Project Overview:

To decarbonise the heating plant of a 200-bedroom accommodation block by replacing the existing kerosene-fired boiler installation with a heat pump–based system, while retaining the building’s existing Quinn-type radiators as the heat emitters. The design provides both low-temperature hot water (LTHW) and domestic hot water (DHW), with a cascade of electric boilers installed as backup.

Scope of Works:

• Primary Heating (LTHW)
• A cascade of 5 × BA60iS air source inverter-driven heat pumps supplies LTHW to the building.
• Units operate with weather-compensated curves, optimising SCOP while maintaining radiator setpoint temperatures.
• The system is designed to operate at flow temperatures compatible with existing Quinn-type radiators, typically 50–55 °C flow with 20 K ΔT, ensuring adequate space heating without radiator replacement.
• All units are hydraulically connected to Primary Distribution Manifold No. 1, serving the building’s heating zones.

DHW Generation:

• 2 × AQ75ZHX water-to-water heat pumps are connected to Manifold No. 1 and configured to lift temperatures for DHW production.
• These units feed calorifiers, supplying high-temperature water to meet large-scale DHW demand.
• Priority sequencing is in place, allowing the AQ75ZHX cascade to switch capacity based on DHW demand without compromising LTHW delivery.

Backup System:

• A cascade of electric boilers provides redundancy and peak-load support.
• Boilers are connected to Manifold No. 2, with the flexibility to supply either LTHW or DHW circuits.
• Operation is fully integrated into the control logic, with boilers automatically enabled when additional capacity is required or during maintenance of the heat pumps.

Controls & Integration:

• The entire installation is managed by MasterTherm PLC-based control (Carel platform).

Features include:

• Full sequencing of heat pumps and electric boilers.
• Weather compensation for LTHW operation.
• DHW priority control with adjustable setpoints.
• Energy metering and system performance monitoring.
• Control flexibility ensures maximum renewable operation while maintaining security of supply.

Installed Equipment Summary:

• 5 × BA60iS air source heat pumps (R410A) – Primary LTHW supply.
• 2 × AQ75ZHX water-to-water heat pumps (R410A) – Dedicated DHW supply via calorifiers.
• Cascade of electric boilers – Integrated backup for both LTHW and DHW.

System Benefits:

• Full replacement of kerosene-fired boilers with renewable-led heating.
• Continued use of existing Quinn-type radiators, avoiding disruptive and costly emitter replacement.
• Integrated electric backup provides redundancy and resilience.
• Optimised efficiency through advanced PLC control and weather-compensated operation.
• Scalable, modular design providing both operational flexibility and redundancy across heating and DHW production.

Tech Notes & Smart Control

• Quinn-type radiators retained with 50–55 °C flow regime; weather‑comp optimises SCOP while preserving comfort.
• Five BA60iS serve LTHW; two AQ75ZHX handle DHW via calorifiers; electric boiler cascade provides N+1 resilience.
• Dual-manifold topology segregates backup capacity for flexible dispatch.

Guest Experience & Operations

• Minimal disruption retrofit—no emitter changeouts; consistent room comfort across the stack.

Energy & Carbon (SEAI)

• Switching from fossil-fired plant to high-efficiency heat pumps reduces on‑site combustion (Scope 1) and cuts overall CO₂ per guest‑night.
• Heat recovery (where fitted) further lowers electrical input per kWh of useful heat or DHW.
• Aligned with SEAI guidance for decarbonising hospitality; suitable for M&V and public‑sector style reporting where applicable.
• Benefits grow as the Irish electricity grid continues to decarbonise, improving the carbon intensity of delivered heat over time.