low-no pressure at brew head, boiler fine

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bionic_hip

low-no pressure at brew head, boiler fine

Post by bionic_hip »

The other day I noticed that I am getting little to no pressure at the brew head when I try to pull a shot. The boiler works fine (at least when I use the hot water button). Any idea what it could be? Also, I have it hooked up to a FloJet pump, pulling out of a water bottle (office style).
Thanks,
MDL
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Re: low-no pressure at brew head, boiler fine

Post by MDL »

To help others help you complete your profile so that we know where you are and also which machine you have.

The hot water comes from the steam boiler and has nothing to do with the brew boiler and water to the group from the brew boiler.

If you use a blind basket or the rubber backflush disc do you get pressure building up? If you let the pump run do you get the overpressure lights flashing (can you do a backflush)?

If you run the pump for a shot without having a portafilter on the group do you get water coming out?
bionic_hip

Re: low-no pressure at brew head, boiler fine

Post by bionic_hip »

Sorry, I forgot to include that info. I have an S1 VI, '05/06ish.
When I run it without the portafilter, little to no water comes out. I've taken the diffuser and screens out and water does flow. I've cleaned the screens and diffuser, so I'm fairly certain it's not that. Haven't tried the backflush/blind basket, will do that this afternoon.
Thanks,
richardcoffee
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Re: low-no pressure at brew head, boiler fine

Post by richardcoffee »

So, I'm also interested in your history with this machine. Have you had it the entire time, ie: since 05/06? Always used softened and filtered water? Do you backflush regularly?
bionic_hip

Re: low-no pressure at brew head, boiler fine

Post by bionic_hip »

I have had it the entire time. I will admit that I haven't been as regular on the backflush as I should. I use filtered water primarily.
It's been in fairly regular use, minus the past 2 months.
Endo

Re: low-no pressure at brew head, boiler fine

Post by Endo »

GIcleur valve starting to close up due to mineral deposits I would guess:

viewtopic.php?f=38&t=1216&p=14740
bionic_hip

Re: low-no pressure at brew head, boiler fine

Post by bionic_hip »

Thanks Endo. Is that pretty easy to get at? (I've been lucky in that I haven't had to open my machine up much!)
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chas
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Re: low-no pressure at brew head, boiler fine

Post by chas »

Endo wrote:GIcleur valve starting to close up due to mineral deposits I would guess:

viewtopic.php?f=38&t=1216&p=14740
Endo, that part controls the flow of water into the steam boiler. So probably not the solution for this problem.
Chas
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chas
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Re: low-no pressure at brew head, boiler fine

Post by chas »

bionic_hip wrote:Sorry, I forgot to include that info. I have an S1 VI, '05/06ish.
When I run it without the portafilter, little to no water comes out. I've taken the diffuser and screens out and water does flow. I've cleaned the screens and diffuser, so I'm fairly certain it's not that. Haven't tried the backflush/blind basket, will do that this afternoon.
Thanks,
The S1 plumbed version's group boiler will fill from street pressure and water will flow via that pressure even if the pump doesn't come on. Of course, you won't get more than street pressure coming out. The pump/motor has to be running to get 9 bar. So I figured I'd better rule out the obvious and be sure you are hearing the pump running when you try to pull a shot. It should come on the instant you press the one or two-cup buttons.

No matter how good your water, after 7 years of use unless you are using distilled water, you may very well have substantial build up in both boilers.
Chas
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bionic_hip

Re: low-no pressure at brew head, boiler fine

Post by bionic_hip »

Ah, ok. So I'm looking at pulling it apart to check the boilers?
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chas
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Re: low-no pressure at brew head, boiler fine

Post by chas »

Any success yet? Hopefully it doesn't come to this since it is the most expensive item(s) on the machine. However, given the age of your machine it could be the motor and/or pump. That combo doesn't have to build up much pressure to keep the steam boiler filled but if it doesn't produce 9bar you won't have much luck making coffee.

A typical failure mode is for the pump seal to leak slightly. Over time this can get into the bearing of the motor and cause it to fail. It's pretty easy to pull the pump out so that you can inspect this area. 1) Disconnect both the inlet and outlet water hoses from the pump. 2) Use a regular screwdriver to loosen the screw holding the collar that connects the pump and the motor. With that collar greatly loosened or removed, you can pull the pump right out.

Check out this thread.
Chas
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bionic_hip

Re: low-no pressure at brew head, boiler fine

Post by bionic_hip »

Chas,
Unfortunately, I haven't had any time this week to get to it (darn kids!) I'm hoping to pull it apart this weekend. Hoping that it isn't the boiler(s)..................
southpaw
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Re: low-no pressure at brew head, boiler fine

Post by southpaw »

I'd been having intermittent low to no pressure at grouphead and I think it I've diagnosed to a sticky opv. A quick adjustment back and forth and all is now well. Would this fit with your description?
bionic_hip

Re: low-no pressure at brew head, boiler fine

Post by bionic_hip »

Yeah, sounds like the issue I'm having. Easy to get at the OPV?
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chas
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Re: low-no pressure at brew head, boiler fine

Post by chas »

southpaw wrote:I'd been having intermittent low to no pressure at group head and I think it I've diagnosed to a sticky opv. A quick adjustment back and forth and all is now well. Would this fit with your description?
I don't think I would call the OPV sticky. It consists of a stiff spring that has a rubber cap on the end. The spring holds the cap up against the opening of a copper tube that goes to the steam boiler. The OPV should be set (screwed in tight enough) that when the group pressure exceeds 12bar the spring gets pushed down to let the excess pressure out. So if this was stuck, it would be stuck closed and you'd have too much pressure.

