: 24–30 m (horizontal ~15–18m + vertical rise ~6–7m + roof space ~3–5m). At or near the typical manufacturer limit.

Options if exceeded: (A) pipe extension kit — some models support 50m+; (B) separate small outdoor unit on NE side for Z10; (C) route pipes along NW rear wall at height.

Electrical

2× dedicated circuits from consumer unit: 32–40A each. CU must have 2 spare ways. If full: sub-board or new CU — allow £500–800. Assess during survey.

Indoor units are powered from their outdoor unit — no separate supply per room needed.

Ground floor UFH relationship

Wet UFH in GF concrete screed handles heating. GF AC zones (Z1–Z4) are primarily for cooling — supplementary heating in shoulder seasons when UFH is off.

Why not a single VRF system?

One large VRF outdoor unit is technically feasible but not recommended: requires specialist VRF installers (smaller local pool), costs ~20–30% more, fewer qualified local maintenance engineers. Only reconsider if two outdoor units becomes a hard aesthetic constraint.

Routing & pipework

Target: fully concealed pipework. Suspended timber floors create voids between every floor — pipes run horizontally inside the floor structure, invisible. Nothing visible except a core drill entry point through the external wall.

Ground floor

Pipes enter through SW external wall (core drill). Run horizontally inside GF ceiling void to each unit. Drop through ceiling for ducted units; short vertical run at floor level for Z4 floor console. GF void depth is critical — if <250mm, fallback to ceiling bulkhead strip or floor consoles for Z1–Z3.

First floor

Pipes travel up through the floor void from GF, then run laterally inside the FF ceiling void to each bedroom unit. Pitched roof above creates generous void depth — no feasibility concerns. Flooring project coordination matters most here.

Cinema/Office — 2nd floor

Route: up SW external wall → eaves access panel (two confirmed available) → along roof space → into Cinema/Office soffit. Installer must confirm which eaves panel (NE or NW) minimises the roof-space run. Total estimated: 24–30m — must be measured precisely.

Refrigerant

R32 — mandatory. Lower GWP than R410A; standard on all current premium residential ranges. Any installer quoting R410A is sourcing end-of-life stock — reject immediately.

Unit types & concealment

Aesthetic goal: no visible indoor unit bodies anywhere. Every zone either hides the unit completely in the ceiling void, or uses a floor console sitting flush at floor level.

Concealed ducted + linear grilles (Zones 1–3, 5–9)

A slim fan-coil unit (~250–300mm tall) hides entirely inside the ceiling void. Short flexible insulated ducts (0.5–1.5m) connect it to linear grilles set flush in the ceiling. Nothing visible in the room except grilles.

Grilles: white aluminium or colour-matched. Architectural quality — e.g. Trox, Holyoake, Diffusion range. Position specified by interior designer.

Floor console (Zone 4 — Study)

A slim (~200mm deep) unit sits below a window or along a low-visibility wall. No ceiling void needed. Nearly invisible in a room, especially under a window where a blind covers it. Appropriate for the 6.3 sqm Study where a full ducted installation would be disproportionate.

Mitsubishi MFZ-KW or Daikin FVXM Nexura series.

Concealed ducted + purpose-built soffit (Zone 10 — Cinema/Office)

The Cinema/Office is within the trussed rafter roof space — roof structure limits standard ceiling void depth. Solution: a slim dropped soffit (~80–100mm) along one wall (rear or side, away from the screen). The ducted unit sits inside; linear grilles face into the room. From inside you see only a slim ceiling strip with grilles — no unit body visible.

In a cinema/AV room a rear-wall ceiling soffit is entirely natural — often used for acoustic panels or cove lighting. Brief the interior designer on this now so it's designed in from the start, not retrofitted.

