Very high pressure mains supply causing boiler fault?

Servotech · 24 Aug 2012

Been called to a property today that is suffering all kinds of plumbing problems due to excessively high mains pressure.

One of the things that I'm struggling with is when I open any cold water tap or flush the loo it causes the combi boiler to fire up and briefly cycle.
I'm gong back next week to fit a pressure reducing valve above the stop tap hoping it will sort out the many problems that the customer is experiencing.

Could it be that the mains water pressure is so high that when a cold tap is open the combi boiler briefly senses a drop in mains pressure which fools it into thinking hot water is being drawn?
Anyone else come across this type of thing before?
Cheers,
servotech

swbjackson · 24 Aug 2012

Had it a few times. Fit a check valve in the cold supply to the boiler along with a shock arrestor between the check valve and the boiler to take up any expansion.

Agile · 24 Aug 2012

I fit a NR valve on the HW output from the boiler!

dcawkwell · 24 Aug 2012

Pressure reducing valve and an expansion vessel on the cold in to
the combi boiler. Sounds like you have a mixer tap letting
water pass between hot and cold firing the boiler.

Servotech · 24 Aug 2012

dcawkwell said:
Pressure reducing valve and an expansion vessel on the cold in to
the combi boiler. Sounds like you have a mixer tap letting
water pass between hot and cold firing the boiler.

Had there been any cheapo mixers fitted here this would also have been my first thought too; alas no taps at the property are mixers.
servotech

yerino · 24 Aug 2012

Have you got a mixer shower though?

The ideas above will sort the problem.

GasBod · 24 Aug 2012

really roger ?pmsl

Dan Robinson · 25 Aug 2012

Servotech · 25 Aug 2012

yerino said:
Have you got a mixer shower though?

The ideas above will sort the problem.

The customer has an electric shower (this is one of the customers other complaints) due to this extraordinary high water pressure the solenoid valve in the electric shower still keeps spinning (letting water through) after being switched off!

I just wasn't sure about if the really high pressure could be effecting the Baxi or NOT.
Mike gave me a really good reply regarding the problem and his answer seems to fit into the puzzle SO that's what I'm going to do.

Even plumbing experts like me always have new things to learn.
servotech

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Very high pressure mains supply causing boiler fault?

GasBod

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