{"product_id":"oso-delta-a-rated-300l-pre-plumbed-indirect-unvented-hot-water-cylinder-dc300pp","title":"OSO Delta A-Rated 300L Pre-plumbed Indirect Unvented Hot Water Cylinder DC300PP","description":"\u003cdiv style=\"font-size:16px;font-family:Arial,sans-serif;color:#1a1a1a;max-width:900px;margin:0 auto;line-height:1.6;\"\u003e\n\n\u003cp\u003eThe \u003cstrong\u003eOSO Delta DC300PP\u003c\/strong\u003e is an \u003cstrong\u003eErP A-rated, pre-plumbed indirect unvented hot water cylinder\u003c\/strong\u003e at 300 litres — the largest capacity in OSO's award-winning Delta series. It achieves its Class A energy rating through a combination of \u003cstrong\u003eVacuum Insulation Panels (VIPs)\u003c\/strong\u003e and 4th-generation polyurethane foam — a world first across a full capacity range. The \u003cstrong\u003epre-plumbed (PP) configuration\u003c\/strong\u003e saves up to 70% of installation labour thanks to its factory-assembled integral expansion vessel and cold-feed assembly. At \u003cstrong\u003e595 mm diameter × 1745 mm height\u003c\/strong\u003e and 58 kg empty, it is significantly shorter than most 300-litre competitors, producing the same volume of hot water in a more airing-cupboard-friendly footprint. Suited to \u003cstrong\u003elarge family homes, HMOs, developer new-builds\u003c\/strong\u003e and any installation where hot water demand is high and energy efficiency is paramount.\u003c\/p\u003e\n\n\u003cdiv style=\"display:flex;flex-wrap:wrap;gap:12px;margin:20px 0;\"\u003e\n  \u003cdiv style=\"flex:1;min-width:110px;background:#008377CF;color:#fff;border-radius:8px;padding:14px 10px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:22px;font-weight:700;\"\u003eErP A\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eEnergy rating\u003c\/div\u003e\n\u003c\/div\u003e\n  \u003cdiv style=\"flex:1;min-width:110px;background:#008377CF;color:#fff;border-radius:8px;padding:14px 10px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:22px;font-weight:700;\"\u003e300 L\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eCapacity\u003c\/div\u003e\n\u003c\/div\u003e\n  \u003cdiv style=\"flex:1;min-width:110px;background:#008377CF;color:#fff;border-radius:8px;padding:14px 10px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:22px;font-weight:700;\"\u003e37 min\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eRecovery time\u003c\/div\u003e\n\u003c\/div\u003e\n  \u003cdiv style=\"flex:1;min-width:110px;background:#008377CF;color:#fff;border-radius:8px;padding:14px 10px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:22px;font-weight:700;\"\u003e1745 mm\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eHeight\u003c\/div\u003e\n\u003c\/div\u003e\n  \u003cdiv style=\"flex:1;min-width:110px;background:#008377CF;color:#fff;border-radius:8px;padding:14px 10px;text-align:center;\"\u003e\n\u003cdiv style=\"font-size:22px;font-weight:700;\"\u003eVIP\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eVacuum Insulation Panels\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\n\u003cdiv style=\"background:#fff3f3;border-left:4px solid #cc0000;padding:14px 16px;border-radius:6px;margin:16px 0;\"\u003e\n  \u003cstrong style=\"color:#cc0000;\"\u003eInstaller requirement:\u003c\/strong\u003e Must be installed by a \u003cstrong\u003eG3-qualified engineer\u003c\/strong\u003e under Building Regulations Part G. Benchmark Commissioning Checklist must be completed and provided to the customer.\n\u003c\/div\u003e\n\n\u003cdiv style=\"background:#fffbea;border-left:4px solid #e6a817;padding:14px 16px;border-radius:6px;margin:16px 0;\"\u003e\n  \u003cstrong style=\"color:#b07d00;\"\u003eStructural note:\u003c\/strong\u003e When full, a 300 L cylinder weighs approximately \u003cstrong\u003e358 kg\u003c\/strong\u003e. Confirm the floor or installation surface can bear this load before installation — particularly in upper-floor plant rooms or loft spaces. A structural assessment may be required.\n\u003c\/div\u003e\n\n\u003cdiv style=\"background:#e6f4f3;border-left:4px solid #008377CF;padding:14px 16px;border-radius:6px;margin:16px 0;\"\u003e\n  \u003cstrong style=\"color:#005c54;\"\u003eShorter than most 300 L competitors:\u003c\/strong\u003e OSO produces up to \u003cstrong\u003e20% more hot water per unit of height\u003c\/strong\u003e. The 300 L Delta at 1745 mm is compact enough for many standard airing cupboards that cannot accommodate taller rivals.