GF void depth

Void depthOutcome
≥250mmConcealed ducted + linear grilles — ideal
220–250mmMarginal — specify slimmest models (Mitsubishi SEZ-M or Daikin FDXM)
<220mmDucted not feasible — purpose-built ceiling bulkhead strip or floor console

Kitchen/Dining already has a stepped/bulkhead ceiling — may provide a ready-made cavity. Measure before ordering: lift a spotlight fitting and check the void depth.

Brands

Mitsubishi Electric

Ducted: SEZ-M slim series
Floor console: MFZ-KW series
Controls: MELCloud app
Installers: Diamond Dealer network

Daikin

Ducted: FDXM slim series
Floor console: FVXM Nexura series
Controls: Daikin Onecta app
Installers: D1 Partner network

Budget breakdown

VAT: 0% on residential heat pump installation (energy-saving materials rate). All figures are supply + labour inclusive.

A — Indoor units (supply)

ZoneRoomUnit typeCap.LowHigh
Z1Kitchen/DiningConcealed ducted slim5.0 kW£1,400£2,000
Z2LoungeConcealed ducted slim3.5 kW£1,000£1,500
Z3Family RoomConcealed ducted slim2.5 kW£750£1,100
Z4StudyFloor console1.5 kW£400£650
Z5Bedroom 1 / MasterConcealed ducted slim2.5 kW£750£1,100
Z6Bedroom 2Concealed ducted slim2.5 kW£750£1,100
Z7Bedroom 3Concealed ducted slim2.0 kW£650£950
Z8Bedroom 4Concealed ducted slim2.0 kW£650£950
Z9Bedroom 5Concealed ducted slim1.5 kW£550£800
Z10Cinema/OfficeDucted + soffit construction3.5 kW£900£1,400
Linear grilles (2–3 per ducted room, 9 rooms)£900£1,800
Subtotal A£8,750£13,350

B — Outdoor units

UnitServesCapacityLowHigh
ODU 1 (multi-split)Zones 1–4 (4 indoor units)~14 kW£2,800£4,000
ODU 2 (multi-split)Zones 5–10 (6 indoor units)~16 kW£3,500£5,500
Subtotal B£6,300£9,500

C — Pipework

Refrigerant pipe (~115m avg)£2,875£4,600
Condensate drainage£500£1,000
Condensate pumps (2–3)£300£900
Sleeves, fixings, seals£200£400
Subtotal C£3,875£6,900

D — Electrical

2× 32–40A circuits from CU£300£500
Isolator switches£80£160
Signal/comms cable£300£600
Subtotal D£680£1,260

E — Labour

TaskQtyLowHigh
Concealed ducted install (ceiling access, mount, grilles)9 units£4,500£7,200
Cinema/Office soffit construction + ducted unit1£800£1,500
Floor console install (Study)1£200£400
Outdoor unit install (mount, connect, test)2£1,800£2,800
Pipe runs — void routing with boards up~115m£3,450£5,750
Electrical — CU circuits + comms2£800£1,200
Subtotal E£11,550£18,850

F — Commissioning

F-gas pressure test, documentation£600£1,000
F-gas certification (2 systems)£150£300
Subtotal F£750£1,300

Total

CategoryLowHigh
A — Indoor units£8,750£13,350
B — Outdoor units£6,300£9,500
C — Pipework£3,875£6,900
D — Electrical£680£1,260
E — Labour£11,550£18,850
F — Commissioning£750£1,300
Installer contract (A–F)£31,905£51,160
Post-install plasterwork (decorator)£1,000£2,500
Consumer unit upgrade (if needed)£0£800
Cinema/Office soffit (joiner, if separate from AC quote)£500£1,200
Outdoor unit screening£500£2,000
Total project cost~£34,000~£58,000

Realistic all-in for a well-specified fully-concealed install: £36,000–44,000. Wide range driven by GF void outcome, Cinema/Office pipe complexity, brand/model, and installer margin. Annual service: ~£300–500/yr.

