{"id":1522,"date":"2026-03-22T21:15:48","date_gmt":"2026-03-22T21:15:48","guid":{"rendered":"https:\/\/mywarmhome.co.uk\/stage\/?p=1522"},"modified":"2026-10-12T06:42:42","modified_gmt":"2026-10-12T06:42:42","slug":"system-design-and-sizing","status":"publish","type":"post","link":"https:\/\/mywarmhome.co.uk\/stage\/2026\/03\/22\/system-design-and-sizing\/","title":{"rendered":"Understanding Design and Sizing of Our Heating Systems.."},"content":{"rendered":"\n
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HEATING DESIGN \/ MY WARM HOME<\/p>\n\n\n\n

Efficiency should define affordability.<\/h1>\n\n\n\n

Designing any heating or renewable system\u2014whether it is a heat pump, electric storage, gas boiler, unvented cylinder, underfloor heating or radiator system\u2014must begin with a single guiding principle: efficiency comes first.<\/p>\n\n\n\n

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HEAT LOSS<\/p>\n\n\n\n

SYSTEM DESIGN<\/p>\n\n\n\n

RADIATORS + \u0394T<\/p>\n<\/div>\n<\/div>\n\n\n\n

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01<\/p>\n\n\n\n

The science<\/h3>\n\n\n\n

Heating design should be based on testing, modelling and evidence rather than assumptions about what a home might need.<\/p>\n<\/div>\n\n\n\n

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02<\/p>\n\n\n\n

Sizing homes<\/h3>\n\n\n\n

Every property is different. Heating systems need to reflect the building, its occupants and how the home is actually used.<\/p>\n<\/div>\n\n\n\n

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03<\/p>\n\n\n\n

Heat loss<\/h3>\n\n\n\n

Walls, floors, roofs, windows and ventilation all lose heat. Understanding those losses is the starting point for proper system design.<\/p>\n<\/div>\n\n\n\n

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04<\/p>\n\n\n\n

Radiators & \u0394T<\/h3>\n\n\n\n

Emitter output changes with operating temperature. A radiator rated at \u0394T50 will produce considerably less heat at lower temperatures.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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IN SHORT<\/p>\n\n\n\n

True affordability starts with using less energy.<\/h2>\n\n\n\n

Cutting the upfront cost of a heating system does not necessarily make it affordable. Good design aims to deliver the heat a home actually needs, at suitable operating temperatures, without unnecessary energy use.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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01 \u2014 EVIDENCE BEFORE OPINION<\/p>\n\n\n\n

The science<\/h2>\n\n\n\n

We are human\u2014and often stubborn. It is natural to trust what we can see and what we believe, even when the science tells a deeper story.<\/p>\n\n\n\n

When it comes to keeping homes warm, the science is extensive and uncompromising. Facilities such as the Energy House in Salford<\/a> test and thermally model real-world conditions, while manufacturers expose materials to extremes of heat and cold to understand how they retain or lose energy.<\/p>\n\n\n\n

Before a legitimate product reaches the market, it undergoes testing and certification. Its declared performance values allow designers to model it within properties and demonstrate compliance with UK requirements.<\/p>\n\n\n\n

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What looks simple on the surface is supported by testing, modelling and proven performance.<\/strong><\/p>\n<\/blockquote>\n<\/div>\n<\/div>\n\n\n\n

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02 \u2014 DESIGN FOR THE PROPERTY<\/p>\n\n\n\n

Sizing for our homes<\/h2>\n\n\n\n

When a heating system is specified or upgraded, many factors must be considered.<\/p>\n\n\n\n

When I first started as a heating engineer, it was common to visit a plumbers\u2019 merchant and order a combi boiler and five radiators as a standard heat pack.<\/p>\n\n\n\n

That is not a proper way to size a system for a property.<\/strong><\/p>\n\n\n\n

Electric storage heaters can also be difficult to size correctly because they use cheaper overnight energy to heat the property during the day. Work patterns, occupancy and social factors\u2014including prepayment meters\u2014can all affect the result.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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A NOTE BEFORE WE CONTINUE<\/p>\n\n\n\n

Heating and hot water are different design requirements.<\/h3>\n\n\n\n

The next sections look at primary heating using gas boilers or heat pumps. Hot-water requirements should be assessed separately.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n

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03 \u2014 START WITH DEMAND<\/p>\n\n\n\n

Heat loss<\/h2>\n\n\n\n

Are we robbing Peter to pay Paul\u2014or neither? In heating terms, are we unintentionally drawing warmth from neighbouring homes, if we have any?<\/p>\n\n\n\n

Understanding heat loss starts with the basics: losses through walls, floors, roofs, windows and ventilation; the size and exposure of the property; and the heat emitters needed in each room.<\/p>\n\n\n\n

Once heat loss is understood, we can balance comfort, radiator or underfloor-heating output and energy use.<\/p>\n\n\n\n

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EARLY-STAGE ESTIMATE<\/p>\n\n\n\n

Q = V \u00d7 F \u00d7 M<\/h3>\n\n\n\n

A simplified early-stage estimate\u2014not a substitute for a room-by-room heat-loss calculation.<\/p>\n<\/div>\n\n\n\n

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Q<\/p>\n\n\n\n

Heat required<\/h3>\n\n\n\n

Watts<\/strong>
The approximate heating output needed.<\/p>\n<\/div>\n\n\n\n

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V<\/p>\n\n\n\n

Room volume<\/h3>\n\n\n\n

m\u00b3<\/strong>
Length \u00d7 width \u00d7 height.<\/p>\n<\/div>\n\n\n\n

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F<\/p>\n\n\n\n

Base factor<\/h3>\n\n\n\n

A broad heat-loss allowance for the property age and condition.<\/p>\n<\/div>\n\n\n\n

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M<\/p>\n\n\n\n

Modifiers<\/h3>\n\n\n\n

Allowances for insulation, construction and exposure.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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\"Heat-loss\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button><\/figure>\n<\/div>\n\n\n\n
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\"Heat-loss\n\t\t\t\n\t\t\t\t\n\t\t\t<\/svg>\n\t\t<\/button><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n
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INTERACTIVE TOOL<\/p>\n\n\n\n

Heat-loss and heating design tool<\/h2>\n\n\n\n

Use this for an early indication only. A final system design needs a competent room-by-room calculation using verified construction data, ventilation rates and the relevant design outside temperature.<\/p>\n\n\n\n

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