No hot water? What to check

Waking up or coming home to find the hot water not working… is one of those things you could have done without today. Don’t let it ruin your day! We’re here to help you find out what causes hot water to stop working, and sort it out.

Hot water not working?

There’s a quick checklist you should run through. This should isolate the problem. Then you can take the next steps: getting your hot water back.

Is your boiler working?

Most issues with hot water boil down to your boiler. Think of it as the heart of your home. It needs to run smoothly, and is the prime cause of what causes hot water to stop working. Most modern standard or combi boilers have a display that tells you its current status.

Check for fault or error codes

If that display looks different than usual, it could be your boiler telling you something’s up. Your Baxi boiler has a range of fault codes that tell you what might be wrong in the most accurate way possible. If you don’t have a Baxi boiler, you’ll need to check the manual that came with your own boiler: hopefully it’ll give you a good idea of what’s wrong!

The good news is that the majority of codes usually require only a boiler reset. It could explain ‘why is my heater working but no hot water?’ Or it could be due to a number of factors, where giving it a reset might do the trick.

Check the boiler's controls

You might need to consult your manual or user guide for this. Boilers come with many different controls; timers, thermostats, or how to re-pressurise your boiler. They’re fairly complex machines. They do, after all, keep an entire home safe and warm for years.

Whatever controls your boiler may have, there will be at least one setting you can change. Check any settings haven’t been altered. A simple switch flicked, or dial twisted might be the reason for hot water not working. Put everything back to how it was, and it might just fix your problem.

Boiler control checklist. If your boiler has any of these settings, check they’re in the right place:

• Timer: some boilers have the ability to switch on or off at certain times of the day. Having the timer set to off could be what causes hot water to stop working.
• Thermostat: easily done, but check to see the thermostat dial’s pointing to your preferred level of warmth.
• Cut-off controls: more technical (or fancy) than the others, but these are settings around water pressure. You probably shouldn’t mess with these; they’re for safety. But they may indicate low water pressure. At which point you’ll need to know how to re-pressurise your boiler, which we deal with below.

Check the diverter valve

This is a common issue, but unfortunately a tricky one. A dodgy diverter valve might be when your heating’s working but there’s no hot water.

Unfortunately, they do get stuck sometimes. Especially with older boilers, if you’ve traced your hot water not working to your diverter valve, you’re going to have to call in a heating engineer.

Check the boiler pressure

This is a quick check, and a simple one to fix, but you might need to have a good idea about how to re-pressurise your boiler.

Low water pressure will usually show as an error on your boiler’s control panel, and is the main reason for what causes hot water to stop working. To rectify it, you need to increase the pressure. The sweet spot for most boilers is 1 bar. Don’t know what this means? Your boiler should have a pressure gauge on it. Take a good look; the needle needs to be as close to 1 bar as possible. If it’s not, you’ll need to know how to re-pressurise your boiler.

Because all boilers are different, we can’t tell you where the valve that controls the water pressure on your boiler is. If you’re unsure, please consult a heating engineer! We cannot stress this enough. You can do a lot of damage if you’re not sure what you’re doing.

But if you’re confident, and you got this, then go ahead and open the valve, closing it when the needle reaches the magic 1 bar. Bear in mind: not all boilers think 1 is the sweet spot; the manual will let you know.

Anyway, if your boiler is, as far as you can tell, in good working order, it’s time to try the next step.

Why is my heating working but no hot water?

Run through this checklist, and tick them off one by one.

• How are the electrics? A tripped switch in your fuse box could be the key
• Is the pilot light on? (modern boilers do not have pilot lights) Re-light it if not (but check your boiler manual for how to do this)
• Separate water tank? It might have its own settings that are interfering
• Frozen pipes? If you’re wearing sunglasses and shorts right now, this might not be an issue. But if it’s the middle of a frosty winter, you might want to take a look at the pipes, especially the boiler’s condensate pipe, and any outside your home. See how to thaw a frozen condensate pipe. 
• Reset the boiler? A try at “turning it off and then on again” might sort things out. Find out how to reset your boiler here.

If you’ve tried all of these things, and your hot water’s not working, then it might be time to call in a heating engineer.