# How to replace the pressurestat on an Isomac Tea.



## marcuswar (Aug 19, 2013)

I've just replaced the pressurestat on my Isomac Tea and apparently it's not unusual to have to replace these every few years so I thought I'd post some pictures and tips on how to do it.

The cheapest place I found in the UK for a replacement Mater XP110 pressurestat was Bella Barista. BB sell them for £19.95 + £2.95 postage http://www.bellabarista.co.uk/izzo-pressure-stat.html It seems that the Mater XP110 comes in different versions and its the 1/4BSP version that the Isomac requires (not the 1/8 BSP). The pressure range of the XP110 is 0.5 to 1.5bar.









Fitting is really very straight forward and simply involves using a spanner behind the exiting pressurestat to unscrew it. Then wrapping a few turns of PTFE tape around the thread of the new pressurestat and screwing it in. There are no washers or anything it just screws in as far as it will go.









The only slight issue with removal (and installation) is that the pressurestat can't be fully withdrawn because the switch hits the water inlet pipe. A quick way around this is to unscrew the switch and remove it from the pressurestat during removal or installation then replace it after installation. The switch is simply held on with two screws, although in the case of the new pressurestat the screws actually had torx heads. Luckily I had a set of Torx screwdrivers handy otherwise I would have had to resort to disconnecting the water pipe.









The new pressurestat had a longer thread than the old one and I was a little concerned it wouldn't fit but it seems to fit fine. The old pressurestat although also a Mater XP110 was rated at 1.0 to 2.5bar so different than the new one even though its the same model.

















Once fitted its simply a case of adjusting the pressure screw on the end to set the required maximum pressure, in my case I set to 1.3bar. To set the pressure turn on the machine and let it get up to pressure. DO NOT LEAVE IT UNATTENDED while it is doing this as the default pressure on new XP110 was set higher than required and may well have resulted in the safety valve venting the boiler. Once the pressure builds and the antivacum valve closes keep an eye on the pressure and if it gets to 1.4bar with no sign of stopping then turn the machine off quickly and let the pressure drop. Wind the screw on the end of the pressurestat back half a turn (anticlockwise) and then try again.


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## soundklinik (May 31, 2013)

Thanks 😊 6 years later, just the information I needed


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## Gilly (Jul 29, 2019)

soundklinik said:


> Thanks 😊 6 years later, just the information I needed


 Me too, Mr. Trout mask replica!


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## Norvin (Sep 10, 2014)

Another Beefheart fan here.

Got his autograph once. He spelled my name wrong, didn't feel in a position to complain 😄


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## soundklinik (May 31, 2013)

Ahhh finally some Beefheart fans...

Never got his autograph but have seen them at least 6 times...

Got Zappa's autograph in Munich 1968 on his "sitting on toilet" poster....where I saw the Mothers for the first time ❤

Glad to have met you guys.


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