Hi, Just had a new Veissman fitted, 10 days ago.100-w.Installer, registered Veismann, said my 22mm pipe was ok, 0.8mlbar drop from meter to boiler. Had teething trouble, so Veissman engineer just left and said my boiler is operting 10% less due to 22mm pipe, needs upgrading to 25mm as much as possible.Underfloor run approx 15 metres, access by a hatch, but tapers, so a bit of scrawling necsessary.gas rate or burner pressure or combustion reading 9.2%co or 9.2degrees nco. cannot read his writing.inlet working pressure 19.9mbar.I am confused at why installer didn,t mention pipe upgrade, we did discuss posibility, but not cost, said I was ok.10% means my 30 kw boiler is only a 20 kw now.Any advice on whether the pipework upgrade is nescessary and a rough cost would be appreciated. Methinks the installer just wanted a straight change, as I did, no scrawling under floors.To add to things, Veisman engineer put f4 fault down as electrode change .never had a f4 fault, and he didn,t change any electrode, he was only here 15 mins.Had to justify his call out I presume, Not by me, but by the Installer.Bit confused.
new veissman
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A 10% reduction of 30 equates to 27 not 20!!
If the working pressure at the boiler is 19.9 mb there is no problem with the gas supply.
If the working pressure at the boiler is 19.9 mb there is no problem with the gas supply.
The boiler should operate at full power down to less than 18 mB.
The gas supply can drop up to 1 mB between meter and boiler. To assess the pipe both meter and boiler pressures are required at full power.
The engineer had to put down a fictitious fault otherwise the visit would be chargeable to you.
So what problem do you think you have?
Tony
The gas supply can drop up to 1 mB between meter and boiler. To assess the pipe both meter and boiler pressures are required at full power.
The engineer had to put down a fictitious fault otherwise the visit would be chargeable to you.
So what problem do you think you have?
Tony
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Hi Tony, Just confused at why Engineer says 25mm needed, yet installer told me 22mm was ok.Both took water temps and pressure at Max at meter and boiler.Engineer says water should be 10 degrees higher on max.50 not 40.Will 25mm be beneficial or not?
Sorry;;,he said 10kw reduction.That,s why I am so confused at such a big anomoly.10% wouldn,t have bothered me.
If the gas pressure at the inlet to the boiler is 19.9 mB then the boiler should deliver its full rated power with no problem.
The temperature of the DHW depends on four factors! Boiler power input, successful heat transfer to DHW, DHW flow rate and the input temperature of the cold water to the boiler.
Anyone who just quotes one parameter does not have an understanding of physics!
Tony
The temperature of the DHW depends on four factors! Boiler power input, successful heat transfer to DHW, DHW flow rate and the input temperature of the cold water to the boiler.
Anyone who just quotes one parameter does not have an understanding of physics!
Tony
Thanks Tony, I quote Engineers report.AIWP.18.5mb.gas rate or burner pressure or combustion reading.22.84kw gross.Gas rated boiler.@22kw gross.Advised new 25/28mm supply.Told Installer,awaiting a replyThe Engineer has left 5 sheets of reports.My white says AIWP.18.5mb.The othersGreen/yellow/white, say, AIWP, 19.9mb.30kw boiler.So, according to him I am 7kw down, on max, hence upgrade of pipe.Is it worth it?? No reports or verbal match.Accordin to you I should get 30kw approx,ok???
How strange that mysteryman is nowhere to be seen when his beloved Viessmann is up for critism!! 
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