Hot Water Problems
"No hot water" isn't a single fault — the actual cause depends heavily on what type of system is producing your hot water (a combi boiler, a hot water cylinder, or an electric immersion heater), and each has different likely culprits. This page is a starting point for diagnosing which situation you're in before booking the specific fix.
What's Included
- Diagnosis across combi, cylinder, and immersion-based hot water systems
- Distinguishes a hot-water-specific fault from a whole-heating-system issue
- Clear next step depending on what's actually found
- Same-day fixes in most cases where the cause is straightforward
How It Works
- 1 Establish what type of system produces your hot water and exactly what symptom you're seeing
- 2 Check the most common causes for that system type first (pressure, thermostat, element, or valve)
- 3 Diagnose and explain the actual cause before fixing it
- 4 Fix on the same visit wherever the cause is a standard, common one
Common Issues
- • Heating works but hot water doesn't (often a diverter valve fault)
- • Hot water pressure dropping when multiple taps are used
- • Water temperature that's inconsistent or unexpectedly very hot
Pricing: Typically £80–£180 depending on the cause (indicative — confirm actual pricing with Rainbow Fix Ltd)
Hot Water Problems — Frequently Asked Questions
I have heating but no hot water — what does that tell you?
This pattern — heating working, hot water not — points toward a fault specific to the hot water side of the system rather than the boiler failing outright: on a combi boiler this is often a diverter valve fault (the valve that switches between heating water for the radiators and for the taps); on a system with a separate cylinder, it's more likely to be a cylinder thermostat or a valve controlling flow to the cylinder. Mentioning this exact combination of symptoms when you call helps narrow down the likely cause before the engineer even arrives.
My hot water is fine but takes a long time to get hot at the tap — is that normal?
A short delay is normal in most homes simply due to pipe length between the heat source and the tap, but a delay that's got noticeably worse over time, or is much longer at one tap than others, can point to a partially blocked pipe (sometimes from limescale, given how hard the water is across this region) or a failing non-return valve. It's worth noting whether it's every tap or just one specific one, since that distinction changes where the likely fault sits.
Why does my hot water pressure drop when someone else in the house uses a tap or shower?
This is usually either a mains pressure/flow limitation being shared across multiple outlets at once (more likely in a combi system, which heats water on demand and has a maximum flow rate) or, in a cylinder-based system, a sign the cylinder or its associated pump isn't providing enough flow to cope with simultaneous demand. Combi boilers in particular have a fixed maximum output, so if your household regularly needs hot water at two taps simultaneously, that's worth discussing as a genuine sizing question, not just a fault.
My hot water is scalding hot even on a low setting — is that dangerous?
Yes, this should be looked at rather than worked around by mixing in cold water manually — it usually points to a failed or wrongly set thermostat (on a cylinder or immersion heater) or, on a combi, a fault in the temperature control, and scalding-hot water is a genuine safety risk, particularly for children or elderly household members. This is worth booking promptly rather than treating as a minor inconvenience.