# quick mill 3004 steam heat exhange fault



## Assaf Aman (Apr 26, 2021)

Hi everyone

I have been gladly using this machine for the past 12 years!

Recently I noticed that I do not get steam when activating. I opened the top cover and saw that the hose from the steam pump to the boiler is pushing air while the hose from the tank to the pump is filled with water. this led me to believe that the pump is fault. so I replaced it with a new one, only to realize that its not the fault 🤔...what I havent noticed before replacing the pump is that the heat exchange does not heat at all (while the coffee heat exchange heats fine). so I conducted the following tests:

1. I checked the two power inlet fuses (just in case)

2. I checked the boiler thermostat for continuity => OK

3. I checked power to the thermostat => OK

I tried to cunduct a test for the boiler solenoid and the boiler nodes, but I am not sure what exactly I need to check...

for the nodes I guess I need to check for resistence?. what about the solenoid? how to check power for the boiler? power for the solenoid?

just to mention that portafilter circle is OK, meaning I can activate the machine and make coffee

Thanks


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## DavecUK (Aug 6, 2013)

@Assaf Aman welcome to the forum. That model has twin thermoblocks. With the machine unplugged from the power, remove the power connectors from the steam thermoblock. Then check the resistance of the thermoblock heating element with a multimeter.


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## Assaf Aman (Apr 26, 2021)

Hi Dave

Thanks for replying

I understand I need to test between the two thermoblock nodes as marked in the drawing attached? what should be the expected resistence?

what about the solenoid? if the solenoid is fault, doesnt it mean that water from the pump will not flow into the thermoblock? if yes, how to test the solenoid?

.https://drive.google.com/file/d/1-VuztzxgvxRNP_-ukJYMJYoaUw_oUn3B/view?usp=sharing

Thanks

Assaf


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## DavecUK (Aug 6, 2013)

@Assaf Aman One thing at a time (otherwise we write a book)...test the thermoblock first. Look at the rating stamped on the thermoblock or the machines maximum rating/voltage (which may be the wattage for both added together), then use ohms law to calculate the expected resistance based on that. Or just check it's not open circuit...which if it's failed, it probably could be. Depending on voltage it will read anything from 20 ish to 40 ish ohms at a guess.

The reason I say to test the thermoblock, you don't mention having to reset the limit stat, which means it's not heating. If it was heatingthe limit stat would trip with no water getting to it. It's the easiest test to do.

Once you have confirmed the thermoblock is fine...then you can test the solenoid, valve as they might use one terminal on the solenoid valve to fire up the thermoblock when it moves to the open state.


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## Assaf Aman (Apr 26, 2021)

Yes Sir! I will do as you say and start with testing the thermoblock. can you please confirm the points I need to test between, as per the diagram I attached?

Thanks


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## Assaf Aman (Apr 26, 2021)

Hi

So... I checked the boiler nodes...looks OK
I checked the thermostat for continuity ... seems OK
Then I checked the load resistor ... looks broken ... it has no resistance at all...

I understand that this element provides power to the boiler...I tried to locate the part number on the element but it got wiped out from wear...

can you help with part number?

B.T.W I saw in other forums that people are replacing this element with a safety thermostat like this one:

https://www.drtradingshop.nl/en_GB/a-48797198/spare-parts-quickmill-3000-3002-3004/safety-thermostat-167-degrees/#description

any thoughts about this?

Thanks


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## DavecUK (Aug 6, 2013)

@Assaf Aman Are you talking about replacing the Limit Stat with one of those which looks like a one time fuse?

Are you able to take a photo of the boiler and indicate the part you think is broken?


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## Assaf Aman (Apr 26, 2021)

Hi thanks

I would be glad to share photos but for some reason, specifically in this forum, *I dont know how to do it*

Im not sure if I understand what is the limit stat...on each one of the boilers there are two round elements, one light brown rounded which is the thermostat, second black rounded one which I realized by trial and error, that is providing power to the boiler...is this the limit stat?


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## DavecUK (Aug 6, 2013)

I suspect the option to upload photos only appears once you have made 5 posts....this is what it looks like. You are using terms that are unfamiliar to me when describing components on espresso machines, so I would like to be sure what you mean, by seeing a photo.


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## Assaf Aman (Apr 26, 2021)

Thank you so much

so in this photo you can see the suspected element









in the following picture, an alternative installation I found


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## DavecUK (Aug 6, 2013)

if the fusible link is self resetting and the right temperature, great, if it's a one time fuse, I would not use it and buy the correct limit stat, that screws onto the boiler. If the thermostat is bad, at least you can reset it and then get a thermostat.