The most likely failure mechanisms for losing pressure through the OPV are 1) the OPV is adjusted to open at too low a pressure 2) The spring is pushing the rubber cap up a bit off-center causing a pressure leak 3) The rubber is getting old and is cracking causing a pressure leak.

It sounds like it is fixed for now. Should it happen again, I would recommend removing the OPV so you can inspect that rubber cap. Where the rubber cap seats up against the pipe leaves a circular indentation in the top of the cap. You can easily spot if it is seating off center. Any cracks will be easy to spot as well.
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Re: low-no pressure at brew head, boiler fine

Post by chas »

bionic_hip wrote:Yeah, sounds like the issue I'm having. Easy to get at the OPV?
You should be able to easily tell if the OPV is leaking. Remove the grate from the drip tray and check the bottom of the OPV valve. Now put the blind basket or rubber disk in your PF and hit the One or Two Cup button. If the OPV is not set right or is leaking pressure due to a worn rubber cap, you will see quite a bit of water coming out of the OPV. On the other hand, if you do this and the OPV remains closed during the "shot", it is most likely something else.
Chas
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bionic_hip

Re: low-no pressure at brew head, boiler fine

Post by bionic_hip »

So here's what I found after running with just the rubber disk in the PF......
La Spaz.docx
(393.39 KiB) Downloaded 444 times
(Leaking at arrow)
I got an over pressure alarm (3 lights flashing) when this happened.
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chas
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Re: low-no pressure at brew head, boiler fine

Post by chas »

In hindsight I guess doing the blind basket test doesn't tell us much without also knowing what the group pressure is during the test. It looks like you have an old S1 so unless you also have a PF pressure gauge you don't know this parameter. A better way to tell would be to check while you're actually pulling a shot to see if water is coming out of the expansion valve. There should definitely not be any coming out in this case. There probably shouldn't be any or at least not much more than a few drops with the blind basket in place but we'd need to know what your group pressure reads with the blind basket in pace to know for sure.

If the Group pressure AND the expansion valve are both adjusted correctly you should only see a couple of drops come out when the group boiler cycles and nothing much at any other time. If the expansion valve setting is so far off that it is impacting the pressure while you are trying to pull a shot then a lot of water will be coming out while you are pulling a shot and none should be coming out at that time.,
Chas
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bionic_hip

Re: low-no pressure at brew head, boiler fine

Post by bionic_hip »

OK. I'll run that tonight. When I ran the blind, there were only a few drops coming out...I'm looking into piecing together the parts for a PF gauge.
Thanks again for the help!
southpaw
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Re: low-no pressure at brew head, boiler fine

Post by southpaw »

chas wrote:
southpaw wrote:I'd been having intermittent low to no pressure at group head and I think it I've diagnosed to a sticky opv. A quick adjustment back and forth and all is now well. Would this fit with your description?
I don't think I would call the OPV sticky. It consists of a stiff spring that has a rubber cap on the end. The spring holds the cap up against the opening of a copper tube that goes to the steam boiler. The OPV should be set (screwed in tight enough) that when the group pressure exceeds 12bar the spring gets pushed down to let the excess pressure out. So if this was stuck, it would be stuck closed and you'd have too much pressure.

The most likely failure mechanisms for losing pressure through the OPV are 1) the OPV is adjusted to open at too low a pressure 2) The spring is pushing the rubber cap up a bit off-center causing a pressure leak 3) The rubber is getting old and is cracking causing a pressure leak.

It sounds like it is fixed for now. Should it happen again, I would recommend removing the OPV so you can inspect that rubber cap. Where the rubber cap seats up against the pipe leaves a circular indentation in the top of the cap. You can easily spot if it is seating off center. Any cracks will be easy to spot as well.
Well the problem is back. I get a loud noise from the pump and no flow from the grouphead.
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Re: low-no pressure at brew head, boiler fine

Post by chas »

You didn't mention in any previous posts that the pump was making a lot of noise when you had this issue. Usually pump noise is due to low water availability at the input of the pump. Normally I get this noise every time I shut off the water to work on the S1 and then forget to turn it back on when I restart the machine.

In your case, I would suspect the Flojet is not working right and/or is powered off.
Chas
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southpaw
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Re: low-no pressure at brew head, boiler fine

Post by southpaw »

My machine is a mini but I guess the water input at pump is still valid?

Just realised after you mentioned it that I didn't say about the pump before.

Edit: got flow again after taking tank in and out a few times. Water is cutting out after a couple of seconds rather than the normal for single/double. I'm going to let it warm up and check again in 10 minutes.
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Re: low-no pressure at brew head, boiler fine

Post by southpaw »

Volumetric dosing had reset somehow. All appears to be good now. Thanks for replying Chas it was enough of a pointer for me to sort :)
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