Is there a way to zero this boiler pressure gauge?

The one in the machine I am starting to rebuild sits at 1 bar when the boiler is cold.

Thanks.

There are a few reasons why the pointer can be off zero.
- Gauge over pressure damaged.
- High impact caused pointer shift.
- Worn, corroded mechanism.

In general, none of these are repairable and the best option is to replace the gauge.
1 bar is a 40% error, so it's definitely toast

You can likely open up the gauge, lift off the needle and push it back on at the zero location. However, you still don't know if it's accurate. I guess at this point you could then use an external gauge attached to the steam wand to see how accurate the built in gauge turns out to be.

Mark

I thought the gauge was liquid-filled (why else would it cost $55?). But that wasn't the case. So I just removed the faceplate and reset the needle to 0. Thanks for the suggestions.

I thought the gauge was liquid-filled (why else would it cost $55?). But that wasn't the case. So I just removed the faceplate and reset the needle to 0. Thanks for the suggestions.

Opps... Don't care about Zero... Did teh value now change for your shot ??? Maybe now 1 bar out...

Linearity is what it is about. It could be 1 bar out at 0 but 100% correct at 9 Bar,,

With out cross checking you have in effect added a potential for a 40% error that may not have been there.

If my temp gauge is out at 0 by say 10 and reads 10F but 100% correct at my true body temp of 98.6F and I only use it to measure my temp... Then the range that is of interest to me is 98 +/- 10F I do not care about Zero...

Thus with a coffee machine what shots are pulled at 0 or 1 or 2 BAR ?? All I want to know is that it is accurate at 9 Bar and if it could be +/- 0.5 then you would be jumping for joy.

Note: The reading error is at least another +/- 0.5 on top of that again.. So at best these gauges at just an INDICATOR... But even then Fit for Purpose... Thus an indicator at the working pressure not 0.

Sorry, I don't follow... Are you suggesting that I replace the gauge or are you saying that the needle should not be moved to 0?

Q1: What do you want ?

A. gauge that reads 0

OR

B. A gauge that reads 9bar when it is at 9bar


If you want A. Then adjust the gauge and be happy it reads 0

If you want B. A gauge that reads the group pressure to allow you to know if you in the 9bar area etc. Then I would have left it as is AND obtained another ACCURATE GAUGE to CHECK IT FIRST.

MY standard gauge reads any where from 0 to 2 bar at rest... But by taping or flicking the brew lever etc I can drop any minor back pressure trapped and / or allow the needle that may be a bit sticky, to settle to 0.

WHO cares... NOT IMPORTANT.... I do not make coffee at such low BAR.

But I am 100% confidant that from 6bar to 12bar my gauge is accurate, as I have had it checked and referenced with a calibrated and precision gauge. Thus I know when I pull a shot and it displays 8bar or 9bar etc it reads what it is and it is correct...

Put it another way... Do you want your car speedometer to say 0 at stop or do you want it to be accurate at the speeds you drive so you do not get booked when driving on the highway.

Yes it is a slight visual frustration, but the basic coffee gauge in a machine is cheap and not very accurate at the best of times.

My manual calibrated gauge which is referenced to national standards is about $475 and cost me $50 every year to be tested. My precision digital sensor and reader, is worth about $1.2k and costs about $200 every year to have checked; as it goes down to very low values and is accurate etc.

A gauge that costs a few dollars at time of manufacture is just that; cheap and gives you a visual indication. It is NOT a device that can be considered a measuring device. Even the mass produced oil filled units are not great; BUT they are more reliable and can be more accurate (at a cost that most manufactures see no reason to spend) and due to the oil less; prone to sticking and bounce.

What you've done by moving the needle makes no sense to me. Now you have a ornament that fills the hole but lacks any semblance of accuracy until tested. At this point you have two options, rent a Scace meter and test the pressure and try to calibrate your meter or replace the meter. I would replace it and test the new one personally.

I doubt that the meter reading is any less accurate that before since in either state it's unknown what the reading is. Buy an inexpensive gauge at the plumbing store (aka << $50), read up on how to temporarily clamp this onto the steam arm and figure out the pressure. Adjust the needle on the other gauge accordingly.

A possible cause of the needle settling above zero would be a sticky vacuum breaker valve. In this case the pressure in tank gets slightly negative and pulls the needle against the pin (assuming there is one at zero) and moves it slightly. If the gauge was accurate before this occurred, resetting it makes it accurate again. If it wasn't accurate before, then no big deal, it's still not accurate.

Mark

It's also worth bearing in mind that gauges with a stop post can sometimes cause problems since, as others have commented, the zero position is often the least accurate and stable, meaning that the gauge pin can move back beyond (below) the zero position while the indicator hand is prevented from moving by the stop post, shifting it forwards. The next time boiler pressure falls to zero, the hand indicates more than zero.

That's why Olympia stopped using gauges with a stop post.