\n\u003c\/div\u003e\n\n\u003cdiv style=\"background:#008377CF;color:#fff;padding:12px 18px;border-radius:6px;margin:28px 0 16px;font-size:17px;font-weight:700;\"\u003eKey Features\u003c\/div\u003e\n\u003cdiv style=\"display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;margin-bottom:24px;\"\u003e\n\n  \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:8px;padding:16px;\"\u003e\n    \u003cdiv style=\"font-weight:700;color:#008377;border-bottom:2px solid #008377CF;padding-bottom:6px;margin-bottom:10px;\"\u003eVacuum Insulation Panels — ErP A Rated\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe OSO Delta is unique in achieving \u003cstrong\u003eErP Class A across its full capacity range\u003c\/strong\u003e. This is made possible by combining \u003cstrong\u003eVacuum Insulation Panels (VIPs)\u003c\/strong\u003e — a technology borrowed from cryogenic engineering — with 4th-generation polyurethane foam. The result is dramatically lower standing heat loss than any C-rated competitor: saving approximately \u003cstrong\u003e1 kWh per day\u003c\/strong\u003e in the popular 210 L size versus a C-rated cylinder. Over a year, that is meaningful energy and cost saving for every household.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:8px;padding:16px;\"\u003e\n    \u003cdiv style=\"font-weight:700;color:#008377;border-bottom:2px solid #008377CF;padding-bottom:6px;margin-bottom:10px;\"\u003eAward-Winning OSO Design\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe Delta series is \u003cstrong\u003eindustry award-winning\u003c\/strong\u003e and recognised as the most energy-efficient unvented hot water cylinder range available. OSO cylinders are \u003cstrong\u003eshorter than most competitors at equivalent volume\u003c\/strong\u003e — producing up to 20% more hot water per unit of height. This means you can often \u003cstrong\u003edownsize the floor plan footprint\u003c\/strong\u003e when switching to OSO without losing capacity.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:8px;padding:16px;\"\u003e\n    \u003cdiv style=\"font-weight:700;color:#008377;border-bottom:2px solid #008377CF;padding-bottom:6px;margin-bottom:10px;\"\u003ePre-Plumbed — Up to 70% Labour Saving\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe DC pre-plumbed (PP) configuration includes an \u003cstrong\u003eintegral expansion vessel\u003c\/strong\u003e and pre-fitted cold-feed assembly — saving up to \u003cstrong\u003e70% of installation labour\u003c\/strong\u003e compared to an unplumbed cylinder requiring separate component fitting. This makes the DC PP particularly popular with \u003cstrong\u003ehousebuilders, developers and new-build programmes\u003c\/strong\u003e where installation speed and repeatability matter.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:8px;padding:16px;\"\u003e\n    \u003cdiv style=\"font-weight:700;color:#008377;border-bottom:2px solid #008377CF;padding-bottom:6px;margin-bottom:10px;\"\u003eDigital Thermostat with Anti-Legionella and Holiday Modes\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe OSO Delta is supplied with a \u003cstrong\u003edigital adjustable thermostat\u003c\/strong\u003e (20–70 °C, preset 60 °C) with built-in \u003cstrong\u003eanti-legionella pasteurisation\u003c\/strong\u003e and \u003cstrong\u003eholiday mode\u003c\/strong\u003e. The anti-legionella cycle automatically heats the cylinder to above 60 °C at set intervals to suppress Legionella bacteria — a requirement under HSG274 guidance for commercial and multi-occupancy buildings.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:8px;padding:16px;\"\u003e\n    \u003cdiv style=\"font-weight:700;color:#008377;border-bottom:2px solid #008377CF;padding-bottom:6px;margin-bottom:10px;\"\u003eHoneywell Motorised Valve Included\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe pre-plumbed kit includes a \u003cstrong\u003eHoneywell V4043H 2-port motorised valve\u003c\/strong\u003e — a market-standard, widely-stocked component that installers and service engineers are familiar with. If a valve ever needs replacement, sourcing is straightforward from any plumbing merchant. The full G3 kit is included: strainer, PRV, expansion relief valve, drain cock, tundish, T\u0026amp;P relief valve (10 bar \/ 90–95 °C).