No hot water — quick checks and what to do next
'No hot water' means different things on a combi versus a system boiler with a cylinder. Two minutes of the right checks and we'll know whether it's a £30 fix or a Gas Safe call-out.
Make it safe — before anything else
Only Gas Safe registered engineers work on gas
Diagnostics on a gas boiler must be done by a Gas Safe registered engineer — we'll bring the card. Never remove the boiler casing yourself.
Scald risk on cylinders
Unvented cylinders can produce very hot water. If a thermostat has failed high, treat first flow with care — don't let children run the tap unattended.
What Kevin (our AI) will check first
Message Kevin and he'll ask exactly these questions before we send an engineer, so we bring the right parts on the first van.
- Combi boiler or system boiler with a hot water cylinder in the airing cupboard?
- Is the central heating still working normally?
- Any error code on the boiler display?
- For cylinders: is the immersion switch on, and is the timer set correctly?
- Boiler make, model and rough age.
Common causes of a no hot water
Diverter valve stuck on 'heating' (combi)
Mirror image of the no-heating fault. Combi runs radiators fine but never diverts to hot water. £180 – £320 fitted.
Failed DHW flow sensor
The sensor that tells the combi you've opened a tap has failed. Boiler doesn't fire on hot demand. £120 – £220 fitted.
Cylinder thermostat / motorised valve (system boiler)
Cylinder stat fails or the two-port valve stops opening — cylinder never gets heat from the boiler. £150 – £280 depending on part.
Failed immersion heater
If you rely on the electric immersion as a backup or main source, the element or thermostat can go. £120 – £220 fitted.
No gas supply
Meter valve off, prepayment credit run out, or a wider supply issue. Free to check yourself before booking.
Honest cost band — why we won't quote blind
Typical
£90 – £180 for sensor swaps, cylinder-stat replacement or immersion element
Complex
Diverter valve or full DHW rebuild £180 – £340. Motorised valve on system boilers £150 – £280.
£50 diagnostic covers a full pressure, flow and combustion check plus a fixed written price before we lift a spanner.
Fixed £50 diagnostic
Flat fee. No hourly meter running.
Fair quote or refund
Transparent pricing — refunded if we don't fix it.
Vetted UK engineers
DBS-checked, insured, real reviews.
AI-triaged in seconds
KJ chats first so the right engineer arrives.
Related emergencies
Boiler on but no heating
Emergency guide
Boiler leaking
Emergency guide
Thermostat failure
Emergency guide
See all in the emergency plumbing hub — or the leaks & water damage hub.
Areas we cover for no hot water
Same-day across Greater Manchester and Rochdale.
No hot water — FAQs
Dealing with a no hot water? Chat with Kevin now
Real triage in seconds. £50 diagnostic visit — refunded if we don't fix it.
Related hubs: emergency plumbing, leaks & water damage, all services.
Chat with Kevin about No hot water