
Flow Detector (Flow Meter) Glow-worm 25C/30C/35C - Ref. 0020197555
If no hot water comes out when you turn on the tap, a technical diagnosis must confirm if you need the Glow-worm 25C/30C/35C flow detector (flow meter). This part is responsible for detecting the flow of water and activating the ignition for the production of domestic hot water. In case of a fault, the boiler will not provide hot water, even if the tap is open. It is compatible with Hermann Micraplus Condens 25-A and 30-A boilers, as well as with Saunier Duval models such as Thema Condens 25-A and Themafast Condens 30-A, among others. A technician must confirm through diagnosis if replacement is necessary when these symptoms occur.
- Type of part
- Flow detectors
- Status
- Refurbished
- Catalogue reference
- 0020197555
- Warranty
- 1 year
Hermann boilers compatible with reference 0020197555
Flow meter with reference 0020197555. 12 verified compatibilities: Micraplus Condens 25-A and Micraplus Condens 30-A.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Hermann Micraplus Condens 25-A | Hermann | Contrasted |
| Hermann Micraplus Condens 30-A | Hermann | Contrasted |
| Hermann Thema Condens 25-A | Saunier Duval | Contrasted |
| Hermann Thema Condens 25-A-H | Saunier Duval | Contrasted |
| Hermann Themafast Condens 25-A | Saunier Duval | Contrasted |
| Hermann Themafast Condens 30-A | Saunier Duval | Contrasted |
| Hermann Themafast Condens 30-B | Saunier Duval | Contrasted |
| Hermann Themaclassic C 25 | Saunier Duval | Contrasted |
| Hermann Thelia Condens 25-A | Saunier Duval | Contrasted |
| Hermann Thelia Condens 30-A | Saunier Duval | Contrasted |
| Hermann Semia Condens 25-A | Saunier Duval | Contrasted |
| Hermann Semia Condens 30-A | Saunier Duval | Contrasted |
Can't see your model or have questions? The printed reference takes precedence. How to check it · Send us a photo via WhatsApp.
How to check if ref. 0020197555 is the part for your boiler
The part reference, model, and equipment revision must be verified against the manufacturer's documentation.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 0020197555. If it is not visible, do not identify the part from its shape alone.
- Check the full boiler model on its data plate and look for it in the model associations on this page.
- Compare the connections and physical body with the original part before installation.
- If anything is unclear, send us a photo of the marking via WhatsApp before placing your order.
Symptoms that require diagnosis in the flow meter 0020197555
The flow meter detects the passage of water to activate the domestic hot water. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The domestic hot water comes and goes suddenly, as if it cuts off and returns every few seconds.
Cause: The detector's turbine gets stuck with lime and transmits an intermittent flow signal.
Open and close the tap with a strong flow a couple of times; if the turbine frees up and the cut-off disappears, don't change the part yet.
- 02
When requesting hot water, the boiler displays a fault code related to the flow instead of igniting.
Cause: The turbine does not spin enough to provide the minimum signal that the control unit needs to recognize demand.
Check the water inlet filter first: if it is clogged, it reduces the flow rate and triggers the same warning.
- 03
In heating mode, the boiler works fine, but when opening any hot water tap, the burner does not start.
Cause: Without the signal from the flow detector, the PCB cannot detect a demand for domestic hot water.
Turn the tap fully open for several seconds in a row; if it still doesn't start with maximum flow, the detector is the first suspect.
- 04
The boiler turns on in domestic hot water mode without any tap being open.
Cause: The detector keeps indicating flow even though there is no actual water passage, due to wear on the turbine or the magnet.
Close all the domestic hot water taps in the house and check if the startup persists before replacing the part.
These symptoms can have more than one cause. If your boiler displays a fault code, send it to us via WhatsApp along with a photo of the labeling, and we'll tell you if this is the part.
Hermann 0020197555 flow meter datasheet
- Catalogue reference
- 0020197555
- Uniclima internal SKU
- CMC25A
- Brand
- Hermann
- Type of part
- Flow detectors
- Units in stock
- 0 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Part data and available documentation
Contrast the label codes, PCB, and revision with the installed part; they are not necessarily equivalent references.
- Body
- Black
- Connector
- White, 3 tabs (contacts)