\u003c\/p\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv style=\"background:#f0faf9;border:1px solid #c8e6e3;border-radius:8px;padding:16px;\"\u003e\n    \u003cdiv style=\"font-weight:700;color:#008377;border-bottom:2px solid #008377CF;padding-bottom:6px;margin-bottom:10px;\"\u003eAdjustable Factory-Fitted Feet\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe cylinder sits on \u003cstrong\u003efactory-fitted adjustable feet\u003c\/strong\u003e, making it straightforward to level on uneven plant room floors without shimming. The feet also raise the cylinder slightly off the floor, helping to protect against damp and making inspection of the base easier during annual servicing.\u003c\/p\u003e\n  \u003c\/div\u003e\n\n\u003c\/div\u003e\n\u003cdiv style=\"background:#008377CF;color:#fff;padding:12px 18px;border-radius:6px;margin:28px 0 16px;font-size:17px;font-weight:700;\"\u003eTechnical Specifications — DC300PP\u003c\/div\u003e\n\n\u003ctable style=\"width:100%;border-collapse:collapse;font-size:15px;margin-bottom:24px;\"\u003e\n  \u003cthead\u003e\u003ctr style=\"background:#005c54;color:#fff;\"\u003e\n\u003cth style=\"padding:10px 12px;text-align:left;\"\u003eParameter\u003c\/th\u003e\n\u003cth style=\"padding:10px 12px;text-align:left;\"\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eModel \/ MPN\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eDC300PP\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eCapacity\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e300 L\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eErP energy rating\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eA\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eDimensions (H × D)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e1745 mm × 595 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eWeight (empty)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e58 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eWeight (full, approx)\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e~358 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eRecovery time\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e37 minutes\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eMax working pressure\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e10 bar\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eT\u0026amp;P relief valve\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e10 bar \/ 90–95 °C\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eThermostat\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eDigital, adjustable 20–70 °C, preset 60 °C\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eMotorised valve\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eHoneywell V4043H1056C 2-port\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eExpansion vessel\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e12–24 L (included, integral to pre-plumbed assembly)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eInsulation technology\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eVacuum Insulation Panels + 4th-generation PU foam\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eConnections\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e28 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003ePre-plumbed\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eYes — integral expansion vessel, cold-feed assembly\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eFeet\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eAdjustable — factory fitted\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cdiv style=\"background:#008377CF;color:#fff;padding:12px 18px;border-radius:6px;margin:28px 0 16px;font-size:17px;font-weight:700;\"\u003eFrequently Asked Questions\u003c\/div\u003e\n\n\u003cdetails style=\"border:1px solid #c8e6e3;border-radius:6px;margin-bottom:10px;\"\u003e\n  \u003csummary style=\"background:#008377CF;color:#fff;padding:12px 16px;border-radius:5px;cursor:pointer;font-weight:600;list-style:none;\"\u003eWhat makes the OSO Delta A-rated when most cylinders are C-rated?