Heating Engineers in Northwood

What we do here

• Boiler repairs and fault finding
• Annual servicing, with a written report
• New boilers and replacements
• Central heating, radiators, valves and controls
• Hot water cylinders, vented and unvented
• Power flushing and system cleaning
• Zoned, smart and weather compensating controls
• Underfloor heating
• Landlord gas safety records
• General plumbing, from a dripping tap upwards

Three Northwoods, and the heating is different in each

Most towns we work in were built in one push. Northwood was built in three, and you can date them by the railway.

The 1887 layer. Northwood station opened on 1 September 1887, on the Metropolitan Railway's extension out towards Rickmansworth. The town went from 257 people in 62 houses in 1881 to around 2,500 people in 500 houses by 1902. What went up were large individually designed villas, and the council describes its Frithwood conservation area as "large individually designed detached houses in the Arts and Crafts style". In heating terms these are the demanding ones: solid walls, generous rooms, long pipe runs, original chimneys, and a century of alterations layered on top of each other.

The 1933 layer. Northwood Hills station opened on 13 November 1933 and the suburb around it was built largely through the thirties by Belton Estates. Northwood Hills is 31.3% semi-detached, almost exactly the national figure, and these are the most predictable houses on our patch: one bathroom, a familiar layout, and usually a straightforward combi.

The 1970s layer, which surprises people. In one of the two areas that make up Northwood, the single largest block of housing dates from 1973 to 1982. That is a vintage with its own habits: microbore pipework that blocks, first generation cylinders on their second or third replacement, and systems that were designed around a boiler nobody makes any more.

So there is no single Northwood system to expect, and that matters most when somebody quotes a replacement without looking properly.

Flats and converted houses, which Northwood has more of than anywhere

This is the number that separates Northwood from every other town we cover.

Nearly seven per cent of households in Northwood ward live in a converted or shared house. For comparison, the equivalent figure is 1.5% in Rickmansworth town, 2.1% in Stanmore and 0.6% at the Moor Park end of this same postcode. Add 35.4% in purpose-built flats, against 21.7% across England and Wales, and more than four households in ten are in a flat of some kind.

A converted house is an Edwardian or Victorian villa carved into flats, and the heating tells you so. Pipework was threaded through a building never designed to carry it, usually in stages by different people. Soil stacks and sometimes the water supply are shared. Meters end up in odd places. Boilers end up in odd places. And there is normally a freeholder or a managing agent whose agreement matters as much as ours does.

Two practical points. A flat has no permitted development rights, so a flue on a flat is a planning question regardless of anything else, which is worth establishing before you choose an appliance. And where a system is shared or communal, the first job is working out what is actually yours before anybody starts pricing repairs to it.

If there is a freeholder or a managing agent in the picture, tell us when you call. It changes what can be agreed and how long agreeing it takes, and it is much better established at the start than discovered halfway through.

Flues, and a council rule that catches more than its neighbours'

If you are in one of Northwood's conservation areas, the flue position is worth checking properly, because Hillingdon words its rule more widely than the councils on either side.

Their published wording is that installing, replacing or altering a chimney, or installing a flue, biomass heating system or vent pipes "on a wall or roof slope on the principal, or side elevation of the dwelling house, or on an elevation fronting the highway" would require permission.

The word doing the work there is or. In Watford and St Albans the equivalent rule catches a flue only where it is on a principal or side elevation *and* fronts a highway, so both have to be true. In Hillingdon either one is enough. A principal elevation that faces away from the road is caught here and would not be a few miles north.

There are three conservation areas in Northwood: Frithwood, designated 1989 and extended in 2009; The Glen, designated in 2007, which the council describes as "a 1950's planned development comprising blocks of maisonettes"; and the Green Lane town centre area, designated in 2009. Hillingdon also runs a second, lower tier called an Area of Special Local Character, and four of those are in or beside Northwood, including the Copse Wood and Gatehill Farm estates and Hillside in Northwood Hills.

Worth being precise about one thing, because people get it wrong: the Copse Wood and Ducks Hill area is an Area of Special Local Character, not a conservation area. Different status, different rules.

We treat the flue route as part of the survey and tell you if your address is caught, rather than finding out once the job has started.

The chimney you stopped using

A lot of Northwood houses have a chimney that went quiet the day the central heating went in, and then got forgotten.

Historic England's guidance is worth quoting on this. All disused flues need regular maintenance, they say, because bird nests or old building debris can block a flue "in unexpected places, leading to damp, smells, staining and other problems", and the simplest fix is to have the disused flues swept. A ventilated cap keeps water, insects and birds out without sealing the chimney up entirely.

That matters here because of the stock. If you have damp on a chimney breast that nobody can explain, or a smell that comes and goes with the weather, the flue is worth ruling out before the plumbing gets the blame.

Servicing, and what 348 mg/l does

Affinity Water's supply zone here is named Northwood, and its 2025 report puts total hardness at 348 mg/l as calcium carbonate, with calcium at 139 mg/l. That is near the top of the range across the area we cover, and well above the Rickmansworth zone at 283.

The honest caveat is that the figure rests on a single sample across the reporting year, and the zone is wider than the town. What it does is not in doubt. Scale settles wherever water is heated: on the hot side of a heat exchanger, in a cylinder, around an immersion element. In the older houses, where cylinders have often been in place for decades, it turns up as a cylinder that never quite gets hot. In flats it turns up as reheat times creeping up.

Our service means opening the boiler up: combustion checked with an analyser, heat exchanger and seals inspected, safety devices tested, flue and terminal checked, and a written note of what we found. If the boiler is inside its warranty, that annual service is what keeps the cover valid. On a new installation we fit scale protection as standard in this water, and on an existing system we will tell you whether it is worth adding.

Repairs

A boiler that has locked out, lost pressure or gone cold is not automatically a dead boiler. Repeated pressure loss is usually a weeping valve or a flat expansion vessel. Noise is usually scale or sludge. Andrew has spent forty years fault finding on heating systems, and the expensive mistake in this trade is replacing a boiler that needed a part. If somebody has condemned yours, it is worth a second opinion before you accept it.

We quote before we touch anything, and if a repair is not worth doing we say so.

Who turns up

Andrew Millward, founder. Forty years in the trade, Viessmann accredited and a Heat Geek Elite, and the one to send at a fault nobody else has pinned down. Elis Harizi, director, in the trade since 2007 and a Heat Geek member, who does most of our installation, cylinder and underfloor work. No subcontractors.

We are Viessmann accredited and it is the brand we recommend most often, but we service and install every major make and we are not paid to prefer one.

How we work

• No call-out fee, no charge for quoting
• A fixed price agreed before the work starts
• One year guarantee on our workmanship
• Monday to Friday 8am to 9pm, Saturday and Sunday 9am to 5pm

Around Northwood

We also work at Moor Park at the other end of HA6, in Rickmansworth, and in Watford where we are based. The full range of heating work is on our heating page, and we take plumbing work in Northwood too, from leaks and taps to full bathrooms, which is on our plumbing page.

To book a service, get a fault looked at, or get a price for a replacement, call Andrew or Elis on 07970 632 064.