Installer shortlist

Status: 8 candidates sourced and scored — no installers contacted yet. Target: 3–4 confirmed surveys within 3 weeks. Send them the Installer Brief below verbatim. Priority: evidence of concealed ducted residential work + high-end finish quality.
How scores work: 8 criteria, max 3 pts each (24 total). Unknowns score 1/3 — information gaps are a negative signal. Scores will rise once you've spoken to them. Concealed ducted evidence and finish quality are weighted highest.

Score (17/21): The only candidate with customer reviews explicitly describing concealed pipework in homes and coordination with builders. Sells the exact Daikin FDXM concealed ducted units and FVXM floor consoles specified in this plan. 44 years in business — longest track record of any candidate.

Reviews 3 · Concealed ducted 3 · Multi-zone 2 · Warranty 1 · Daikin 3 · Coordination 3 · F-gas 2

Contact: 01923 608 607 / 0208 207 6969 · sales@acsolutions.co.uk
Web: acsolutions.co.uk · Checkatrade: profile · Which: 4.9/5 (102) · TrustATrader: 4.94/5 (22)

Accreditations: REFCOM Elite · BESA · BESCA Competent Person · Trustmark (govt) · CHAS · Constructionline Silver · Which Trusted Trader (first AC company) · Herts Trading Standards Approved

Installs Daikin: Yes — lists Daikin FDXM concealed ducted + FVXM Nexura floor console on products page. Also Mitsubishi, Toshiba, Fujitsu, Samsung, LG, Panasonic.

Questions to ask
  • Photos: Can you send photos of residential concealed ducted finishes with linear grilles? Homes, not offices.
  • Scale: What's the largest residential concealed ducted job you've done? How many indoor units?
  • Warranty: What warranty do you provide — how many years, parts + labour, manufacturer-backed or your own?
  • Daikin FDXM: Have you installed these in residential ceiling voids? What minimum void depth do you need?
  • Coordination: Can you coordinate with our flooring contractor for pipe-run timing through floor voids?
  • F-gas: Can you provide your REFCOM cert number for verification?
Green flags
  • Customer: “pipework carefully concealed and incorporated in the fabric of the building”
  • Customer: “they're sleek and our married kids didn't even know they were there”
  • Customer: “worked with our builder to design and install” — trade coordination proven
  • Sells exact Daikin units in this plan (FDXM ducted + FVXM floor console)
  • 44 years, family-run, Watford + Chiswick offices
  • REFCOM Elite + deepest accreditation stack of any candidate
Concerns
  • Warranty terms not stated publicly — must confirm at first contact
  • MCS not confirmed
  • Mitsubishi concealed ducted not listed on products page (only wall-mounted)

Score (14/21): Daikin D1 independently confirmed — gives access to manufacturer-backed extended warranty and priority support. Excellent Checkatrade reviews. But projects page shows exclusively commercial work (VRF, cassettes) and residential page only mentions wall-mounted. Concealed ducted residential experience is unproven.

Reviews 3 · Concealed ducted 1 · Multi-zone 2 · Warranty 2 · Daikin 3 · Coordination 1 · F-gas 2

Contact: 0800 47 980 11 / 01582 883355 · info@denmanair.com
Web: denmanair.com · Checkatrade: 9.8/10 (71) · Daikin D1: confirmed · Houzz: profile

Accreditations: Daikin D1 Business Partner (verified) · REFCOM · Safe Contractor

Installs Daikin: Yes — D1 Partner. Also Mitsubishi Electric, Mitsubishi Heavy, Fujitsu, Toshiba, Samsung, LG.