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eErP heat loss ratings for indirect hot water cylinders are primarily determined by \u003cstrong\u003estanding heat loss in kWh\/24h\u003c\/strong\u003e. The Delta achieves Class A by combining \u003cstrong\u003eVacuum Insulation Panels (VIPs)\u003c\/strong\u003e — panels containing near-vacuum cavities with a thermal conductivity far lower than any foam — with 4th-generation dense polyurethane foam. Together they reduce heat loss to a level that no foam-only design can match. OSO is the only brand offering A-rated cylinders across the full 150–300 L range.\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails style=\"border:1px solid #c8e6e3;border-radius:6px;margin-bottom:10px;\"\u003e\n  \u003csummary style=\"background:#008377CF;color:#fff;padding:12px 16px;border-radius:5px;cursor:pointer;font-weight:600;list-style:none;\"\u003eWhat is the difference between the pre-plumbed (PP) and standard (unplumbed) Delta?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eThe \u003cstrong\u003epre-plumbed (PP) version\u003c\/strong\u003e — this product — has the integral expansion vessel and cold-feed pre-plumbing factory-assembled. This saves installers from fitting the expansion vessel, hose and inlet group assembly on site, cutting installation time by up to 70%. The unplumbed version gives the installer more flexibility in component positioning but takes longer to install. For new-build programmes, the PP version is the natural choice.\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails style=\"border:1px solid #c8e6e3;border-radius:6px;margin-bottom:10px;\"\u003e\n  \u003csummary style=\"background:#008377CF;color:#fff;padding:12px 16px;border-radius:5px;cursor:pointer;font-weight:600;list-style:none;\"\u003eWho must install an unvented hot water cylinder?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eInstallation must be carried out by a \u003cstrong\u003eG3-qualified engineer\u003c\/strong\u003e registered under the Building Regulations Part G competent person scheme (or a suitably supervised engineer working under G3 oversight). The Benchmark Commissioning Checklist must be completed and handed to the customer at handover. Non-compliant installation invalidates the warranty and may breach building regulations.\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails style=\"border:1px solid #c8e6e3;border-radius:6px;margin-bottom:10px;\"\u003e\n  \u003csummary style=\"background:#008377CF;color:#fff;padding:12px 16px;border-radius:5px;cursor:pointer;font-weight:600;list-style:none;\"\u003eIs the OSO Delta compatible with heat pumps?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eYes — the OSO Delta Coil (DC) indirect range is designed to work with \u003cstrong\u003egas, oil and LPG boilers, electric boilers, and air source heat pumps\u003c\/strong\u003e via the single heating coil. For heat pump applications, the recovery time will depend on the heat pump output. If you are pairing with a heat pump, ask about the OSO Supercoil (SC) variant which has a larger coil surface area optimised for the lower flow temperatures typical of heat pumps.\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003cdetails style=\"border:1px solid #c8e6e3;border-radius:6px;margin-bottom:10px;\"\u003e\n  \u003csummary style=\"background:#008377CF;color:#fff;padding:12px 16px;border-radius:5px;cursor:pointer;font-weight:600;list-style:none;\"\u003eDoes the OSO Delta need annual servicing?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eYes — \u003cstrong\u003eannual servicing by a G3-qualified engineer\u003c\/strong\u003e is required. During the annual service, the engineer checks the T\u0026amp;P relief valve, expansion relief valve, PRV, strainer, motorised valve operation, expansion vessel pre-charge, and the digital thermostat settings. The anti-legionella function should also be verified as active.\u003c\/div\u003e\n\u003c\/details\u003e\n\u003c\/div\u003e","brand":"OSO Hotwater","offers":[{"title":"Default Title","offer_id":64644274913629,"sku":"DC300PP","price":1700.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0958\/2051\/3629\/files\/OSOHotWaterDeltaDC300PPPre-plumbedIndirectUnventedHotWaterCylinder.webp?v=1778251960","url":"https:\/\/qualityheating.co.uk\/products\/oso-delta-a-rated-300l-pre-plumbed-indirect-unvented-hot-water-cylinder-dc300pp","provider":"AIZO Quality Heating","version":"1.0","type":"link"}