Yes. A heat pump works in a Victorian terrace or a 1930s semi, and most of the homes we insulate in London are exactly that. The condition is fabric first: a heat pump runs at 35 to 55°C, so the walls, loft and floor need to hold heat or the unit ends up oversized and expensive to run. Get the insulation right, size the radiators for a low flow temperature, find a home for the cylinder and the outdoor unit, and an old house heats as well on a heat pump as any new build.
Key takeaways
- An old house can take a heat pump; the question is how much heat it loses, and insulation decides that.
- Solid walls (most pre 1930 homes) are the biggest loss. EWI at £110 to £140/m² or IWI at £100 to £140/m² brings a Victorian house into heat pump territory.
- Radiators are sized for the low flow temperature. In an uninsulated house most change; in an insulated one usually two or three.
- A hot water cylinder of 150 to 250 litres replaces a combi. Find the cupboard before you order the heat pump.
- On a terrace the outdoor unit usually goes in the rear garden or side return; modern units are around 40 to 45 dB at one metre and need an MCS 020 noise assessment.
- Order of works: survey, loft and draughts, floor, walls, then the heat pump. The £7,500 grant no longer requires insulation first, but the system will be smaller and cheaper if you do.
Can an old house run on a heat pump?
A heat pump does not care how old the house is. It cares how much heat the house loses on a cold day, because that sets the size of the unit, the size of the radiators and the temperature it has to run at. A leaky house makes the heat pump run hot, and a heat pump running hot is inefficient. An insulated house lets it run at 35 to 45°C, where the SCOP sits at the top of the 3 to 4 range.
So the honest answer for a Victorian terrace or a 1930s semi is: yes, once the fabric is dealt with. The rest of this guide covers the five things that come up on every old house survey.
Solid walls: the big one
Most homes built before about 1930 have solid brick walls with no cavity. They lose more heat than any other part of the house. A heat pump fitted to an uninsulated solid wall house will work, but it will be a large unit, most radiators will change, and the running cost will disappoint. Insulating the walls changes all three.
| Measure | Typical cost (our hubs) | Fits which house |
|---|---|---|
| External wall insulation | £110 to £140/m², 3 bed semi £12,000 to £22,000 | 1930s semis, rear and side walls of terraces, pebbledash and rendered homes |
| Internal wall insulation | £100 to £140/m², full 3 bed £8,000 to £15,000, single room from £1,800 | Victorian front elevations, conservation areas, flats |
| Hybrid (EWI rear, IWI front) | Priced per elevation | Terraces where the front must stay as brick |
On a mid terrace only two walls face outside, which is why terraces can be brought up to standard for less than a semi. See insulating a Victorian terrace, insulating a 1930s semi and EWI vs IWI. All wall insulation is 0% VAT until 31 March 2027 and installed by our own PAS 2030:2023 certified team with a 25-year insurance backed guarantee.
Why the radiators change
A gas boiler pushes 60 to 75°C water through the radiators. A heat pump runs at 35 to 55°C. A cooler radiator gives out less heat, so to warm the same room it needs more surface area: a double panel where there was a single, or a longer one. The installer works this out room by room from the heat loss calculation.
- Uninsulated old house. Most radiators change, sometimes all of them. This is a big part of why heat pump quotes for old houses land at the top of the £8,000 to £15,000 range.
- Insulated old house. Heat loss per room drops, so the existing radiators are often big enough. Typically two or three change, usually in the bay window room and the bathroom.
Where does the hot water cylinder go?
Most London terraces and semis lost their cylinder when a combi went in. A heat pump needs it back: 150 to 250 litres, roughly 600 mm wide and up to 2 m tall with the pipework. The usual homes for it are the airing cupboard, a bathroom corner, under the stairs or a landing cupboard. Decide this at survey stage, because it sets the pipe runs and the price.
Where does the outdoor unit go on a terrace?
The unit needs an outside wall or a patch of ground with clear air around it, and it should be close to the cylinder to keep pipe runs short. On a terrace the usual spots are the rear garden against the kitchen wall, the side return, or the flat roof of a rear addition. Front gardens are possible but rarely the first choice. Semis usually use the side passage or the rear.
Noise is the question neighbours ask. Modern units run at around 40 to 45 dB at one metre, which is fridge level. In England a heat pump is permitted development subject to the MCS 020 noise assessment, which checks the sound level at the nearest neighbouring window and sets how close to the boundary the unit can sit. Listed buildings and flats need consent. The MCS installer does the assessment as part of the design.
The right order of works
- Free heat loss survey. Walls, loft, floor, windows, ventilation and heating, with a written plan. Book it in the heating season if you want thermal imaging. See heat loss survey.
- Loft top-up and draught proofing. £400 to £900 and £250 to £700. Cheapest, fastest, and they cut the heat loss the heat pump is sized for.
- Floor. Suspended timber floors are common in both house types and lose 10 to 15% of heat. Median job £4,320 from our quote book.
- Walls. EWI, IWI or a hybrid, with ventilation checked so the house does not trap moisture. See ventilation after insulation.
- Heat pump. Designed against the insulated heat loss, so the unit is smaller, the radiator list shorter and the SCOP higher. Arranged and project-managed by Stay Warm, installed by an accredited, MCS certified installer who claims the £7,500 grant off the quote.
The Boiler Upgrade Scheme dropped its insulation requirement in 2024, so nothing stops you fitting the heat pump first. In an uninsulated old house you pay for a bigger unit and more radiators, then pay again in running cost. See insulate before a heat pump.
Frequently asked questions
Can a Victorian terrace have a heat pump?
Yes. The terrace shape helps because only the front and rear walls face outside. Insulate the solid walls (IWI on the front if the brick must stay, EWI on the rear), top up the loft, insulate the floor, then size the heat pump to the insulated house. The unit usually sits in the rear garden or side return.
Can a 1930s semi have a heat pump?
Yes. Many 1930s semis have an early cavity wall; some have solid walls. A survey tells you which. Cavity fill or EWI on the walls, a loft top-up and draught proofing bring the heat loss down enough for a standard sized unit and few radiator changes.
Do I have to insulate before I get the grant?
No. The Boiler Upgrade Scheme removed the loft and cavity insulation condition in 2024. Insulating first is advice, not a rule, and it makes the system smaller and cheaper to run.
Where does the outdoor unit go on a mid terrace?
Usually the rear garden against the kitchen wall, the side return, or the flat roof of a rear extension. It needs clear air around it, short pipe runs to the cylinder, and to pass the MCS 020 noise assessment at the nearest neighbouring window.
Is a heat pump noisy for the neighbours?
Modern units are around 40 to 45 dB at one metre, similar to a fridge. The MCS 020 noise assessment is part of the permitted development rules in England and sets the minimum distance from a neighbour's window.
What if my house is listed or in a conservation area?
Listed buildings need consent for the outdoor unit and usually for external wall insulation. Conservation areas often restrict EWI on the front elevation, so IWI on the front and EWI on the rear is common. See our guide to insulating a period or listed home.