
Bithermal Heat Exchanger Ariston Microtec T2 LLS 23 MFFI Ref. 998619
The Ariston Microtec T2 LLS 23 MFFI dual heat exchanger is a component that allows simultaneous heating of the heating circuit and domestic hot water. When it fails, you may notice that the water comes out lukewarm, there are temperature fluctuations, or there is a mixing of circuits. This heat exchanger is compatible with several boiler models, such as the 23 MCSI, 23 MI, and others from the Microtec range, among others. It is advisable to replace it when you experience heating issues or internal leaks.
VAT included
Consult via WhatsAppAriston boilers compatible with reference 998619
Bithermal heat exchanger with reference 998619. 17 confirmed compatibilities: 23 MCSI and 23 MI.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Ariston 23 MCSI | EST | Contrasted |
| Ariston 23 MI | EST | Contrasted |
| Ariston GENUS 23 MFFI | M | Contrasted |
| Ariston 23 MFFI | MICROTEC | Contrasted |
| Ariston 23 MI | MICROTEC | Contrasted |
| Ariston 23 MFFI | MODULA | Contrasted |
| Ariston 23 MI | MODULA | Contrasted |
| Ariston R2 23 MI | NEW | Contrasted |
| Ariston 23 MFFI | NEXT | Contrasted |
| Ariston 23 MI | NEXT | Contrasted |
| Ariston 23 MCSI | ONE | Contrasted |
| Ariston 23 MI | ONE | Contrasted |
| Ariston MFFI | T2/23 | Contrasted |
| Ariston MI | T2/23 | Contrasted |
| Ariston PLUS 23 MI | THISA | Contrasted |
| Ariston 23 MFFI | TX | Contrasted |
| Ariston 23 MI | TX | 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 the part number 998619 is the correct one for your boiler.
What determines it is not the boiler model, but the reference printed on the part you already have installed.
- Find the reference printed on the installed part and check whether it matches the catalogue reference 998619. 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 and faults that the bivalent heat exchanger 998619 solves.
The bivalent heat exchanger transfers heat to heating and domestic hot water. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
No hot water comes out or only lukewarm water comes out when the tap is opened.
Cause: The double heat exchanger is not heating the water properly because it is scaled and does not transfer enough heat.
Check the cold water inlet filter and the flow rate before replacing the heat exchanger, as a dirty filter can cause the same issue.
- 02
Water or moisture is observed in the area of the heat exchanger inside the boiler.
Cause: Over time, the gaskets or the body of the heat exchanger may develop small leaks due to scale.
Dry the area and turn on the boiler in domestic hot water and heating mode separately to identify where the dripping is coming from.
- 03
The boiler heats less domestic hot water than before, less and less each time.
Cause: The accumulation of scale in the domestic hot water circuit of the heat exchanger reduces its heat exchange capacity.
Is the water in the area hard, and has the boiler ever been descaled? If not, limescale could be the main cause.
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.
Data sheet for the Ariston 998619 double heat exchanger.
- Catalogue reference
- 998619
- Brand
- Ariston
- Type of part
- Bithermic heat exchanger
- Units in stock
- 3 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- Delivery time shown at checkout
- Return
- 14 days
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Ariston T2/23 MI Manual (PDF)Document © Ariston, provided as a technical reference.









