Error No hot water

Safety precautions:

1. If you smell gas, evacuate the property immediately and call the gas emergency number. Do not operate electrical switches or the boiler.

2. Isolate electrical supply to the boiler at the fused spur before touching electrical connections. Do not open the boiler casing or attempt internal repairs unless you are Gas Safe registered.

3. If you are unsure at any step, stop and call a Gas Safe engineer.

Initial checks homeowners can do:

1. Confirm the symptom: turn on a hot tap for a few minutes. Note whether there is any warm water or if it is cold only.

2. Check the boiler display for a message or fault code. If the display shows 0 (standby), the boiler is not being asked to heat water.

3. Check the programmer/timer and hot water selector on your heating controller. Ensure hot water is scheduled or the hot water demand is selected.

4. Check the cylinder thermostat (if accessible) is set to a normal temperature (e.g. ~55–60°C) and hasn’t been turned down.

5. Check the mains power: is the boiler switched on at the fused spur and is the display powered? Check your fuse box if necessary.

6. Check other gas appliances (hob, gas fire) to confirm gas supply is present. If none work, check gas meter/credit or call the gas supplier.

7. Check the boiler pressure gauge. For system boilers the normal static pressure cold is around 1–1.5 bar. If pressure is well below 1 bar, the boiler may not operate for hot water.

Specific diagnostic and fix steps:

1. If boiler display = 0 (standby) but you expect hot water:

a. Ensure hot water is demanded from the programmer/room thermostat. Manually call for hot water via the programmer and check display changes from 0.

b. If boiler remains at 0 despite a demand, try a full power reset (switch off at fused spur for 30 seconds then back on). If still stuck, record any other displayed codes and contact an engineer.

2. If pressure is low (F1 or low-pressure symptom):

a. Repressurise the heating system to the level recommended in the boiler manual (commonly around 1.0–1.5 bar cold) using the filling loop. Open the filling loop valves slowly until pressure reaches the target, then close and secure the loop.

b. After repressurising, reset the boiler and check for hot water. If pressure drops repeatedly, there is a leak or faulty component—call an engineer.

3. If central heating works but no hot water (system boiler specific):

a. Check the motorised hot water zone valve (or mid-position valve). When hot water is called for the valve should move; many valves have a manual lever or indicator that shows position. If it does not move or is stuck in the CH position, the valve motor or its microswitch could be faulty and will usually require an engineer.

b. Check the cylinder thermostat and any immersion heater isolation—if the cylinder stat is very low or has failed the boiler may not heat the cylinder.

4. If boiler shows flame loss or ignition lockout codes (F2, L2, LN, FN):

a. Check gas supply and isolation valve (under the boiler, yellow valve) is open.

b. Check other gas appliances. If gas supply to property is interrupted, contact the gas supplier or your installer.

c. Reset the boiler once. If lockouts continue, do not repeatedly attempt to reset—call a Gas Safe engineer.

5. If the boiler shows fan fault, thermistor fault, PCB unconfigured or other electronic faults (F3, F4, F5, F9, L9 etc.):

a. Try a single power cycle/reset of the boiler (off at fused spur, wait 30s, on). If the fault persists, these are component faults that require a qualified engineer.

6. If the condensate pipe is blocked (common in cold weather) or frozen:

a. Locate external condensate discharge pipe; if frozen, carefully thaw with warm (not boiling) water or by contacting an engineer. A blocked/ frozen condensate will cause the boiler to lock out.

7. If you suspect circulation problems (no flow to cylinder):

a. Bleed air from radiators to reduce airlocks and encourage circulation. Check system pressure after bleeding and repressurise if needed.

b. Listen to the pump when hot water is demanded—if the pump is not running when it should (and CH call works), pump fault or wiring could be the cause and will need an engineer.

When to call a professional:

1. Call a Gas Safe registered engineer if any checks point to gas supply issues, repeated ignition/flame loss lockouts, fan/PCB/thermistor faults, motorised valve replacement, pump replacement, or if you opened the boiler casing or are required to work on internal components.

2. Call an electrician if you suspect a low mains voltage issue (boiler voltage below safe operating limits) or persistent electrical supply problems.

3. Call a heating engineer if you cannot restore hot water after basic checks (controls, pressure, reset) or if pressure keeps dropping, suggesting a leak.

Notes:

- Do not attempt internal gas/electrical repairs yourself. Only qualified Gas Safe engineers may work on gas appliances.

- Record any fault codes shown on the display and share them with the engineer; that speeds diagnosis.

- If the boiler is under warranty, contact Ideal or the installer before independent repairs to avoid invalidating cover.