Common Faults Of A Boiler & Potential Fixes

Nicholson Heating Services - GasSafe registered heating engineers - professional combi boiler installers

Trouble With Your Combi Boiler?

It’s never a great time when your combi boiler starts to act up. It’s even worse when the fault is serious enough to warrant calling an engineer (although we offer free no obligation advice and quotes – just contact us!), which is why we’ve pulled together these tips to help you diagnose a problem and what may need to be done to get it fixed.

NOTE:  Please DO NOT try to fix a problem yourself unless it’s an extremely simple fix such as topping up your water pressure or defrosting a frozen condensate pipe – for everything else, always call a Gas Safe registered heating engineer.

Fault 1:  Boiler Indicates Low Pressure

If your boiler pressure has fallen to 0.5 bar or lower there’s a good chance your boiler will refuse to start and most likely go into a boiler lock-out mode. In most cases it’s a fairly simple fix however you might want to check there are no leaks in your radiators, pipework and safety valve first.

The Fix:  Locate the filling loop (usually underneath the boiler) and turn the small tap counter-clockwise. The boiler pressure should start to rise and you should turn the tap clockwise again when it reaches around 1.5 bar.

Fault 2:  Blocked Or Frozen Condensate

If it’s particularly cold outside, with frost visible, and your boiler refuses to spring to life, it may be a sign your condensate is frozen or blocked.

The Fix:  First, check outside to locate the condensate. If possible, try using a kettle of hot water to thaw it out. Next, remove the condensate pipe below the boiler and drain into a bucket. That should fix the problem however you should consider asking a professional heating engineer if he/she can retro-fit a condensate trace heater for added protection in the future.

Fault 3:  No Heating

If your hot water works ok but your radiators aren’t getting hot despite the thermostat telling you the heating is on, check the thermostat is not flashing a low battery symbol or displaying a flashing light on the receiver unit near the boiler.

The Fix:  Replace the batteries in your thermostat, they usually need two AA’s. If you remove and replace the batteries within one minute your time and temperature settings should be saved. If not, you will have to reset your settings to the manufacturers defaults. This isn’t a boiler issue but most people often blame their combi’s when the heating fails to come on!!

Fault 4:  Lukewarm Water/Only Hot When Heating Is On

If your hot water is staying lukewarm when you run the tap, or you’re only getting hot water when the heating is on, the chances are it could be a faulty diverter valve or faulty hot water thermistor. We’ve actually got an entire blog dedicated to helping you diagnose this problem.

The Fix:  First, ask a heating engineer to replace the thermistor as this is small relatively cheap component. However they may also need to replace the diverter valve &/or strip down and replace the diagram washer and spindle.

Fault 5:  Boiler Cuts Out With ‘Chugging’ Sounds

If your boiler cuts out or goes into lock-out mode while making audible sounds like it’s chugging or gasping for air it may simply need a service. This could mean there is an issue with build-up in the flue causing a blocked air intake, a corroded flue, or dirt to build-up on the boiler’s burners.

The Fix:  Arrange for your boiler to be serviced with the burners and jets cleaned and a detailed gas analysis done. If the problem persists a heating engineer should check your flue and disassemble to look for blockages and corrosion, as well as to clean the venturi, replacing any parts as necessary. We recommend annual boiler servicing to ensure optimum performance, safety and reliability. To find out more please contact us.

Consider An Upgrade Or Replacement

Combi boilers are a lot more reliable than they were 10yrs ago. Older combi boilers were only just starting to incorporate condensing technology and went through a period of refinement and improvement. So if you’re having trouble with an older combi boiler ask yourself if the best option is spending money on extensive repairs or investing in a modern, high efficiency boiler that comes with a 10yrs guarantee. We supply and install a wide range of high quality energy efficient combi boilers to suit every budget and property. You can view our comprehensive FIXED PRICE boiler packages by clicking here.

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