NORTH LONDON, HERTFORDSHIRE & BEDFORDSHIRE
Boiler Replacement in Harrow
Boiler replacement and new boiler installation across Harrow, Stanmore and Pinner, priced after a survey and fixed in writing. A scale reducer on every combi because Affinity’s water here is very hard, and the flue planned around the house. Call 01462 506 374. Swaps from £2,375 + VAT (£2,850 including VAT), fixed before we begin.
BOILER REPLACEMENT IN HARROW
Replacing the boiler in a house built in the 1930s
Almost two-thirds of Harrow’s homes went up between the wars, and many of them have been through two or three heating systems since. When we survey one, we often find a mix of eras: a combi on the kitchen wall, or an older boiler with a cylinder in the airing cupboard and a cold water tank in the loft, feeding pipework that has been extended every time the house has.
A good boiler replacement deals with all of it. We check the gas supply can carry the new boiler’s demand, measure the mains to decide between a combi and a cylinder, clean the system so the new boiler is not fed old sludge, and plan a flue position that meets the clearances. Gas Safe registered under 956889, with manufacturer cover of up to 12 years depending on the model and 12 months on our own labour.
200
mg/l: above this, Part L guidance says treat a combi’s cold feed. Harrow runs well above it
Affinity Water, and it is very hard
Affinity Water’s 2025 reports show a mean of 363 mg/l in Harrow South and 268 mg/l in Rayners Lane, with a single Harrow North reading of 360. A combi heats water through a small plate heat exchanger, and in water this hard that is the part that scales and fails. So an inline scale reducer is on every Harrow combi quote as standard, not as an extra.
Which boiler suits which Harrow home
Semis, terraces and flats
The Metroland semis of Headstone, Kenton and Harrow Garden Village, the Rayners Lane terraces and the borough’s purpose built flats mostly have one bathroom. A combi suits them: no tank, no cylinder, hot water on demand, and the loft and airing cupboard back. If the existing system is a sound regular one, we can also replace like for like.
Larger detached houses
Canons Park, Pinner Hill and the bigger Stanmore houses often run a family bathroom and one or two en suites. A combi struggles there. A system boiler with an unvented cylinder sized to the outlets keeps two showers running at once, and a softener on the incoming main protects the lot.
Get a fixed price before we start
Call and talk to an engineer, or send us the details and we will come back to you with a price.
Flues, Article 4 streets and the design guide
A boiler inside the house is rarely a planning matter. The flue on the outside can be. Harrow has 30 conservation areas, and about half of them have Article 4 directions: on Stanmore Hill that brings alterations to houses under control, and in Harrow on the Hill Village it covers any façade that faces a road or open space. The council’s Residential Design Guide adds that flues which appear as “add-on” elements will not be accepted.
In practice we route flues to the side or rear wherever the clearances allow, keep them tidy and short, and tell you on the quote if a position needs the council’s agreement.
Thinking about a heat pump instead?
A Harrow semi with a back garden is the sort of house heat pumps were designed for. The £7,500 Boiler Upgrade Scheme grant helps, and the national permitted development rules set the limits.
Size: the outdoor unit can be up to 1.5 cubic metres on a house.
Number: on a semi or terrace only the first unit counts as permitted development. A detached house can have two.
Position: not on a pitched roof, and outside a conservation area not above ground floor on a wall facing a road.
Certification: the installation must meet MCS 020a for the permitted development right to apply.
In a conservation area the unit also cannot go on a wall or roof facing a road, and a listed building has no permitted development rights at all. We check which applies at survey, and we fit both boilers and heat pumps, so the advice is not skewed by what we sell.
The replacement, from survey to sign off
Survey
Outlets counted, mains flow measured, gas supply traced, flue route and condensate drain found, and the conservation area status of the address checked. Then a written fixed price.
Fitting day
Old boiler out, system flushed, new boiler, flue, filter and scale reducer fitted, inhibitor added, combustion tested with an analyser and the controls set up with you.
Paperwork
Guarantee registered, Building Control notified through Gas Safe, Benchmark checklist filled in. Nothing left for you to chase.
Parking in Harrow, arranged before the van turns up. Controlled zone hours change from street to street and are printed on the signs. Where the job needs a bay, we apply to the council for a suspension: a £57 admin fee when we give more than 10 working days’ notice, then £11, £22 or £35 a day per bay depending on the zone. A skip on the road carries a council licence of £82.30 per 14 days, applied for by the skip firm. Each one is a separate line on your quote.
Harrow boiler replacement prices
A like for like combi swap starts at £2,375 + VAT (£2,850 including VAT), fitted, with the clean, filter, scale reducer, flue and registration included. In Harrow the usual additions are a conversion from tanks to a combi, an unvented cylinder for a bigger house, a longer flue to reach a side or rear wall, or a bay suspension on a controlled street. Each appears as a line on the quote, and the total is fixed before we begin.
