Expansion Vessel Boiler Isomax / Duomax / Isotwin - Ref. 0020048250
The expansion vessel for the Isomax / Duomax / Isotwin boiler - Ref. 0020048250 absorbs the increase in water volume when heated, preventing pressure issues. When it fails, you will notice that the boiler pressure fluctuates sharply, and the safety valve may leak. This vessel is compatible with several Saunier Duval models, such as the Isomax Condens F 35-B, Isotwin Condens F 30-A, among others. It is recommended to replace it if you observe these irregularities in the operation of your boiler.
VAT included
Consult via WhatsAppSaunier Duval boilers compatible with reference 0020048250
Expansion vessel with reference 0020048250. 19 verified compatibilities: Isomax Condens F 35-B and Isomax Condens F 35 E.
Proven compatibility
| Boiler model | Family | Verification |
|---|---|---|
| Saunier Duval Isomax Condens F 35-B | Saunier Duval | Contrasted |
| Saunier Duval Isomax Condens F 35 E | Saunier Duval | Contrasted |
| Saunier Duval Isomax Condens 35-B (H-P) | Saunier Duval | Contrasted |
| Saunier Duval Isomax Condens F30-B | Saunier Duval | Contrasted |
| Saunier Duval Isomax C 30 | Saunier Duval | Contrasted |
| Saunier Duval Isomax F 35 H-MOD | Saunier Duval | Contrasted |
| Saunier Duval Isotwin Condens F 30-A | Saunier Duval | Contrasted |
| Saunier Duval Isotwin Condens F 30-E | Saunier Duval | Contrasted |
| Saunier Duval Isotwin Condens 30-B (H-P) | Saunier Duval | Contrasted |
| Saunier Duval Isotwin F 30 H-MOD | Saunier Duval | Contrasted |
| Saunier Duval Isotwin C 30 | Saunier Duval | Contrasted |
| Saunier Duval Isofast 21 Condens F 25 | Saunier Duval | Contrasted |
| Saunier Duval Isofast 21 Condens F 35-B | Saunier Duval | Contrasted |
| Saunier Duval Isofast 21 Condens F30-B | Saunier Duval | Contrasted |
| Saunier Duval Isofast Condens F 35-A | Saunier Duval | Contrasted |
| Saunier Duval Isofast F35E H-MOD | Saunier Duval | Contrasted |
| Saunier Duval Duomax Condens F30 90/1 | Saunier Duval | Contrasted |
| Saunier Duval Duomax Condens F34 90/1 | Saunier Duval | Contrasted |
| Saunier Duval Heliotwin Condens F24 150/01 | 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. 0020048250 is the part 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 0020048250. If it is not visible, do not identify the part by 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 expansion vessel 0020048250 resolves.
The expansion vessel absorbs the expansion of water when heated. These are the typical symptoms and what to do:
Common symptoms and faults
- 01
The boiler shows low pressure or keeps shutting down repeatedly.
Cause: The expansion vessel does not compensate for the water volume in the circuit, and the pressure drops below the minimum required.
Fill the circuit to the appropriate pressure and observe how long it takes to drop; if it takes days instead of months, the expansion vessel is usually the problem.
- 02
The safety valve intermittently discharges water, especially when the heating is on.
Cause: Without an air cushion, the hot water cannot expand in the tank and exits through the safety valve, which is the weakest point.
Check that the safety valve is not dirty or damaged: clean it and check again before considering the vessel as the culprit.
- 03
When you hit the glass with your hand, it sounds full, without the hollow sound of air.
Cause: This indicates a broken diaphragm or a total loss of nitrogen charge, causing the vessel to function as a water tank.
Perform the test with the cold system and without pressure: a dull sound across the entire surface indicates that there is no air left inside.
- 04
When turning on the heating, the pressure gauge needle rises quickly.
Cause: Without expansion margin in the vessel, the increase in water volume results in a pressure increase in the circuit.
Record the pressure with the boiler cold and check it again a few minutes after turning it on; an increase of more than 0.5 bar in a short time is characteristic of a depleted expansion vessel.
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 Saunier Duval expansion vessel 0020048250
- Catalogue reference
- 0020048250
- Brand
- Saunier Duval
- Type of part
- Expansion vessels
- Units in stock
- 5 units
- Status
- Refurbished
- Warranty
- 1 year
- Shipping
- 1-2 business days
- Return
- 14 days
Manuals and technical documentation
Official documentation of the boiler, useful for locating the part and cross-referencing the fault codes.
- Saunier Duval Isomax Condens F 35 E Manual (PDF)Document © Saunier Duval, provided as a technical reference.
Frequently asked questions about the expansion vessel 0020048250
Is this expansion vessel suitable for the Isomax Condens F 35?
When should the expansion vessel of the Heliotwin Condens F24 be replaced?
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