Boiler House Replacement — Tender Submission
We are pleased to submit our revised Tender Letter Proposal for the replacement of the heat source and associated mechanical, electrical, public-health and controls infrastructure at the B99 Malthouse Block boiler house, Kettlewick College, Somerset. This tender is submitted to Grimshaw & Bolt Ltd as Principal Contractor in their capacity acting on behalf of Kettlewick Estates as Employer.
This submission supersedes any earlier draft. It reflects further commercial review undertaken with the Grimshaw & Bolt team (in particular discussions with Jamie at GB on 24 April 2026), revised scope decisions on temporary heating provision and licensed asbestos removal, and refined preliminaries reflecting Built AI's role as MEP sub-contractor under the Principal Contractor.
A schedule of six independently-electable Value Engineering options is presented in the dedicated VE Options tab of the Priced Bill of Quantities workbook. These offer a maximum potential aggregate saving of £56,736.86 if all six are accepted:
Built AI Ltd is a Gas Safe registered, NICEIC approved contractor with a proven track record on heritage and Defence-estate mechanical installations. All works are priced under our standard JCT IC 2016 sub-contract terms with Contractor's Design Portion.
We look forward to supporting Grimshaw & Bolt Ltd in delivering this critical heat-source upgrade to Malthouse Block and remain available for tender clarification, post-tender interview and pre-contract survey at your convenience.
Yours faithfully,
Built AI LtdThis Tender Letter Proposal contains seven principal sections. Each section addresses a distinct facet of the proposal — scroll through, or jump to a section using the navigator above.
The Kettlewick College at Kettlewick is a Grade II* listed, operationally-live officer-training establishment of the Royal Navy. The Malthouse Block boiler house in Building B99 serves the principal accommodation block via a primary LTHW circuit and DHW secondary. Existing plant — five Wessex boilers, two Hamworthy DHW generators and associated Nalco pressurisation equipment — is end-of-life and requires complete replacement during the summer-term stand-down window of July–September 2026.
Kettlewick Estates, on behalf of the Kettlewick Estates, has procured Grimshaw & Bolt Ltd as Principal Contractor for the delivery of this project. Built AI Ltd is engaged as the Mechanical, Electrical, Public Health and Controls-interface sub-contractor under the JCT IC 2016 sub-contract with Contractor's Design Portion.
The tender is priced on the basis of the following governing documents and standards:
In the event of conflict between source documents, the following hierarchy of precedence is adopted:
| Role | Party |
|---|---|
| Employer | Kettlewick Estates |
| Employer's Agent / Contract Administrator | Grimshaw & Bolt Ltd (or as nominated by Kettlewick Estates) |
| Principal Contractor (CDM 2015) | Grimshaw & Bolt Ltd |
| Principal Designer (CDM 2015) | As nominated by Grimshaw & Bolt / Employer |
| MEP Designer (RIBA Stage 3/4) | Services Design Solution Ltd |
| MEP / PH / Controls Sub-Contractor (CDP) | Built AI Ltd |
| Licensed Asbestos Removal Contractor | Separately appointed (TBC) |
| Temporary Heat Continuity Provider | Grimshaw & Bolt Ltd |
This Tender Letter Proposal is issued in commercial confidence to Grimshaw & Bolt Ltd and the Employer and may not be reproduced or disclosed to third parties without the written consent of Built AI Ltd.
The solution strips out the redundant Wessex boilers, DHW generators and Nalco pressurisation equipment in the B99 boiler house and installs a new fully-condensing modular gas-fired cascade, packaged thermal storage, paired DHW plate-heat-exchanger skids, new pressurisation, gas-safety and cold-water boost packages, plus all associated controls, electrical and builders' work.
Three IDEAL Commercial EVO Max 2 — 150 kW fully-condensing, pre-mix gas-fired modular boilers in back-to-back cascade, 450 kW combined, turndown to ~11 kW. Per SBS Quote 18-SQ0023969 Ver 1.
3 × 2,000 L vertical thermal stores (PD 5500 Cat 3) on bespoke 3-vessel frame. 2 × Stokvis Econoplate 700 kW DHW PHEs. VE 1, 2, 4, 5 offer alternatives.
