How to Choose a New Boiler in Norwich: 2026 Buying Guide

Replacing a boiler is the most expensive single purchase most homeowners make for their property apart from the property itself. £2,000-£5,000 for a like-for-like swap. £4,000-£12,000 if you're changing system type. £15,000+ if you're switching to a heat pump. Getting it right matters — and so does getting honest advice rather than the boiler the installer happens to have in the back of the van.

This guide is what we'd tell you if you called us asking what to buy. No vendor lock-in, no commission distortions — just the version of the truth most homeowners get from a friend in the trade.

Step 1: Combi, system, or heat-only — which type do you need?

The first decision is fundamental and depends on your home, your water pressure, and your hot water habits. Get this wrong and the boiler underperforms regardless of how much you spent.

Type	Best for	Hot water	Indicative cost installed
Combi	Smaller homes (1-2 bathrooms), tight space, good mains pressure	On demand, no tank	£1,900 – £3,500
System	Medium-large homes (2-4 bathrooms), high simultaneous demand	Stored in cylinder	£2,500 – £4,500
Heat-only (regular)	Older homes with existing tank and cylinder, low mains pressure	Stored in cylinder + cold tank	£2,500 – £4,000

Combi is the default modern choice — no tank, no cylinder, hot water on demand straight from the boiler. Brilliant for smaller homes and flats. The catch: if two showers run at once, you'll feel it. Combi flow rates of 12-15 litres/min are typical; turn two on and each gets 6-7 litres/min, which feels noticeably weaker.

System boilers feed a hot water cylinder. They handle multiple simultaneous outlets without flow loss. Best for 3+ bedroom homes, especially with two or more bathrooms. You need cupboard space for the cylinder.

Heat-only (regular) is the traditional UK setup — boiler, cold water tank in the loft, hot cylinder in an airing cupboard. Still useful in old Norwich properties with low mains pressure (the loft tank provides gravity-fed flow). New installations are rare; most replacements go to system or combi.

Step 2: Get the size right (kW rating)

Oversizing is the most common mistake. A 35kW combi sounds powerful but wastes gas and cycles inefficiently if your house only needs 18kW. Undersizing is rarer but a real problem — you'll never reach radiator temperature on cold days.

Rules of thumb for combi sizing in Norwich (mid-pressure mains, average insulation):

• 1 bedroom, 1 bathroom: 24-28kW
• 2-3 bedroom semi: 28-30kW
• 3-4 bedroom detached: 30-35kW
• 4+ bedrooms or 2+ bathrooms: consider a system boiler instead

The kW figure on a combi is its hot water output. Heating output is usually 75-80% of the headline number (so a 30kW combi gives ~24kW for the radiators). A proper heat-loss calculation is the only way to size accurately — any installer who doesn't do one is guessing.

Step 3: Choose a brand (this matters less than you'd think)

The differences between premium brands in 2026 are smaller than the marketing suggests. Most use similar components from a handful of OEM suppliers. The real differences are in warranty length, parts availability, and engineer familiarity.

Brand	Reputation	Typical warranty	Parts availability
Worcester Bosch	Premium, gold standard	10-12 years	Excellent
Vaillant	Premium, very reliable	10 years	Excellent
Viessmann	Premium German engineering	10-12 years	Good
Ideal	Mid-range, good value	10 years	Excellent
Baxi	Mid-range, British made	7-10 years	Very good
Alpha	Budget premium	10 years	Good
Glow-worm	Budget (Vaillant-owned)	5-10 years	Very good

The headline warranty length is only valid if the boiler is installed by an accredited installer and serviced annually. Miss a service and the warranty drops to the manufacturer's minimum (often 2 years).

Our default recommendation is Worcester Bosch for like-for-like swaps in Norwich. Reasoning: every Gas Safe engineer in Norfolk knows Worcester systems, parts are stocked by every local trade counter, and the 10-12 year warranty actually delivers in practice (we see fewer warranty disputes with Worcester than other brands). Vaillant and Viessmann are equally good technically; their warranties are slightly more contested in our experience.

Step 4: Real costs broken down

A "£1,900 installed" headline price almost never includes everything you actually need. Here's what a real Norwich combi swap looks like:

Item	Cost
30kW Worcester Greenstar 8000 combi (boiler only)	£1,200 – £1,500
Standard installation labour (1-2 days)	£600 – £900
Magnetic system filter (required for warranty)	£80 – £150
Thermostat (smart or basic)	£80 – £250
Power flush of existing radiators (often necessary)	£400 – £600
Gas Safe registration and Building Control notice	£50 – £80
Typical total for Norwich like-for-like swap	£2,400 – £3,500

If you're changing system type (system to combi, or vice versa), add £400-£800 for pipework alterations. If you're moving the boiler location, add £500-£1,200 for new pipework runs and flue. If the existing cold water tank or hot cylinder needs removing, add £200-£400 for disposal.

Step 5: The £7,500 Boiler Upgrade Scheme

Before you commit to a new gas boiler, know about the alternative. The Boiler Upgrade Scheme (BUS) is a UK government grant of £7,500 towards replacing a gas, oil, or LPG boiler with an air source heat pump (£5,000 for biomass).

Heat pumps cost £8,000-£14,000 installed in 2026. After the £7,500 grant, your out-of-pocket cost is £500-£6,500 — comparable or cheaper than a new gas boiler installation, with much lower running costs (typically 50% cheaper than gas heating once electricity is on a heat-pump tariff).

The catches:

• Heat pumps need outdoor space for the external unit and decent insulation to perform well
• Existing radiators may need upgrading (heat pumps run at lower temperatures, requiring larger radiator surface area)
• Hot water comes from a stored cylinder, so combi-boiler homes need new airing cupboard space
• Installation takes 2-4 days (vs 1-2 for a gas boiler swap)

For a typical Norwich property, the BUS is worth considering if you have decent insulation, outdoor space, and a 10+ year planning horizon. It's not the right choice if you have poorly-insulated solid walls, no outdoor space, or plan to sell within 3 years (heat pump capital cost is harder to recoup quickly through energy savings).

Step 6: Get three quotes — and what to look for

The standard advice is "get three quotes". The non-obvious part is what to actually compare:

• Boiler make AND model: "Worcester boiler" isn't enough — Greenstar 8000 vs Greenstar i are very different products
• Warranty length: Confirm whether it's manufacturer-backed or "installer warranty"
• What's included: Flush? Filter? Thermostat? Building Control notice? Old equipment removal?
• Engineer qualifications: Gas Safe number, and whether they're brand-accredited (matters for warranty)
• Payment terms: Avoid anyone demanding more than 25% deposit
• References or reviews: Real Norwich addresses, not just Google reviews

The cheapest quote often isn't the best deal. The middle quote, with a brand you've heard of, an installer you can verify, and a warranty you can read in writing, is usually the right answer.