What is the difference between a combi and a system boiler?

While a combi heats water instantly as needed for 1 shower at a time, a system boiler works directly with a separate unvented hot water cylinder. It stores 150 to 300 litres of high-pressure hot water, enabling multiple showers to run at the same time without any drop in flow rate or temperature.

Do system boilers need cold water tanks in the loft?

No. Unlike regular (conventional) boilers, system boilers feature a closed, sealed heating circuit with built-in expansion vessel and circulating pump. When paired with an unvented cylinder, no loft cold water storage tanks are needed.

// MULTI-BATHROOM HOMES · STORED HOT WATER //

System Boilers Glasgow
High-Flow Multi-Shower Power

Supplying high-capacity A-rated system boilers and unvented hot water cylinders across Greater Glasgow. Designed specifically for homes with 2+ bathrooms where simultaneous hot water delivery is essential.

⚡ Fixed Wholesale From £1,495

🚿 2+ Showers Simultaneously

☀️ Solar & Heat Pump Ready

🏡 3 to 6 Bedroom Properties

Calculate System Boiler Price →

System Boiler Circuit

UNVENTED CYLINDER

Built-In System Components Pump and expansion vessel are integrated inside the boiler chassis.

Unvented Cylinder Storage Stores 150L–300L of water at mains pressure for peak demand.

Zero Cold Water Tanks in Loft No header tank required; mains water feeds cylinder directly.

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No Shower Pressure Drop Run showers in two bathrooms at once with zero temperature fluctuations.

Performance Engineering

Why Choose a System Boiler in Glasgow?

While combis are ideal for 1-bathroom flats, larger detached homes in Bearsden, Newton Mearns, Giffnock, and Southside Victorian villas require a system boiler to satisfy high simultaneous water demand.

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Simultaneous Shower Operation

Multiple family members can shower at the exact same time without the water pressure halving or running lukewarm, thanks to high-volume unvented cylinder storage.

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Integrated Components

Key hydraulics—such as the circulating pump and expansion vessel—are built directly inside the boiler casing, ensuring cleaner pipework and quicker installation.

☀️

Future-Proof Renewable Integration

Twin-coil unvented cylinders can easily connect to solar thermal panels or hybrid air-source heat pumps, future-proofing your Scottish home for decades.

Capacity Matrix

System vs Combi: Which Fits Your Property?

Property Profile	Bathrooms	Recommended System	Boiler Output	Cylinder Capacity
3 Bed Semi-Detached	1 Bathroom + Ensuite	Combi 32kW or System 18kW	18kW – 24kW	150 – 180 Litres
4 Bed Detached (Bearsden, Clarkston)	2 Full Bathrooms	System Boiler + Unvented Cylinder	24kW – 30kW	200 – 250 Litres
5–6 Bed Period Villa (Pollokshields, Kelvinside)	3+ Bathrooms	High-Output System Boiler	30kW – 35kW	300 Litres

System Boilers GlasgowHigh-Flow Multi-Shower Power