Hi everyone!  I am having a bit of a problem with my Nuova Simonelli 2 group Appia Compact.  The pump pressure(the bottom half of my pressure gauge) keeps going up to about 12 or 15 even at rest.  I adjusted it back down manually a couple of times back to 3 - 5 bars at rest and 9-10 while pouring and it seemed to work fine for a couple of weeks each time.  Now it just won’t stay where it should when adjusted anymore.  A friend of mine suggested it might be that the solenoid valve went bad but I certainly don’t know.  Any suggestions or ideas would be greatly appreciated.  Thanks so much!

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You still on a Flojet, or did you switch over to a different pump setup on your mobile setup?

Short answer - I think the problem is your supply pump, not the one on your machine.

Here's why...

On hx machines like your Appia the resting pressure reading is determined by incoming line pressure to the machine. The internal pump only serves to temporarily boost this pressure - usually from 2-5 bars to 9 bars. Once the shot is finished the exhaust on the 3-way valve returns system pressure to match incoming line.

Adjusting the pump only effects this "boost" pressure on the machine.

For example... Lets say your incoming pressure is 4 bars. You adjust the pump so that while you are pulling a shot it goes to 9 bars. So the internal pump is providing +5 bars to incoming line. If your incoming line (resting) pressure suddenly jumps to 6 bars, when you pull a shot your pressure will now be 11 bars (6+5, right?). This is an annoyance in shops that see swings in line pressure, but sounds like a bigger problem for you.

Another feature of modern espresso machines is a cold water expansion valve. This valve is usually located on a side branch of the piping leading to the heat exchangers or coffee boiler. It is usually set to open around 12 bars, and gives the trapped cold water a place to go when it heats up and expands. My guess is that if you were to remove your drip tray and look into the drain cup when the pressure was super high you'd see a whole bunch of water shooting into it.

My guess is that you have a problem with the pump supplying water to your machine. This needs to be addressed ASAP, as excessive incoming line pressure can damage your machine.

If what you were seeing was a problem with the pump on your Appia, your resting pressure would be fine and your dispense pressure would be high. There are a couple of pump problems that can cause this.

Something you may consider, in addition to fixing your supply pump, is installing a pressure regulator and accumulator tank. This will even out pressure fluctuations and limit spikes. I think they have a couple of setups on Espresso Parts.

Hope that helps. Give me a call anytime if you have additional questions about this. I know you don't want to bug me, but I really don't mind.

I'd have to agree with Brady as it sounds as if incoming pressure may be the problem. BUT most FloJet or ShurFlo pumps will only hit 45-60psi MAX. Our van is plumbed so that 1 pump supplies the espresso machine, sinks and hot water heater. Not a problem keeping up as it simply pulses faster to keep up with the 3.3gpm flow rating if need be. I've noticed that when the hot water heater kicks ON the line pressure will rise slowly and go as high as 10 bars on the machine gauge, but I'm so used to it I simply bleed a bit of pressure off at a sink and it's all good. Obviously I have no idea how your equipment is plumbed and this may not apply to you in any way. 


 I have considered installing an accumulator tank to minimize workload on the pump and smooth that pulsing to more steady flow and could install a pressure regulator leading to espresso machine. Problem is the van was plumbed entirely with Kitec and it's hard to find the material/fittings to make any changes because of some serious issues with homeowners in the past that caused most Kitec to be pulled from shelves. Also, Kitec isn't compatible with PEX, CPVC, etc. SO if I need to do any plumbing repairs I'd need to rip it all out and re-plumb entire setup with PEX.

How are you adjusting it? Cause you said you adjusted for both. If you set the pump pressure, and the pump is working correctly, it really won't matter what the incoming pressure is.  These are bypass regulated pump heads.  If set to nine bar, they will make nine bar pressure without having to be constantly adjusted - doesn't matter if your incoming line pressure fluctuates between 10 and 100 psi, the pump output will always be nine bar.  After adjusting the acorn nut on the pump head, did you tighten down the lock nut?

The resting pressure is set by the line pressure and expansion valve.  The expansion valve opening pressure needs to be set higher then the pump pressure, or you'll get a pressure leak (not to mention wasting water) and that will affect the shot.  

I've had stores loose water pressure, and the baristas not notice for like 45 minutes cause the espresso machines were siphoning water from the brewer cause the fill valve opened.  Really.  