Grundfos MAGNA3 D / MAGNA1 / AP50 pump suite. Flamco PressDS digital pressurisation. Arrow Boost-A-Break Tank Set. VE 6 offers DAB ESYTANK substitute.
New Gas Safety Panel (Merlin 1000) with pressure-proving, fail-safe SBS GSV065 solenoid valve, leak detection, BMS volt-free shutdown contact.
Section F6 carried as Prime Cost Sum. Allowance for Mechanical Control Panel, 54-point I/O outstation, field sensors and control valves, programming, SAT.
New Schneider Merlin Gerin Acti 9 12-way 125 A TP&N DB. New sub-main from Malthouse Block main LV panel. Full BS 7671:2018+A2:2022 + NICEIC certification.
Strip-out, EI 120 fire-stopping (BS 9999), reinforced-concrete plinths, sump pit, skylight remove-store-reinstate, chimney top repointing.
Provided directly by Grimshaw & Bolt Ltd as Principal Contractor. Built AI provides hydraulic / electrical / BMS interface points only.
BS 5422 closed-cell phenolic foam to all LTHW, DHW and gas pipework, with proprietary boxes and removable jackets at valves and large-bore equipment.
Hydraulic pressure test, BSRIA BG 29/2020 chemical clean and dose, gas tightness IGEM/UP/1, BS 7671 Part 6, BMS point-by-point, witness commissioning, BG 1/2007 O&M.
Single-page interface map for all parties on the project. Built AI sits in the centre as MEP sub-contractor and provides interface points to all other parties.
Twelve detailed sections covering every aspect of the works. Click any section to expand. The full PDF version contains line-by-line detail across 17 pages — the headline content is captured below.
The Works comprise the complete replacement of the existing heat source and associated mechanical, electrical, public-health and controls infrastructure within the B99 Malthouse Block boiler house at Kettlewick College.
Kettlewick College, Malthouse Lane, Kettlewick, Somerset, BA22 9KW. Grade II* listed, live-operational Defence estate with restricted access and site-specific safety rules administered by the Estate.
Mechanical / electrical / public-health sub-contract under JCT Intermediate Building Contract 2016 with Contractor's Design Portion, executed between Built AI Ltd and Grimshaw & Bolt Ltd.
Precedence as set out in Section 8.2.3 of this Tender Letter Proposal.
As set out in Section 8.2.2 of this Tender Letter Proposal.
Grimshaw & Bolt Ltd is the Principal Contractor under CDM 2015 Regulations 13–16. Built AI operates as a sub-contractor under the GB Construction Phase Plan, Site Rules and inductions.
Project management delivered by an experienced part-time Project Manager aligned with the 14-week programme. Site supervision delivered by a Site Supervisor (SSSTS / SMSTS) full-time on site.
Temporary Works Coordinator (TWC) appointed in accordance with BS 5975:2019 covers all Built AI-instigated temporary works — heavy-plant lift-in rigging, scaffold access, temporary supports.
Site office, welfare, secure storage, perimeter HERAS fencing, compound signage, site electrical / water / sewer connections, broadband, daily site cleaning and waste management — all administered by GB.
Detailed programme issued at LOI; weekly progress reports; risk register maintained throughout.
ISO 9001-aligned QA processes; ITP register; BIM-360 / equivalent for snagging; Final Account documentation.
CAR; EL £10m; PL £10m; PI £5m on CDP element. Certificates available on instruction.
≥ 95 % waste diverted from landfill; chemical spill containment; noise / dust mitigation per BS 5228.
Daily site coordination meetings; weekly progress meetings; monthly H&S audit. RFI and document control via project record system.
BSRIA BG 1/2007 format; final O&M issued at PC; manufacturer warranties registered.
Built AI 24-hr named contact maintained throughout the works.
Stage 4a confirmatory surveys verifying SDS Ltd Stage 3/4 design before procurement commitment.
Total-station dimensional check; lift-in path verification; clash-detection against retained M&E.
Supply pressure, capacity, meter ratio verification — pre-commissioning gas tightness test to IGEM/UP/1.
Existing Malthouse main LV panel: spare way confirmation, fault level, earthing reference.
Existing flue void confirmed structurally adequate for new flue. Termination, weather sealing, backdraught design verified.
