{"product_id":"baxi-ashp-cylinder-210l-250l-300l-stainless-steel-unvented-hot-water-cylinder-for-air-source-heat-pumps","title":"Baxi ASHP Cylinder 250L Stainless Steel Unvented Hot Water Cylinder for Air Source Heat Pumps","description":"\u003cdiv style=\"font-size: 16px; font-family: -apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,Helvetica,Arial,sans-serif; color: #222; line-height: 1.55; max-width: 900px; margin: 0 auto;\"\u003e\n\u003cp style=\"margin: 0 0 14px; line-height: 1.6;\"\u003eThe \u003cstrong\u003eBaxi ASHP Cylinder\u003c\/strong\u003e is a duplex stainless steel unvented hot water cylinder engineered specifically for air source heat pump systems. Available in \u003cstrong\u003e210, 250 and 300 litre capacities\u003c\/strong\u003e, it features a \u003cstrong\u003ehigh-surface-area 'coil-in-coil' heat exchanger\u003c\/strong\u003e for exceptionally fast recovery and includes \u003cstrong\u003etwo 3 kW immersion heaters\u003c\/strong\u003e — a lower main element and an upper boost — to support the heat pump for continuous hot water and Legionella protection. Manufactured by \u003cstrong\u003eMegaflo and Heatrae Sadia\u003c\/strong\u003e, with \u003cstrong\u003e60 mm of high-efficiency PU insulation\u003c\/strong\u003e and supplied with a complete Immersion Heater Relay Kit for straightforward integration.\u003c\/p\u003e\n\u003cdiv style=\"display: flex; flex-wrap: wrap; gap: 12px; margin: 18px 0 24px;\"\u003e\n\u003cdiv style=\"flex: 1; min-width: 160px; background: #f0faf9; border-left: 4px solid #008377CF; padding: 14px 16px; border-radius: 6px;\"\u003e\n\u003cdiv style=\"font-size: 24px; font-weight: bold; color: #005c54;\"\u003e2 + 3 m²\u003c\/div\u003e\n\u003cdiv style=\"font-size: 13px; color: #444;\"\u003eCoil-in-coil surface area\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"flex: 1; min-width: 160px; background: #f0faf9; border-left: 4px solid #008377CF; padding: 14px 16px; border-radius: 6px;\"\u003e\n\u003cdiv style=\"font-size: 24px; font-weight: bold; color: #005c54;\"\u003e2 × 3 kW\u003c\/div\u003e\n\u003cdiv style=\"font-size: 13px; color: #444;\"\u003eDual immersion heaters\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"flex: 1; min-width: 160px; background: #f0faf9; border-left: 4px solid #008377CF; padding: 14px 16px; border-radius: 6px;\"\u003e\n\u003cdiv style=\"font-size: 24px; font-weight: bold; color: #005c54;\"\u003e60 mm\u003c\/div\u003e\n\u003cdiv style=\"font-size: 13px; color: #444;\"\u003ePU foam insulation\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"flex: 1; min-width: 160px; background: #f0faf9; border-left: 4px solid #008377CF; padding: 14px 16px; border-radius: 6px;\"\u003e\n\u003cdiv style=\"font-size: 24px; font-weight: bold; color: #005c54;\"\u003eSec. return\u003c\/div\u003e\n\u003cdiv style=\"font-size: 13px; color: #444;\"\u003eAvailable on all sizes\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background: #fff8e1; border-left: 4px solid #f59e0b; padding: 14px 18px; border-radius: 6px; margin: 18px 0;\"\u003e\n\u003cdiv style=\"font-weight: bold; color: #7a4d00; margin-bottom: 6px;\"\u003eCylinder only — designed for installer-built control schemes\u003c\/div\u003e\n\u003cdiv style=\"line-height: 1.6; font-size: 14px;\"\u003eThis is the \u003cstrong\u003ecylinder vessel and immersion heater relay kit\u003c\/strong\u003e, intended for installations where the heating manifold, diverter valve and controls are designed and assembled separately by the installer. If you'd prefer an all-in-one solution with the diverter valve, expansion vessel and integrated controller already factory-fitted, look at the \u003cstrong\u003eBaxi ASHP Pre-plumbed Cylinder\u003c\/strong\u003e instead.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background: #008377CF; color: #ffffff; padding: 14px 20px; border-radius: 8px; margin: 32px 0 18px; font-size: 20px; font-weight: bold; letter-spacing: .2px;\"\u003eEngineered for heat pumps\u003c\/div\u003e\n\u003cdiv style=\"display: grid; grid-template-columns: repeat(auto-fit,minmax(260px,1fr)); gap: 14px; margin: 18px 0 24px;\"\u003e\n\u003cdiv style=\"background: #f0faf9; border: 1px solid #c8e6e3; border-radius: 8px; padding: 16px 18px;\"\u003e\n\u003cdiv style=\"font-weight: bold; color: #005c54; margin-bottom: 6px;\"\u003eCoil-in-coil heat exchanger\u003c\/div\u003e\n\u003cdiv style=\"font-size: 14px; line-height: 1.55;\"\u003eA high-performance \u003cstrong\u003e'coil-in-coil' design\u003c\/strong\u003e delivers a large heat-transfer surface area in a compact footprint. The 250L and 300L models use a \u003cstrong\u003e3 m² coil\u003c\/strong\u003e; the 210L uses a 2 m² coil — both delivering \u003cstrong\u003eexceptionally fast recovery times\u003c\/strong\u003e from heat pump flow temperatures.