★★★★★
Rated 4.9 on Google by the people we work for
Why choose Vantage
Rated 4.9 on Google from more than 700 reviews across Google, Checkatrade and Trustatrader. Qualified, accredited engineers, a fixed price before any work begins and a labour guarantee on every job, from an established local company with an office team you can actually reach. No job too small.
Gas Safe registered
Company registration 956889. Every gas engineer carries their own Gas Safe ID card, and you can ask to see it.
Refcom F-Gas certified
REF1024550. Legally required for air conditioning installation and servicing, and we hold it.
CHAS Elite accredited
Veriforce CHAS assessed for health and safety, which is why commercial clients and landlords use us.
City & Guilds and BPEC qualified
Qualified, insured engineers on every job. No subcontracted strangers.
700+ reviews, 4.9 on Google
Across Google, Checkatrade and Trustatrader. Read them before you book.
Labour guarantee on every job
12 months on repairs, installations and everything else. Two years on a full bathroom refit. If anything we did develops a fault, we come back and put it right.
Fixed price before we start
The price is agreed with you before any work begins. No hidden extras on the invoice.
24/7, answered by a person
The emergency line is answered every day of the year by someone who can send an engineer, not a call centre.
Fully stocked vans
Five vans carrying the parts that fail most often, so most jobs are fixed on the first visit.
An office team behind every job
An established local business with multiple engineers and a dedicated office team to keep you informed.
Vaillant myREWARDS and Ideal Max accredited
Accredited installer status means extended manufacturer warranties on the boilers we fit.
Emergency response within the hour
Our average response to an emergency call is under an hour across Hertfordshire, Bedfordshire and Cambridgeshire.
Trusted & Accredited Professionals
Why choose Vantage
Because a boiler replacement in a ninety year old house is more than a swap, and we survey it that way. Gas Safe registered under 956889. Water treated because Affinity’s supply calls for it, flues kept off protected fronts, cylinders sized to the outlets. Company number 13248357, VAT number 392 8946 37. Twelve months on our own labour, and up to 12 years from the manufacturer on a serviced boiler.
Where we replace boilers in Harrow
Across the whole borough, including:
Harrow on the HillStanmoreCanons ParkPinnerHatch EndHarrow WealdHeadstoneNorth HarrowRayners LaneHarrow Garden VillageKentonSudbury HillRoxeth
Beyond the borough line
The HA postcodes that make up Harrow, both sides of Kenton Road where Harrow meets Brent, and on into:
BrentBarnetEdgwareHertfordshire
See the rest of the area on our North London page.
Frequently asked questions
What does a boiler replacement cost in Harrow?
Like for like swaps start at £2,375 + VAT, which is £2,375 + VAT (£2,850 including VAT), fitted. That covers the system clean, magnetic filter, scale reducer, flue and guarantee registration. A move from tanks to a combi, a new cylinder, a longer flue or a bay suspension are shown as their own lines, and the total is fixed before we start.
Is a boiler replacement a one day job?
A like for like combi swap usually is. Replacing a system boiler and cylinder, or converting an older tank fed system to a combi, normally takes two days. Your quote gives the number of days.
My 1930s semi still has tanks in the loft. Do I have to go combi?
No. If the house has one bathroom and the mains pressure is good, a combi frees the loft and the airing cupboard. If there are two bathrooms or a busy household, a system boiler with an unvented cylinder is often the better fit. We measure the mains flow at survey and advise from that.
Does Harrow’s hard water shorten a boiler’s life?
It can. Affinity’s Harrow zones averaged between 268 and 363 mg/l in 2025, and government guidance under Part L asks for a combi’s cold feed to be treated above 200 mg/l. Every combi we fit in Harrow has an inline scale reducer, and the annual service keeps an eye on the rest.
Can the new flue come out on the side of the house?
Often, yes, as long as it keeps its required clearances from windows, doors and the boundary, which in the gap between two semis can be tight. Where it cannot, a plume kit or a different route solves it. In an Article 4 area we also check the council’s view before the flue position is fixed.
Could a heat pump replace the boiler in a Harrow semi?
Possibly. A semi with a garden, reasonable insulation and radiators that can run cooler is a good candidate, and the Boiler Upgrade Scheme pays £7,500 towards it. We install both, so we will tell you plainly which suits your house.
What paperwork do I get?
The manufacturer’s guarantee registered in your name, the Building Regulations compliance certificate notified through Gas Safe, and the Benchmark checklist completed and left with the boiler. Our own workmanship is covered for 12 months.
Have the old boiler surveyed
Call 01462 506 374 or use the quote form. We measure the mains, plan the flue and send a fixed written price for the new boiler.
Related pages
Full refits, en suites and wet rooms, 12 month guarantee
Wall mounted splits and multi room systems, 0% VAT
The services we bring to Harrow homes
Twenty-five finished rooms, photographed
Every rate, in full, including VAT