Baxi 117 Boiler Fault Code
Here, we're going to discuss the 117 fault code on the Baxi boiler. Emergency Boiler Repair..
The Baxi Boiler Fault Code 117 high water pressure Common Q&A
Just below, we have a list of common questions relationing to the 117 fault code on the Baxi boiler.
- What does the 117 fault code mean on my Baxi boiler?
- What is the correct operating pressure for a Baxi boiler?
- What happens if the boiler runs at a high pressure?
- What other parts in the central heating system are affected by high boiler pressure?
- What causes high boiler pressure?
- I’ve used the filling loop to add water (and pressure) and it’s too high, what can I do?
- How do I bleed a radiator?
- My radiator is hissing when I open the bleed valve, is this normal?
- Why does my boiler pressure increase when the heating is on?
- What pressure should I top up my boiler to, using the filling loop?
- Where is the filling loop on my Baxi boiler?
- What problems can occur with a filling loop?
- How can the PRV or expansion vessel cause problems?
- Can the expansion vessel and PRV be repaired?
What does the 117 fault code mean on my Baxi boiler?
The 117 fault code will be displayed on your Baxi boiler when the boiler’s pressure exceeds it’s working tolerance.
The boiler pressure is too high, and it needs to be reduced.
What is the correct operating pressure for a Baxi boiler?
Boiler’s are typically set to 1.5-1.6 bar. But, they’ll operate without issues between 1-3 bar.
When the pressure exceeds 3 bar or drops below 1 bar, the majority of boilers will lock out.
A lock out is the boiler’s electronic circuit board telling all components to stop working.
It does this to protect internal boiler parts from being damaged and in some cases, to protect people within a property when a boiler is unsafe.
What happens if the boiler runs at a high pressure?
Boilers are built to be robust, and will withstand high pressures.
However, high pressure puts excess strain on components. With older boilers, it’s unlikely these parts can deal with the additional pressure. So, boiler parts will still to fail.
A typical example would be worn pump seals. The high pressure can cause these to leak. In turn, that can lead to expensive water damage to electrical components.
But high pressure in your system doesn’t just induce leaks on your boiler, but all aspects of your central heating.
What other parts in the central heating system are affected by high boiler pressure?
The pressure in your boiler indicates system pressure; the whole of your central heating.
That includes things such as:
- Pipework
- Radiators
- Towel rails
- Valves
As these items age, they become more fragile. High pressure can induce leaks (such as pin holes in radiators).
So, instead of high pressure, you’ll see your boiler locking out due to a loss of pressure. Because, a boiler loses pressure when there’s a leak in the system.
The problem here is that a lot of these leaks won’t be visible (such as pin holes in the back of radiators, or pipework that’s behind coving), and issues with damp could arise in your property without you knowing.
What causes high boiler pressure?
There are a few things that cause high boiler pressure:
- Using the filling loop to “top up” the boiler pressure (by adding water)
- A faulty filling loop
- A failed PRV or expansion vessel
- Turning on the heating, or running hot water
I’ve used the filling loop to add water (and pressure) and it’s too high, what can I do?
If you’ve topped up the pressure on your boiler and it’s too high, you can release pressure easily.
The quickest and easiest way to release pressure and clear the 117 fault code on your Baxi, is to bleed a radiator.
How do I bleed a radiator?
First, make sure you have towels to protect flooring, and a container to catch water.
Next, you’ll need to locate the bleed valve. This is located on one side of the radiator.
Using a radiator bleed key, slowly open the valve. This will allow water to escape and slowly start to reduce the pressure in your boiler.
And, if you bleed too much water from your radiators (i.e. the boiler pressure drops below 1.6 bar), you can top up the pressure using the external filling loop.
My radiator is hissing when I open the bleed valve, is this normal?
It’s worth noting you might hear a slight “hissing” noise before water starts to drip out. This is air escaping from the radiator.
Trapped air can affect the efficiency of radiators. So, if the first radiator shows signs of air, it’s worth bleeding others too.
When removing pressure, you’ll wait for the hissing to stop, and that’s when water will be released (which in turn, releases pressure).
However, if you’ve already adjusted the pressure by releasing water, simply close the valve on each radiator when the hissing stops, and that hissing is replaced with a dribble of water.
This is a sign that all air has escaped.
My radiator is hissing when I open the bleed valve, is this normal?
It’s worth noting you might hear a slight “hissing” noise before water starts to drip out. This is air escaping from the radiator.
Trapped air can affect the efficiency of radiators. So, if the first radiator shows signs of air, it’s worth bleeding others too.
When removing pressure, you’ll wait for the hissing to stop, and that’s when water will be released (which in turn, releases pressure).
However, if you’ve already adjusted the pressure by releasing water, simply close the valve on each radiator when the hissing stops, and that hissing is replaced with a dribble of water.
This is a sign that all air has escaped.
Why does my boiler pressure increase when the heating is on?
Pressure on your boiler will increase when the heating is on, or when you fill a bath/run a shower.
Water expands, and this increases pressure, but rarely more than 0.5 bar.
If the pressure on your boiler increases by more than 0.5 bar when using your boiler, then that indicates an issue with components such as the PRV or expansion vessel.
What pressure should I top up my boiler to, using the filling loop?
To determine where the 117 fault is coming from, you first need to ensure that the boiler pressure is set correctly.
When cold, aim to top up your boiler to 1.5 bar using the external filling loop.
Realistically, a boiler can be set between 1-2 bar and work fine, but most manufacturers will suggest 1.5-1.6 bar to provide optimal conditions for the boiler to work.
Where is the filling loop on my Baxi boiler?
The filling loop is usually located on the underside of the boiler. Look for a braided hose with a valve on it.
Opening this valve will allow water to enter the heating system and increase the pressure.
What problems can occur with a filling loop?
First, make sure you turn off the filling loop valve after topping up the boiler. If the valve is even slightly open it will continue to add pressure to the boiler until it locks out.
Although it’s very uncommon, it’s not unheard for filling loops to get partially seized or blocked. This could mean a slight let-by of water, which continues to add pressure to the boiler even when the valve is in the “off” position.
The cause could be as simple as a small particle of heating sludge, blocking the last section of movement in the valve.
Filling loops are relatively cheap to buy and replace (under £100 including labour), so a replacement rather than repair, would be the most sensible option in this case.
How can the PRV or expansion vessel cause problems?
Boilers are fitted with a device to allow excess pressure to escape from the boiler. This allows rapid rises in pressure (when you turn on the heating) to escape so boiler parts don’t get damaged.
Your boiler will either have a PRV (pressure release valve), an expansion vessel, or both.
When these components fail, there’s nowhere for the excess pressure to go. So, pressure on your boiler increases and the 117 error code is displayed.
Can the expansion vessel and PRV be repaired?
The most common fault with expansion vessels, is they need their pressure topped up. A boiler engineer will be able to do this for you, and that means you won’t need a replacement.
If topping up the vessel doesn’t help, a replacement will be needed.
The PRV is incredibly cheap. So, rather than wasting time trying to repair an old part that might fail again soon, it’s worth replacing it.
Other Baxi boiler issues
For more boiler issues regarding the Baxi Boiler then please visit the Baxi Boiler Problems And Cures page.