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background: #f0faf9; border: 1px solid #c8e6e3; border-radius: 8px; padding: 16px 18px;\"\u003e\n\u003cdiv style=\"font-weight: bold; color: #005c54; margin-bottom: 6px;\"\u003eDual immersion heaters\u003c\/div\u003e\n\u003cdiv style=\"font-size: 14px; line-height: 1.55;\"\u003eA \u003cstrong\u003e3 kW lower immersion\u003c\/strong\u003e works with the heat pump for primary backup heating; a \u003cstrong\u003e3 kW upper immersion\u003c\/strong\u003e provides a high-temperature boost for fast top-up and the Legionella cycle. Total backup heating capacity is \u003cstrong\u003e6 kW\u003c\/strong\u003e when both elements run.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background: #f0faf9; border: 1px solid #c8e6e3; border-radius: 8px; padding: 16px 18px;\"\u003e\n\u003cdiv style=\"font-weight: bold; color: #005c54; margin-bottom: 6px;\"\u003eImmersion Heater Relay Kit included\u003c\/div\u003e\n\u003cdiv style=\"font-size: 14px; line-height: 1.55;\"\u003eEach cylinder ships with the Baxi \u003cstrong\u003eImmersion Heater Relay Kit\u003c\/strong\u003e — relay, relay box and \u003cstrong\u003eDHW temperature probe extension\u003c\/strong\u003e — so the immersion control logic and sensor wiring required to interface with the Baxi heat pump is included in the box.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background: #f0faf9; border: 1px solid #c8e6e3; border-radius: 8px; padding: 16px 18px;\"\u003e\n\u003cdiv style=\"font-weight: bold; color: #005c54; margin-bottom: 6px;\"\u003eDuplex stainless steel build\u003c\/div\u003e\n\u003cdiv style=\"font-size: 14px; line-height: 1.55;\"\u003eInner vessel manufactured by \u003cstrong\u003eMegaflo and Heatrae Sadia\u003c\/strong\u003e from corrosion-resistant duplex stainless steel for long, low-maintenance service life — the same proven build quality used across Baxi's residential cylinder range.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background: #f0faf9; border: 1px solid #c8e6e3; border-radius: 8px; padding: 16px 18px;\"\u003e\n\u003cdiv style=\"font-weight: bold; color: #005c54; margin-bottom: 6px;\"\u003eSecondary return and 60 mm insulation\u003c\/div\u003e\n\u003cdiv style=\"font-size: 14px; line-height: 1.55;\"\u003eAll three capacities support a \u003cstrong\u003esecondary return circuit\u003c\/strong\u003e for properties with long pipe runs to outlets. \u003cstrong\u003e60 mm of PU foam\u003c\/strong\u003e keeps standing losses low — from \u003cstrong\u003e1.5 kWh\/24h on the 210L\u003c\/strong\u003e up to 2.05 kWh\/24h on the 300L.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background: #008377CF; color: #ffffff; padding: 14px 20px; border-radius: 8px; margin: 32px 0 18px; font-size: 20px; font-weight: bold; letter-spacing: .2px;\"\u003eAir source heat pump compatibility\u003c\/div\u003e\n\u003cp style=\"margin: 0 0 14px; line-height: 1.6;\"\u003eDesigned to pair with the full Baxi air source heat pump portfolio — the \u003cstrong\u003eHP40 standard-temperature monobloc\u003c\/strong\u003e, the \u003cstrong\u003eBaxi Assure HP50\u003c\/strong\u003e, the \u003cstrong\u003eHP55 high-temperature monobloc\u003c\/strong\u003e and the \u003cstrong\u003eHP60 high-temperature monobloc\u003c\/strong\u003e. The cylinder is also suitable for use with other heat pump brands when sized correctly: refer to the heat pump's specification sheet for required coil rating and flow rates. \u003cstrong\u003eFlow rates of up to 76 L\/min at 3 bar\u003c\/strong\u003e can be achieved when the cylinder is supplied with a 3.5 bar pressure-reducing valve and adequate cold mains supply.