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## El carajillo (Mar 16, 2013)

That is not an element, it is a resettable limit thermostat. You are talking about changing that for a single use thermostat = if / when it blows it will have to be replaced. Possibly why one is 4 eu and the other is 13 eu.


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## Assaf Aman (Apr 26, 2021)

Thanks

I ordered a new limit thermostat.

I also took apart the solenoid and cleaned it internally.

I suspect it is also faulty. if I take out the solenoid valve, to allow flow from the pump to the boiler, and try to blow air from the pump inlet, almost no air comes out from the outlet to the boiler, of course I close the valve side by one finger, so air will not go that way...


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## El carajillo (Mar 16, 2013)

The pressure you can apply by blowing compared with the pressure the pump supplies is negligible.


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## Assaf Aman (Apr 26, 2021)

How many psi/bars does the pump applies?


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## El carajillo (Mar 16, 2013)

Depending on pu model up to 16 bar / 235 psi


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## Assaf Aman (Apr 26, 2021)

Just to verify... We are talking on the steam pump... Not the coffee pump... Its a dual heat exchange machine


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## Assaf Aman (Apr 26, 2021)

DavecUK said:


> @Assaf Aman One thing at a time (otherwise we write a book)...test the thermoblock first. Look at the rating stamped on the thermoblock or the machines maximum rating/voltage (which may be the wattage for both added together), then use ohms law to calculate the expected resistance based on that. Or just check it's not open circuit...which if it's failed, it probably could be. Depending on voltage it will read anything from 20 ish to 40 ish ohms at a guess.
> 
> The reason I say to test the thermoblock, you don't mention having to reset the limit stat, which means it's not heating. If it was heatingthe limit stat would trip with no water getting to it. It's the easiest test to do.
> 
> Once you have confirmed the thermoblock is fine...then you can test the solenoid, valve as they might use one terminal on the solenoid valve to fire up the thermoblock when it moves to the open state.


 Hi

So, situation now, after replacing the steam pump, the solenoid and the safety thermostat of the steam boiler:

when powering the machine without activating any pump, the fuse burns

after replacing fuse, and trying again, this time with the steam switch (on the back) off, fuse is OK.

Made some checks:
resistance between 230V terminals when the switch is ON (but the steam switch is OFF) = 4.2 ohm
resistance between 230V terminals when the switch is ON (but the steam switch is ON) = 1.6 ohm
I went on and did the following tests:
I disconnected the lines to the steam boiler thermostat.
tested again the resistance between 230V terminals. now I get 4.2 ohms for both cases, steam switch ON or OFF (quite obvious)
I then checked resistance between the steam boiler poles and compared it to the resistance on the coffee boiler:
steam boiler resistance = 2.6 ohm
coffee boiler resistance = 4.1 ohm

I guess this means that the steam boiler is dead? of course if this is the case, I should consider whether or not to replace it or to say goodbye to the machine ... I see that a used boiler costs around 100 euros ???

I also checked the resistance between the legs of the thermostat.
at first I got zero ohms on the steam boiler thermostat, while ~ 4 ohms on the coffee boiler thermostat .... so I thought that the thermostat is shortcutting ...
but then I took both of them out ... and both gave zero ...? (the coffee boiler works fine, heats and stops when reaching temperature)

so I not sure if its the thermostat or the boiler...tough choice as one cost 10 euros and the other 100...


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## DavecUK (Aug 6, 2013)

If your numbers are correct for the steam boiler electrical terminal resistance...then it's going to draw approximately 92 amps, or 22kW. Which is obviously not right. As for the other thermoblock with that resistance at 240V it's going to try and draw 14kW, which also doesn't sound right. I don't know what the voltage is in your country, but Ohms law will tell you the power draw.

*I make the assumption you removed all connectors from the heaters and measured directly?*

The thermostats read zero because they don't have any resistance until they reach a temperature at which they go open circuit to interrupt power to the heaters

I'm not really sure of exactly what you tested, except for that final photo...and you seem to have replaced a lot of parts?


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## Assaf Aman (Apr 26, 2021)

DavecUK said:


> If your numbers are correct for the steam boiler electrical terminal resistance...then it's going to draw approximately 92 amps, or 22kW. Which is obviously not right. As for the other thermoblock with that resistance at 240V it's going to try and draw 14kW, which also doesn't sound right. I don't know what the voltage is in your country, but Ohms law will tell you the power draw.
> 
> *I make the assumption you removed all connectors from the heaters and measured directly?*
> 
> ...


