Replace Nuova Simonelli Oscar 1 boiler with Oscar 2 boiler

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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#1: Post by gkleding »

I am very new to home coffee/espresso machines, so please excuse me if I sound a little dull. I have owned Gaggias in the past but recently purchased a Dacor(rebadged Nuova Simonelli Oscar) built in, plumbed semi-automatic coffee machine. The machine was mint until FedEx got ahold of it:| It suffered cosmetic and damage and the original left water in the lines. It would run but not heat up. So I completely disassembled, descaled and cleaned everything. The boiler arrived with some small dents in it and I was wondering if I could replace it with a boiler made for the Oscar 2? I have read numerous how to's and mods but haven't seen any that apply to my situation. My machine is almost identical to the rebadged Blanco with the exception of the water tank, mine is plumbed. I ran a plumb line in my kitchen then a temp line in my office so I could work on it unseen :D

gkleding (original poster)
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#2: Post by gkleding (original poster) »

I would be more than happy to pay for advice and time taken to help me. I have no local appliance repair that services my machine. And I know that knowledge and experience are worth paying for.
Thank you so much


#3: Post by vas »

how small the dents are? they have to be quite considerable to justify the boiler replacement. Not heating up is unlikely the result of the dents. Have you tried to measure the voltage on the heating element? or just ensure the continuity across the element and the thermal fuse that's inserted in the heater?


#4: Post by vas »

answering to the original quiestion - the boiler from Oscar II has two top outlets, instead of 4, and the one of them will be right under the grouphead supply tube, so you'll have to put the water probe in it and use a flag spade connector instead of straight one to fit under the tube. Also you'll have to bend the steam tube to connect it to another outlet, where all the rest of the stuff will be. So it's not impossible, but isn't a straightforward one.

gkleding (original poster)
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#5: Post by gkleding (original poster) »

The dents are fairly small maybe the size of a quarter, perhaps larger. I pulled the boiler diagrams from simonelli website to understand what you are referring to. I see. Did you mean it was or was not possible? I checked the heating element, and it was running 120+- V when I checked. I am just now putting it all back together after cleaning. it did have considerable scale where the water had been setting. I am wondering if the gicar box that attaches to the finder should have the greenlights on while the unit is turned on, and if the cubic ricerca electrical box red light should be on or off when unit is turned on. the fuse in the heating element test good too. Thank you so much for your reply. I really appreciate it!


#6: Post by WWWired »

haha!!!! gkleding!! . . . that is brilliant and what on earth is that!! :) A bit of research shows a model of Dacor that is designed to be fitted into a cabinet . . . is that what this is? Miele and Bosch modles are a bit like that but those are Super-Automatics usually . . . fascinating!

More photo's please! That is unlike any Oscar (other than sharing some base components) and is amazing :) . . . a custom mod perhaps? It seems to have several additional components but definitely an Oscar type grouphead fitting on the interior side of the chassis. Any details about the model number and photos from different angles would be very fun!

*EDIT . . . haha think its been found . . . here's a link to Dacor's PDF (appears to be a model "CM24PBISAS") . . . ⟪Dacor CM24PBISAS PDF Link⟫ . . . even comes complete when new with two slides to roll in and out of cabinet area! . . .

As mentioned by vas wisely above, and raised as an excellent question to open this thread, its worth considering the differences with the Oscar 1 and 2 in the fitting ports in the Boilers. In the Oscar boilers, it appears the usually configuration involves the Boiler Fill port and the two HX line connectors are on one end of the boiler and the Heating Element Fitting is on the opposite end. There are several models of these boilers and different numbers of fitting ports may be on top depending on the model and version. As well, sometimes these boilers are dented on the ends or around fittings at the factory during assembly (should never be done but it seems to be commonplace with certain manufacturers . . . all rubber mallets should be banned from espresso machine factories).