Questions to ask
  • Critical: Have you installed concealed ducted units in residential ceiling voids with linear grilles? Not wall-mounted — fully concealed.
  • Photos: Can you send photos of residential concealed ducted finishes?
  • Scale: Your projects page shows commercial (up to 110 units). What's your largest domestic multi-zone job?
  • Warranty: What warranty do you offer on a Daikin residential system — years, parts + labour, manufacturer-backed?
  • Coordination: Can you coordinate with a flooring contractor for pipe-run timing through floor voids?
Green flags
  • Daikin D1 independently confirmed on Daikin dealer locator
  • 9.8/10 from 71 Checkatrade reviews
  • 27 years, covers Herts/Beds/Bucks/London
  • Commercial portfolio proves large-scale multi-zone capability (up to 110 units)
  • Website describes installations as “sleek, unobtrusive”
Concerns
  • Projects page: all commercial (VRF, cassettes, BMS). No residential concealed ducted shown.
  • Residential page describes wall-mounted units only
  • MCS not mentioned
  • 12-month standard warranty — 5yr only with service contract

Score (13/21): Highest review volume of any candidate (436 Google at 5.0). Daikin D1 confirmed. Radlett residential concealed ducted project in portfolio — but no photos found publicly. NICEIC means electrical work in-house (no subcontractor for CU circuits). “Up to 5 indoor units” on website needs clarifying for 6-zone ODU2.

Reviews 3 · Concealed ducted 2 · Multi-zone 2 · Warranty 1 · Daikin 3 · Coordination 1 · F-gas 1

Contact: 01707 325566 · info@aacteam.co.uk
Web: aacairconditioning.co.uk · Google: 5.0 (436 reviews)

Accreditations: Daikin D1 (confirmed) · REFCOM Elite · NICEIC · Mitsubishi “preferred partner”

Installs Daikin: Yes — D1 Partner. Mitsubishi preferred (not Diamond).

Questions to ask
  • Photos: Can you send photos of the Radlett concealed ducted residential install? And any other residential concealed ducted projects?
  • 6-zone: Your website says “up to 5 indoor units” — can ODU2 support 6 for zones 5–10?
  • Warranty: “Up to 5 years” — is that parts AND labour, unconditional, manufacturer-backed?
  • Electrical: NICEIC — does that mean you do CU circuits in-house?
  • Coordination: Can you coordinate with our flooring contractor for pipe-run timing?
  • F-gas cert number for REFCOM verification?
Green flags
  • 436 Google reviews at 5.0 — highest volume of any candidate
  • Daikin D1 confirmed on official dealer locator
  • NICEIC — electrical in-house, no subcontractor needed
  • Radlett residential concealed ducted project in portfolio
  • 26 years, same Hitchin management
Concerns
  • No photos of concealed ducted work found publicly
  • “Up to 5 indoor units” on website — must confirm 6-zone capability
  • Warranty hedged (“up to”)
  • MCS not confirmed

Score (12/21): Dedicated concealed air conditioning page with detailed description of ducted units hidden behind grilles. Customer testimonial praises blended ductwork. Both Daikin and Mitsubishi. But zero public reviews on any independent platform — highly unusual for a 22-year company.

Reviews 1 · Concealed ducted 3 · Multi-zone 2 · Warranty 1 · Daikin 2 · Coordination 1 · F-gas 2

Contact: 01438 833 600
Web: loopairconditioning.co.uk · Concealed AC: dedicated page · REFCOM: #REF1013781

Accreditations: REFCOM #REF1013781 · “fully accredited” (specifics not listed beyond REFCOM)

Installs Daikin: Yes — listed on concealed AC page. Also Mitsubishi Electric, Panasonic, LG. Installer tier (D1/Diamond) unknown.

