Biasi Boiler ER04 Fault Code
The Biasi fault code ER04 related to the water pressure which we include Q & A or require an engineer for an emergency boiler repair.
The Biasi Fault Code ER04 Error Common Q & A
Just below, we have a list of common questions relating to the ER04 fault code on the Biasi Boiler.
- What does the ER04 fault code mean on my Biasi boiler?
- Why doesn’t resetting my boiler fix the ER04 fault code?
- What’s the most likely cause of the ER04 fault on my Biasi boiler?
- What pressure should my boiler be?
- My boiler pressure is low, or is dropping, what could cause this?
- What parts could be leaking on my central heating system?
- I can see water beneath my boiler, what’s likely to be leaking?
- My boiler’s pressure is fine and there are no leaks in the system, what could be the problem?
- What problems could occur with the pump?
- How can airlocks affect my heating system, and how can they be removed?
- How can heating sludge and limescale affect my heating system, and can it be removed?
- After removal, can my boiler be protected, to stop this happening again?
What does the ER04 fault code mean on my Biasi boiler
If your Biasi boiler is showing the ER04 fault code, it means there’s an issue with the water pressure in the system, or a problem with circulation.
In terms of water, it’s likely that your boiler is suffering from low pressure. And, for circulatory related issues, it’s likely there’s a blockage, airlock, or problem with the pump.
Why doesn’t resetting my boiler fix the ER04 fault code
What you’re experiencing is a boiler lockout. Your Biasi boiler is controlled by the printed circuit board (PCB). It’s the PCB that controls all components, as well as monitoring readings from a range of sensors.
In the case of the ER04 fault code, it’s noticed that there’s a lack of water pressure in your central heating system, or there’s a circulation fault. Continued operation at this point could lead to further expensive repair bills, so the boiler locks out instead.
You shouldn’t try to keep resetting your boiler. Instead, call a boiler repair company. They’ll be able to determine the exact problem, fix it, and once fixed, they can reset your boiler to fix the ER04 fault code.
What’s the most likely cause of the ER04 fault on my Biasi boiler
Your boiler repair company first needs to determine if the fault relates to circulation, or low water pressure. The list of potential problems is extensive, so there’s a few ways for them to narrow down what the issue is, like checking the pressure on the boiler.
What pressure should my boiler be
It should become obvious if low water pressure is the issue. Your Biasi boiler has a pressure gauge, which should read somewhere in the region of 1-1.5 bar. Typically, your engineer would set your boiler at 1.3 bar (or per manufacturer’s recommendations). By looking at the pressure gauge, they’ll be able to determine if your boiler’s pressure is too low.
In general, a boiler will still work when it’s just below 1 bar. However, if it continues to drop below 0.5 bar, this is when a boiler will lockout. Among other things, a boiler with low pressure is going to mean components like the pump work overtime, and that’s going to lead to them wearing out prematurely. Instead of continuing operation, your boiler will lockout.
My boiler pressure is low, or is dropping, what could cause this
If your boiler engineer sees that low pressure is the issue, the most likely cause is a leak.
You can quickly top up your boiler using the external filling loop, and that’s going to adjust the pressure. As you open the valve on the filling loop, water is allowed into the system, and more water is going to mean more pressure.
However, it’s not advisable to do this without the help of an engineer. Because, whilst low boiler pressure is an easy fix, the leak is the real problem. Even if it’s not immediately visible, if you top up your boiler’s pressure and the pressure continues to drop, its likely water is escaping somewhere. And, leaks are going to mean water damage, whether that’s to walls and floors, or inside your boiler.
Due to the amount of water contained in a heating system, a reasonable leak that could cause major damage, might only be indicated by a pressure drop over the space of hours. And, that’s why we suggest waiting for an engineer’s help.
What parts could be leaking on my central heating system
Almost any part on your central heating system could be leaking, and it might not be immediately visible. The leak could originate from a pin hole in a radiator, leaking radiator valve, pipework that’s hidden behind walls, or even inside your boiler.
The leak needs to be found and fixed, before you top up the boiler’s pressure.
