Re: Help! No steam!! For a few minutes, anyway...
I call it a "false pressure", and it happens when the ANTI VACUUM valve is stuck SHUT. ie it did not open when you turned off the machine and it cooled down, and therefore it did not allow atmospheric pressure to equalise into the boiler.
When you turn the machine back on it goes into a false pressure situation exacty as you have found, then rights itself after you bleed off a steam valve.
Anti vacuum valves are supposed to open and shut every time the machine is swiched on and off, to stop false pressure. But they stick shut eventually due to a build up of scale from the passage of steam.
You get around this in the following way: when you turn off the machine you open a steam tap and let all the steam bleed off...leave the valve open. When the steam is exhausted, atmospheric pressure equalises into the boiler.
When you switch on again, make sure the steam valve is still open. Leave it open until the machine has built up enough steam for it to start leaking out the steam pipe. When you see it leaking, close the tap. The machine will then very quickly reach operating pressure, and there will be NO false pressure situation.
If you do the above all the time, it doesnt matter if the anti vacuum valve is stuck shut.
To stop the anti vacuum valve from sticking shut you can occasionally just tap the top of the valve with something (screw driver handle) while the machine is on, to make sure its not stuck. The steam pressure will just bounce it straight back up and reseat it.
A stuck valve is not a failed valve...its just struck. Tap it occasionally and you will stop it sticking. If it is stuck, tapping will unstick it and make it reseat itself.
Anti Vacuum valves eventually fail in that the passage of steam will create a "track" through the valve, or the valve will wear in some way, or a seal will fail ( depends on the type of valve). In this case the valve wont reseat itself properly and will leak steam all the time. Only then will I consider replacing the valve.
Otherwise, you just make the spare parts man very well off indeed from selling anti vacuum valves to people that didnt need to buy them...they just needed to tap them!
By the way, remember these items are directly concerned with steam delivery so if you are going to tamper with or "tap" these valves, please take care not to burn yourselves.
Apologies for the lengthy reply (but how else would you describe and explain the above?????).
I call it a "false pressure", and it happens when the ANTI VACUUM valve is stuck SHUT. ie it did not open when you turned off the machine and it cooled down, and therefore it did not allow atmospheric pressure to equalise into the boiler.
When you turn the machine back on it goes into a false pressure situation exacty as you have found, then rights itself after you bleed off a steam valve.
Anti vacuum valves are supposed to open and shut every time the machine is swiched on and off, to stop false pressure. But they stick shut eventually due to a build up of scale from the passage of steam.
You get around this in the following way: when you turn off the machine you open a steam tap and let all the steam bleed off...leave the valve open. When the steam is exhausted, atmospheric pressure equalises into the boiler.
When you switch on again, make sure the steam valve is still open. Leave it open until the machine has built up enough steam for it to start leaking out the steam pipe. When you see it leaking, close the tap. The machine will then very quickly reach operating pressure, and there will be NO false pressure situation.
If you do the above all the time, it doesnt matter if the anti vacuum valve is stuck shut.
To stop the anti vacuum valve from sticking shut you can occasionally just tap the top of the valve with something (screw driver handle) while the machine is on, to make sure its not stuck. The steam pressure will just bounce it straight back up and reseat it.
A stuck valve is not a failed valve...its just struck. Tap it occasionally and you will stop it sticking. If it is stuck, tapping will unstick it and make it reseat itself.
Anti Vacuum valves eventually fail in that the passage of steam will create a "track" through the valve, or the valve will wear in some way, or a seal will fail ( depends on the type of valve). In this case the valve wont reseat itself properly and will leak steam all the time. Only then will I consider replacing the valve.
Otherwise, you just make the spare parts man very well off indeed from selling anti vacuum valves to people that didnt need to buy them...they just needed to tap them!
By the way, remember these items are directly concerned with steam delivery so if you are going to tamper with or "tap" these valves, please take care not to burn yourselves.
Apologies for the lengthy reply (but how else would you describe and explain the above?????).


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