Navien
Navien Buffer Tank 30023173A
Buffer tank for Navien LCB 700 Combi boilers, identified by part number 30023173A.
£391.49
£326.24 ex. VAT · VAT at 20%
Same-day dispatch
Ordered by 4pm Mon–Fri, 10:30am Sat.
30-day returns
Unused, in original packaging.
What it is
The buffer tank is a Navien component used within the LCB 700 Combi boiler family. It provides a volume of stored water within the heating circuit to help stabilise system temperatures and reduce short cycling. This part is identified by the manufacturer part number 30023173A.
Signs this part needs replacing
- The boiler short cycles frequently, firing for brief periods rather than running steadily.
- Domestic hot water temperature at the outlets swings noticeably during draw-off.
- System temperature is difficult to hold steady, with repeated fluctuations at the boiler.
- The boiler responds rapidly to small changes in demand instead of modulating smoothly.
Before you order
- Confirm the appliance model matches one of the LCB 700 Combi variants listed above.
- Check the kW output of the installed boiler against the fit list.
- Confirm whether the appliance is the internal or external variant.
- Verify the existing part number 30023173A before ordering.
No specification data held for this part.
| Make | Model / assembly | Reference | Years | Fitment |
|---|---|---|---|---|
| NAVIEN LCB 700 COMBI EXTERNAL 21KW (Serial Number 1705) | — | — | — | |
| NAVIEN LCB 700 COMBI EXTERNAL 21KW (Serial Number 1705) | — | — | — | |
| NAVIEN LCB 700 COMBI EXTERNAL 28KW (Serial Number 1710) | — | — | — | |
| NAVIEN LCB 700 COMBI EXTERNAL 28KW (Serial Number 1710) | — | — | — | |
| NAVIEN LCB 700 COMBI EXTERNAL 36KW (Serial Number 1709) | — | — | — | |
| NAVIEN LCB 700 COMBI EXTERNAL 36KW (Serial Number 1709) | — | — | — | |
| NAVIEN LCB 700 COMBI INTERNAL 21KW (Serial Number 1704) | — | — | — | |
| NAVIEN LCB 700 COMBI INTERNAL 21KW (Serial Number 1704) | — | — | — | |
| NAVIEN LCB 700 COMBI INTERNAL 28KW (Serial Number 1706) | — | — | — | |
| NAVIEN LCB 700 COMBI INTERNAL 28KW (Serial Number 1706) | — | — | — |
Showing 10 of 12 compatible appliances.
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.
No technical questions yet for this part.
Not sure which part?
Tell the parts assistant what it's going into — the appliance make and model, or the GC number off the data badge — and it will check this part is on the fit list.