Why Do I Have Heat, But No Hot Water?

For homeowners, the joy of a hot shower or washing dishes in warm water can be taken for granted—until you turn on the faucet and discover that you have heat but no hot water. This can be especially confusing when your heating system, which is usually connected to the same boiler or furnace that heats your water, is functional.

Before you call a technician, there are several DIY fixes you can try to troubleshoot this common household inconvenience. Here are the most prevalent causes of this issue and how to address them.

Common Causes of No Hot Water When Heating Is On

If you have no hot water despite your heating system being operational, several issues might be at play. These faults are relatively common and can be fixed independently or through professional service.

Gas Leak

A gas leak from your heater can lead to a loss of hot water and be very dangerous. When there's a leak, it means that gas is escaping from the pipes or connections of your water heater. This can happen if there's a problem with the seals or if the pipes are damaged.

Gas leaks are serious because gas is flammable and can cause fires or explosions if it's not handled safely. If you think there's a gas leak, acting quickly is important. First, turn off all the gas appliances in your home, including your water heater. Then, shut off the main gas supply to your house.

After that, you should contact a professional engineer right away. They'll be able to come and find out where the gas leak is coming from and fix it safely.
Serviceteam is just a call away for emergency gas leak repairs and routine maintenance.

Leaking Water Heater Tank

Think of your water heater tank as a large container that stores and heats the water. If there's a leak in this container, the hot water will gradually drain out, reducing the amount of hot water available for use. So, when you use the heating, there might not be sufficient hot water left in the tank to meet your needs.

To check for a leaking water heater tank, look around the base for water pooling or dampness. If you see signs of a leak, the tank is likely damaged and needs replacing. Repairing a leaking tank isn't usually possible, so it's best to replace it to restore hot water and avoid further damage.

Gas Valve Failure

This valve is like a gate that controls how much gas goes to the burner in your water heater. When it works properly, it lets the right amount of gas through to heat up your water. But if the valve stops working, it can cause your water heater to stop making hot water, even when the heating is on. To see if the gas valve is causing the issue, make sure it's completely open.

Sometimes, if it's only partially open, it can cause issues. But if the valve is open and you're still not getting hot water, then the valve might be broken and need to be replaced. It's a job best left to a professional to ensure it's done safely and correctly.

Pilot Light is Out

When the pilot light on your water heater goes out, it means the flame that heats the water isn't burning. This can cause your water heater to struggle to heat the water to the right temperature, especially on older models where the pilot light needs to be lit for the burner to work. Follow the manufacturer's instructions to relight it safely, make sure the area is well-ventilated, and follow all safety precautions.

Most modern water heaters no longer have pilot lights. Instead, they use glow plugs or spark ignitors. If yours has one of these, you might need to call a professional or check the owner's manual to fix it.

If your water heater does have a pilot light, check if there are any marks on the burner. If you don't see any, here's an easy way to relight it:

• Turn off the gas regulator and wait for at least 5 minutes to let it dissipate.
• Then, move the regulator to "pilot" mode.
• If your water heater has a self-ignition feature, hold down the ignition knob for about 60 seconds. After that, switch the regulator to "on."
• If you need to use a flame to relight the pilot, use a long lighter. Hold it over the gas supply tube and turn it on. This should relight the pilot light.
• If the pilot light still doesn't light up, check if the gas inlet valve is open. If it's closed, turn the handle on the valve until it lines up with the gas line. Wait for some time to let the gas flow before trying to relight the pilot light again.

Electric Water Heater Malfunction

If your electric water heater isn't giving you hot water, it might be because the heating elements or thermostat are worn out and need replacing. First, check if the power is reaching the water heater by testing another device in the outlet. If there's no power, there might be an electrical problem.

You can also inspect for loose connections and reset any tripped fuses in the breaker box. After waiting about an hour, the water should start warming up again if the breaker tripped. But if the breaker keeps tripping or there's still no hot water, it's best to call an electrician for help.

Thermostat Malfunction

Your water heater includes a thermostat to regulate the water temperature. If it malfunctions, it might not signal the heating elements or burner to kick in, leading to a cold. These are relatively simple to replace if you're comfortable with the electrical connections involved.

Faulty Heating Element

The heating element in an electric water heater is the part that actually heats the water. Over time, these elements can accumulate mineral deposits that reduce their efficiency. If you've ruled out other issues, the heating element might need to be cleaned or replaced.

Broken Diverter Valve

When you have central heating but no hot water, the likely culprit is often a faulty diverter valve.

