# VBM blew it's top a couple of times today, is there any way to 'clean' a pstat?



## Dylan (Dec 5, 2011)

The boiler pressure maintenance has been a bit iffy for a while, when the pstat is set low it will sometimes let the boiler pressure drop right off and the water from the idle HX will be in the mid 80's.

Just today the pressure built right up and the machine ejected steam everywhere. I observed it doing it once more then switched it off, i then switched it back on and it was fine for an hour or so when it blew its top again.

My guess is the pstat - its a jaeger in this machine which is frustrating because they are meant to be the best, and they are expensive to replace.

So... first up is there anything else it could be... and if not is it possible to repair/clean a pstat or am I going to be buying a new one?

As an aside... I could potentially add a PID control to the boiler in place of the pstat couldn't I? (I know there isn't much point on a HX, but if I can get better control for not much more money with a PID, then why not)


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## h1udd (Sep 1, 2015)

Have you descaled recently ? ...might be as simple as a blocked pstat pipe restricting the pressure form registering


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## DavecUK (Aug 6, 2013)

Dylan said:


> My guess is the pstat - its a jaeger in this machine which is frustrating because they are meant to be the best, and they are expensive to replace.
> 
> So... first up is there anything else it could be... and if not is it possible to repair/clean a pstat or am I going to be buying a new one?
> 
> As an aside... I could potentially add a PID control to the boiler in place of the pstat couldn't I? (I know there isn't much point on a HX, but if I can get better control for not much more money with a PID, then why not)


Just get yourself a Mater XP110 stat

https://www.bellabarista.co.uk/izzo-pressure-stat.html

It's only £20 and will work better than a PID (which would be best paired with an SSR) and cheaper too. For steam boilers, you don't really want PID, you want simple on/off electronic control. and an SSR...or just stick with the stat.


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## Dylan (Dec 5, 2011)

h1udd said:


> Have you descaled recently ? ...might be as simple as a blocked pstat pipe restricting the pressure form registering


I stripped down the whole machine a year or so ago, but the pstat deals with steam pressure in any case and scale builds up at the waterline I don't think steam can carry scale so it shouldn't be a scale problem.

In any case the scale would be inside the pstat if it was as I every pipe was soaked in descaler.



> Just get yourself a Mater XP110 stat
> 
> https://www.bellabarista.co.uk/izzo-pressure-stat.html
> 
> It's only £20 and will work better than a PID (which would be best paired with an SSR) and cheaper too. For steam boilers, you don't really want PID, you want simple on/off electronic control. and an SSR...or just stick with the stat.


Cheers dave, I though a PID would be more accurate... the pstat controls the boiler to about .2bar is the temp read on a PID not quick enough to be more accurate than this?

Is there much between the Mater and the Jaeger when using at home? You can also pick up a Sirai pstat for £35... is it still the Mater that you would go for?


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## Dylan (Dec 5, 2011)

Just took the pstat off and the pipe was actually full of water, this must be from the steam condensing in it but it this normal for the pstat pipe or is the pstat only going to work properly if its just steam in there?


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## DavecUK (Aug 6, 2013)

Dylan said:


> I stripped down the whole machine a year or so ago, but the pstat deals with steam pressure in any case and scale builds up at the waterline I don't think steam can carry scale so it shouldn't be a scale problem.
> 
> In any case the scale would be inside the pstat if it was as I every pipe was soaked in descaler.
> 
> ...


If you can fit a sirai in there...then go for that.


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## Dylan (Dec 5, 2011)

Just looked it up and it's a big old pstat... but there is oodles of room in the VBM so I'll grab one of those, cheers Dave.

I just stuck the pstat back in and fiddling with it has made it worse. Hopefully the sirai arrives pronto.

edit: Someone was selling one on ebay which they bought then didn't need, so £30 posted. Lovely.


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