What to do when hot water is not running but cold water works normally

A situation where only cold water comes from the tap and no hot water arrives at all is unpleasant, but fairly common. Many households immediately assume a major failure of the water heater or boiler. Sometimes that is true, but very often it is a simpler issue: heating turned off, a failed thermostat, a blown fuse, a valve problem, or a local fault at a specific outlet.

It is important to distinguish whether there is no hot water anywhere in the apartment, or only at one location. If it does not work anywhere, the problem is usually at the heat source or in the main hot-water distribution. If it does not work only at one tap, a local fault in the faucet, valve, or supply line is more likely. This distinction alone can save you time and unnecessary stress.

First, make sure where exactly the problem occurs

1. Test the hot water in the kitchen, bathroom, and at other outlets.
2. Find out whether it affects only one tap or shower.
3. If you have your own water heater or boiler, check whether it is on and active.
4. If you live in an apartment building with central hot water, check whether your neighbors have the same issue.

This is the most important first step. Without it, you do not know whether you are dealing with a local issue at the faucet or a broader issue at the heat source. People often skip this basic check and call service immediately, even though the fault is limited to one outlet.

If there is no hot water anywhere in the apartment

1. Check the water heater or boiler

If you have your own electric water heater or gas boiler, suspicion first points here. It may be switched off, in an error state, without power, or not actively heating. Sometimes the issue is simple: a tripped breaker, a faulty thermostat, the temperature set too low, or a heating failure.

• is the unit or display lit up?
• is the circuit breaker or power supply on?
• is there an error or alarm active?
• is the temperature set too low?
• was the water heater or boiler turned off recently?

If it is a boiler, this article can also help: What to do when the heating is not working?, because some causes of heating failure are also related to hot-water heating.

2. Check the pressure or operating condition of the system

With some boilers, a hot-water outage may also be related to incorrect pressure or the general condition of the heating system. If the boiler reports a problem or the pressure is out of range, the unit may not work properly even in water-heating mode.

This is also related to the article Why does the pressure in the boiler drop and what does it mean.

3. Check whether the issue is with the building's hot-water supply

In apartment buildings with central heating, the problem may not be in your apartment, but in the hot-water supply for the whole building or part of it. If several neighbors also have no hot water, contact the building manager or property administration before calling individual service to your apartment.

If hot water is not running only at one place

If hot water works in the kitchen but not in the bathroom, or vice versa, the problem is more likely local. In that case, the likely suspects are the faucet itself, the valve, the connection, or a blockage in some part of the piping.

1. The problem may be in the faucet

Mixer taps and cartridges wear out or become clogged over time. Then it may happen that cold water passes normally, but hot water is blocked or significantly restricted. This is more common with older single-lever faucets or after long operation without service.

2. Closed or damaged valve

There may be shut-off valves under the sink, basin, or shower. If the hot-water valve is closed, partially closed, or damaged, hot water will not reach that particular place even though it works normally elsewhere in the apartment.

3. Clogged supply line or filter

Sometimes it is not a complete outage, but rather that hot water flows very weakly or almost not at all. The culprit may be a clogged aerator, filter, or internal parts of the faucet. This is especially typical where the water is harder or the system is older.

The most common causes of hot-water outages

What you can check yourself at home

1. Find out whether hot water is missing everywhere or only at one outlet.
2. Check whether the water heater or boiler is on and shows no fault.
3. Check the fuses, breakers, and the basic temperature setting.
4. If it affects only one tap, check the valve underneath it.
5. Verify whether your neighbors or the whole building have the same problem.

These steps matter because they help determine the right direction quickly. Without them, it is easy to start dealing with the water heater even though the issue is only in the bathroom faucet, or, on the contrary, call local service to the apartment even though the outage affects the whole building.

When to call a professional

If the unit is on, cold water works, but no hot water arrives at all and you have not found a simple cause, it makes sense to call service. This also applies when the water heater or boiler reports an error, when there is water near the unit, or when the problem keeps returning.

• the water heater or boiler reports an error
• there is no hot water anywhere in the apartment and the cause is not obvious
• there is moisture or water near the unit
• the problem keeps coming back
• only one place does not work, but the fault is not in the valve or faucet

In that case, plumbing work in Bratislava can help. If the problem is directly with the boiler, heating work in Bratislava may also be relevant. If water starts leaking near the water heater, this article is also related: Why water is leaking from the safety valve on a water heater.

What not to do

• do not randomly change boiler settings if you do not know what you are doing
• do not ignore device error messages
• do not assume the problem is always in the whole system
• do not use force on valves and shut-offs
• do not postpone service if the problem keeps returning

Conclusion

When hot water is not running but cold water works normally, the key is to first determine the extent of the problem correctly. If it is only one tap, the cause is often the faucet, valve, or local supply line. If there is no hot water anywhere, the issue is more likely at the heat source or in the supply for the entire apartment or building.

Correct diagnostics at the beginning significantly shortens the path to a solution. The more precisely you find out whether the fault is local or system-wide, the faster and cheaper it will be to fix.