Boiler Installation
New combi and system boilers, sized and quoted properly.
See prices & book
- Boiler installation (combi swap)
- From £2,500
- One heating control
- Free
- Extra 2-year warranty
- Free
Gas engineer & plumbing services in South London
InstaGasWorks is a Gas Safe registered plumbing and heating company working across South West London, Croydon, Sutton and the Surrey borders. Boilers, central heating, bathrooms, kitchens and everyday plumbing — one team, one visit, one price agreed before anyone starts.
Most firms in this trade will not put a number in front of you until an engineer is standing in your kitchen. We publish all 45 of ours. Everything below is what you would actually pay.
- Gas Safe registered
- Rated 5.0 on Google
- Written fixed quotes
- 24/7 emergency call-outs
Fixed prices, published
- Powerflush
- From £580
- New combi boiler, fitted
- From £2,500
No call-out charge on quoted work. The £120 diagnostic comes off your repair if you go ahead.
What we do
Six things, done properly, by engineers who do them every week. Each one has its own page with the full price list, before and after photos, and the questions we get asked most.
Boiler Repair
Breakdowns, servicing and gas safety certificates.
Prices & details
- Breakdown call-out & diagnostic
- £120
- Emergency gas leak call-out
- £180
- Radiator not heating
- £60-£80
Boiler Service
Annual servicing from £120, basic or full.
Prices & details
- Basic service
- £120
- Full service
- £220
- Landlord CP12
- £80
Powerflush
Restore cold radiators and protect your boiler.
Prices & details
- Powerflush (up to 6 radiators)
- £580
- Underfloor heating service
- £110
- Cleanser & inhibitor protection
- £180
Kitchen Fitting & Plumbing
Sinks, appliances, gas hobs and full kitchen fits.
Prices & details
- Gas hob installation
- From £120
- Taps & mixers replacement
- From £90
- Full kitchen fitting
- Free quote
Bathroom Fitting & Installation
Full refits, showers, basins and toilets.
Prices & details
- Shower installation
- £120-£200
- Toilet repairs
- From £80
- Full bathroom installation
- Free quote
Plumbing Services
Taps, toilets, leaks and everyday plumbing repairs.
Prices & details
- Emergency water leak call-out
- £150
- Taps & mixers replacement
- From £90
- Toilet repairs
- From £80
Answered 24/7
Something happening right now?
Burst pipe, gas leak, no heating, water through a ceiling. Fixed emergency call-out prices with no night or weekend surcharge.
How our pricing works
There are two kinds of job in this trade, and they are priced differently. Repairs and servicing have a fixed published rate, because we already know what the work involves. Installations are surveyed first and quoted in writing, because a combi swap in a Victorian terrace and one in a 1960s flat are not the same job.
What never happens is an hourly rate that grows while you watch, or a price that changes once the engineer is already under your floor. If we find something we did not expect, we stop and tell you what it means before we carry on.
More on call-out charges and response times.
Fixed-price work
Servicing, safety certificates, diagnostics and most repairs. The price on this page is the price on the invoice. Book it and we come.
Surveyed work
New boilers, powerflushes, bathrooms and kitchens. A free survey, then a written fixed quote that itemises parts and labour. No obligation, no pressure, no salesperson.
Emergencies
Leaks, gas escapes and total heating failures, 24/7. We tell you the call-out cost on the phone before we set off, not when we arrive.
Schedule of rates
Every price we publish, in one place
All 45of them. Prices include parts where stated, and are the same across every area we cover — there is no travel surcharge for being at the far end of the patch. Wondering why there's no hourly rate on this list? How our rates work.
- Boiler installation (combi swap)
- From £2,500
- System conversion
- Free survey & quote
- Controls & thermostats
- £150
- Radiator installation
- From £150 per radiator
Like-for-like replacement of an existing combi. Includes:
Replacing an older conventional or back-boiler setup:
Install and upgrade heating controls and thermostats. One control is included free when we fit a new boiler - this price is for controls fitted on their own, or for additional controls.
- Boiler / system breakdown call-out
- £120
- Emergency gas leak call-out
- £180
- Radiator not heating / cold radiators
- £60-£80
- Controls & thermostats
- £150
What the diagnostic visit covers:
Install and upgrade heating controls and thermostats.
- Basic service
- £120
- Full service
- £220
- Landlord Gas Safety Certificate (CP12)
- £80
- Basic service added to a CP12 visit
- £100
- Full service added to a CP12 visit
- £200
- Gas fire service
- £110
All of the above, plus:
Both jobs on one visit - £180 in total, instead of £200 booked separately.
Both jobs on one visit - £280 in total, instead of £300 booked separately.
Natural gas fires. £85 when carried out alongside a boiler service.
- Powerflush - up to 6 radiators
- £580
- Powerflush - 6 to 10 radiators
- £680
- Powerflush - 10 to 15 radiators
- £740
- Powerflush - 15 to 20 radiators
- £820
- Radiator not heating / cold radiators
- £60-£80
- Underfloor heating service
- £110
- Cleanser & inhibitor protection
- £180
One-day flush or less, including chemicals and magnetic filter.
