Luke warm water with New Combi Boiler

[Blabber]

I have recently had a new Vaillant combi boiler installed its an 860 eco i think, it is 28 KW and i live in a house with 8 rads and one bathroom

The central heating works fine no issue there

However the hot water coming out of the shower is luke warm, first i recalibrated the shower thermostat, then i tried shutting off the cold water completely no change. i then contacted the people who installed it and they said teh boiler must have a problemn so Vaillant came round and said there was no problem with the boiler. it was just that it is not powerful eenough for the mains water pressure i have and i should have been advised to get the 35KW version the installers are saying this is not the case

any ideas, if they are both missing something or where do i go from here

thanks

 

[Bobbo 85.]

Properly running tofast through shower.if its no better with mains off to shower,was it ok before ,was it off a conventinal system then?,is the hot ok elsewere

 

[Blabber]

It was a gravity fed system with a old gas boiler and was fine before, the hot water is ok on the taps in the sink and kitchen basin but not particularly hot either

 

[ChrisR]

Turn the temp knob on the boiler fully up.
SLower flow will be hotter.

Set say the shower to showerng temperature (about 38) with the cold water turned off - or use a tap .
Measure the flow, using a 9 litre bucket or similar.
28kw will give about 12 litres/minute.
It's usually flow-limited in the boiler so it get s hot enough for a bath (about 45) ...?

 

[bengasman]

Your installer is obliged by law to leave you ALL instructions and manuals, including those meant for the engineer, and MUST explain the working of the system. If he failed to explain properly, the manuals should tell you all you want to know.

 

[gas4you]

No such thing as an 860

If it is a new 28Kw it must be the Ecotec Pro 28.

It could well be that the water flow you have is too great to produce hot water, but then you could always not turn the shower on as fast

Assuming you have had a Vaillant engineer out and not a group service numptie who knows nothing about Vaillants then you can assume they are correct.

Otherwise I would suspect that it has not been commissioned properly with the correct CO2 setting and/or WP at the gas meter correct.

As Chris says, you cannot expect to get more than 12 l/m at 35C temp rise out of this boiler.

I would also suspect the quality and commitment of your installer if they did not attend first to check it out before calling in Vaillant.

 

[Blabber]

Thanks fopr everyones help

The installer came back last night and found i had a broken governor on the gas meter, this was replaced and i had my first hot shower for a fortnight

 

[gas4you]

He obviously done all the basic checks well during commissioning then

 

[frank uk]

Gas4u.How long and what do you do to commision a new boiler.If the gas pressure was ok at the boiler,it wouldnt be easy to find as the h/w was ok

 

[gas4you]

The first thing I do is the tightness test obviously, then the working pressure at the meter, which was the point I was trying to make. Without testing the WP first how can you start to set up the boiler? You wouldn't even be able to tell if your pipe sizing was correct.

As long as you get 17mbar at the gas inlet on an ecotec you know you have 20mbar at the boiler inlet.

Once this is set then I use my FGA to set up the co2 % depending on whether it is NG or LPG.

I then tweak a few other settings in the 'd' menu.