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NIBE S2125 Air Source Heat Pump in Bath, South West England

SwedenClimate Zone 3

Looking at a NIBE S2125 air source heat pump for your Bath home? NIBE S2125 publishes no installed price, and no credible third-party figure exists; the UK median install is £12,908 before any support (DESNZ Boiler Upgrade Scheme median, April to June 2026). After the £7,500 Boiler Upgrade Scheme grant, that is your quote less £7,500 out of pocket; your MCS-certified installer claims the grant for you. Buyers who put quiet running and a long warranty first, and will use a NIBE Pro installer.

NIBE S2125 does not publish an installed price and no credible third-party figure exists, so we show none. For scale, the median Boiler Upgrade Scheme install cost £12,908 before the grant (DESNZ Boiler Upgrade Scheme median, April to June 2026). The typical pre-grant installed range for Bath is £8,150 - £14,150.

Air source heat pumps perform strongly in this part of the UK. With comparatively mild winter temperatures, a correctly sized unit holds its seasonal efficiency (SCOP) well, and running costs sit toward the lower end of estimates. The MCS heat-loss survey that comes with every Boiler Upgrade Scheme installation confirms the right output and radiator sizing for your home.

Price on quote
No published price
Price on quote
After grant (illustrative)
4.8
Best SCOP at 35°C (MCS)
2 yr (up to 7)
Warranty (standard)

NIBE S2125 Models Available

NIBE S2125-8

Price on quote
no published installed price
Size
8kW
NIBE size label; rated heat output 5.3 kW at 35°C (Pdesignh, average climate), 5.52 kW maximum at -7°C
SCOP 35°C / 55°C (MCS)
4.8 / 3.59
Running cost (est.)
~£625/yr
Sound power
49 dB(A)
Suitable for
smaller or well-insulated 2-3 bed homes
After £7,500 grant (illustrative)
Price on quote
Outdoor unit (HxWxD)
1080x1128x831mm
Weight
163kg

NIBE S2125-12

Price on quote
no published installed price
Size
12kW
NIBE size label; rated heat output 6.8 kW at 35°C (Pdesignh, average climate), 8.34 kW maximum at -7°C
SCOP 35°C / 55°C (MCS)
4.8 / 3.71
Running cost (est.)
~£620/yr
Sound power
49 dB(A)
Suitable for
typical 3-bed semi
After £7,500 grant (illustrative)
Price on quote
Outdoor unit (HxWxD)
1080x1128x831mm
Weight
163kg

Specifications and pricing are indicative for the UK market as at June 2026. Running costs assume ~10,000 kWh of heat a year at 26.32p/kWh (Ofgem cap average, October to December 2026; changes quarterly). Confirm current models and exact pricing with your MCS-certified installer.

How NIBE S2125 Performs in Bath's Climate

ExcellentClimate Zone 3 | R290 refrigerant

NIBE S2125 performs at its best in this mild southern climate (zone 3 on our 1-7 scale). Expect seasonal efficiency in line with its certified SCOP (4.8 at 35°C, 3.59 at 55°C) and running costs at the lower end of estimates. It reaches 75°C flow, which helps existing radiators carry the load without a full re-pipe.

Noise Levels in a Built-Up Area

NIBE S2125 declares a sound power of 49 dB(A) for this model: the noise the unit itself emits. What you hear next door is much lower and falls with distance, and permitted development rules require the installation to meet the MCS noise standard at the nearest neighbour. In built-up areas the outdoor unit often sits close to neighbouring homes, so ask your installer to show you the noise calculation for your spot.

Pros

  • R290 refrigerant
  • Quiet Mark certified (S2125-8 and S2125-12) with 49 dB(A) declared sound power
  • Up to 75°C flow, and up to 65°C at -25°C outdoor
  • Up to 7-year parts and labour warranty through NIBE Pro Partner installers
  • British Gas became an approved NIBE service partner in March 2025

Cons

  • Standard warranty is 2 years unless a NIBE Pro installer registers the extended cover
  • Heavy and deep: 163 kg and 831 mm deep for both the 8 and 12
  • Size labels overstate output: the S2125-12 is rated 6.8 kW at 35°C, 8.34 kW maximum at -7°C
  • Annual servicing is a condition of every NIBE warranty
  • No published installed price

Grants for NIBE S2125 in Bath

Boiler Upgrade Scheme

£7,500 off, claimed for you by your MCS-certified installer

Every NIBE S2125 air-to-water model on this page qualifies for the Boiler Upgrade Scheme in South West England when fitted by an MCS-certified installer, who applies on your behalf so the grant comes straight off the quote. Homes heated by oil or LPG get £9,000 until March 2027. The EPC precondition was removed in April 2026 and the scheme runs to 2030. 0% VAT until 31 March 2027 applies on top. Accurate as at July 2026.