Here's a link to Home-Barista site Sponsor Elektros that shows photos of a brand new boiler that sports several dents (likely inflicted during manufacturing at a factory) ... usica.html

. . . and here's a link to Elektros' Oscar II boiler page showing the different fitting configuration on the top of the boiler . . . ... ar-II.html

And finally here's an Oscar 1 Boiler from a photo that shows three fittings on top, (Left is Pressurestat/SafetyValve Fitting, Center is the Water Level Probe Fitting, and Right is the Steam Tap Fitting). The Left Fitting on the Top could further have one branch of the T- Fitting holding the Safety-Valve further split into a Y-Fitting to hold both a Safety-Valve and a Vacuum-Breaker/Anti-Vacuum Valve). What that demonstrates is it may be possible to use Oscar Boilers with different configurations of fittings in different machines with some splitter fittings. Some folks will split a fitting port into multiple branches and add a Pressure Gauge, Anti-Vacuum-Valve (Vacuum Breaker) or other feature. Here's the photo I have of an Oscar 1 model boiler with the three fittings on top. . .

gkleding (original poster)
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#7: Post by gkleding (original poster) »

You all are so smart! I contacted Dacor who has absolutely NO internal diagrams or available parts. At the risk of sounding like the dumb girl, I called Nuova Simonelli. They did not have a breakdown either. but he did send me a manual and wiring diagram. this was from a Sirius scm-3 Romantica. So far I have seen 4 different brands rebadging the SCM-3 ROMANTICA. Dacor, Sirius Caple and Blanco. I really love the concept and am getting ready to test the unit. Caple had some great diagram breakdowns! ... _ref=86323
Thank you so much for all the replies! I will post my updates!


#8: Post by vas »

Oscar I's electrical diagram can be found here
Gicar control box needs to connect pins 5 and 10 for the boiler to start heating up. If you're saying you have 120V on the boiler terminals then I don't see why it wouldn't heat up unless the heating element itself is faulty.

gkleding (original poster)
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#9: Post by gkleding (original poster) »

After cleaning and reassembling, I was still not getting heat. The 2 connections on the boiler testested 0. I pulled the two connectors(the double blue and the black wires) and together the the voltage tested 124. So I pulled the thermal wrapped fuse and it tested 0 HMS and the heater tested 13 OHMS. SO im thinking my heater is bad? Am I on the right track? Dont want to think its my gicar/finder or other electrical box. But if it is, it is. Thank you for your replies. I have donated to the sight, but will donate to individuals who have helped also. I really appreciate everyone taking the time to help me :)


#10: Post by WWWired »

Doing fantastic gkleding! Narrowing the source of any faults brilliantly :)

Those Finder Power Relays do experience some wear and tear. The energizing of these units can be quite shocking . . . Arcs and all lol . . . Regular annual or biennial inspection of such a Power Relay on a regularly used machine could be worthwhile. The contacts can come off on these types of Power Relays as there is a lot of lightning in a bottle going on and a terminal-contact that has broken free can result in unusual performance or a full failre as the pole transfer cannot make the contact properly. I think you are onto to something with the Finder (pronounced "Fin-dur" apparently) Power Relay. It does appears from the parts manuals that there may be a Finder Power Relay in this Model. A similar issue rendered a Bezzera that was refurbished recently when it wouldn't power up either. Here's a few photos of the Finder Power Relay that needed to be replaced for obvious reasons (10 to 12 years of enjoyment, not bad the Power Relay lasted that long) . . .

Note: Please be very careful as there can be over 10 Amps on certain components. High quality espresso machines are much different than coffee appliances and there can be large amounts of electricity in certain items.

