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Heat pumps

How they work, how they are sized, and what makes one cheap or expensive to run.

Calculators

MIS 3005-D Start here

What size heat pump do I need?

Estimates a house's heat loss and the heat pump that covers it, from a year of gas or oil bills, and says whether a quoted size looks plausible.

MCS 020

Heat pump noise assessment

Works out the sound pressure level at a neighbour's window and whether it clears the permitted development limit.

MIS 3005-D

Room heat loss

Works out one room's design heat loss, the figure a heat pump and its radiators are sized from.

MGD 007

Radiator flow temperature

Works out what flow temperature a radiator needs for its room, and the Heat Emitter Guide star rating that follows.

Reading

Article Heat pumps

Heat pump grant applications hit a record

The latest Boiler Upgrade Scheme statistics show the busiest quarter since the scheme began in 2022. The article explains what the figures say about demand, the new £9,000 grant, waiting times and installation costs.

7 min read
Article Heat pumps

Which refrigerant a heat pump uses, and whether it matters

New domestic heat pumps use one of two refrigerants, R32 or propane. This article covers what the choice changes for a household: how hot the water can get, where the unit can stand, who can work on it, and what the rules in Great Britain say about each.

8 min read
Article Heat pumps

Do you need a smart meter for a heat pump?

No standard, grant or network rule requires one, and a heat pump will run without it. What a smart meter changes is which electricity tariff you can be on, and on a heat pump the tariff decides a large part of the running cost.

6 min read
Article Heat pumps

Keeping a heat pump running well

A heat pump is set up once, on commissioning day, for a house the installer had known for a few hours. The settings that decide the running cost can be improved through the first winter and checked every year after. This covers the settings worth revisiting and the checks worth making each year.

10 min read
Guide Heat pumps

What to sort out before a heat pump

The things worth doing before you spend anything, because each one makes the machine you end up buying smaller, cheaper, or better matched to the house. Most of them cost nothing.

7 min read
Guide Heat pumps

Should I get a heat pump?

What changes in a house that gets a heat pump, the conditions it needs to work well, and how to tell early on whether yours is a good candidate.

8 min read
Questions Heat pumps

Heat pumps: common questions

Short answers on whether a heat pump suits your house, what it costs to run, how loud it is, and what has to change before one goes in.

14 questions
Article Heat pumps

Why a heat pump runs all the time

It is meant to. A heat pump that ticks over all day costs less than one switched on and off, and the radiators are supposed to feel lukewarm. Here is why, and what that means for how you use it.

4 min read
Guide Heat pumps

Flow temperature, radiators, and the Heat Emitter Guide

The temperature a heat pump has to produce is set by the radiators it is connected to, and that temperature governs the running cost. This is how the two are related and how the Microgeneration Certification Scheme (MCS) measures the relationship.

7 min read
Article Heat pumps

Hot water with a heat pump

A heat pump cannot make hot water on demand, so a house that has lived without a cylinder gets one back. How it is sized follows a formula in MIS 3005-D and a table in MGD 007.

6 min read
Guide Heat pumps

How a heat pump heats a house

A heat pump moves heat instead of making it, which is why it can deliver more heat than the electricity it consumes. What that means for your radiators and for the way the house is heated.

7 min read
Article Heat pumps

Ground source or air source

Both collect heat from outside the house instead of making it. The difference is where they collect it from, and that one difference sets the cost, the efficiency and the disruption.

5 min read
Article Heat pumps

Reading a heat loss calculation

A heat pump quotation should come with a room-by-room heat loss calculation. Here is what its columns mean and the handful of checks that catch most errors.

5 min read