Vaillant Turboxmax boiler gaining pressure

paddyb · Post by **paddyb** » Wed Oct 30, 2024 9:51 am

My hot water stopped working and I noticed the pressure on my Vaillant Turbomax boiler had dropped to zero. I increased the pressure to 1.5 by opening the Filling Loop valve, but after I closed the valve, the pressure kept on rising getting very close to the red area.

I bled a radiator and it decreased a little, but then start rising again. I then released pressure using the Pressure Relief Valve and it quickly dropped down, but then immediately went up again when I released the valve, and is continuing to creep up. Is this something to worry about? Hopefully an easy fix?

wine~o · Post by **wine~o** » Wed Oct 30, 2024 11:26 am

sounds like the isolating valve isn't closed correctly, there should be 2 valves (one at each end of the filling loop )

paddyb · Post by **paddyb** » Wed Oct 30, 2024 3:40 pm

Thanks for getting back to me.

This boiler doesn’t have the usual taps to open and close the valves.

I've atacched a pic of the filling loop.

I increased the pressure by turning the screw in the brass cubed shaped end.

By Isolating Valve, do you mean the large black cross head at the other end of the hose? I didn’t touch this and have just had a look at it seems firmly closed, in fact I’m not sure I can loosen it with a screwdriver.

The gauge has been fluctuating over the last 24hrs, but remains high and is currently approaching maximum now. Is this dangerous?

dewaltdisney · Post by **dewaltdisney** » Wed Oct 30, 2024 3:56 pm

A filling loop invariably has a valve on the incoming water pipe and a valve on the boiler water inlet. You turn on the water inlet and then control the boiler fill with the other to stop contamination of the mains by possible back flow. From what you describe the boiler inlet might be letting in increasing the pressure or it might be a defective gauge giving false readings. There will be a pressure release valve that will automatically discharge if the pressure gets too high. Check if there are any apparent drips on the end of the PRV drain pipe which is normally outside.

DWD

paddyb · Post by **paddyb** » Wed Oct 30, 2024 4:47 pm

Sorryu, forgot to mention, I did try the Pressure Release Valve and the gauge quickly dropped down, but then immediately went up again when I released the valve, and continued to creep up. Before that, I also bled a radiator (the only one inn the hous3e I can do with a key).

Someone-Else · Post by **Someone-Else** » Wed Oct 30, 2024 5:30 pm

I am NOT a plumber or heating engineer.
You started by saying the pressure was Zero, this usually happens if you have a leak or the PRV operates.
You then on purpose opened the filling loop. Since then the pressure keeps rising (slowly)
My guess is the filling loop is and has been letting water past for some time, just that you did not know. I would suggest either remove the filling loop or change it.

wine~o · Post by **wine~o** » Wed Oct 30, 2024 5:54 pm

paddyb wrote: ↑Wed Oct 30, 2024 3:40 pm I've atacched a pic of the filling loop.

IF that is your own filling loop AND it has been removed from your boiler then you have a big issue internally on your boiler, get a gas safe registered engineer in to advise. IT IS NOT a Diy-able job.

paddyb · Post by **paddyb** » Wed Oct 30, 2024 6:27 pm

Thanks both. To clarify, it's not my own filling loop and it has not been removed.

I tried to take a picture to show the valve I adjusted, but it was too difficult, so the pic was taken from an ebay listing for the part, the one on the boiler looks exactly the same. This forum doesn't seem to let me post links, so I had to download the picture and attach it. I also wanted to post the youtube clip that explained how to fill the boiler, but couldn't get the yoube link to work. If you casn be bothered, the video number to put after the youtube URL is: vspiFvhSjxc

The event that triggered this was the hot water stopped running andf thhere was an F.22 error on thr boiler. Several videos and online sources suggested increasing the pressure to solve this.

Someone-Else · Post by **Someone-Else** » Wed Oct 30, 2024 6:37 pm

As You are new, you can't insert links (Answers that question) But a picture and or video of your filling loop would make no difference. The answer is still the same, the pressure goes up when the filling loop is not 100% closed, you need to close it, change it, or remove it.

gas4you · Post by **gas4you** » Wed Nov 06, 2024 12:22 pm

The valves are the square brass block.

I would think the screw in the block hasn't been closed properly. They can be very stiff/awkward to use if you are not using the proper Vaillant key.