Baxi Combi Boiler High Pressure Error 117

Itchyness

Hi all,

My Baxi boiler is 2 years old and is starting to play up. I have 2 zone heating in the house but when both zones are on, the pressure in the boiler shoots up to 3 bar and stops heating giving me an e117 error. However, each zone will work independently (sometimes it will turn off if it has been on for a couple of hours). My boiler pressure is 2.2 bar cold and will go to 2.8/2.9 bar when heating a zone. All rads in each zone work and heat up fairly quickly.

One thing I have been noticing lately is that when the heating has timed off there is a loud bang and a dump of water from the PRV. This normally drops the pressure from 2.8 to 2.2. I dont recall this happening when we first started using the boiler, the house was a new build so everything was in order. I know this because when I first heard the noise and investigated it, I found that no pipework had actually been fitted to the PRV on the underside of the boiler and I had found a wet flour under it! I fitted a pipe to the drain myself.

Im not sure if this is an expansion vessel problem?

Cheers,

K.Flyer

By the sounds of it your filling valve (pressure top up valve) has been left open, otherwise the water pressure wouldn't replenish itself.
Check the filling valve and shut it off.
You can then gradually reduce the pressure back to approx 1.5 bar by draining from a radiator vent.

Itchyness

K.Flyer wrote: »

By the sounds of it your filling valve (pressure top up valve) has been left open, otherwise the water pressure wouldn't replenish itself.
Check the filling valve and shut it off.
You can then gradually reduce the pressure back to approx 1.5 bar by draining from a radiator vent.

Thanks for the reply. Yes that makes sense. I changed a rad about 2 months ago and got major flow out of it when I was taking it down. I had to turn off the water at the mains to stop it. So that indicates you're correct.

The thing is, I haven't modified any of the boiler settings or pipe work since the install. Is there any scenario where mains flow is supposed to go through the system?

Where would I find the pressure filling valve? Under the front of the boiler I have 3 taps; gas, heat flow and heat return. All open and look in order. I have a Baxi combo EcoBlue if that helps?

Thanks

K.Flyer

Can you find something like this picture either near the boiler, or in the hot press near your hot water cylinder?

Itchyness

K.Flyer wrote: »

Can you find something like this picture either near the boiler, or in the hot press near your hot water cylinder?

K, thanks for the help. Thats a filling loop?

No I dont have something like that but having had a nose around the hot press I can see the pipework in the picture. The pipe leads in to the heating flow and is clearly open.

When the boiler pressure gets close the max shutoff pressure, the gauge in the picture rises from 1.5 to 2.5 bar.

Is the course of action to fix my problem;
1) close the valve
2) lower the pressure to normal (~1.5 bar) by draining from the rad bleed valve

Thanks,

K.Flyer

Itchyness wrote: »

K, thanks for the help. Thats a filling loop?

No I dont have something like that but having had a nose around the hot press I can see the pipework in the picture. The pipe leads in to the heating flow and is clearly open.

When the boiler pressure gets close the max shutoff pressure, the gauge in the picture rises from 1.5 to 2.5 bar.

Is the course of action to fix my problem;
1) close the valve
2) lower the pressure to normal (~1.5 bar) by draining from the rad bleed valve

Thanks,

You should shut off the valve and drop the pressure when the system is cold.

I noticed that the gauge is at 1.5 bar.
Based on the presumption that is the pre set pressure through the valve, I would say, based on everything so far, that you may also have an issue with the expansion vessel in the boiler. It either needs recharging with air, or replacing.

After adjusting the system pressure start to get the system back up to temperature. The pressure shouldn't really rise by more than 0.5 bar. If it goes much higher, or reaches 2.5 - 3.0 bar, then the expansion vessel needs attention.

Itchyness

K.Flyer wrote: »

You should shut off the valve and drop the pressure when the system is cold.

I noticed that the gauge is at 1.5 bar.
Based on the presumption that is the pre set pressure through the valve, I would say, based on everything so far, that you may also have an issue with the expansion vessel in the boiler. It either needs recharging with air, or replacing.

After adjusting the system pressure start to get the system back up to temperature. The pressure shouldn't really rise by more than 0.5 bar. If it goes much higher, or reaches 2.5 - 3.0 bar, then the expansion vessel needs attention.

OK thanks for all of that, ill give that a go and see how I get on. Failing that its time for the pros!

So the last thing; It says in the installation manual that there is a de-aeration program on the boiler to be run on commissioning and when a rad is changed. Basically its says to turn off the gas and run the program. I did swap out a rad, however I have bled most of them in the house so im satisfied there is no residual air in them.

Itchyness

I have the valve closed and the system is working better. I havent had a chance to drain and lower the pressure cold. I will hopefully get it tomorrow.