I can see water beneath my boiler, what’s likely to be leaking
Assuming all connections are secure, it’s most likely your boiler engineer will head straight for the heat exchanger and pump. Both parts are known for leaking, and they could also contribute to a circulatory issue.
The pump will leak if it’s put under excess pressure, or the seals degrade. Whilst on some occasions the pump can be fixed by replacing the seals, it might be beyond repair. When this is the case, it’s likely the replacement cost will be in the region of £250; that includes labour, as well as a pump from a leading brand such as Grundfos.
The heat exchanger leaks when it’s excessively worn and cracks. These cracks create small leaks, and that water ends up on other electrical components in your boiler. Left untreated, the damage can be catastrophic, and sometimes end up in the boiler needing to be replaced.
Heat exchangers are one of the most expensive parts to replace, costing in excess of £400 on most Biasi boilers.
My boiler’s pressure is fine and there are no leaks in the system, what could be the problem
If the ER04 fault code is being displayed and low water pressure and leaks aren’t to blame, your boiler repair company needs to focus on issues relating to water circulation.
There a few things they’ll want to look at, including:
- Heating pump problems
- Airlocks
- Heating sludge and limescale build-up
What problems could occur with the pump
The first point of call is to check the heating pump. We’ve mentioned above that pumps can be prone to leaking, but that’s not the only common problem.
Your boiler repair company will want to check that the pump is on the right speed setting. If it’s set on the lowest speed setting and your heating system is extremely large, it won’t be providing the level of circulation needed. Water travelling around the system will cool, and when it reaches the temperature sensor on the return pipe (where it re-enters the boiler to be heated), the differential in temperature from when it left the boiler will be too high.
Assuming the pump is on the right speed setting, your boiler engineer will want to check for power, and that the pump isn’t stuck. They’ll be able to check for power using a multi-meter. If it’s getting power, but is running hot and making loud humming noises, it’s likely to be stuck, due to the bearings and/or shaft wearing. It’s most likely it will need to be replaced in this case.
Other problems relate to blockages, which can come in the form of heating sludge, limescale and airlocks, all mentioned below.
How can airlocks affect my heating system, and how can they be removed
When your system is topped up with water, air can enter. And, this air acts like a blockage; it reduces the heating system’s ability to circulate water. That’s why a system needs to be bled after it’s topped up.
All aspects of the heating system need to be bled for it to work efficiently. If not, you’ll not just have problems such as the ER04 fault code appearing, you’ll have radiators that are hot at the bottom but cold at the top, a pump that makes banging noises and more.
Each radiator and towel rail have a bleed screw. These need to be opened manually to allow air to escape; you’ll hear a hissing noise. Once the hissing noise is replaced with a slight dribble of water, that radiator/towel rail is bled. As air escapes, pressure on your boiler will drop. So, you’ll need to consistently top up pressure as you bleed the system.
The pump may also need to be bled to improve circulation. But, as this involves taking apart the boiler, this is a job for a Gas Safe engineer.
How can heating sludge and limescale affect my heating system, and can it be removed
Heating sludge is essentially, rust that breaks off the inside of towel rails, radiators, and even copper pipe work. As it travels around your heating system, it breaks down to create dirty heating water. Any large particles not dissolved into this water can get lodged in components, causing a whole host of problems.
Limescale comes from minerals in water. So, those living in hard water areas will be affected more than those in an area with a low-moderate water hardness rating.
Your boiler repair company can get rid of most of the heating sludge by running a hot flush. This essentially involves heating up your system to max temperature, after adding specifically designed cleaning chemicals. They’ll then drain the system of the water, chemicals, sludge and limescale.
After removal, can my boiler be protected, to stop this happening again
After draining the system, your boiler and heating system can be protected.
When your boiler repair company tops up your boiler this time, they’ll add central heating inhibitor; this helps to break down heating sludge and limescale particles.
They’ll then fit two filters; a magnetic boiler filter and limescale filter. The magnetic filter will catch heating sludge, where as the limescale filter helps to catch limescale.
To ensure that the filters can keep doing their job effectively, both filters will need to be cleaned out with each annual boiler service.
Other Biasi boiler issues
For more boiler issues regarding the Biasi Boiler then please visit the Biasi Boiler Problems And Cures page.