Types of Boilers Explained

Quick Answer: Combi boilers heat water on demand (best for smaller homes), system boilers use a cylinder (good for multiple bathrooms), and regular/conventional boilers need a cylinder AND loft tank (for older systems or low pressure areas).

The Three Boiler Types

1. Combi (Combination) Boilers

How it works: Heats water instantly from mains when you turn on a tap. No stored water.

Pros	Cons
Compact (no tanks)	Limited flow rate
Instant hot water	One shower at a time
Energy efficient	Depends on mains pressure
Lower install cost	Not for large homes

Best for:

• Flats and apartments
• 1-3 bedroom houses
• Single bathroom homes
• Space-limited properties

Glasgow popularity: 70% of installations

2. System Boilers

How it works: Heats water and stores in a cylinder. Pump built into boiler.

Pros	Cons
Multiple taps simultaneously	Needs cylinder space
Compatible with solar thermal	Water can run out
Good water pressure	Higher install cost
Faster hot water	Standby heat loss

Best for:

• 3+ bedroom houses
• Multiple bathrooms
• Larger families
• Solar panel compatible homes

3. Regular (Conventional) Boilers

How it works: Uses cylinder AND cold water tank in loft. Traditional system.

Pros	Cons
Works with existing system	Needs most space
Good for low pressure areas	Complex system
Replaceable parts	Less efficient
High hot water demand	Tanks need maintenance

Best for:

• Older properties
• Low mains pressure areas
• Existing open vent systems
• Very large properties

Quick Comparison

Feature	Combi	System	Regular
Hot water	On demand	Stored	Stored
Cylinder needed?	No	Yes	Yes
Loft tank?	No	No	Yes
Space required	Minimal	Medium	Most
Multiple showers	Poor	Good	Good
Install cost	Lowest	Medium	Higher
Best for	Flats/small houses	Medium houses	Large/old homes

Switching Boiler Types

Can You Switch?

From	To	Feasibility
Regular	Combi	Usually possible
Regular	System	Easy
System	Combi	Usually possible
System	Regular	Rarely needed
Combi	System	Possible (add cylinder)
Combi	Regular	Rarely done

Switching Costs

Conversion	Additional Cost
Regular to combi	+£300-£600 (remove tanks)
System to combi	+£200-£400 (remove cylinder)
Combi to system	+£400-£800 (add cylinder)

Which Is Right for Your Glasgow Home?

Choose Combi If:

• 1-3 bedrooms
• 1 bathroom
• Good mains pressure
• Limited space
• Want simplicity

Choose System If:

• 3+ bedrooms
• 2+ bathrooms
• Cylinder space available
• Multiple people showering
• Want solar in future

Choose Regular If:

• Low mains pressure
• Existing system works well
• Very old property
• Large hot water demand
• Don't want to modify pipework

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