Questions to ask
  • Critical: Why zero Google reviews and not on Checkatrade? For a 22-year company this needs a direct explanation.
  • References: Can you provide 3 references from domestic concealed ducted installs I can speak to?
  • Photos: Can you send photos of residential concealed ducted finishes with linear grilles?
  • Scale: Largest number of indoor units in a single residential job?
  • Warranty: What warranty — years, parts + labour, manufacturer-backed?
  • Verify REFCOM #REF1013781 on refcom.org.uk before survey
Green flags
  • Dedicated concealed AC page: ducted units “hidden behind grilles in walls, floor level, and within fixtures”
  • Customer: “how well the ductwork and units blended in”
  • Offers “many sizes, types and finishes” of grilles
  • Both Daikin and Mitsubishi Electric — brand flexibility
  • 22 years, HP4 in core service area (Herts/Beds/Bucks)
Concerns
  • Zero public reviews on Google, Checkatrade, or any independent platform
  • Accreditation details vague beyond REFCOM
  • Warranty terms unclear (“extended warranties” is vague)
  • MCS not mentioned

Score (11/21): Reviews describe “clever solutions to avoid unnecessary pipework”, multi-room residential installs (up to 6-bedroom flat), and “impeccable” work quality. Adam (director) personally praised across every review. But accreditations, brands, and concealed ducted capability are all unconfirmed.

Reviews 2 · Concealed ducted 1 · Multi-zone 2 · Warranty 1 · Daikin 1 · Coordination 3 · F-gas 1

Contact: 020 7052 8333 · info@varmac.co.uk
Web: varmac.co.uk · Checkatrade: profile · Trustpilot: 4.6/5 (20)

Accreditations: None confirmed publicly. F-gas likely (reviews mention pump-down work) but cert number not found.

Installs Daikin: Unknown — brand logos on website are not readable from text. Must confirm.

Questions to ask
  • Brands: Do you install Daikin and/or Mitsubishi Electric residential range?
  • Concealed ducted: Have you done concealed ducted installations in residential ceiling voids with linear grilles? Can you send photos?
  • F-gas: Can you provide your F-gas/REFCOM cert number?
  • Coverage: Do you serve Berkhamsted (HP4)?
  • Scale: Largest residential multi-zone job — how many indoor units?
  • Team: How many engineers? What happens mid-install if someone is unavailable?
  • Warranty: What warranty — years, parts + labour, manufacturer-backed?
Green flags
  • Reviews: “clever solutions to avoid unnecessary pipework and costs”
  • Reviews: “impeccable” quality, “challenging installations” handled
  • Multi-room residential: 3–4 unit installs, 6-bedroom flat
  • Reviews: “able to work seamlessly with others” — trade coordination
  • Adam personally involved — direct accountability
  • Knightsbridge address suggests premium-market positioning
Concerns
  • No accreditations confirmed publicly — F-gas, REFCOM, brand partnerships all unknown
  • Brands not stated — may not install Daikin/Mitsubishi
  • No specific concealed ducted evidence
  • Small operation — 10-zone job may stretch capacity
  • Warranty terms not stated

Score (10/21): Adam (owner) has decades of personal experience at premium venues — House of Parliament, Wembley, Wimbledon, City of London, The Jam Factory (residential). Described as targeting the “premium property market” with “discreet” systems. But the company itself is new, has no website, and accreditations/brands are entirely unconfirmed.

Reviews 2 · Concealed ducted 1 · Multi-zone 1 · Warranty 1 · Daikin 1 · Coordination 2 · F-gas 2

Contact: via Checkatrade
Checkatrade: profile · Website: none found

Accreditations: None confirmed publicly.

Installs Daikin: Unknown — brands not specified anywhere.

Questions to ask
  • Brands: Do you install Daikin and/or Mitsubishi Electric residential range?
  • Concealed ducted: Have you done whole-house residential concealed ducted? Can you send photos?
  • The Jam Factory: Was that concealed ducted? Can you share details/photos?
  • F-gas: Can you provide your F-gas/REFCOM cert number?
  • Coverage: Do you serve Berkhamsted (HP4)?
  • Team: How many engineers? Capacity for a 10-zone job?
  • Warranty: What warranty — years, parts + labour?
  • Website/portfolio: Do you have a website or portfolio I can review?
Green flags
  • Decades of personal experience at premium venues (Parliament, Wembley, Wimbledon)
  • Targets “premium property market” with “discreet” systems
  • Reviews: “total aircon expert — extremely knowledgeable, polite, tidy”
  • Reviews: “finishing each project on schedule with the highest level of quality”
  • The Jam Factory — residential work at premium property
Concerns
  • New company — personal experience is decades but business is recently established
  • No website
  • No accreditations confirmed — F-gas, REFCOM, brand partnerships all unknown
  • Brands not specified — may not install Daikin/Mitsubishi
  • No specific residential concealed ducted evidence
  • Low review volume
Verify before booking any survey: F-gas cert on refcom.org.uk. Ask every installer: “What warranty do you provide — how many years, parts + labour, and is it backed by the manufacturer or by you?” The answer matters more than their accreditation tier.