SDS Ltd Doc 23 Risk Tracker B2.1 to B2.6 closed out via Stage 4a investigations.
Skylight survey, chimney condition, condensate / foul drainage adequacy.
Temporary heating and DHW continuity is provided by Grimshaw & Bolt Ltd as Principal Contractor. Built AI excludes temp boiler hire, fuel, daily maintenance, gas-safety check and removal.
Built AI provides hydraulic / electrical / BMS interface points; pre-cut-over briefing; post-cut-over de-mobilisation handover.
Joint programme issued at LOI; cut-over Phase 9 (Week 13–14) under AP (Heating) Permit-to-Work; single-day operation.
GB retains full responsibility for temp boiler performance, fuel supply continuity, statutory compliance.
Controlled, sequenced removal of redundant plant. Built AI commences only after LARC Certificate of Reoccupation issued.
5 × Wessex boilers; 2 × Hamworthy DHW generators; 2 × Nalco buffer vessels; existing MCP and pipework; redundant flue.
All ACMs (asbestos-containing materials) handled by separately-appointed LARC under CAR 2012. Pre-condition for Built AI strip-out.
Scrap metal removal in Built AI scope; scrap metal audit / value reconciliation excluded.
Phase 2 (Week 1-4) under continuous LARC Certificate. Heat continuity maintained via GB temp boiler throughout.
All penetrations made good ready for new plant installation. Floor protection maintained.
All builders' work in connection with the Works. Internal redecoration excluded.
EI 120 fire-stopping (BS 9999) at all penetrations. Intumescent collars to plastic services. Fire-stopping certificates issued.
Internal boiler-house redecoration (D8 / D9 / D10 series) excluded.
Skylight removed Phase 4 Mon AM; reinstated Phase 4 Fri PM. 5-day window. Heritage-compliant reinstatement.
Lime mortar repointing to match existing. Conservation Officer sign-off as required.
Reinforced concrete plinths to BS EN 1992 design. 7-day cube test verification before plant lift-in.
Existing low-level services diverted clear of lift-in path. Reinstated post-lift.
New sump pit + AP50 submersible pump for condensate drainage.
Boarded floor protection throughout. Final clean at PC.
Existing fittings (light fittings, signage) removed and reinstated as required.
Plant-room final clean at PC; common-route clean throughout the works.
Complete installation of all M&PH plant and pipework per SDS Ltd design. 15 sub-sections covering boilers through water treatment.
3 × IDEAL Commercial EVO Max 2 — 150 kW. 450 kW combined. Common header. Per SBS Quote 18-SQ0023969 Ver 1.
Common header arrangement; primary LTHW circulation; thermal store charge / discharge.
3 × 2,000 L vertical thermal stores (PD 5500 Cat 3) on 3-vessel frame. VE 1 offers consolidation.
2 × Stokvis Econoplate 700 kW DHW PHE skids providing N+1 resilience. VE 2 offers consolidation; VE 4 offers UKE substitution.
1 × Stokvis Econoplate 250 kW. VE 5 offers UKE-5 bare format.
Grundfos MAGNA3 D twin-head; MAGNA1; AP50 sump pump.
2 × Flamco Flexfiller 225DS digital + expansion vessels.
Arrow Valves Boost-A-Break Tank Set, WRAS Cat 5. VE 6 offers DAB ESYTANK PRO substitute.
Twin-wall CE-marked V-band clamped, 4-hr FR. VE 3 offers 3-hr FR.
Gas Safety Panel (Merlin 1000); SBS GSV065 65 nb solenoid; pressure-proving; leak detection; BMS shutdown.
Albion brand schedule per SDS specification. Strainers, regulators, gauges, drain points.
BS 5422 closed-cell phenolic foam to all primary services. Removable jackets at valves.
BSRIA BG 29/2020 chemical clean & dose. Sentinel X100 corrosion inhibitor.
Boosted cold water; condensate drainage; trade-effluent discharge to standard surface-water drainage.
Section F6 carried as Prime Cost Sum within Section F tender total. Drawn down at GB instruction.
Mechanical Control Panel (MCP); 54-point I/O outstation; field sensors & control valves; cause-and-effect programming; Site Acceptance Testing; head-end licensing.
