Vailliant eco tec plus 832 poor water flow at taps

[L33lad]

Hi all
I have just had a Vailliant eco tec plus 832 installed, which precedes a new bathroom install.
Now to start with, I’m a spark, not a plumber...
I know I have just over 2bar static pressure before the boiler, & I know that is giving me just over 12L/min (to the boiler)
At the taps I have measured 7L/min hot water (every tap in the house). Not happy with this, I have split the pipe to a hot water tap, & had the water flowing full bore (15mm) this only gives me 8L/min!
I have adjusted the hot water temp, from lowest to highest at various temps, & the flow rate never changes! I assume that is what’s meant by the “delta t”?!
Does anyone have any ideas as the what this could be...has the plumber/gas engineer set all the settings correctly. I never seen him adjust anything, almost like plug & play

thanks in advance

 

[cross thread]

Delta is nothing to do with flow rates, is the cold isolation valve fully open?

 

[L33lad]

It is fully open.....the cold is at about 12L/min at all taps & outside.
As for the delta t...yeah, I thought it would affect the flow rate from your boiler dependant on the difference in temperature between your incoming & desired temperature of your hot water, the bigger the difference, the lower the flow rate.......shows you what I know!

thanks

 

[Gasguru]

If you've got 2 bar static then you must have some restriction in the pipework from the road..so either the boundary stopcock's blocked or not fully open/likewise for internal stopcock or a scaled up old lead service pipe etc.
Loosing a few litre/min through the boiler would be expected...there's the plate heat exchanger/turbine/flow limiter/pipework etc all adding friction and reducing the flowrate.
Did you have a combi before or a conventional cold water cistern and cylinder?

 

[L33lad]

I had a WB 28i junior combi before...everything went on it all at once, so changed to a Vailliant, heard they were pretty good.
I understand 2 bar is fairly low pressure, I also live at the top of a hill, so I didn’t expect too much.
I have 2bar & 12L/min going into the boiler, so basically I’m getting 40% loss of flow rate through the boiler.
The thing is, I’ve on to Vailliant, to ask, what criteria needs to be met, for this boiler to achieve the figures they put on their data sheet, also mains pressure & flow rate to the boiler....they just throw “deltas” at me, like I know what they’re talking about!!
If they require a certain pressure at the mains, & I was below that, then I’d say ok, but I can’t seem to get an answer from anyone.
So I may have over done it, on the boiler...a total let down.

thanks

 

[Gasguru]

Why aren't you getting the installer to resolve this...how did he successfully commission the boiler. Have you fallen out with him?
Most of London has barely 1 bar pressure...some flats have no water peak demand. 2 bar is good pressure but you should be able to achieve a better flowrate than 12 litres. If your previous boiler was the non condensing Junior model then the pressure drop through the boiler will almost certainly have been a lot less and hence a better flowrate.
Get the installer back to check the boiler strainer/flow limiter for debris to rule out the boiler.

 

[L33lad]

Gas guru
You know....I was discussing this with my Dad yesterday. Every single job, in this house, that I have had to get someone to do, has turned out a disaster in some form or another...windows, previous boiler, windows, guttering, & bathroom is turning out this way!!
I think it must be me, they must instantly dislike me , which is silly, because I’m an all round decent chap, just ask me!
Anyhoo, Vailliant have been on, took me through some of the settings, just to confirm my bucket test, which was spot on (7L/min) hopefully they can narrow it down.
Must say, thanks for your response there pal, I’m sure we’ll get to the bottom of it.

oh yes...the installer said, that it’s due to demand! But if I’m still getting the same pressure & L/min all through the day, it can’t be?!
Anyway, I will wait on Vailliant, see what they have to say.Then I’ll get the installer. Shame really, visually, the work is bang on, soldering, pipes etc, even the prep for the bathroom, he doesn’t seem to keen about this issue though!

thanks

 

[Gasguru]

Connect that pressure gauge showing 2 bar with no flow and then open a hot tap fully and report back the pressure the gauge drops to.

 

[L33lad]

Ok...I connected it to the cold water isolator valve before the boiler (full bore) reads just over 2bar, turned on a hot tap fully open, it now reads just over 1bar.
Is this what we call dynamic pressure?

thanks

 

[Gasguru]

Yes..so it would seem that the pressure is holding up with a reasonable flowrate...I'd get the installer back to check the strainer/flowlimiter is free of debris.

 

[L33lad]

Then that will be the next step...

thanks for this....will let you know how it goes


thanks