\u003c\/p\u003e\n\u003cdiv style=\"color: #005c54; font-size: 17px; font-weight: bold; margin: 18px 0 10px;\"\u003eSpecifications by capacity\u003c\/div\u003e\n\u003cdiv style=\"overflow-x: auto; margin: 8px 0 18px;\"\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; font-size: 14px;\"\u003e\n\u003cthead\u003e\n\u003ctr style=\"background: #008377CF; color: #ffffff;\"\u003e\n\u003cth style=\"padding: 10px 12px; text-align: left; border: 1px solid #005c54;\"\u003eSpecification\u003c\/th\u003e\n\u003cth style=\"padding: 10px 12px; text-align: left; border: 1px solid #005c54;\"\u003e210L\u003c\/th\u003e\n\u003cth style=\"padding: 10px 12px; text-align: left; border: 1px solid #005c54;\"\u003e250L\u003c\/th\u003e\n\u003cth style=\"padding: 10px 12px; text-align: left; border: 1px solid #005c54;\"\u003e300L\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eProduct code\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e7837416\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e7837491\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e7837562\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eNominal capacity\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e210 L\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e250 L\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e300 L\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eStorage volume\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e209 L\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e246 L\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e287 L\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eHot water at \u0026gt;40 °C\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e204 L\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e242 L\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e289 L\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eCoil heat-up time\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e21.5 min\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e22.8 min\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e27.8 min\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eCoil surface area\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e2 m²\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e3 m²\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e3 m²\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eCoil rating\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e33.2 kW\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e36.8 kW\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e35.5 kW\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eStanding heat loss\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e1.5 kWh\/24h\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e1.78 kWh\/24h\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e2.05 kWh\/24h\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eEnergy efficiency class\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003eB\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003eC\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003eC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eExternal expansion vessel\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e18 L\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e24 L\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e24 L\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eHeight\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e1516 mm\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e1767 mm\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e2082 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eWeight (empty)\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e46 kg\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e54 kg\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e62 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eWeight (full)\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e255 kg\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e300 kg\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8;\"\u003e349 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"color: #005c54; font-size: 17px; font-weight: bold; margin: 18px 0 10px;\"\u003eCommon specifications (all capacities)\u003c\/div\u003e\n\u003cdiv style=\"overflow-x: auto; margin: 8px 0 18px;\"\u003e\n\u003ctable style=\"width: 100%; border-collapse: collapse; font-size: 14px;\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600; width: 