 We have 230V

*Yes, I have removed all connectors from the steam heater, except for the ground cable *(the coffee heater connectors are hard to reach so lets ignore the reference measurement...)

could be that my tester is bad....will try another one...what should be the correct resistance?

I will also take the heater out completely before measuring again, just in case.

as for other parts, as I mentioned, when power to heater is disconnected (by disconnecting the the cables from the thermostat) the pump and solenoid are working OK (by pressing on the hot water button


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## DavecUK (Aug 6, 2013)

@Assaf Aman Just work back via Ohms law, you know the voltage, the power of the thermoblock is probably printed on it or on the plate of the machine, that's 2 values, which will give you the resistance you need to have...it will be in the range I said in an earlier post


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## Assaf Aman (Apr 26, 2021)

DavecUK said:


> @Assaf Aman Just work back via Ohms law, you know the voltage, the power of the thermoblock is probably printed on it or on the plate of the machine, that's 2 values, which will give you the resistance you need to have...it will be in the range I said in an earlier post


 Unfortunately, there is no marking...but from total power stated, 1750watts, I can assume ~ 900watts, which gives ~59 Ohms...so Ill get another tester and check again

Thanks


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## DavecUK (Aug 6, 2013)

Assaf Aman said:


> Unfortunately, there is no marking...but from total power stated, 1750watts, I can assume ~ 900watts, which gives ~59 Ohms...so Ill get another tester and check again
> 
> Thanks


 You might find it's wired so only 1 thermoblock can be on at once...but it should be in the region of 35 to 50 ish ohm


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## Assaf Aman (Apr 26, 2021)

DavecUK said:


> You might find it's wired so only 1 thermoblock can be on at once...but it should be in the region of 35 to 50 ish ohm


 I know for a fact that I can activate both at the same time...plus...otherwise...whats the point in having a double heat exchange?


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## DavecUK (Aug 6, 2013)

Assaf Aman said:


> I know for a fact that I can activate both at the same time...plus...otherwise...whats the point in having a double heat exchange?


 fair enough, there are some machines where they can't run at the same time...


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## Assaf Aman (Apr 26, 2021)

DavecUK said:


> fair enough, there are some machines where they can't run at the same time...


 👍


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## Assaf Aman (Apr 26, 2021)

DavecUK said:


> @Assaf Aman Just work back via Ohms law, you know the voltage, the power of the thermoblock is probably printed on it or on the plate of the machine, that's 2 values, which will give you the resistance you need to have...it will be in the range I said in an earlier post


 OK so resistance is 52 ohms. perfectly normal.

which means:

A. my multitester is dead

B. back to square one with investigating.

Ill use another tester to re-test all elements for resistance and infinity to ground...hope Ill find it.

At least I know it is in the steam/hot water subsystem...


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## Assaf Aman (Apr 26, 2021)

DavecUK said:


> @Assaf Aman Just work back via Ohms law, you know the voltage, the power of the thermoblock is probably printed on it or on the plate of the machine, that's 2 values, which will give you the resistance you need to have...it will be in the range I said in an earlier post


 MACHINE UP & RUNNING!

Thanks so much for your help


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## Nightrider_1uk (Apr 26, 2020)

I must admit, I was very concerned with the first photo you showed with the thermostats in. One was horrendously corroded. The wiring on both stats showed signs of overheating.

What did you do to get it working?

Now that you have it working, i'd suggest regular inspection to ensure that it doesn't get like that again.


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## Assaf Aman (Apr 26, 2021)

Nightrider_1uk said:


> I must admit, I was very concerned with the first photo you showed with the thermostats in. One was horrendously corroded. The wiring on both stats showed signs of overheating.
> 
> What did you do to get it working?
> 
> Now that you have it working, i'd suggest regular inspection to ensure that it doesn't get like that again.


 1. replaced the safety thermostat (the corroded one)

2. I have replaced all cable terminals

3. I have zippered the wires

bottom line:

I assume that the root cause for the boiler not heating was the safety thermostat.

As I said, at the same time, I decided to replace also the pump, because the plastic tube was completely worn out.

After doing that, I probably made some stupid mistake that caused the fuse to burn.

from that point forward, I entered a loop of breaking my head trying to understand what could be the problem....only to realize that I put the wrong fuse, 1.6A instead of 10.0A (I had a bunch of them lying around with all my machine stuff, so I mistakenly assumed that they are the correct rating without even looking on them (I know, stupid))

So finally I got the 10A fuse and now all is OK


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