vaillant combi boiler - shower too hot - low pressure?

26 Jun 2010
Reaction score
United Kingdom
Hi. I have read a number of threads, but would like to check my particular situation.

When I use my power shower, the water is way too hot unless I turn the power down to 1 and heat to around 7, which means I don't get much more than a trickle water pressure wise. It only started doing this recently - I used to get good pressure at a nice temperature at 2 for power and heat at around 5. I can't work out what has changed - we haven't done anything to the boiler.

I have a Vaillant combi (can't see the model number anywhere on boiler & manual is lost but have posted some pics which may help, think it might be an EcoTec). When the boiler is 'resting', pressure is well below 1, which I think means it's too low. When I use the hot tap in the sinks, I get nice hot water & pressure doesn't move. When I turn the heating on, it fires up OK and pressure rises to around 1.5 after about 5-10 minutes of running.

I've tried to use the 2 filler taps (sorry if wrong terminology) as described elsewhere on the site, but I can't hear any noise of the boiler filling and the pressure doesn't change.

Could the low pressure be causing the excessive heat in my shower?

Sponsored Links
PS - have just found the filling tap. I thought it was the two 'screws' either side towards the back of the boiler, after having yet another look, I found a single one towards the front, and bingo - filling noises and pressure up! However doesn't seem to have fixed the shower problem - any other thoughts on why my shower has all of a sudden started to run too hot when at the higher power setting?
Probably because the incoming cold water is now at a higher temprature. The lower flow rate through a shower will give a higher temprature just turn the boiler hot water down and see what happens. When it is cold outside again turn it back up because the incoming water will be a lower temprature.
Thanks for response. I was also just investigating the site further looking at shower queries rather than boiler now that I have the pressure back up. I've found that my shower head was probably just clogged up with limescale (which, despite regular cleaning, is the bane of my life here in the hard water of Norfolk!) - the boiler pressure was just a red herring! So thanks to all those who post on here - it's an extremely useful site.
Sponsored Links
Hi mate the boiler u have is a turbomax made from may 2000 to 2005 not an exited that's a newer model also u say u have a power shower? Hopefully not type with electric pump as u can't use these with combis
Not a Vaillant Erotic then?

By the way you can correct errors in your own posts using the "edit" button.
A picture/make model of your shower is needed.
I think you may have an electric shower.
Lizmillar, Can you please tell me what the filling tap looks like that you located? I have the identical problem that you had and I have your exact boiler! I also tried turning the 'filler tap screws' but it turns out, as you discovered, they're not the filler taps... but I still have no idea what actually is! Thanks ever so much.
sorry kevplum no offence meant i got a wireless keyboard an batteries had gone changed em now lol

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links