Summary

A central heating installation is one of the highest-skill domestic jobs in plumbing. It combines gas work (registered engineer only), water systems design, electrical wiring for controls, and structural awareness (joist drilling, masonry penetrations). The pricing logic is dominated by the number of radiators (each radiator adds £180-£350 fitted including pipework run), the boiler choice, and the controls strategy.

The most common pricing mistake is treating central heating as a "boiler plus radiators" project. The pipework run is the most labour-intensive part — running 22mm/15mm copper or push-fit plastic through joists, under floors and through walls accounts for 40-50% of the total labour. Pipework on an existing house (lifting floorboards, working around plaster) takes 2-3× longer than on a new build.

This guide covers new central heating installs (no existing system), system upgrades (replacing radiators and pipework), and partial extensions (adding heating to a new extension). For boiler replacement only see boiler installation pricing guide.

Key Facts

Quick Reference Table

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Job Type Property Size Material Cost Labour Total (Regional) Total (London)
New install (basic) 2-bed flat £2,000-£3,200 £1,500-£2,500 £3,500-£5,800 £4,500-£6,800
New install (basic) 3-bed semi £2,800-£4,200 £2,200-£3,500 £5,000-£7,800 £6,000-£9,000
New install (mid) 3-bed semi (smart TRV, designer rads) £3,800-£5,500 £2,500-£4,000 £6,500-£10,000 £8,000-£12,000
New install (premium) 4-bed detached £6,500-£10,000 £4,000-£6,500 £11,500-£17,500 £14,000-£21,000
Full system upgrade 3-bed semi £3,000-£5,000 £3,000-£4,500 £6,500-£10,500 £8,000-£12,500
Heating extension to new room 1-2 rads £400-£800 £400-£800 £800-£1,800 £1,000-£2,300
Wet UFH (single zone) Kitchen-diner £1,500-£2,500 £1,200-£2,000 £3,200-£5,200 £4,000-£6,500

Detailed Guidance

Sizing the System

A central heating system is sized to deliver the heat demand of the dwelling at -3°C external temperature. The calculation:

  1. Heat loss per room — typically 50-100 W/m² for older homes, 30-50 W/m² for newer insulated homes
  2. Radiator output sizing — match output (in W) to room heat loss at design flow temp (50-75°C)
  3. Boiler output — sum of all radiator outputs + DHW (combi) or cylinder reheat (system) demand
  4. Pipe size — 22mm primary loop where flow rate >12 L/min; 15mm to individual radiators

Tools: free heat loss calculators online; spreadsheets from Heat Geek and Heat Pump Source; manufacturer apps from Stelrad, Myson.

Most domestic systems have:

Pipework — Where Time Goes

The pipework run is the most time-intensive element. Typical sequence:

  1. Site assessment — identify boiler location, manifold/pump position (if multi-zone), radiator positions
  2. Drilling — joists for through-floor runs (Building Regs limits: hole position within zones marked in joist; max diameter 25% of joist depth); masonry for wall penetrations
  3. Pipework first fix — bring all flow/return loops to room positions; pressure test
  4. Decoration / second-fix prep — pipes capped, ready for tilers/joiners
  5. Radiator hang and connect — wall brackets, valves, TRVs
  6. Boiler install and commission
  7. Smart thermostat and TRV pairing
  8. System fill, flush, pressure test, commission

Copper vs plastic push-fit:

A 3-bed semi typically needs 80-130m of mixed-diameter pipework, including 22mm primary loop and 15mm to each radiator.

Radiator Selection

Radiator Type Output (W at 50°C) for 600 × 1000mm Cost £ Supplied
K1 single panel single convector 700-900W £40-£90
K2 double panel double convector 1300-1700W £85-£180
K3 triple panel 1800-2400W £120-£250
Column (Stelrad Vita) 1100-1800W £180-£400
Towel radiator (chrome) 400-700W £80-£250
Designer (Bisque, Aestus) varies £300-£900+

For oversized systems (heat pump-ready), specify K2 or K3 to compensate for lower flow temperatures (45°C vs traditional 70°C). Heat pump–ready radiators output ~50% less at 45°C than at 70°C.

Smart Controls — The Modern Default

Boiler Plus 2018 requires smart control or compensation on new installs. The market splits into:

Recommendation in pricing: include smart thermostat as standard; multi-zone smart TRVs as upgrade.

Wet Underfloor Heating Integration

Where wet UFH is included (typically kitchen or bathroom), the cost adds:

Wet UFH replaces or supplements radiators in the floor area covered. Cost per m² installed: £80-£140 (excluding final floor finish). For a 25m² kitchen, ~£2,500-£3,500 added to overall cost.

Cylinder vs Combi

Combi boiler suits:

System boiler + unvented cylinder suits:

System boiler + cylinder adds £700-£1,500 vs combi (cylinder cost + extra pipework + commissioning).

Pricing Walkthrough — 3-Bed Semi New System, Regional

Item Cost
Worcester Greenstar 30Ri combi £1,200
Hive smart thermostat £180
Magnaclean filter £75
Inhibitor + cleaner £35
9 K2 radiators (mixed sizes) £900
9 TRVs + 9 lockshield valves £200
Pipework (mixed 22mm/15mm copper + push-fit) £450
Fittings + sundries £200
Pump, manifold, expansion, programmer £180
Engineer 4 days + apprentice 3 days £2,200
Power flush + commissioning £400
Building Notice + Gas Safe self-cert £120
Margin 20% £1,236
Total £7,376

Common Pricing Mistakes

Frequently Asked Questions

How long does a central heating install take?

A new installation in a 3-bed semi takes 5-8 working days. A full upgrade of existing pipework takes 7-12 days. A heating extension to a new extension takes 1-3 days. Customer is typically without heat for 24-48 hours during the changeover; engineers schedule for warmer months where possible.

Is copper better than plastic pipe?

For visible installations: copper is neater, slightly more durable, and the traditional choice. For concealed first-fix: plastic push-fit is faster, has fewer joints (lower leak risk), and is more flexible. Most modern installs mix the two — plastic for first fix in floors/walls, copper for exposed connections. Both are compliant with WRAS and BS EN standards.

Should I install wet UFH instead of radiators?

UFH is more efficient, more comfortable, and works well with heat pumps. Capital cost is 2-3× radiators per m². Best in tiled or stone-finished rooms (kitchen, bathroom, hallway). Less appropriate for bedrooms with thick carpets (insulation reduces effective output). Many homes mix: UFH in tiled areas, radiators elsewhere.

What's the cheapest brand of radiator?

Stelrad Compact, Henrad, Kudox all sit in the £40-£90 supply range for K1/K2 standard sizes. Quality is consistent across these brands. Premium options (Bisque, Aestus, Vasco) are £300+ for designer appearance. For most installs, mid-range Stelrad K2 is the rational default.

Do I need to flush an existing system if I'm replacing radiators?

Yes — adding new radiators to a fouled system contaminates the new units within months. Power flush before connection: £350-£550. Cheaper option: chemical clean (£180-£250) acceptable for newer systems. Always include flushing in quotes — skipping voids manufacturer warranty.

Can I run radiators off a heat pump?

Yes, but radiators must be sized for lower flow temperature (typically 45°C instead of 70°C). Existing radiators usually need to be 1.5-2× larger output than for a gas boiler. Many heat pump retrofits involve upgrading radiators to K2 or K3 panels, or to specifically rated heat pump radiators (Stelrad K3 LST, Myson Hi-Style).

Regulations & Standards