ASHP Semi-Detached Teddington Case Study: Representative Family Retrofit

What Was the Brief for This ASHP Semi-Detached Teddington Case Study?

This ASHP semi-detached Teddington case study models the kind of family retrofit we regularly assess in TW11. According to Energy Saving Trust (2026), a typical air source heat pump installation costs around £11,000 before support, so the brief was to replace an ageing gas boiler with a correctly sized low-temperature system at a sensible post-grant cost.

The representative house is a three-bedroom semi with a conventional wet-heating circuit, an older boiler approaching replacement age, and enough outside space for a credible outdoor-unit position. That makes it a useful local profile because semis in Teddington often sit in the “good candidate if surveyed properly” category rather than in the “obviously easy” or “obviously unsuitable” extremes.

For this representative profile, we assumed:

According to Nesta (2024), 80% to 90% of UK homes are already suitable for heat pumps. For a Teddington semi, that usually means the key questions are about room-by-room heat loss, emitter outputs, and hot-water layout rather than about whether the property can ever work with a heat pump.

For wider context, read our complete guide to heat pumps in the UK, heat pump cost guide for 2026, and BUS grant (subject to eligibility) complete guide.

Why Was This Teddington Semi a Good Heat Pump Candidate?

This Teddington semi was a good heat pump candidate because semis often combine workable outdoor-unit positions, predictable pipe routes, and manageable heat demand. According to Energy Saving Trust (2026), heat pumps perform best in reasonably efficient homes, and many suburban semis can meet that threshold with survey-led radiator upgrades rather than major rebuilding.

The representative property worked because it had:

1. enough outside access for sensible siting
2. a straightforward two-storey heating layout
3. manageable room-by-room heat losses
4. a homeowner willing to upgrade selected emitters

That last point matters. In semi-detached retrofits, the project usually becomes much more credible when the homeowner accepts that some radiators may need to change. The best systems are rarely the ones that try to preserve every old assumption from the gas-boiler era.

Teddington is also a useful local fit because many homes here are family houses where comfort, quiet operation, and long-term cost control all matter. That tends to favour proper system design over rushed boiler-replacement logic.

What System and Installation Work Were Involved?

The representative Teddington system used an 8 kW air source heat pump, a domestic hot-water cylinder, upgraded controls, and selected radiator changes. According to Energy Saving Trust (2026), domestic heat pump retrofits involve much more than the outdoor unit alone, so emitter checks, cylinder planning, and commissioning work were all part of the representative scope.

The installation scope looked like this:

The project logic here is typical of many TW11 semis. The heating circuit usually stays wet, the heat source changes, and the rest of the job is about making lower-temperature heating practical room by room. That is also where the difference between a good survey and a poor one becomes obvious very quickly.

Using our current London and Surrey pricing context, a representative cost frame would often be:

If you want to test the semi-detached route before the boiler fails, you can book a free home survey and compare likely emitter work, cylinder options, and grant viability while the job is still planned rather than urgent.

What Did the Timeline, Cost and Before/After Bills Look Like?

For a representative Teddington semi, the timeline is usually shaped by survey, design sign-off, and lead times more than by on-site labour. According to Ofgem (April 2026), planning assumptions still use electricity at around 24.5p/kWh and gas at around 7.4p/kWh, so the running-cost picture depends on both boiler efficiency and heat pump performance.

For this representative profile, we assumed:

1. annual heat and hot-water demand of about 12,000 kWh
2. an older gas boiler operating near 75% efficiency
3. a heat pump seasonal performance factor of around 3.0

That gives a representative comparison like this:

That points to a representative reduction of roughly £150 to £250 a year on heating and hot water, depending on weather, controls, hot-water use, and real system setup. It is not a typical results, but it is a credible planning range for a well-designed semi retrofit with an older boiler.

What Does This Mean for Similar Semi-Detached Homes in Teddington?

For similar semi-detached homes in Teddington, this case study means a heat pump is often strongest when the boiler is ageing and the house has a workable outdoor-unit position. According to Ofgem (April 2026), current dual-fuel costs still make efficiency-led upgrades relevant even where the running-cost gain versus gas is moderate.

The practical takeaway is:

1. semis are often among the easier local retrofit candidates
2. selective radiator upgrades are normal rather than exceptional
3. early surveys beat breakdown-led decisions
4. solar or battery storage can be added later if needed

That is why many Teddington semis suit a staged but coherent low-carbon plan. You do not need to make every upgrade at once, but you do need the first step to be designed honestly so it does not box the home into a poor long-term outcome.

For related reading, see our heat pump running costs guide, heat pump installation process guide, and renewable energy for London homes guide.

How Electromatic Can Help

If your home looks similar to this representative Teddington semi, Electromatic can assess whether the property is a straightforward heat pump candidate or better suited to a staged route. According to Energy Saving Trust and Ofgem, the strongest outcomes come from proper sizing, emitter review, and realistic grant handling rather than from simple boiler-swap marketing.

We help homeowners across London, Surrey and nearby TW areas assess suitability, plan costs, and handle the BUS grant route, subject to eligibility, through one practical survey process. We work under MCS certification via our accredited umbrella partner, so established low-carbon heating routes follow the correct compliance framework.

Book your free home survey →

Call us: 07718 059 284 | Email: admin@electromatic.uk

Frequently Asked Questions

These are the questions Teddington homeowners usually ask after seeing a semi-detached heat pump case study. According to Energy Saving Trust (2026) and Ofgem (April 2026), the right answer usually depends on boiler age, room heat loss, and whether the house can run efficiently at lower flow temperatures.

How much would a semi-detached heat pump project in Teddington usually cost?

A representative Teddington semi retrofit often sits around £12,000 to £13,500 before support, with many projects landing at roughly £4,500 to £6,000 after the £7,500 BUS grant, subject to eligibility.

Can I keep my existing radiators in a Teddington semi?

Often you can keep some of them, but not always all of them. Many good retrofits keep stronger existing radiators and upgrade only the colder or undersized rooms.

Do I need planning permission for a heat pump in Teddington?

Usually not, because many domestic ASHP projects fall under Permitted Development rights. You still need checks for siting, sound, and any site-specific planning sensitivities.

Will a heat pump definitely cut my bills in a semi?

No installer should promise that. But where the old boiler is inefficient and the new system is designed well, a modest but real reduction in heating spend is often achievable.

Is it better to add solar later?

Sometimes yes. Many semi-detached homes switch the heating system first and then add solar or battery storage once the initial retrofit is complete and the budget is clearer.

The information in this article is for general guidance only and does not constitute financial, legal, or technical advice. Energy savings estimates are based on typical UK household data from the Energy Saving Trust and Ofgem (April 2026 price cap). Actual savings depend on your property type, insulation levels, energy usage patterns, and electricity tariff. The Boiler Upgrade Scheme (BUS) grant of £7,500 is subject to eligibility criteria set by Ofgem — not all properties qualify. Electromatic M&E Ltd operates under MCS certification via an accredited umbrella partner. All installations comply with Building Regulations Part L and MCS standards. E&OE.

Written by Electromatic M&E Ltd — ASHP & Solar installer, London & Surrey (electromatic.uk)

Last updated: April 2026 | Electromatic M&E Ltd, Company No. 13837345