Is this Flojet pump a variable speed pump? (Not variable load) Cause if it ain't, you should install an RP tank ( or accumulator as Brady called it).  It will save the brushes in the pump from wearing out.  And provide consistent water pressure.  Single speed pumps, while they may be rated at 60 psi, this is generally only true for the first 10% of the rated flow.  So a 3.3 gpm pump, puts out 60 psi at like .3gpm and it drops off significantly from there down to 10 psi at the 3.3 flow rating.  And the other reason why I bring this up is that it's not good for the pump in you machine.  It will only have to work harder when demand is high on your water system.  

Brady - Most, if not all, three way valves release pressure from the brew chamber once the shot is done, not the boiler/heat exchanger.  The pressure in the boiler system drops because the pump shuts off.   

Hey Scott and Shadow. A couple of great points. Glad you jumped in.

Scott, the way you've described pump bypass function is how I understand it as well. That's why seeing pumps deliver pressure higher than setpoint has always puzzled me a bit. Perhaps there were other factors at work when I made those observations? I should revisit that...

Your description of three-way function was also correct. If the pump continues to run with the brew valves closed you'll see pressure stay high. Thanks for catching that, and apologies to all for any confusion.

So, given this, and Shadow's description of mobile pump setup limitations... I'm less apt to suspect the supply pump. Still worth verifying that the function is correct though.

Scott, sounds like maybe you think the machine pump has burned up from having to work too hard?

Hey guys,

Thanks for all the input, I truly do appreciate it. Brady, I am still using the flojet and it hasn't knowingly given me a problem ever. The tech guys at simonelli think its the machine pump.  I described it to them the same way I described it to you and that was their conclusion.  I was hesitant to think it was the machine pump because its so new (my  machine is just a little bit more than a year old though i do use it rather strenuously).  my flojet pump seem to be working fine (water is coming out in a steady stream) but I don't think its a variable speed pump. so you guys think I should just order the machine pump? And if I do replace the machine pump would it benefit me to also think about installing the pressure regulator and expansion tank for the flojet? Once again I really appreciate the input.  I am just starting to explore the exciting(and expensive) world of the inside of my machine. It's a big learning curve for me but I am digging it.  Though i would be digging it more when I am not in a bind. :)

Personally I'd install an expansion tank (a.k.a. accumulator) as that will minimize wear on the pump and smooth out any pulsing. Think of it the way a pressure tank is used to work in conjunction with a well pump for water usage. If not for using one the pump would simply overwork itself to death by constantly kicking ON/OFF and the high/low fluctuations would drive you insane.

thanks shadow. the accumulator definitely seems like something to look into. 
After I put in a new pump I don't want to burn that out too.  :)

wait wait.  the appia has an expansion valve in the brew system that should be set to open at 12 bars.  its the little valve in your drain box.  I would replace it unless the unit is new.  You might need to adjust it.  Short story at rest who cares what the pressure is as long as you are at 9bars when you are pulling a shot.  What happens after is that as the water heats it expands.  The expansion valve opens to allow the expansion to escape so that your brew valves aren't damaged.  This is usually set between 12-13 bars.  

good luck

Hey Eli - Here's something practical you can do.  Shut the water off, loosen the acorn nut on the pump in the machine and remove the spring.  Squeeze the spring a few times (with a pair of  pliers/ or your hand or in a vise) , then re-install. Then set the pressure again.  Wonder why this will make a difference?  So do I, but I try it sometimes and it works.  

It could be your pump is failing, though a common symptom is the pump relay sticking and the pump running all the time. Though in the Appia, not sure if it's a relay or some other solid state switch.  

And for the Love of Mike, quit buying Flojet pumps (unless you are getting a killer deal).  Get an Aquatec 5800 series and an RP tank (like this - http://www.precisioninstallationproducts.net/p-5278-32-gal-black-me...) . These things will last for 10 years or more.  Or if space is tight get a 550 series, 1-4 gallon variable speed pump - though the mileage on these things varies more, and they are very dear.  And don't even think about a Shurfail, I mean Shurflow.

And like Mickael said, who cares what resting pressure is.    

Scott, opinions vary on equipment brand. I run my ShurFlo pumps rather hard and haven't killed one yet.

Eli - I forgot something.  If the pump in the machine has a start capacitor, verify that it's within +/- 5% of it's rating.  If not replace.  That could be causing pressure problems as well.

Thanks guys. this gives me a good base of troubleshooting knowledge to go on.  Tomorrow I'll be testing everything from my flojet to the connections, to retrying the pump after taking the spring out for some spring squeezing. I have a feeling, though, that it comes down to the internal pump. time we'll tell and so will I when i finally get it back to go.  :)

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