45%;\"\u003eDiameter\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #f0faf9;\"\u003e579 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eInsulation thickness\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #fff;\"\u003e60 mm CFC\/HCFC-free PU foam\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eLower immersion heater\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #f0faf9;\"\u003e3 kW\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eUpper immersion (boost)\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #fff;\"\u003e3 kW\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eBoost immersion heat-up time\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #f0faf9;\"\u003e67 minutes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eSecondary return\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #fff;\"\u003eYes — supported on all sizes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eConnections\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #f0faf9;\"\u003e3\/4\" BSP male flow \u0026amp; return · 22 mm \/ 3\/4\" BSP cold inlet · 22 mm \/ 3\/4\" BSP DHW outlet\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr style=\"background: #f0faf9;\"\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eInner vessel\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #fff;\"\u003eDuplex stainless steel — by Megaflo \/ Heatrae Sadia\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; font-weight: 600;\"\u003eIncluded accessories\u003c\/td\u003e\n\u003ctd style=\"padding: 9px 12px; border: 1px solid #d4eae8; background: #f0faf9;\"\u003eImmersion Heater Relay, Relay Box, DHW probe extension\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"font-size: 12px; color: #666; margin-top: -6px; margin-bottom: 14px;\"\u003eCoil heat-up times measured at 15 L\/min. Cylinders tested in conformance to Annex A, BS EN 12897:2016. Energy efficiency class measured per European Commission regulations 814\/2013 and 812\/2013. Manufacturer warranty applies — see baxi.co.uk\/terms for details.\u003c\/div\u003e\n\u003cdiv style=\"background: #fef2f2; border-left: 4px solid #dc2626; padding: 14px 18px; border-radius: 6px; margin: 18px 0;\"\u003e\n\u003cdiv style=\"font-weight: bold; color: #7f1d1d; margin-bottom: 6px;\"\u003eInstallation requirements\u003c\/div\u003e\n\u003cdiv style=\"line-height: 1.6; font-size: 14px;\"\u003eInstallation, commissioning and annual servicing must be carried out by a \u003cstrong\u003ecompetent person\u003c\/strong\u003e — typically G3 unvented hot water qualified, and MCS registered for grant-funded heat pump installations. The unit must be installed in accordance with \u003cstrong\u003eBuilding Regulations Part G\u003c\/strong\u003e, BS EN 12897:2016 and the Baxi Installation \u0026amp; Service Manual. An \u003cstrong\u003eexternal expansion vessel\u003c\/strong\u003e (18 L on the 210L; 24 L on the 250L \/ 300L) and a 3.5 bar pressure-reducing valve are required and must be sized and fitted by the installer.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"background: #008377CF; color: #ffffff; padding: 14px 20px; border-radius: 8px; margin: 32px 0 18px; font-size: 20px; font-weight: bold; letter-spacing: .2px;\"\u003eFrequently asked questions\u003c\/div\u003e\n\u003cdetails style=\"margin: 8px 0; border: 1px solid #c8e6e3; border-radius: 6px; overflow: hidden;\"\u003e\n\u003csummary style=\"background: #008377CF; color: #fff; padding: 12px 16px; cursor: pointer; font-weight: 600; list-style: none;\"\u003eShould I choose the standard ASHP cylinder or the pre-plumbed version?\u003c\/summary\u003e\n\u003cdiv style=\"padding: 14px 18px; line-height: 1.6; background: #fff;\"\u003eChoose this \u003cstrong\u003estandard cylinder\u003c\/strong\u003e if you want flexibility to design and assemble your own heating manifold, diverter valve scheme and controls — common on bespoke or larger installations. Choose the \u003cstrong\u003eBaxi ASHP Pre-plumbed Cylinder\u003c\/strong\u003e if you want a faster, lower-labour install with the diverter valve, expansion vessel and integrated controller already factory-fitted. Both share the same duplex stainless steel inner vessel build.\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails style=\"margin: 8px 0; border: 1px solid #c8e6e3; border-radius: 6px; overflow: hidden;\"\u003e\n\u003csummary style=\"background: #008377CF; color: #fff; padding: 12px 16px; cursor: pointer; font-weight: 600; list-style: none;\"\u003eWhat does the 'coil-in-coil' heat exchanger do?