Two Pressure Valves, Which to Believe?

[BlackMesaUK]

Hi, I have two pressure valves on my central heating system. One is built into the boiler and the other is separate, located less than a meter away.

Both go up and down with the heating, but both show different values and are out by about 0.5 bar. The one built into the boiler is always lower than the other. Should I care, which should I trust or is the difference too little to worry about? Thank you.

 

[ShaunCorbs]

i would trust/ go on the higher one eg the one not in the boiler

 

[Best]

Get somebody to replace one to see if that then shows same pressure reading.
Then if it doesn’t, swap the removed gauge with the other original.

I should point out that some gauges have different size threads

 

[Welder]

How about putting a test gauge on the system - say into a rad?

 

[king of pipes]

As above get it tested with a calibrated gauge and replace as necessary. Cheers kop

 

[Last Plumber]

If this is when the Boiler is running, it is possible that they are effected by their position in relation to the pump.
If not, then I would drain the system and see what they are like with zero pressure. Or as above, test with a calibrated Gauge.