Full grant details for South West England→

The heating picture in South West England

Most homes here heat with a mains-gas boiler, and the Ofgem price cap gas rate has risen 39% since spring 2026 (5.74p per kWh in April-June to 7.97p from 1 October 2026). With £7,500 off through the Boiler Upgrade Scheme and 0% VAT until March 2027, replacing the boiler with an air source heat pump at end-of-life is now cost-competitive up front and on running costs. The South West has the highest share of oil-heated homes in England - prime territory for the £9,000 oil/LPG uplift (until March 2027).

There is no gas ban in the UK and nobody is forcing the switch. The pressure is price: the Ofgem price cap gas unit rate has risen 39% since spring 2026 (5.74p per kWh in April-June to 7.97p from 1 October 2026). For Bath households on a gas boiler, the practical takeaway is to plan ahead: keep using and repairing the boiler you have, but when it reaches end-of-life, pricing a heat pump against a new boiler (with the £7,500 Boiler Upgrade Scheme and 0% VAT in the maths) is now the rational default.

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Heat pump guides for South West England

NIBE S2125 in Bath: Frequently Asked Questions

How much does an air source heat pump cost in Bath?
Most Bath households pay £650 to £6,650 out of pocket (indicative, June 2026) after the £7,500 Boiler Upgrade Scheme grant is deducted from a typical pre-grant installed price of £8,150 to £14,150. Your MCS-certified installer claims the grant for you, so the discount comes straight off the quote. 0% VAT on residential installations (until 31 March 2027) is already reflected in quoted prices. Combi-to-cylinder conversions and radiator upgrades push costs toward the top of the range.
What heat pump grants are available in Bath?
Bath households can use the Boiler Upgrade Scheme: £7,500 off an air-to-water or ground-source heat pump (£2,500 for air-to-air, £5,000 for biomass), rising to £9,000 for homes heated by oil or LPG until March 2027. The EPC-certificate precondition was removed on 28 April 2026, and the scheme has been extended to 2030. Your installer must be MCS-certified and applies on your behalf, so the grant comes straight off the quote. 0% VAT on residential installations applies until 31 March 2027 on top.
Do air source heat pumps work in Bath's climate?
Bath has a mild southern climate with relatively gentle winters. Air source heat pumps perform strongly in this part of the UK. With comparatively mild winter temperatures, a correctly sized unit holds its seasonal efficiency (SCOP) well, and running costs sit toward the lower end of estimates. The MCS heat-loss survey that comes with every Boiler Upgrade Scheme installation confirms the right output and radiator sizing for your home.
Is a heat pump cheaper to run than a gas boiler in Bath?
On the Ofgem price cap (electricity 26.32p per kWh, gas 7.97p per kWh from 1 October 2026), a heat pump running at a seasonal efficiency (SCOP) of 3.8 to 4.5 delivers heat at roughly 5.8 to 6.9p per kWh, against roughly 8.9p for a 90%-efficient gas boiler, so it runs below gas-boiler cost on cap rates. The 39% rise in the gas rate since spring 2026 has tilted the comparison further toward the heat pump. Households on heat-pump time-of-use tariffs typically do better again, though tariffs change so compare current offers. These are estimates: your actual costs depend on your tariff, your home's heat loss and how the system is set up.
How does the installation process work in Bath?
Every grant-backed installation starts with a heat-loss survey of your home (an MCS requirement), which determines the heat pump output, the radiator sizing and whether your hot water cylinder needs upgrading or adding. The installer then fits the outdoor unit, cylinder and controls, commissions the system and walks you through it. If a gas boiler is being removed, that part of the work must be done by a Gas Safe registered engineer. Timescales are usually measured in days, not weeks; your installer will confirm after the survey.
What size air source heat pump do I need in Bath?
Sizing in the UK is driven by your home's heat loss, not just bedroom count: the heat-loss survey that comes with every Boiler Upgrade Scheme installation calculates it room by room. As a rough guide from the current UK model ranges, smaller well-insulated homes suit units around 5 to 8kW of heat output, typical 3 to 4 bed homes around 8 to 12kW, and large or older properties may need more. In your milder climate, correctly sized systems hold their efficiency well through winter.
Which air source heat pump brand is best for Bath?
In Bath's milder climate (zone 3 on our 1-7 scale), every brand we track performs well, so price and installer support matter most. Octopus says its median quote for the Cosy was £4,064 after the grant (June to September 2026), installed by Octopus or its accredited installers; the other brands are fitted by independent MCS-certified installers, so you can compare quotes.
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