What are my water pressure gauges showing?

wootberg

Greetings,

I have two water gauges, one at the automatic refill valve at the mains feed, another at the refill valve (not sure if it's automatic) at the boiler, feeding the boiler loop. For quite some time the one at the boiler was showing zero or very small pressure. A plumber visited recently, and adjusted the mains refill valve. What I have now is that the mains gauge is showing 0.8 bar, and the boiler gauge is showing over 2 bar - and I can't make sense of that.

The gauges are attached to the valves, so I can't easily tell which side they are measuring the water pressure on. I presume that the mains one is measuring mains pressure and the boiler one is measuring the feed pressure (i.e. one past the mains refill valve), but not the actual pressure in the boiler loop, as it's not varying significantly when the boiler is running. What I can't understand is how it can be showing 2 bar inside the system, when the mains is at 0.8 bar? Is one of those gauges busted?

Thanks.

aujopimur

The one on the fill valve is probably faulty, it should be discarded as their use can mask leaks in your system.
Only a filling loop is recommended for filling & servicing, and should be disconnected when not in use.
2 bar is a bit on the high side, 1.5 would be about right.