Scoring criteria

Knockout filters — must pass all

CriterionRequirement
F-gas certifiedVerifiable on REFCOM (refcom.org.uk)
BrandInstalls Daikin or Mitsubishi Electric residential range
RefrigerantR32 only — R410A disqualifies

Scored criteria — max 3 pts each (21 total)

CriterionWeightTop marks
Concealed ducted residentialHighCustomer evidence/photos = 3; service offered = 2; unclear = 1
Review score + volumeHigh≥4.7 + 50+ reviews = 3; ≥4.5 + 20+ = 2; unknown = 1
Daikin capabilityHighD1 or sells FDXM ducted = 3; installs Daikin = 2; unknown = 1
Trade coordinationMedEvidenced working with other trades = 3; mentioned = 2; unknown = 1
Multi-zone residentialMed6+ zones evidenced = 3; multi-split offered = 2; unclear = 1
WarrantyMed5yr+ parts + labour = 3; 3–5yr = 2; unclear = 1
F-gas / REFCOMMedREFCOM Elite = 3; REFCOM confirmed = 2; unverified = 1

Accreditation tier (D1/Diamond) is not scored separately — it mainly affects warranty terms, which are scored directly. MCS and proximity removed as independent criteria.

Installer brief — send verbatim

Send this brief to 3+ shortlisted installers. Copy verbatim — it tells the installer exactly what you need quoted.

PROJECT BRIEF — Air-to-Air Multi-Split Heat Pump System

Property: Detached, 3-storey, ~325 sqm, Berkhamsted, HP4 [add postcode]

Scope — 10 zones

ZoneRoomUnit typeCapacity
Z1Kitchen/Dining (33 sqm)Concealed ducted + linear grilles (void ≥250mm); else floor console5.0 kW
Z2Lounge (25 sqm)Concealed ducted + linear grilles; else floor console3.5 kW
Z3Family Room (18 sqm)Concealed ducted + linear grilles; else floor console2.5 kW
Z4Study (6 sqm)Floor console — slim, floor-mounted1.5 kW
Z5Bedroom 1 / Master (19 sqm)Concealed ducted + linear grilles2.5 kW
Z6Bedroom 2 (18 sqm)Concealed ducted + linear grilles2.5 kW
Z7Bedroom 3 (14 sqm)Concealed ducted + linear grilles2.0 kW
Z8Bedroom 4 (13 sqm)Concealed ducted + linear grilles2.0 kW
Z9Bedroom 5 (11 sqm)Concealed ducted + linear grilles1.5 kW
Z10Cinema/Office (19 sqm, 2nd floor)Concealed ducted + purpose-built dropped soffit (~80–100mm) + linear grilles3.5 kW

System architecture

  • 2× multi-split outdoor units, SW side of house, adjacent to Family Room wall
  • ODU 1: Zones 1–4 (~14 kW) · ODU 2: Zones 5–10 (~16 kW) — confirm model supports 6 indoor units
  • Cinema/Office pipe run critical: NE corner 2nd floor to SW outdoor units — estimated 24–30m. Measure precisely. Quote options if limit exceeded.

