No Hot Water From a Worcester Boiler

Start with what the display is telling you

Worcester boilers are fairly good at saying what is wrong, so look before you touch anything. Older Greenstar i and Si models have a small display and a blue indicator light; the newer 2000, 4000 and 8000 ranges have a digital display, with a fuller menu on the higher models. Note three things: whether there is a code, whether the blue light is on steady or flashing, and whether the radiators still heat.

If the heating has stopped as well and a code such as EA with 227 is showing, the boiler has tried to light and failed to see a flame, then locked out. That is not a hot water fault at all. Our page on the Worcester EA 227 code covers it. A flashing blue light with no hot water and no heating also points to a whole-boiler lockout, explained in Worcester boiler flashing blue light.

If there is no code, the radiators work and only the taps are cold, carry on down this page.

Safe checks on a Worcester, in this order

Each of these takes a minute and none needs the casing off.

• Pressure gauge: between 1 and 1.5 bar with the boiler cold. If it has dropped near zero, the boiler will usually stop working entirely. Topping up is covered in Worcester boiler pressure low.
• Hot water setting: make sure the hot water knob or menu setting has not been turned to its lowest point or switched off.
• ECO button: on Greenstar i, Si and CDi models, a lit ECO light means preheat is off. That gives a short wait before the water runs hot, not no hot water. Leave it as it is while you test.
• Cold supply: run the kitchen cold tap. If that is weak, the boiler may not see enough flow to fire for hot water.
• Reset: if a code is showing, press and hold reset once, as the user manual for your model describes. If the code comes back, stop and write it down.

If you smell gas at any point, open windows first, then turn the gas off at the meter if it is safe to reach. Do not reset anything or use electrical switches. Leave the property and call the National Gas Emergency Service on 0800 111 999.

Heating works but the taps stay cold: the usual Worcester causes

Open the kitchen hot tap fully with the heating turned down at the thermostat. On most Worcester combis you should hear the fan start within a few seconds and see a tap symbol or hot water indication on the display. What happens next points to the part.

If the boiler does nothing, the flow turbine on the cold inlet is not registering the water moving. Most Worcester combis use a small turbine sensor, often with a fine filter ahead of it, and scale or debris from the mains can jam it. An engineer can clean or replace it.

If the boiler fires but the radiators start warming, the diverter valve is stuck on heating. On Greenstar models the diverter has a motor head on top of a valve body, and either can fail. Sometimes only the motor needs replacing, which is the cheaper of the two.

If the boiler fires, the radiators stay cold and the water only reaches lukewarm, the plate heat exchanger is the likely cause. London water is very hard, and any combi without a working scale reducer slowly furs up its plate heat exchanger. For the same symptom on any make, see heating on but no hot water.

One more Worcester pattern is worth knowing. If the water runs hot for a minute, turns cold, then comes back hot, the boiler is usually overheating on the hot water side and shutting the burner off to protect itself. A scaled plate heat exchanger is the common cause, because the heat cannot get into the water fast enough. It is the same part as the lukewarm symptom, just further along.

What an engineer will do on the visit

On a Worcester, the engineer runs a tap and watches how the boiler responds, using the service menu readings on models that provide them, so the diagnosis rarely involves guesswork. They will check the inlet filter first because it is the cheapest fix, then test the diverter motor, then measure the hot water temperature against the flow rate to judge the plate heat exchanger.

Typical market ranges, parts and fitting together, are roughly £150 to £300 for a flow turbine, £250 to £450 for a Worcester diverter valve or motor, and £350 to £700 for a plate heat exchanger. The engineer should tell you which part it is before quoting, so you are not paying for guesses.

Before booking, check the paperwork that came with the boiler. Worcester guarantees usually depend on the boiler being serviced every year, and if yours is still inside its guarantee, call Worcester before anyone else.

Out of guarantee, our Worcester boiler repair visit starts with the £60 call-out at any hour, and the repair price is agreed with you on site before any work starts. Gas work is carried out by Gas Safe registered engineers.

Is it time to replace the Worcester instead?

A single hot water part is almost never a reason to replace a boiler. The calculation changes when the boiler is past about 12 to 15 years, when it has already had a heat exchanger or fan, or when the engineer reports that the main heat exchanger is corroded. In those cases, ask for the repair price and a rough replacement figure side by side before agreeing to either.

If you rent, your landlord is responsible for repairing the boiler within a reasonable time; see your rights when there is no hot water. Landlords can book our no hot water repair visit for rented homes across London and inside the M25.