Intelligent Heating Design That Reduced a 90kW Boiler Plant to Just 26kW

At Wood & Williams Plumbing & Heating, we believe the best commercial heating systems are designed around accurate heat loss calculations and intelligent system design, rather than simply installing larger boilers.

We were asked to investigate ongoing heating and hot water issues at an assisted living facility that had experienced years of unreliable performance despite having a large commercial boiler installation. Rather than recommending a like for like replacement, we carried out a detailed assessment to identify the root cause of the problems. What we discovered was that the issue wasn't a lack of heating capacity, but poor system design.

By carrying out a complete commercial heating system redesign, we transformed an inefficient 90kW boiler plant into a highly efficient 26kW system, delivering reliable heating, consistent hot water and significantly lower running costs.

The Challenge

The assisted living facility had been experiencing frequent boiler breakdowns, intermittent hot water, rising gas bills and increasing maintenance costs for several years. Although the plant room contained a large commercial heating system, it had become unnecessarily complex and still failed to deliver reliable performance for residents.

The existing installation included:

A 90kW dual commercial boiler cascade
Five circulation pumps
A low loss header
Two 210 litre domestic hot water cylinders
A secondary hot water circulation loop
Multiple thermostatic blending valves throughout the building

Despite this extensive equipment, heating and hot water remained inconsistent.

Diagnosing the Underlying Issues

Rather than replacing the existing boilers on a like for like basis, we carried out a comprehensive commercial heating survey to diagnose the underlying issues affecting the system's performance.

Our investigation revealed that the boiler plant was significantly oversized and unnecessarily complicated. The system relied on excessive pumping, hydraulic separation and an inefficient secondary hot water return loop, while several blending valves were suffering from backflow issues that caused hot and cold water to mix internally.

Instead of improving performance, the complexity of the installation had increased maintenance requirements, wasted energy and contributed to the ongoing reliability issues.

Accurate Heat Loss Calculations

Before recommending any replacement equipment, we completed detailed heat loss calculations for the entire property.

The building, which serves 22 radiators and seven bathrooms, required just:

14kW for space heating
Approximately 19kW to meet peak domestic hot water demand

These calculations confirmed that the existing 90kW commercial boiler installation was vastly oversized, meaning the system was using far more energy than necessary.

This project highlights why accurate heat loss calculations should always form the foundation of a commercial heating upgrade. Simply installing a larger boiler doesn't guarantee better performance. In this case, the original system was significantly oversized, yet still struggled to provide reliable heating and hot water. By designing the new system around the building's actual heating and hot water requirements, we delivered a solution that is more efficient, more reliable and considerably easier to maintain.

Our Heating System Redesign

Rather than replacing the existing installation with another oversized system, we completely redesigned the heating and hot water system around an Ideal Vogue Max 26kW System Boiler.

The new installation included:

Removal of the oversized 90kW boiler cascade
Installation of two 180 litre high recovery hot water cylinders
Removal of the low loss header and secondary circulation loop
Correction of blending valve backflow issues
Simplified hydraulic pipework with significantly fewer components

By reducing unnecessary complexity, the system is now easier to service, more reliable and considerably more efficient to operate.

Low Temperature Heating for Maximum Efficiency

To maximise boiler efficiency, the heating and domestic hot water systems were designed to operate independently.

The heating circuit operates at a 60°C flow temperature, while the hot water cylinders charge at 78°C. This allows the boiler to spend much more of its operating life in condensing mode, improving seasonal efficiency while still providing rapid domestic hot water recovery.

Hot Water Priority Control

Another key improvement was introducing a hot water priority control strategy.

Whenever the cylinders require reheating, the full output of the 26kW boiler is automatically directed to the twin high recovery cylinders before seamlessly returning to the heating circuit. This intelligent approach provides rapid hot water recovery, reduces boiler cycling and improves overall system efficiency.

Combined with accurate heat loss calculations and low temperature heating design, this strategy enables a boiler with less than one third of the original output to comfortably meet the building's heating and hot water demands.

The Results

The completed installation has transformed the performance of the assisted living facility, delivering:

Reliable heating throughout the building
Consistent domestic hot water
Lower gas consumption and improved energy efficiency
Reduced servicing and maintenance costs
A simpler, more reliable plant room
Greater long-term reliability and occupant comfort

This project demonstrates that successful commercial heating upgrades aren't defined by boiler size alone, but by accurate heat loss calculations, intelligent system design and selecting equipment that matches the building's actual requirements. Through a carefully engineered approach, we transformed an oversized, inefficient installation into a heating system that is reliable, energy efficient and built to deliver long-term performance.

Looking for Commercial Heating Specialists?

Whether you manage an assisted living facility, care home, school or commercial premises, our experienced engineers can design heating systems that are efficient, reliable and tailored to your building's specific requirements.

From commercial boiler installations and plant room upgrades to heat loss calculations, hydraulic redesign and energy efficiency improvements, Wood & Williams delivers bespoke commercial heating solutions that reduce running costs while improving performance.

Our Projects

Commercial Heating System Redesign for an Assisted Living Facility

Have a Similar Project?