\u003c\/summary\u003e\n\u003cdiv style=\"padding: 14px 18px; line-height: 1.6; background: #fff;\"\u003eA coil-in-coil arrangement places a finer secondary coil inside a primary coil, which significantly \u003cstrong\u003eincreases heat-transfer surface area\u003c\/strong\u003e within a compact footprint. This matters for heat pumps because they deliver heat at lower flow temperatures than a gas boiler, so a large, efficient coil is essential to recover hot water in a reasonable time — the design here delivers \u003cstrong\u003erecovery times of 21–28 minutes\u003c\/strong\u003e depending on capacity.\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails style=\"margin: 8px 0; border: 1px solid #c8e6e3; border-radius: 6px; overflow: hidden;\"\u003e\n\u003csummary style=\"background: #008377CF; color: #fff; padding: 12px 16px; cursor: pointer; font-weight: 600; list-style: none;\"\u003eWhy does this cylinder have two immersion heaters?\u003c\/summary\u003e\n\u003cdiv style=\"padding: 14px 18px; line-height: 1.6; background: #fff;\"\u003eThe \u003cstrong\u003elower 3 kW immersion\u003c\/strong\u003e is positioned to heat the bulk of the cylinder volume, providing primary backup if the heat pump is unavailable. The \u003cstrong\u003eupper 3 kW boost immersion\u003c\/strong\u003e sits higher in the vessel and only heats the top portion — useful for a fast hot-water top-up and for running the high-temperature Legionella cycle without consuming as much energy as heating the whole tank. Together they offer \u003cstrong\u003eflexible backup heating\u003c\/strong\u003e tailored to the situation.\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails style=\"margin: 8px 0; border: 1px solid #c8e6e3; border-radius: 6px; overflow: hidden;\"\u003e\n\u003csummary style=\"background: #008377CF; color: #fff; padding: 12px 16px; cursor: pointer; font-weight: 600; list-style: none;\"\u003eWhat size cylinder do I need?\u003c\/summary\u003e\n\u003cdiv style=\"padding: 14px 18px; line-height: 1.6; background: #fff;\"\u003eAs a guide: \u003cstrong\u003e210L\u003c\/strong\u003e matches a typical 3-bed, 1-bathroom home; \u003cstrong\u003e250L\u003c\/strong\u003e is a strong fit for a 3–4 bed property with two bathrooms; and \u003cstrong\u003e300L\u003c\/strong\u003e serves a 4-bed home with two or more bathrooms or an en-suite. For ASHP systems we recommend sizing slightly larger than you would for a gas boiler installation, because heat pumps reheat more slowly and benefit from drawing on a larger reservoir of pre-heated water.\u003c\/div\u003e\n\u003c\/details\u003e\n\u003cdetails style=\"margin: 8px 0; border: 1px solid #c8e6e3; border-radius: 6px; overflow: hidden;\"\u003e\n\u003csummary style=\"background: #008377CF; color: #fff; padding: 12px 16px; cursor: pointer; font-weight: 600; list-style: none;\"\u003eWhat's included with the cylinder, and what do I need to source separately?\u003c\/summary\u003e\n\u003cdiv style=\"padding: 14px 18px; line-height: 1.6; background: #fff;\"\u003eThe cylinder ships with the \u003cstrong\u003eImmersion Heater Relay Kit\u003c\/strong\u003e (relay, relay box and DHW temperature probe extension) and both factory-fitted immersion heaters. You'll typically need to supply separately: an \u003cstrong\u003eexternal expansion vessel\u003c\/strong\u003e (18L for 210L cylinder; 24L for 250L\/300L), a \u003cstrong\u003e3.5 bar pressure-reducing valve\u003c\/strong\u003e, a 6 bar pressure relief valve, a tundish, a 3-port motorised diverter valve, the heat pump's room\/cylinder thermostat, and any zone valves or wiring centres needed for your control scheme.\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e","brand":"Baxi","offers":[{"title":"Default Title","offer_id":64574255563101,"sku":"7837491","price":2350.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0958\/2051\/3629\/files\/BaxiASHPCylinderStainlessSteelUnventedHotWaterCylinderforAirSourceHeatPumps.webp?v=1777621382","url":"https:\/\/qualityheating.co.uk\/products\/baxi-ashp-cylinder-210l-250l-300l-stainless-steel-unvented-hot-water-cylinder-for-air-source-heat-pumps","provider":"AIZO Quality Heating","version":"1.0","type":"link"}