Question 1

Why choose a Telford Tempest over a Megaflo?

Accepted Answer

Both are duplex 2304 stainless steel cylinders with 25-year tank warranties and equivalent G3 safety device sets. The Tempest range goes wider — 90L right up to 500L — where Heatrae Sadia Megaflo Eco caps at 300L for most plumber van stock. Telford is also UK-manufactured (Telford, Shropshire), with strong parts logistics and same-day vessel / T&P / element stock across London merchants. For most 2–4 bed London properties either brand is correct; for studios under 120L, HMOs over 300L or any twin-coil solar / heat-pump pairing the Tempest is the easier specification.

Question 2

What does a Tempest installation cost in London in 2026?

Accepted Answer

Supply-and-fit prices for a like-for-like Tempest swap by a G3 engineer in London: £1,395 for a 90L, £1,495 for a 120L, £1,595 for a 150L, £1,745 for a 180L, £1,895 for a 210L, £2,195 for a 250L, £2,595 for a 300L, £2,995 for a 400L twin-coil, £3,495 for a 500L. Prices include VAT, the Tempest cylinder, full G3 inlet group, expansion vessel, T&P relief valve, discharge pipework, commissioning, Benchmark logbook and Building Regulations G3 notification via our Competent Persons Scheme. Labour-only installs of a customer-supplied Tempest start at £695.

Question 3

Do I need a G3 engineer to install a Telford Tempest?

Accepted Answer

Yes — without exception. Approved Document G3 of the Building Regulations makes unvented hot water installation, commissioning and modification a controlled service. The engineer must hold a current G3 ticket (BPEC HWSS, LCL Awards or City & Guilds 6035), renewed every five years. Anyone fitting a Tempest without a G3 ticket invalidates the 25-year tank warranty, breaches Building Regulations, and exposes the property owner to enforcement under the Building Act 1984 and to refusal of any related insurance claim.

Question 4

Direct or indirect Tempest — which do I need?

Accepted Answer

Indirect is the default for any London property with a working gas system boiler, heat-only boiler, heat pump or hybrid system. The indirect coil recovers hot water 2–3 times faster than electric immersion and at roughly a third of the running cost. Direct (immersion-only) is the right call where there is no boiler at all — typically top-floor flats with electric-only heating, studios without gas, or properties on Economy 7 thermal storage. A direct Tempest still includes one immersion element as back-up; an indirect Tempest can be heated by either source if the boiler fails.

Question 5

How long does a Tempest install take?

Accepted Answer

A like-for-like Tempest swap in a London flat with accessible pipework is a 4–6 hour single-day job — strip out, set, connect, fill, pressurise, vent, commission, certificate. A first-time unvented install replacing an old vented cylinder + loft tank is a 1–2 day job because all the cold inlet, discharge pipework and electrical work is new. Large-format installs (Tempest 400L / 500L for HMOs or townhouses) typically take two days because of access, sized primary pipework and secondary circulation work.

Question 6

Will my mains pressure support a Telford Tempest?

Accepted Answer

A Tempest needs a minimum 1.5 bar dynamic pressure at the cold inlet group, with at least 20 L/min flow at the system kitchen tap to perform as designed. Static pressure on its own is misleading — a London property can read 4 bar static but drop to 1 bar dynamic once a tap is open, especially on a long lead-in or shared rising main. The on-site survey takes 5 minutes with a hose-tail pressure gauge and a measuring jug. If mains pressure is marginal, options are a mains upgrade through the water company, a cold accumulator vessel, or a pumped-cold solution.

Question 7

Where does the Tempest discharge pipe go?

Accepted Answer

The discharge pipework from the Tempest tundish must be at least one pipe size larger than the inlet to the T&P relief valve — typically 22 mm copper from a 15 mm valve. It runs with a continuous fall, no more than three bends, terminating to a visible safe location at low level — usually a gully or external wall above the gully. Internal discharges into a hopper, soil pipe or void are a Building Regulations breach. In flats and mid-floor properties the discharge route is often the hardest engineering decision in the whole install — the survey addresses it first.

Question 8

How long does a Tempest cylinder last?

Accepted Answer

The duplex 2304 stainless tank itself carries a 25-year manufacturer warranty when serviced annually. In London hard-water postcodes most Tempest tanks run 20–30 years before failure. The ancillary components have shorter lives — the expansion vessel typically 8–12 years, the T&P relief valve 8–10 years, the PRV cartridge 8–12 years, the immersion element 10–15 years depending on hardness. A correctly serviced Tempest will see most of those components replaced once or twice over the tank's life.

Question 9

Does the 25-year warranty really mean 25 years?