A Typical Oscar System Operational Logic
  1. If Steam Boiler Water Level is not filled enough to touch the Water Level Probe (see part 24 in Boiler parts diagram 18.1 below), the Pump and 2-way Solenoid will be energized to Fill the boiler until water touches the lower tip of the Water Level Probe. The water provides continuity in the circuit between the Water Level Probe and the Boiler Wall;
  2. Once water has filled the Steam Boiler enough that Water is touching the Water Level Probe, the pump and 2-way Solenoid are de-energized;
  3. After the Pump and 2-way Solenoid are de-energized, current is passed to the Thermal Fuse (see 19 in Boiler diagram 18.1 below);
  4. If current can successfully pass through the Thermal Fuse (the thing with with red somewhat transparent wrapping around it), then the Heating Element will be energized if is functioning properly and so long as the Pressurestat microswitch is in its Normally Closed (N.C.) passing current state when the pressure in the Stream Boiler is below a user set-point (usually about 1.1 to 1.3 Bar). As well the Pressurestat's membrane (in the Campini TY85-B model Pressurestat in the picture) needs to be intact and functioning. The Membrane in the Campini Pressurestat begins in the downward deflected state and as the pressure in the Steam Boiler increases (due to the Heating Element's energization) the Pressurestat membrane is deflected upwards and this cause a Pole Throw from the Normally Closed (passing current) state to the Normally Open (N.O. non-current passing) state. This membrane will deflect many times during a day's operation and these Campini Pressurestat models are rated to do 100,000 such Throws, but they typically last much longer.
A few diagnostic considerations:
  1. Indications are the Thermal Fuse is good. Original Poster gkleding verified the Thermal fuse and there are two methods for doing this . . .
    1. Continuity: The first is to set a Multimeter to Continuity mode (the one with the radio signal icon that beeps when the probes are touched together) and probing the Thermal Fuse should result in the same tone being heard if the fuse is intact.
    2. Resistance: The second method is to select the mode on the Continuity/Ω setting that does measure Resistance (Ω) . . . touch the probes together and you will see "0" (zero) . . . then touch the probes to the the contacts on the fuse and you should get the same "0.00" (zero) for an intact fuse (it will show "OL" for a fuse that has a fault). At the bottom of this post there is a video from a YouTube channel "GalcoTV" that shows this technique brilliantly;
  2. Based on the Wiring Schematic (at the bottom of this post), is Heating Element light on at the front of the machine (labeled "D" in the schematic below)?
  3. Are any of the other "lamps" (lights) on the front of the machine lit or operational during start up (labeled "B", "C", "D", in Wiring Schematic below)?

Currently Completed Diagnotistics
  1. gkleding wrote:. . . So I pulled the thermal wrapped fuse and it tested 0 OHMS. . .
    . . . yep, all great, you removed it first and disconnected it then tested its resistance (Ω) and got zero indicating an intact Thermal Fuse.
  2. gkleding wrote:. . . I pulled the two connectors(the double blue and the black wires) and together the the voltage tested 124 . . .
    . . . excellent, current is flowing to your Heating Element. If the machine is cold, this should be the correct state where the control system will energize the Heating Element to increase the Steam Boilers internal Water Temperature/Pressure.
  3. gkleding wrote:. . . the heater tested 13 OHMS. . . :)
    . . . also excellent, this is a functioning Heating Element . . . 13 Ohms Ω is perfectly fine . . . depending on the moment of probing Continuity/Ω Ohms on the two Terminals of the Heating Element, between 8 and 15 Ohms could be expected :)
A common Heating Element rating of 1200W can be found in an Oscar I. Here's a photo of an Oscar I Heating Element showing the rating (V115 W1200) stamped onto the Heating Element housing . . .

It is possible to calculate an expected Resistance (ohms) for a 1200W 115V Heating Element. The formula is:
  • ohms = volts² / watts
For the machine in this thread, if the Heating Element is a typical component, rated at 1200 Watts, then:
  • (115V)² ÷ 1200W = ~ 11 Ohms
Heating Elements can be different ratings. If a Heating Element is 1300W, then expect about 10.17Ω; and if the Heating Element is 1500W, then 1500W²/115V=8.8Ω.

As it is mentioned that 13Ω is the tested value, this is a functioning Heating Element. This doesn't mean it is less functional if it deviates from being exactly 11 Ohms, rather it might mean that current is currently being controlled by another component in the machine slightly. As one very experienced HB expert (Nunas) suggests, as long as a Heating Element is not reading infinity ohms (open) or zero ohms (shorted) the reading can vary depending on temperature . . . Click here to read that Nunas post . . .

Here is a video of a test on an Oscar Heating Element (be sure to unplug the machine so you don't have to relearn the alphabet or get your fillings put back in) . . . Nuova Simonelli Oscar 1 Heating Element test (maybe mute this first video lol, the camera refocus clicks sounds like a chipmunk a lot and might be annoying, apologies):
. . . just trying to find a site where I can upload a PDF manual but here's an exploded Diagram for the Dacor Boiler CM24TBISAS Model:

. . . and an Electrical Schematic (still need to confirm this is the correct model) . . .

A great video by YouTube channel "GalcoTV" explaining how to verify a Thermal Fuse . . .
Credit: YouTube and GalcoTV