Ariston
Ariston Union 1/2 Inch DHW Outlet 998406
1/2 inch union for the domestic hot water outlet on Ariston ACO, Ecocombi, Genus and Microgenus gas boilers.
At a glance
- Also known as UNION-12-DHW-OUTLET, 1577050
Showing prices
£20.86
£17.38 ex. VAT · VAT at 20%
Available to order · 3 working days
Available to order · 3 working days
Not certain it's the right part? The technical team verifies fitment before dispatch — no charge, and it stops a second trip.Call the technical teamSend a technical question
Same-day dispatch
Ordered by 4pm Mon–Fri, 10:30am Sat.
30-day returns
Unused, in original packaging.
What it is
The Ariston 998406 is a 1/2 inch union for the domestic hot water (DHW) outlet on Ariston gas boilers. It forms the threaded connection at the DHW outlet, securing the outlet pipework and providing the sealing point. It is used across Ariston ACO, Ecocombi, Genus and Microgenus boiler families.
Signs this part needs replacing
- Water weeping or dripping from the DHW outlet union joint.
- Visible corrosion, scale or cracking on the union body or nut.
- The union will not seal after tightening, suggesting damaged threads or sealing face.
- O-ring deterioration causing persistent leaks at the connection.
- Discolouration or mineral build-up around the outlet connection.
Before you order
- Confirm the boiler model and GC number against the fitment list.
- Check the existing union is 1/2 inch and matches the DHW outlet connection.
- Inspect the sealing face and O-ring condition before ordering.
- Verify the part number 998406 matches the removed component.
Compliance
| Barcode / EAN | 5411692271848 |
|---|---|
| Alternative numbers | UNION-12-DHW-OUTLET, 1577050 |
| Make | Model / assembly | Reference | Years | Fitment |
|---|---|---|---|---|
| ARISTON ACO 27 MFFI GPL | 47-116-34 | 47-116-34 | — | — |
| ARISTON ACO 27 MFFI MET | 47-116-34 | 47-116-34 | — | — |
| ARISTON ACO 32 MFFI GPL | 47-116-35 | 47-116-35 | — | — |
| ARISTON ACO 32 MFFI MET | 47-116-35 | 47-116-35 | — | — |
| ARISTON ACO 35 HP MFFI UK | 47-116-35 | 47-116-35 | — | — |
| ARISTON ARISTON ARISTON ACO 35 MFFI | — | — | — | |
| ARISTON ECOCOMBI 27 MFFI LPG EDITION 1 (OCT 2002) | 47-116-23 | 47-116-23 | — | — |
| ARISTON ECOCOMBI 27 MFFI LPG EDITION 2 (SEPT 2004) | 47-116-23 | 47-116-23 | — | — |
| ARISTON ECOCOMBI 27 MFFI NG EDITION 1 (OCT 2002) | 47-116-23 | 47-116-23 | — | — |
| ARISTON ECOCOMBI 27 MFFI NG EDITION 2 (SEPT 2004) | 47-116-23 | 47-116-23 | — | — |
Showing 10 of 28 compatible appliances.
Fitment listings are a guide, not a guarantee. Plant-room assemblies get modified on site more often than not. Send us the GC number off the data badge and a photo of the existing valve and we will confirm before anything is dispatched.
Documents & drawings
Everything we hold for this part. Where a document exists but we don't hold it, the technical team will source it from the manufacturer — usually the same working day.
manual
ARISTON appliance manual — ACO 27 MFFI GPL (GC 47-116-34), ACO 27 MFFI MET (GC 47-116-34), ACO 32 MFFI GPL (GC 47-116-35), ACO 32 MFFI MET (GC 47-116-35)
manualmanualARISTON appliance manual — ACO 35 HP MFFI UK (GC 47-116-35)
manualmanualARISTON appliance manual — ECOCOMBI 27 MFFI LPG EDITION 1 (OCT 2002) (GC 47-116-23), ECOCOMBI 27 MFFI LPG EDITION 2 (SEPT 2004) (GC 47-116-23), ECOCOMBI 27 MFFI NG EDITION 1 (OCT 2002) (GC 47-116-23), ECOCOMBI 27 MFFI NG EDITION 2 (SEPT 2004) (GC 47-116-23)
manualmanualARISTON appliance manual — GENUS 30 MFFI UK LPG EDITION 2 (JUL 2000) (GC 47-116-13), GENUS 30 MFFI UK LPG EDITION 3 (OCT 2000) (GC 47-116-13), GENUS 30 MFFI UK NG EDITION 2 (JUL 2000) (GC 47-116-13), GENUS 30 MFFI UK NG EDITION 3 (OCT 2000) (GC 47-116-13)
manualmanualARISTON appliance manual — MICROGENUS 23 MFFI LPG EDITION 5 (MAR 2004) (GC 47-116-14), MICROGENUS 23 MFFI NG EDITION 5 (MAR 2004) (GC 47-116-14), MICROGENUS 27 MFFI LPG EDITION 5 (MAR 2004) (GC 47-116-15), MICROGENUS 27 MFFI NG EDITION 5 (MAR 2004) (GC 47-116-15)
manualmanualARISTON appliance manual — MICROGENUS 24 MFFI HE UK NG (GC 47-116-37), MICROGENUS 28 MFFI HE UK LPG (GC 47-116-38), MICROGENUS 32 MFFI HE UK NG (GC 47-116-39)
manualmanualARISTON appliance manual — MICROGENUS II 24 MFFI UK LPG, MICROGENUS II 24 MFFI UK MET (GC 47-116-25), MICROGENUS II 28 MFFI UK LPG, MICROGENUS II 28 MFFI UK MET (GC 47-116-26), MICROGENUS II 31 MFFI UK LPG (GC 47-116-27), MICROGENUS II 31 MFFI UK MET (GC 47-116-27)
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