Accepted Answer

Yes, on the tank, but conditional on three things. First, the install must be by a G3 qualified engineer and the Benchmark logbook completed and signed. Second, the cylinder must receive an annual G3 service every 12 months by a G3 qualified engineer, with each service entered in the Benchmark logbook. Third, registration with Telford within 30 days of install. ERL handles registration on every install and books annual service reminders for landlords and homeowners to keep the warranty live.

Question 10

Can a Telford Tempest pair with a heat pump?

Accepted Answer

Yes — and the twin-coil Tempest is specifically designed for that pairing. The lower coil is sized for the lower flow temperature of a heat pump (typically 55°C primary), the upper coil acts as a boiler or immersion top-up for legionella cycling. Sizes 150L through 500L are available as twin-coil. For ASHP-paired installs we typically recommend sizing one size up from the gas-boiler equivalent (e.g. 250L rather than 210L for a 3-bed family) because the lower primary temperature gives slower recovery.

Question 11

Do I need an annual service on a Tempest?

Accepted Answer

Yes. Annual servicing is a written condition of the Telford 25-year warranty and is also the practical safety requirement — the expansion vessel pre-charge collapses over time, the T&P relief valve seat scales up, the PRV cartridge wears. An ERL annual Tempest service is £155 fixed and includes vessel pre-charge test and recharge, T&P witnessed-lift, PRV outlet pressure check, thermostat cut-out function-test, immersion element resistance check (if fitted), anode inspection where applicable, full Benchmark logbook update and certificate.

Question 12

What size Tempest for a 3-bed family home in London?

Accepted Answer

The standard recommendation for a 3-bed family home with one bathroom and 3–4 occupants is the Tempest 180L indirect — bath fill in around 6 minutes, recovery in ~38 minutes from a 24 kW system boiler. Step up to 210L for a 3-bed with two bathrooms or for 4-occupant households with a daily bath. Anything with a freestanding bath (180L+ fill volume) wants 250L minimum so the cylinder isn't drained in one bath fill. For HMOs and homes with secondary circulation, sizing is calculated against simultaneous-use loadings using the Telford flow curves, not a rule of thumb.

Question 13

Can a Tempest go in a top-floor London flat?

Accepted Answer

Yes — and Tempest installations are common in top-floor flats specifically because they remove the need for a loft tank, header tank freeze risk, and the noise of an open-vented system. The two engineering checks are mains inlet pressure (≥1.5 bar dynamic at the inlet group) and a viable discharge route to outside. In some mansion blocks the discharge is the hardest question — the cylinder may have to live closer to an external wall than the original airing cupboard, or the discharge piped in a fire-rated metallic duct through a riser.

Question 14

Will you remove and dispose of my old cylinder?

Accepted Answer

Yes — included on every supply-and-fit install. The old cylinder is drained, isolated, disconnected, broken down on site if required for stair access, and taken away the same day. Copper is segregated for scrap recycling; the foam-insulated shell is disposed of through our licensed waste carrier. There is no extra charge for removal, parking, or stair access on a quoted Tempest install across Zones 1–4.

Question 15

What's the difference between Tempest, Tribune and Hurricane?

Accepted Answer

All three are Telford ranges. The Hurricane is the entry-level direct (electric) range, 90L–300L, single-coil only. The Tribune HE is the mid-range indirect with a slim-fit footprint, 120L–300L. The Tempest is the flagship — widest size range (90L–500L), direct, indirect, twin-coil and solar variants, and the only Telford range that goes to 400L and 500L. For most London 2–4 bed homes the Tempest indirect is the right specification; for studios with electric-only heating, the Hurricane direct is a fair-priced alternative.

Tempest size	Use case	Recovery / flow	Occupants	Fitted from
90L Tempest	Studio flat / 1 bed, single occupant, shower only	Recovery ~22 min from cold (3 kW immersion) / 18 min on indirect	1	£1,395
120L Tempest	1-bed flat, 1–2 occupants, one shower	Recovery ~28 min indirect / 38 min direct	1–2	£1,495
150L Tempest	2-bed flat, 2–3 occupants, shower + basin demand	Recovery ~32 min indirect, simultaneous shower + basin OK	2–3	£1,595
180L Tempest	3-bed terrace, 3–4 occupants, 1 bath + 1 shower	Recovery ~38 min indirect, bath fill ~6 min	3–4	£1,745
210L Tempest	3–4 bed family home, 2 bathrooms	Recovery ~42 min, two showers in parallel sustainable	4	£1,895
250L Tempest	4–5 bed family home, 2+ baths, freestanding bath	Recovery ~50 min indirect, supports 2 baths + shower	4–5	£2,195
300L Tempest	5+ bed home / 3-bath / large freestanding bath	Recovery ~58 min indirect, multi-outlet simultaneous use	5–7	£2,595
400L Tempest	Large townhouse, HMO, secondary circulation systems	Recovery ~75 min indirect (28kW boiler), needs sized coil	7–10	£2,995
500L Tempest	Multi-storey townhouse, light commercial, HMO 6+ rooms	Recovery ~95 min indirect, twin-coil option for solar/HP	10+	£3,495