One-day flush or less, including chemicals and magnetic filter.
One-day flush or less, including chemicals and magnetic filter.
One-day flush or less, including chemicals and magnetic filter.
The diagnosis visit:
One zone, wet underfloor systems.
The lighter-touch alternative when a full flush isn't needed yet:
- Kitchen fitting
- Free survey & quote
- Gas hob installation
- From £120
- Taps & mixers replacement
- From £90
- Kitchen sink installation
- Quoted
- Leak repairs
- From £90
Complete kitchen fitting, quoted after a free survey of your plans:
Install gas cooker hob - Gas Safe registered work.
Remove old tap and install new kitchen tap.
Install new sink including waste and tap connections. Quoted to your worktop and sink choice.
Fix leaking pipes, valves, joints or traps under the sink.
- Full bathroom installation
- Free survey & quote
- Shower installation
- £120-£200
- Sink & basin installation
- Quoted
- Toilet repairs
- From £80
Complete installation, quoted after a free home visit:
Install new sink or basin including waste and tap connections. Quoted to your suite.
Fix flush issues, fill valve, leaks, blockages.
- Emergency water leak call-out
- £150
- Taps & mixers replacement
- From £90
- Leak repairs
- From £90
- Toilet repairs
- From £80
- Cylinder service
- £110
- Mains pressure test
- £95
- Hot water pressure test
- £85
- Leak detection
- Quoted
- Gas safety check
- £95
- Boiler service alongside
- £100
- Underfloor heating check
- £65
- Cylinder & controls package
- £85
- Mains & hot/cold pressure test
- £140
- Radiator & valve inspection
- £65-£99
- Visible pipework & sanitaryware inspection
- £95-£165
Immediate response for water leaks - available 24/7.
Remove old tap and install new kitchen or basin tap.
Fix leaking pipes, valves, joints or traps.
Fix flush issues, fill valve, leaks, blockages.
Annual service for unvented or standard hot water cylinders.
Test incoming mains water pressure and flow.
Test hot water pressure and flow at the outlets.
Professional leak detection using thermal imaging and acoustic equipment.
Carried out alongside the inspection visit.
Combination or conventional/system boiler.
Wet systems, per zone.
Conventional and system boiler package:
Full pressure and flow check across the property.
Priced by property size:
Taps, toilets, showers, baths, sinks and basins. Priced by bathroom count:
Prices exclude VAT where applicable and were last reviewed in July 2026. Anything not listed — and there is always something not listed — we will price on the phone or after a free survey. Call 0208 226 0205.
Where we work
Every service on this page is available across all 18 areas we cover, at the same price. Each town has its own page with local response times.
Battersea · Putney · Balham · Tooting · Wandsworth · Clapham · Streatham · Wimbledon · Colliers Wood · Morden · Dulwich · Croydon · Thornton Heath · Norbury · Sutton · Mitcham · Carshalton · Wallington · All areas we cover
Questions we get asked
If yours is not here, call and ask. We would rather spend five minutes on the phone than send an engineer you did not need.
Are your engineers Gas Safe registered?
Yes. Every gas engineer who works on your home is Gas Safe registered, and we carry our ID cards on every job — you're entitled to ask to see one before anyone touches your boiler. Only a Gas Safe registered engineer may legally work on gas appliances in the UK; anyone who can't produce a card should not be in your house.
How much does a gas engineer cost?
Our breakdown call-out and diagnostic is £120, which we deduct from the cost of the repair if you go ahead. A basic boiler service is £120, a full service is £220, and a Gas Safety Certificate (CP12) is £80. Larger work — a new boiler, a powerflush, a bathroom or kitchen fit — is surveyed free and quoted in writing before anything starts. Every price on this page is fixed, not an hourly rate that grows while you watch.
Do you charge for quotes?
No. Surveys and written quotes for installation work are free and carry no obligation. For repairs, the £120 diagnostic covers an engineer's time finding the fault, and it comes off the repair price if you go ahead with the work.
What's the difference between a plumber and a heating engineer?
A plumber works on water — taps, toilets, leaks, waste and pipework. A heating engineer works on the heating and hot water system: boilers, radiators, cylinders and controls. Gas work specifically requires Gas Safe registration on top. We are all three, which is why one visit usually settles a problem that would otherwise need two trades.
Do you cover emergencies out of hours?
Yes — we take emergency gas and plumbing call-outs 24/7 across our patch. Uncontrollable leaks, no heating in a cold snap and suspected gas escapes get priority. If you can smell gas, leave the building and call the National Gas Emergency Service on 0800 111 999 first, then call us.
Which areas do you cover?
South West London, Croydon, Sutton and the Surrey borders — 18 towns from Battersea and Putney down to Sutton and Carshalton, all within about 25 minutes of our Streatham base. Every price on this page is the same everywhere we cover, with no travel surcharge.
Know what you need? Book it. Not sure? Call.
Same-day availability across South London. Free surveys and written quotes on installation work, and a Gas Safe registered engineer on every job.