Trouble Shooting: – No Hot Water

washing hands no hot water
No Hot Water?

A water heater that produces no hot water is never welcome and always seams to occur at the most inopportune time. We hope that the information below will help you troubleshoot to find the cause of the problem before you must call in a professional.

Is your boiler working: – It may seem like a silly question but, normally it is the simplest of things that cause us problems. If there is a problem with the boiler it will display an error code (check boiler manual to see what this means) You may simply need to reset the boiler (the manual will also help you with this).

Electricity supply: – check the power source-lights, sockets, main fuse box. If you are not getting an error notice you may not be getting power, or it may have a tripped limit switch or one or more failed heating elements.

First, check the water heater’s circuit breaker in the service panel to make sure it has not tripped. If the breaker has tripped, switch it off, then switch it back on again.

Check your timer: If the clocks have been changed it affects the boiler, any changes in power supply will also impact the timer.

Water Supply: if no water is flowing from the taps this can impact your boiler.

If your heating is working but you still have no hot water, you need to check the diverter valve to make sure it’s not set on heating only. (a problem with the diverter valve will require the help of a professional gas engineer).

For conventional heating systems you need to check to see if there is sufficient water in your header tank, is there a blockage stopping water refilling the tank.

valve for switching between hot water and heating

Check boiler pressure:- Low pressure can cause your water to not heat. Normal pressure for a domestic boiler is around 1.5 bar (you will find this on a gauge ‘Manometer’ located where the water supply pipes are connected to the boiler.

If the pressure is low go to your operating manual to re-pressurise the boiler. (if you are in any way unsure of what you are doing call a professional plumber)

You can higher up the thermostat. Ideal operating temperatures for hot water heaters are between 122- and 140-degrees Fahrenheit.

Check for leaks: Leaks can cause all sorts of problems and most often happen at joints in the pipes, begin there or look for patches on ceilings, peeling paint, swollen woodwork, or mould.

Leaks will cause a reduction in the pressure and can end up causing damp resulting in expensive repairs.

Check water supply – conventional systems: –  Check to see if there is sufficient water in your header tank, is there a blockage stopping water refilling the tank. 

Gas Supply: check other appliances that run off gas (fire-Cooker).

Pilot Light: You may need to relight the pilot light.  Always pay attention to the colour of the flame should be blue, if it has a yellow hue it may be a sign of carbon monoxide and you need to call a professional immediately.

Finally ask yourself if your boiler is the right size for your family’s needs. If the tank is too small to serve your families need and running out of hot water is a regular occurrence, then speak to a professional about installing a larger tank or upgrading your heating system to a combi boiler.


Call us today on 01 497 9838. We have over 30 years’ experience in the industry and our team of professional engineers are fully RGII registered. Give us a call for a no obligation chat regarding problems with immersion heaters, gas, and combi boilers, leaking pipes and more!


                        We turn up on time and when we say we will.