Appointed by GB at Phase 7 (Week 9-10). Built AI provides hook-ups, sensor pockets, conduit / containment ready.
Built AI BMS specialist returns at PC + 4 months for summer / seasonal commissioning revisit (1 day).
Full electrical installation to BS 7671:2018+A2:2022 with NICEIC certification.
Schneider Merlin Gerin Acti 9 DB/BH 12-way 125 A TP&N. Type B/C MCBs.
LSZH-SWA sub-main from existing Malthouse Block main LV panel. Stage 4a-derived rating.
Galvanised cable tray; conduit to outstation; segregation of services.
Full equipotential bonding; supplementary bonding to all metalwork; main earth conductor.
13 A switched outlets at convenience locations; LED task lighting; LED emergency lighting (BS 5266).
Fire alarm loop extension by existing FA maintainer (sub-let). Smoke detection in plant-room.
Bonding to existing lightning protection where applicable. Survey verification.
E-stop button at plant-room entrance; gas solenoid trip; BMS notification.
Hydraulic pressure test; flushing; gas tightness; insulation resistance; loop continuity.
BSRIA BG 29/2020 chemical clean & dose; OEM commissioning attendances; balancing.
IDEAL (4 wks notice, 2 days), Stokvis (2 wks, 2 days), Flamco (2 wks, 1 day), Arrow Valves (2 wks, 1 day).
Formal witness session: 10 working days notice, scheduled Mon 5 to Tue 6 Oct 2026.
Boiler seasonal efficiency test, PHE heat-transfer rate verification, DHW peak functional test, thermal-store charge/discharge logging excluded.
5-month aftercare attendance excluded. BMS summer revisit included in Section E.
As-built drawings; commissioning records pack; BSRIA BG 1/2007 format O&M.
Practical Completion Friday 9 October 2026. PC certificate issued. H&S File contributions to GB.
BSRIA BG 1/2007 format. Hard copy + searchable digital. Manufacturer warranties registered.
2 × 4 hour training sessions for Kettlewick College FM team. Boiler operation, BMS overview, emergency procedures.
12 months Defects Liability from PC. Manufacturer warranties registered.
Routine reactive break-fix maintenance during DLP excluded — covered under separate maintenance contract if required.
£17,500 total across I1.1–I7.1. Client-led drawdown only against Employer instruction.
BMS / Controls Specialist drawn down at GB instruction at Phase 7 mobilisation.
Standard JCT IC 2016 Schedule 2 daywork rates apply. Applicable only to Employer-instructed variations.
See Section 8.5 Exclusions for the full schedule.
For each major project activity, the matrix below shows which party is Responsible (does the work), Accountable (final sign-off), Consulted (provides input), or Informed (kept in the loop).
| Activity | Built AI | Grimshaw & Bolt | SDS LtdMEP Designer | LARC | BMSSpecialist | KettlewickEstates |
|---|---|---|---|---|---|---|
| Pre-construction submittals (RAMS, COSHH, CDP design) | R | A | C | — | — | I |
| Construction Phase Plan & F10 | I | R/A | — | — | — | I |
| Licensed asbestos removal & 4-stage clearance | — | C | — | R/A | — | I |
| Temporary heating & DHW continuity | C | R/A | — | — | — | I |
| Strip-out of redundant boilers & DHW gen. | R | A | — | C | — | I |
| Builders' work, plinths, fire-stopping | R | A | C | — | — | I |
| Heavy-plant lift-in (boilers, TS, PHEs) | R | A | C | — | — | I |
| Primary LTHW / DHW pipework install | R | A | C | — | C | I |
| Gas pipework + Gas Safety Panel | R | A | C | — | C | I |
| Electrical sub-main + DB + BS 7671 install | R | A | C | — | C | I |
| BMS install + 54-point I/O + programming | C | A | C | — | R | I |
| BSRIA BG 29 chemical clean / flush / dose | R | A | C | — | — | I |
| Witness commissioning | R | A | I | — | C | C |
| Practical Completion & handover | R | A | I | — | C | C |
| 12-month Defects Liability Period | R | A | I | — | I | C |
In the event of any conflict between this schedule and the Scope of Works at Section 8.4, this schedule shall take precedence for the purposes of commercial interpretation.
