You order a replacement for a Riello RMG88.62C2, then notice that the new box says CMG88.62D2. Has the supplier sent the wrong control?
In this case, the new name is expected. Riello changed the designation but kept the spare-part number, 3013073. The modulating version received a similar update: RMG/M88.62C2 became CMG/M88.62D2, still supplied under 3013362. The distinction between those two controls matters more than the change from RMG to CMG.
The replacement numbers have stayed the same
| Old control | Replacement | Riello part number |
|---|---|---|
| RMG88.62C2 | CMG88.62D2 | 3013073 |
| RMG/M88.62C2 | CMG/M88.62D2 | 3013362 |
Riello announced the change in October 2024, following changes to production and component supply. Its replacement notice states that the new D-series controls retain the performance, layout and dimensions of their C-series predecessors. Each new unit is interchangeable with the old control shown beside it in the table.
This also explains why an older burner manual, a spare-parts catalogue and a newly delivered box can use different names for the same replacement part. In Riello’s own photographs below, both packages carry 3013073, while the control labels change from RMG88.62C2 to CMG88.62D2.
What the new label tells you
The label carries two model references: the familiar Riello designation and a Siemens manufacturing identifier. On CMG88.62D2, that second reference is LMO88.620D2RL. The /M control uses LMO88.621D2RL—just one digit different.
| Label detail | CMG88.62D2 | CMG/M88.62D2 |
|---|---|---|
| Siemens identifier | LMO88.620D2RL | LMO88.621D2RL |
| Power supply | 220–240 V AC, 50–60 Hz | 220–240 V AC, 50–60 Hz |
| Ignition safety time | TSA 3 s | TSA 3 s |
The “LMO” lettering can be confusing if you know Siemens oil-burner controls. These particular OEM units are gas controls; Gas is printed on both labels. The full identifier is what distinguishes them. Likewise, TSA 3 s describes the ignition safety time, not the burner’s prepurge duration.
Why the /M version matters
The two boxes look almost identical, and their voltage and safety-time markings are the same. But CMG/M88.62D2 belongs to the modulating gas-burner group in Riello’s replacement notice. It is not a higher-spec substitute to choose in place of the non-/M control.
Modulation depends on the burner’s air/fuel controls, actuator arrangement and demand regulator as well as its control box. Fitting the /M box alone does not turn a two-stage burner into a modulating one.
A useful comparison: RS 34 MZ and RS 34/M MZ
These similar burner names make the difference easy to miss on an order. The RS 34 MZ parts list specifies control 3013073; the RS 34/M MZ list specifies 3013362. The same split appears between RS 44 MZ and RS 44/M MZ.
| Burner in the Riello parts list | Control part number | Current replacement |
|---|---|---|
| Riello 40 FS20 | 3013073 | CMG88.62D2 |
| RS 34 MZ / RS 44 MZ | 3013073 | CMG88.62D2 |
| RS 34/M MZ / RS 44/M MZ | 3013362 | CMG/M88.62D2 |
There is an older exception worth checking before ordering for an RS/M BLU burner. Riello introduced RMG/M on that range in February 2007; earlier units used LMG22, part 3002478. Riello explicitly states that LMG22 and RMG/M are not interchangeable. If the fitted box says LMG22, the /M in the burner name is not a reason to order CMG/M.
For an FS20 fitted with RMG88.62C2, the match is straightforward: the label agrees with the 3013073 reference in the parts list, so the replacement is CMG88.62D2. For an older burner with a different control fitted, a clear photo of that label is more useful than a guess based on the burner name.
The oil-burner replacements are different
Riello’s notice also covers RMO and CMO oil controls. Their names are close enough to RMG and CMG to cause confusion, but the part-number changes are different.
For the listed RL one- and two-stage applications, RMO88.53C2, part 3013071, is replaced by CMO88.53D2, part 20183425. Here the Riello part number changes along with the control designation.
The listed PRESS applications need kit 20213738. It contains the CMO control, a Siemens QRB4 flame detector and its mounting support, with the QRB4 replacing the previous photodiode. Ordering only the control would leave out part of that conversion.
Ordering a replacement
A photo of the existing control label, the burner model and the quantity are usually enough to start the enquiry. Include the Riello spare-part number if you have it, plus the delivery destination. Labels ending in A1 or A2 need a separate check: the October 2024 notice covers the C2 predecessors above, not every earlier RMG88 version.
If you are ordering because the burner keeps locking out, it is worth establishing the cause first. A failed ignition, loss of gas pressure or missing flame signal can stop a healthy control box. Record the fault indication and when the burner stops; the Riello lockout guide explains how those symptoms relate to the operating sequence.
A qualified burner technician should isolate the electrical supply, check the base and connections, and complete the burner’s commissioning and safety checks after replacement. Flame and pressure interlocks must remain in service.
