Low pressure taps on a high pressure system

5 Jan 2012
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United Kingdom
Does anyone now the problems associated with fitting low pressure taps on a high pressure system?

I have had a problem with my boiler (Vaillant Turbo Max) tripping out when running a bath. An engineer has been to look at the boiler and after conducting tests has said the boiler is fine the problem is the taps are not letting enough water through and the heat in the water / boiler is hiting the maximum level and shutting down the boiler (it fires back up after a few seconds)

The boiler output is around 1bar and I think the taps are rated for 0.3bar; what is the impact of this? Will the taps act as a barrier?

Any ideas before I go through the expense of buying new taps?
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It won't be the taps that are the problem. How much water is coming through? What is the pipework to them like?
The pipework is 15mm copper, it was replaced about 4 years ago when I fitted the bathroom.
Not sure on the actual volume flow, however the engineer disconnected the flexible from the basin tap and the flow rate was very good and the water stayed constantly hot; the boiler didn't trip out.
It won't be the taps that are the problem.

Of course that advice assumes that the taps are not faulty. You say you have flexible hoses conne cting them, are they twisted? You can easily measure the flowrate with a bucket and a watch.
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No, the flexible are straight.

I guess I need to check the flowrate both through the taps and directly from the flexible connection to compare.

For my benefit, I'm assuming that low pressure taps are designed to minimise the resistance when used with a low pressure system, however when connected to high pressure system the tap internals should not cause a problem to the higher pressure and flowrate; is this correct?
So if I see a significant difference in the flowrate when connected to the tap and when not connected to the tap, could the taps be faulty?
The boiler should modulate down to match the output to a reduced flow rate. Does it do this at the other hot taps?
It does, but only in the bathroom. When the kitchen tap is running it stays warm and the boiler doesn't trip.

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