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Common Biasi Boiler Problems & Repair Advice

Rob Wells
By: Rob Wells
Updated: 10th January 2022

Last Updated: 10th January 2022

We trust our boilers to quietly do their jobs of providing our homes with heating and hot water every day. Sometimes you might even forget that you have a boiler, until the dreaded day that it stops working. There are many common Biasi boiler problems that can be resolved without a heating engineer, but if an engineer is needed (and if in doubt always get in touch with an engineer), you can get free boiler repair quotes using Boiler Guide.

Common Biasi boiler problems

Biasi boiler problems Biasi error / fault code
Low boiler pressure ER04
Heating but no hot water ER07
Boiler overheating ER02
Leaking ER04
Strange noises ER01

1. Low boiler pressure

Low boiler pressure can lead to your central heating system not functioning properly. It's simple to check a boiler's pressure level, you can do this by simply taking a look at it's built in pressure gauge, anything below 1 and you may have an issue. Find out more with our guide to low boiler pressure.

2. Heating but no hot water

The first thing you should do is check your radiators as they may need to be bled, if they look fine then make sure that the central heating on the boiler is switched on and that the thermostat & timers are set correctly. If you don't spot any issues then this is likely to be a diverter valve issue, this is a valve that opens and closes to provide heat to the radiators or to heat your water and will always prioritise hot water. You will need an engineer to take a look at this issue.

3. Boiler overheating

A repeatedly overheating boiler should always be considered an emergency, so don't try to repair anything yourself, turn off the electrical supply and contact an engineer. When a boiler overheats, the internal parts can come under extreme pressure, possibly resulting in permanent damage.

Leaking from the bottom

When a boiler drips water from the bottom it's due to the failure of some internal parts, possibly a connected joint, rusty pipes, corrosion of the heat exchanger, incorrect boiler connections, auto-air opening or leakage of the heating pump.

4. Fixing a leaking boiler

When you spot a leak, don’t attempt to fix it yourself. The best thing to do is turn the mains water supply off and contact a Gas Safe registered engineer. They will be able to stop the leaking and replace the faulty part to prevent it from happening again.

5. Hearing strange noises

This could be one of a variety of possibilities such as air in the boiler, debris, incorrect speed settings or improper installation. There could also be a blockage that’s preventing the burner from doing its job.

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Which Biasi boiler problems need an engineer?

To give you an idea of the most common boiler problems, and what they might mean, we've put together the list below where you'll find out if it's something you can fix yourself or needs an engineer.

Problem Possible cause Do you need an engineer?
No heat or hot water Broken diaphragms and airlocks, failure of motorised valves, issues with the thermostat or low water levels Yes
Leaking and dripping Most common cause is a broken internal component but it will depend where the water is leaking from Yes
Banging, whistling or gurgling noises A common cause is air in the system, alternatively it could be that the water pressure is too low or it's kettling Yes
Pilot light goes out Could be a broken thermocouple which is stopping the gas supply Yes
Losing pressure There could be a water leak in the system, the pressure relief valve needs replacing or the radiators have been bled recently No, unless there's a leak
Frozen condensate pipe Your boiler should display a fault code or warning notification Yes
Thermostat issues Thermostat may be turned off or not set to the correct settings (time etc.) Consider replacing
Kettling Limescale or sludge building up on your boiler's heat exchanger Yes
Radiators not getting hot Sludge or air build up in the system or an unequal distribution of heat You will need to bleed the radiators which doesn't require an engineer unless you don't feel like carrying out the task yourself.
Boiler keeps switching itself off Could be low water pressure, a problem with the thermostat or a lack of water flow due to a closed valve, air in the system or the pump not circulating the water in the system correctly Yes

Biasi boiler warranty

Biasi offer a free 2 year warranty to give you some breathing space after the installation so that if there's an issue, you know you're covered. Depending on the model you get, you can get a longer warranty, ranging from 2-7 years. Take a read of our complete guide to Biasi warranties so that you know exactly what to expect. An important thing to know about the warranty period is that you’ll need to arrange a service of the boiler once every 12 months, find out more with our guide to Biasi boiler services.

Send us an enquiry today to receive free quotes for a new boiler and find trusted engineers near you with our free service.

Boiler Insurance and Ongoing Cover

Taking out boiler insurance once your boiler warranty has expired is an option worth considering. This can be done with your energy supplier but there's absolutely no obligation to do so. When comparing boiler insurance, keep an eye out for ones that offer annual service and safety inspections.

Is it time to replace your Biasi boiler?

Have you had your Biasi boiler for a lengthy period of time? If so, then it's worth considering a new one as you could be saving up to £365* a year in a detached home. Take a look at the table below to see how much you could be saving depending on your current boiler rating and property.

House Type G (< 70%) F (70-74%) E (74-78%) D (78-82%)
Semi-Detached £240 £170 £150 £135
Detached £365 £255 £205 £165
Detached Bungalow £190 £135 £120 £105
Mid Terrace House £205 £145 £130 £115
Flat (Mid Floor) £95 £65 £60 £50

Figures are for England, Scotland and Wales only*.

Who should replace a Biasi boiler?

If you like the sound of a new boiler then you need to choose who to replace it, which can be a big decision. In the end, your choice will come down to either a local engineer or a national company.

In many cases, local engineers can offer very competitive rates and you'll be getting a very personal service from the same person throughout your communications. To make sure you're getting the best deal, it's a good idea to get a quote from more than 1 engineer, we suggest getting up to 3.

Branded manufacturers may end up costing you a little bit more but big brand protection is a huge bonus and they can provide extra services such as ongoing boiler cover.


Data Source: Energy Saving Trust, Heating Your Home: Boilers (2022)
*Based on replacing an old gas boiler with a condensing A-rated boiler with thermostatic radiator valves, programmer and room thermostat in a detached home. Figures are based on fuel prices as of November 2021.

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Rob Wells

About the author

Rob Wells

Rob is another of our resident home heating experts. He manages our external partnerships, making sure you get the most up to date information.

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