This valve directs heat between your boiler and hot water tank, determining where the heat goes. It can be challenging to fix because of its complex function, which involves switching heat between hot water and central heating systems.

Diverter valves switch the heat between your hot water and central heating. When you use hot water, the valve stops the flow to your central heating, and when you're done, it reopens to heat your radiators.

Over time, diverter valves can wear out or get stuck, stopping your hot water. If this happens, it's best to call a professional for boiler repair. Don't try to replace the diverter valve yourself unless you know what you're doing!

Frozen Pipes

Frozen pipes can cause hot water to stop flowing. Ensure outdoor faucets and hose bibs are closed. Check outdoor pipes for ice, which should melt after your furnace or boiler has been running for a few hours.

Water Heater Tank Size

If you've just moved into a new home or installed a water heater with a small tank, you might experience a lack of hot water during peak usage times. This isn't a repair issue but rather a limitation based on the tank size relative to your household's needs.

Look for Error or Fault Codes

Your plumbing or heating systems don't stop working without a reason; there's usually a problem. Your furnace or water heater will often show an error or fault code to indicate the issue.

You can usually find this code near your thermostat, inside your service panel, or in the manual. First, find these codes, then make any needed repairs. To gain further insights into boiler error codes, feel free to explore our boiler error code section under blogs.

How Long Does It Take for a Water Heater to Recover?

The time it takes for a water heater to recover and provide hot water again can vary depending on several factors.

But the time will depend on the size of the tank, the efficiency of the heater, and the temperature setting.

How Do You Reset Your Hot Water Heater?

If you suspect an electrical issue, resetting your water heater can sometimes solve the problem. Here's how to reset an electric water heater:

• Turn off the power to the water heater.
  If it's electric, switch off the breaker at the electrical panel. If it's gas, turn the control knob to the "pilot" setting. Find the high-temperature cutoff reset button on the water heater's thermostat and press it. This will reset the thermostat and can restore hot water.
• Turn the power back on.
  For electric models, switch the breaker back on. For gas heaters, set the control knob to the desired temperature. If resetting the water heater does not restore hot water, it's time to consider other issues or to call a professional.

What is the Most Reliable Type of Water Heater?

The reliability of a water heater relies on various factors, such as the unit's quality, installation, and upkeep.

Here is an overview of the most common types:

• Gas water heaters:
  These are cost-effective and can provide hot water even during power outages. They generally require more frequent maintenance, such as vent clearance and gas leak checks.
• Electric water heaters:
  These typically have a longer lifespan and are more energy-efficient than gas models but may be less reliable during power outages.
• Tankless water heaters:
  These heaters, which heat water instantly, are highly energy-efficient. While they have fewer components that can malfunction, they still need occasional descaling.

Choosing the most reliable type of water heater for your needs involves considering your hot water usage, energy preferences, and the reliability of the power and gas supply in your area.

Reset Your Boiler

Knowing how to safely reset your boiler can help if it stops working unexpectedly. The method for resetting your boiler depends on its make and model, so check your manual first. However, most boiler resets involve common steps, like turning a dial or pressing buttons.

Still No Hot Water?
Call Serviceteam Heating Professionals!

If you've gone through these troubleshooting steps and still find yourself without hot water, it may be time to enlist the help of professionals. Our expert gas and heating engineers can diagnose the issue with precision and make the necessary repairs to make sure you have a reliable supply of hot water once again.

Frequently Asked Questions

Why do I have no hot water?

Not having hot water could be due to various issues, including a gas leak, thermostat malfunction, or water heater component failure. It's important to troubleshoot the issue to identify the root cause.

Why do I have no hot water when the heating is on?

If you have a combined heating and hot water system, a diverter valve may not be directing the flow of hot water correctly, or there could be issues with the shared components that affect both systems.

I have a combi boiler; why is there no hot water when the heating is off?

A combi boiler typically uses a diverter valve to switch between heating and hot water. If you don't get hot water when the heat is turned off, the diverter valve could be clogged.

Why do I have no hot water pressure?

One possible reason for low hot water pressure can be caused by a blockage or malfunction in the hot water supply line or as a symptom of a more significant issue, such as a failing water heater or a leak in the system.

Understanding the common causes of no hot water when heating is on is the first step in determining the cause. With these tips and seeking professional help when needed, you can ensure that your hot water supply is restored promptly and efficiently.

Always prioritise safety, particularly while dealing with electrical or gas systems. If in doubt, it's best to leave the repair work to a qualified engineer.

Don't let the inconvenience of no hot water disrupt your daily life.
You can make sure your home has a steady supply of hot water by being aware of the possible causes and getting help from professionals when necessary.