Ideal Boiler No Hot Water: What to Check and What Fails

Which Ideal have you got?

Ideal sell combi, system and heat only versions of most of their ranges, so the name alone does not tell you. Look at the front panel or the data badge on the underside: it will say Combi, System or Heat. The Logic, Logic+, Logic Max, Vogue, Vogue Max, Independent, Exclusive and Instinct names all come in more than one type.

The quickest test is the airing cupboard. If there is a hot water cylinder in it that the boiler heats, you do not have a combi, and the fault may not be in the boiler at all. If there is no cylinder and the hot water comes straight from the boiler when you open a tap, it is a combi and the repair is almost certainly inside the case.

F1, L2 and the other codes

Write down the exact code before you press reset. A reset clears it, and the code is the first thing an engineer will ask for.

F1 is the code most people see with no hot water. It means the water pressure in the sealed heating circuit has dropped too low for the boiler to run. Check the gauge on the front: with the boiler cold it should normally sit around 1 to 1.5 bar. If it is well below that, top it up through the filling loop as your manual shows, then reset. If it drops back within a few days, water is escaping somewhere, from a weeping valve, a radiator, the pressure relief valve or a tired expansion vessel, and it needs finding rather than topping up every week.

L2 means the boiler asked for gas, sparked and never saw a flame. Check the gas is on at the meter, that a prepayment meter has credit, and in freezing weather that the condensate pipe outside has not frozen. Our page on the Ideal boiler L2 fault code goes through every cause in order. One or two resets is sensible. A code that keeps coming back is the boiler telling you it cannot run safely.

Checks worth doing before you call anyone

None of these need tools or the case taking off.

• Pressure: check the gauge with the boiler cold, as above.
• Gas: light a hob if you have one. If that will not light either, the problem is the supply, not the boiler.
• Hot water setting: on a combi, make sure the hot water temperature has not been turned right down or switched off. Some Ideal combis have a mode that turns hot water off altogether for the summer or a holiday.
• Programmer: on a system or heat only boiler, check the hot water channel is on and the clock is right. A power cut often resets it.
• Every tap: if one tap runs cold and the others are hot, the boiler is fine and the fault is at that tap.
• Flow: open the tap fully. A combi needs a minimum flow before it fires, and a mixer tap barely open can fall below it.

Ideal combi: radiators hot, taps cold

With no code on the display and the heating working, the boiler is lighting and making heat. It is just not sending that heat to the hot water. On an Ideal combi there are three usual reasons.

The diverter valve decides whether the heat goes to the radiators or to the hot water. It sits in the hydraulic block at the bottom of the boiler, and when it sticks on the heating side you get exactly this fault: hot radiators and cold taps. When it sticks halfway, you get radiators warming up whenever you run a tap, and hot water that never gets properly hot. The valve or its motor is a standard replacement, and our guide to diverter valve replacement cost explains what the job involves.

The flow sensor tells the boiler that you have opened a hot tap. If it fails, or the small filter on the cold water inlet blocks, the boiler never knows there is a demand, and it stays silent while the tap runs. The tell is that the boiler does not even try to fire when you open the tap, but fires straight away when the heating calls.

The plate heat exchanger is where the boiler heat passes into your tap water. In London water it scales up over the years, a little at a time. Hot water that starts hot and fades, a boiler that fires and cuts out while the tap runs, or water that is only ever warm at a normal flow all point here. It can sometimes be descaled, but on an older boiler replacing it is usually the lasting repair. Our guide to no hot water from a combi boiler covers the same three parts in more depth.

No hot water from an Ideal system or heat only boiler

With a cylinder, the Ideal may be perfectly healthy and simply never being asked to heat the water. The request goes from the programmer to the cylinder thermostat and then to a motorised valve, which opens the route to the cylinder coil and tells the boiler to fire. A break anywhere in that chain gives you hot radiators and a cold tank.

The motorised valve is the part that fails most, usually its motor or the small switch inside the head. The cylinder thermostat can fail, or get knocked right down. If your cylinder has an immersion heater, switching it on for an hour is a useful test: hot water from the immersion means the cylinder is fine and the fault is in the boiler side of the controls. Our guide to no hot water but the heating works walks through those checks.

What we check, and whether to repair

We start with the fault history and the pressure, then prove each part of the hot water circuit in turn. On a combi that means watching the flow sensor respond, checking which way the diverter sends the heat, and measuring temperatures across the plate heat exchanger. On a system boiler it means proving the call for heat, the motorised valve and the cylinder thermostat. Nothing gets replaced until it is shown to be faulty.

Most Ideal hot water faults are ordinary, one visit repairs with parts that are easy to get. Replacing the boiler starts to make sense when it is old, when the heat exchanger or other major parts are also going, or when the same fault keeps coming back because scale or sludge has never been dealt with. A boiler diagnosis visit gives you that answer with the readings behind it.

Anything inside the case of a gas boiler, including the diverter valve, flow sensor and plate heat exchanger, is gas work and must be done by a Gas Safe registered engineer. If you smell gas, turn it off at the meter, open the windows and call the gas emergency line on 0800 111 999.

When to call us

Call us on 020 4652 5111 or send an enquiry if F1 comes back after a top up, if L2 returns after a reset, if the boiler or the pipes under it are dripping, or if the taps still run cold after the checks above. Tell us the model name on the front and any code on the display, so the engineer can bring the likely parts. We have 20 engineers across London, and our rate is on the pricing page, agreed before anyone attends.