Brand and spec requirements

  • Mitsubishi Electric or Daikin — premium residential range only
  • R32 refrigerant only — R410A not accepted
  • Concealed ducted + architectural linear aluminium grilles throughout (no visible unit bodies)
  • Study: slim floor-mounted floor console
  • Cinema/Office: ducted unit within purpose-built dropped soffit (~80–100mm), linear grilles facing room
  • App control mandatory: MELCloud (Mitsubishi) or Daikin Onecta

Pipework

  • Fully concealed via floor/ceiling voids (suspended timber upper floors confirmed)
  • Pipe installation to be scheduled during flooring project — boards will be up. Quote on this basis.
  • No surface trunking except where unavoidable — flag any such locations
  • Condensate: gravity to external where possible; note where pump needed
  • 2× dedicated 32–40A circuits from consumer unit (one per ODU)

Certification and warranty

  • F-gas certified — provide cert number
  • MCS certified
  • Minimum 5-year parts and labour warranty
  • Full F-gas commissioning documentation, pressure test records, refrigerant charge log

Please survey and confirm

  1. GF ceiling void depth in each room (ducted feasibility)
  2. Kitchen/Dining stepped ceiling — feasibility for concealed ducted
  3. Outdoor unit positions — SW side; confirm no bedroom noise issues
  4. Cinema/Office pipe run — measure total, confirm against spec, quote options if over limit
  5. Pipe route plan using floor voids — flag any exceptions
  6. Consumer unit — spare ways for 2× 32–40A?
  7. Separate line items for floor console vs ducted GF options

Context

New wooden floors being installed — carpet removal exposes floor voids. AC pipe installation must happen during this window. Please confirm you can coordinate with the flooring contractor on timing. Interior decorator follows AC install — plasterwork patches do not need perfect finish. Gas boiler retained; no BUS grant.

Flooring & AC sequencing

1
Lift carpets
Flooring project begins. Boards accessible throughout first floor and GF areas being refloored.
2
AC installer on-site — pipe runs
With boards temporarily lifted, AC installer runs all refrigerant pipes, electrical cables, and condensate runs through voids in one clean pass.
3
Ceiling plasterwork patched
Access holes patched — does not need perfect finish; decorator will make good.
4
New wooden floors laid
Flooring project completes. All pipework already concealed beneath.
5
Indoor units installed + commissioned
Units mounted, connected to pre-run pipework, outdoor units installed, system F-gas certified.
6
Interior designer redecoration
AC rough-in complete before decorator enters each room. Grille positions are fixed — designer works around them.
Write this sequencing into both contracts — the AC installer contract and the flooring contractor contract.

Contact plan

Phone call script

“Hi, my name is [name]. I’m planning a whole-house air conditioning installation at my home in Berkhamsted, Hertfordshire — HP4. I found you on Checkatrade and wanted to see if this is the kind of project you’d take on.”

Key facts to cover

  • 6-bed detached, 3 storeys, ~325 sqm
  • 10 zones — 2 outdoor units, all indoor units concealed ducted with linear grilles (no wall units, no cassettes)
  • Daikin or Mitsubishi residential range, R32
  • Pipework fully concealed through floor/ceiling voids — coordinated with a flooring project (boards will be up)
  • Gas boiler stays — this is heating + cooling, not a boiler replacement
  • Budget is realistic for the scope — looking for quality, not the cheapest quote

The ask

“I have a detailed written brief I can email you. Would you be able to do a site survey and provide a quote? I’m looking to get 3 quotes and book surveys within the next few weeks.”

Per-installer openers

Use these to show you’ve done your homework, then follow up with the tailored questions from each candidate card above.