The following are explicitly excluded from the Built AI tender sum.
The full client-facing Priced Bill of Quantities is issued as a separate workbook — B99_Malthouse_Block_Priced_BoQ_Rev1_Client.xlsx — containing the line-item Priced BoQ, Section Summary, and VE Options tabs. The narratives and headline tender summary below provide the client-facing overview.
| Sec | Description | Section Total (£) |
|---|---|---|
| A | Preliminaries (sub-contractor basis) | 51,525.60 |
| B | Surveys and Investigations | 8,298.32 |
| C | Strip-Out, Removal, Demolition | 26,376.53 |
| D | Builders' Work in Connection | 29,596.31 |
| E | Testing and Commissioning | 27,601.09 |
| F | Mechanical and Public Health Services (incl. F6 PC Sum) | 296,990.48 |
| G | Electrical Services | 24,066.00 |
| H | Statutory | — |
| I | Provisional Sums (Doc 23 Table 18) | 17,500.00 |
| FIXED TENDER TOTAL (ex VAT) | £481,954.33 |
| VE | Option | Saving (£) |
|---|---|---|
| 1 | Thermal Store Consolidation (1 × 6,000 L vs 3 × 2,000 L) | 9,122.00 |
| 2 | DHW PHE Consolidation (1 × vs 2 × 700 kW Stokvis) | 24,200.00 |
| 3 | Flue Fire-Resistance Rating (3-hr vs 4-hr FR) | 3,000.00 |
| 4 | DHW PHE Supplier Substitution (UKE for Stokvis, per PHE) | 9,401.42 |
| 5 | Heating PHE Format (UKE-5 bare for Stokvis packaged) | 6,590.00 |
| 6 | Cold-Water Booster (DAB ESYTANK for Arrow BTBS) | 4,423.44 |
| Maximum Potential VE Saving | £56,736.86 |
Tender total if all VE options accepted: £425,217.47
| Project | B99 Malthouse Block Boiler House Replacement |
| Site | Kettlewick College, Somerset, BA22 9KW |
| Client | Grimshaw & Bolt Ltd (on behalf of Kettlewick Estates) |
| Project Ref | KW-2026-4471 |
| Tenderer | Built AI Ltd (MEP / PH / Controls Sub-Contractor) |
| Principal Contractor | Grimshaw & Bolt Ltd |
| Tender Date | 24 April 2026 |
| Revision | Rev 1 |
| Tender Validity | 90 Working Days |
| Sub-Contract Form | JCT IC 2016 with Contractor's Design Portion |
| Construction Programme | 14 Weeks on-site |
| Ref | Section | Tendered Sum (£) |
|---|---|---|
| A | Preliminaries (sub-contractor basis; PC duties with GB) | 51,525.60 |
| B | Surveys, Investigations and Stage 4a Verification | 8,298.32 |
| C | Strip-Out, Removal and Preparation (asbestos by LARC) | 26,376.53 |
| D | Builders' Work in Connection (redecoration excluded) | 29,596.31 |
| E | Testing, Commissioning and Witnessing (factory tests / aftercare excluded) | 27,601.09 |
| F | Mechanical and Public Health Services (incl. F6 BMS as PC Sum) | 296,990.48 |
| G | Electrical Services Installation | 24,066.00 |
| H | Statutory Notifications and Permits | 0.00 |
| I | Provisional Sums and Defined Allowances (Doc 23 Table 18) | 17,500.00 |
| FIXED TENDER TOTAL (Baseline Specification) | £481,954.33 |
| Tender Sum Basis | Fixed lump sum at the baseline specification (excl. VAT) |
| Daywork Rates | JCT IC 2016 Schedule 2; Employer-instructed variations only |
| Retention | 3 % (moiety at PC, balance end of DLP) |
| Payment Terms | Monthly interim valuations; 21 days payment |
| Insurances | CAR; EL £10m; PL £10m; PI £5m on CDP |
| Performance Bond | Offered at 0.5 % p.a. if required (not in sum) |
| Parent Company Guarantee | Offered at nil cost |
| Liquidated Damages | Up to 10 % of Contract Sum (aggregate) |
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