Brand	Construction	Warranty	Size range	London context
Telford Tempest	Duplex 2304 stainless steel, factory-foamed	25-year tank, 2-year parts	90L–500L (widest range in UK)	Made in Telford, Shropshire — strong UK parts supply, vessels & T&P groups stocked on every van.
Heatrae Sadia Megaflo Eco	Duplex stainless steel, factory-foamed	25-year tank, 2-year parts	70L–300L	Dominant London brand. Widest plumber familiarity. No 400L or 500L option without going to Megaflo HE.
Gledhill StainlessLite Plus	Duplex 2304 / 2205 stainless, foamed	25-year tank, 2-year parts	120L–300L	Slightly faster recovery on indirect models. Less common in London — parts wait can run 24–48 hours.
Kingspan Albion Ultrasteel	Duplex stainless, foamed	25-year tank, 2-year parts	90L–300L	Strong on heat-pump pairings. UK manufacture. Smaller dealer network than Telford / Heatrae.
OSO Super S	Duplex stainless, foamed	25-year tank, 2-year parts	150L–400L	Premium Norwegian build, best high-flow recovery. Price premium of £200–£400 over Tempest equivalent.

Job	What's included	Fitted from
Tempest 120L direct (electric) — supply & fit	Telford Tempest 120L direct cylinder, full G3 inlet group, expansion vessel, T&P relief valve, tundish, 22 mm discharge to outside, RCD-protected immersion circuit, commissioning, Building Regs G3 notification.	£1,495
Tempest 150L indirect — supply & fit (like-for-like swap)	150L Tempest indirect cylinder, removal & disposal of old unit, full G3 group, primary connections to existing system boiler, discharge pipework, Benchmark logbook, 25-year warranty registration.	£1,595
Tempest 180L indirect — supply & fit	180L Tempest indirect, full installation, expansion vessel, all safety devices, primary repipe if needed, commissioning, Building Regulations Part G3 notification.	£1,745
Tempest 210L indirect — supply & fit	210L Tempest indirect cylinder for 3–4 bed family home, G3 commissioning, Benchmark logbook, certificate issued.	£1,895
Tempest 250L indirect — supply & fit	250L Tempest indirect, full G3 install, primary upgrade where required to support 28kW+ boiler output for recovery time, Building Control notification.	£2,195
Tempest 300L indirect — supply & fit	300L Tempest indirect, large-property install, mains supply check (minimum 22 mm), discharge route engineered, full commissioning, certificate.	£2,595
Tempest 400L twin-coil — supply & fit	400L Tempest twin-coil for solar thermal or heat pump pairing, full G3 install, secondary circulation if specified, balancing valves, certificate.	£2,995
Tempest 500L indirect — supply & fit	500L Tempest indirect for HMO / large townhouse, sized coil, secondary return option, full G3 commissioning, Building Control notification.	£3,495
Vented to Tempest unvented conversion	Removal of old vented cylinder + loft tank, new Tempest unvented (size matched to property), full G3 group, expansion vessel, discharge to outside, primary repipe, Building Regs notification. Add +£350–£500 over like-for-like swap.	from £2,495
Labour-only Tempest install (customer supplies cylinder)	G3 install of customer-supplied Tempest cylinder, all safety group components, commissioning, Benchmark logbook, certificate.	from £695

Telford Tempest Installation London

What is the Telford Tempest?

Tempest direct, indirect or twin-coil?

Tempest Direct (electric only)

Tempest Indirect (boiler-fed)

Tempest Solar / Twin-Coil

Tempest sizing guide — bedrooms, baths, occupants

Telford Tempest vs Megaflo, Gledhill, Kingspan, OSO

Telford Tempest install cost London — 2026 prices

Install process — survey to certificate

Survey & fixed quote

Strip out & prep

Set & connect

Fill, pressurise, vent

Commission & certify

G3 compliance & Benchmark commissioning

Approved Document G3 — Hot water supply and systems

HHIC Benchmark Commissioning Scheme

Specification for indirectly heated unvented closed storage water heaters

Water Supply (Water Fittings) Regulations 1999

Design, installation and maintenance of services supplying water

18th Edition Wiring Regulations (2018+A2:2022)

Real London Tempest installs — worked examples

Victorian terrace, Camden — vented to Tempest 210L indirect conversion

1990s flat, Wandsworth — like-for-like Tempest 150L swap

New-build top-floor flat, Hackney — Tempest 120L direct (no gas)

Listed townhouse, Westminster — Tempest 300L for 5-bed renovation

HMO licensed property, Tower Hamlets — Tempest 400L twin-coil

Ready to spec a Telford Tempest?

Areas covered across London

Frequently asked questions

Telford Tempest installers — All London Boroughs