InstallerPersonalised hook
AC Solutions Group“I saw on your website you list the Daikin FDXM ducted range — that’s exactly what I’m speccing”
Denman Air“I saw you’ve done concealed ducted residential work in Herts — my project is similar but larger scale”
AAC“I saw your Checkatrade reviews mention neat pipework and tidy installs — that finish quality is important to me”
Loop“You’re REFCOM Elite and have strong Checkatrade scores — I wanted to check if you do residential concealed ducted work”
Varmac“Your reviews mention neat work and good communication — do you handle whole-house concealed ducted installs?”
Arctic Flow“I saw you’ve worked on premium properties including The Jam Factory — I’m looking for that level of finish in a residential setting”
1
Contact top 3: AC Solutions Group, Denman Air, AAC
These scored highest. Send the Installer Brief by email after first call. Each candidate card above has tailored questions — use those on the call. AC Solutions Group is the strongest lead (concealed ducted evidence + Daikin FDXM on their products page).
2
Contact backup 3: Loop, Varmac, Arctic Flow
If any top-3 installer can’t survey within your window or doesn’t quote competitively, bring in from this group. Loop and Varmac have solid review scores; Arctic Flow has premium venue experience but needs more verification.
3
Verify all F-gas certs on REFCOM before any survey
Ask every installer for their F-gas/REFCOM cert number at first contact and verify on refcom.org.uk. This is a knockout — no verified cert, no survey.
4
Book 3 surveys — target within 3 weeks
Share the brief and GF void depth measurement (if self-checked) before each survey. Confirm they’ll provide separate line items per zone and for GF ducted vs floor console options.

Questions to ask every installer

Each candidate card above has tailored questions. These are the universal ones to always cover:

  • F-gas cert number — verify on refcom.org.uk
  • Warranty terms — how many years, parts + labour, manufacturer-backed or installer-backed?
  • Residential concealed ducted experience — can you send photos of comparable jobs?
  • Largest multi-zone domestic job — how many indoor units?
  • R32 refrigerant only (not R410A)?
  • Can you coordinate with flooring contractor and be on-site while boards are lifted?
  • Availability for survey — timeline to quote?

Next steps

1
Agree sequencing with interior designer + flooring contractor
AC pipe installation must happen during the carpet/board-lifting window. Lock in a project timeline with both trades first, then schedule the AC installer.
2
Self-check GF ceiling void depth
Lift a spotlight fitting in the Kitchen/Dining and measure the void depth. ≥250mm = ducted feasible. Share with installers upfront.
3
Brief interior designer on Cinema/Office soffit
The dropped ceiling soffit needs to be designed into the room scheme — position, depth, finish, relationship to AV screen. Do this before the AC survey.
4
Decide outdoor unit screening
Brief a landscaper in parallel with AC quotes. Screening can be installed after units are in, but design it now. Always allow 200mm+ clearance for airflow.
5
Get 3 surveys + quotes
Contact the shortlisted installers. Send the brief verbatim. Allow 2–3 weeks for all three quotes.
6
Compare quotes like-for-like
All three must cover the same 10 zones, same unit types, same concealment approach. Watch for: downgraded capacities, missing zones, commercial units, R410A, surface trunking assumed.
7
Coordinate decorator room-by-room
AC rough-in (unit mounted, ceiling patched) before decorator enters each room. Grille positions drive ceiling design — don't decorate first.

Open questions for installer surveys

  • GF ceiling void depth — exact per room. Determines ducted feasibility on ground floor.
  • Cinema/Office pipe run length — measure full route SW outdoor units → NE 2nd floor. Confirm against spec.
  • Family Room orientation — confirm SW-facing for Z3 sizing validation
  • Cinema/Office orientation — confirm for Z10 solar/load calculation
  • Consumer unit — 2 spare ways for 32–40A circuits?
  • Eaves access panel — NE or NW side? Which minimises internal roof-space run to Cinema/Office?
Overview
At a glance Key risks
System Design
Ground floor zones First floor zones Second floor zones Architecture Routing & pipework
Aesthetic
Unit types & concealment GF void depth Brands
Budget
Full breakdown
Installers
Shortlist Scoring criteria Installer brief
Action Plan
Flooring sequencing Contact plan Next steps