{"product_id":"oso-acc350-superstream-350l-cold-water-accumulator-tank","title":"OSO Acc350 SuperStream 350L Cold Water Accumulator Tank","description":"\u003cstyle\u003e\n  .dw-wrap{font-family:inherit;color:inherit;line-height:1.7;font-size:16px}\n  .dw-wrap p,.dw-wrap li,.dw-wrap td,.dw-wrap th{font-size:16px!important;line-height:1.7}\n  .dw-wrap h2{font-size:22px!important;font-weight:700;color:#1a3a5c;border-bottom:3px solid #008377;padding-bottom:6px;margin:2rem 0 1rem;line-height:1.3}\n  .dw-wrap h3{font-size:17px!important;font-weight:700;color:#1a3a5c;margin:1.2rem 0 0.4rem;line-height:1.4}\n  .dw-wrap p{margin:0 0 1rem}\n  .dw-wrap ul{padding-left:1.5rem;margin:0 0 1rem}\n  .dw-wrap ul li{margin-bottom:0.5rem}\n  .dw-badge{display:inline-block;font-size:13px!important;font-weight:700;border-radius:4px;padding:2px 10px;margin-right:5px;margin-bottom:4px;vertical-align:middle}\n  .dw-badge.blue{background:#008377;color:#fff}\n  .dw-badge.navy{background:#1a3a5c;color:#fff}\n  .dw-badge.teal{background:#0d9488;color:#fff}\n  .dw-badge.green{background:#1a7a3c;color:#fff}\n  .dw-badge.grey{background:#555;color:#fff}\n  .dw-intro-box{background:#e0f2fe;border-left:4px solid #008377CF;padding:1.1rem 1.4rem;border-radius:0 6px 6px 0;margin-bottom:1.5rem}\n  .dw-intro-box p{margin:0!important}\n  .dw-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(230px,1fr));gap:0.85rem;margin-bottom:1.2rem}\n  .dw-card{background:#e0f2fe;border:1px solid #90caf9;border-radius:6px;padding:1rem 1.1rem;line-height:1.6}\n  .dw-card strong{display:block;color:#1a3a5c;margin-bottom:0.35rem;font-size:16px!important}\n  .dw-info-box{background:#f0fdf4;border:1px solid #86efac;border-radius:6px;padding:1rem 1.2rem;margin:1.2rem 0}\n  .dw-info-box p{margin:0 0 0.5rem!important;color:#065f46;font-weight:700}\n  .dw-comp-box{background:#fff3cd;border:1px solid #ffc107;border-radius:5px;padding:0.9rem 1.1rem;margin:0.8rem 0}\n  .dw-spec-table{width:100%;border-collapse:collapse;margin-bottom:1.5rem}\n  .dw-spec-table th{background:#1a3a5c;color:#fff!important;text-align:left;padding:0.7rem 1rem;font-weight:700;font-size:16px!important}\n  .dw-spec-table td{padding:0.6rem 1rem;border-bottom:1px solid #bde0f5;vertical-align:top;font-size:16px!important}\n  .dw-spec-table tr:nth-child(even) td{background:#e0f2fe}\n  .dw-spec-table td:first-child{font-weight:600;color:#111;width:44%}\n  .dw-faq-item{border-bottom:1px solid #bde0f5;padding:0.9rem 0}\n  .dw-faq-item:last-child{border-bottom:none}\n  .dw-faq-item strong{color:#1a3a5c;font-size:16px!important;display:block;margin-bottom:0.3rem}\n  .dw-contents-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:0.6rem;margin-bottom:1.2rem}\n  .dw-contents-item{background:#f0f9ff;border:1px solid #bde0f5;border-radius:5px;padding:0.6rem 0.9rem;font-size:15px!important}\n\u003c\/style\u003e\n\n\u003cdiv class=\"dw-wrap\"\u003e\n\u003cdiv style=\"margin-bottom:1rem\"\u003e\n\u003cspan class=\"dw-badge blue\"\u003e11007353\u003c\/span\u003e\u003cspan class=\"dw-badge navy\"\u003eAcc350\u003c\/span\u003e\u003cspan class=\"dw-badge teal\"\u003eSuperStream\u003c\/span\u003e\u003cspan class=\"dw-badge green\"\u003e350 L\u003c\/span\u003e\u003cspan class=\"dw-badge grey\"\u003eCold Water Accumulator\u003c\/span\u003e\u003cspan class=\"dw-badge grey\"\u003ePower-Free Booster\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"dw-intro-box\"\u003e\u003cp\u003e\u003cstrong\u003eOSO Acc350 SuperStream 350 L Accumulator\u003c\/strong\u003e — Extra-large power-free cold water accumulator tank booster with patented CAD2 diaphragm technology | Up to ~80 l\/min extra flow | Silent, zero-energy, zero-maintenance | ~175 L usable volume | Vertical install only | WRAS-approved butyl membrane | 5-year warranty | Ideal for large homes, guest houses or light commercial\u003c\/p\u003e\u003c\/div\u003e\n\u003cdiv class=\"dw-comp-box\"\u003e\n\u003cstrong\u003e✅ Serious capacity for high-demand properties – the biggest vertical-only model in the range\u003c\/strong\u003eProvides the longest sustained high-flow period of any domestic SuperStream unit. Perfect when multiple bathrooms, kitchen, utility and appliances run together. No electricity, no noise, no servicing. Easily expandable with add-on kits.\u003c\/div\u003e\n\u003cp\u003eThe OSO SuperStream Acc350 is the heavy-duty vertical accumulator built for properties with exceptional simultaneous demand — larger family homes, bed \u0026amp; breakfasts, small care facilities or light commercial setups where 3–5+ outlets may run at once. With 350 litres total volume and around 175 litres of usable stored water (at 1.5 bar differential), it offers the longest buffer of boosted performance before relying purely on incoming mains supply.\u003c\/p\u003e\n\u003cp\u003ePowered solely by mains pressure via the patented CAD2 diaphragm system, it delivers silent, maintenance-free flow supplementation of up to ~80 litres per minute with zero electricity consumption, zero noise and zero ongoing costs. The robust composite fiberglass\/epoxy shell is corrosion-resistant, weighs only 35 kg empty (much lighter than equivalent steel vessels), and is designed for long-term reliability in demanding environments.\u003c\/p\u003e\n\u003cp\u003eThis model is vertical-mount only (no horizontal cradle option), making it best suited to taller spaces such as plant rooms, garages or dedicated cupboards. Like all SuperStream units, it requires no annual servicing and continues to function perfectly during power outages — a true \"fit and forget\" solution.\u003c\/p\u003e\n\u003ch2\u003eWhat Makes the SuperStream Acc350 Special?\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMaximum Domestic\/Commercial Reserve\u003c\/strong\u003e — ~175 L usable volume — sustains high flow far longer than smaller models.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e100% Passive \u0026amp; Zero Cost\u003c\/strong\u003e — No electricity, no pumps, no filters, no service bills — environmentally and financially sustainable.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePatented CAD2 Diaphragm\u003c\/strong\u003e — Ensures even pressure delivery, prevents waterlogging, and maximises effective storage.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCorrosion-Proof Composite\u003c\/strong\u003e — Fibreglass\/epoxy construction outperforms steel in longevity and weight (35 kg empty).\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eScalable for Bigger Sites\u003c\/strong\u003e — Parallel multiple units for hotels, care homes or multi-occupancy buildings.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eWRAS Hygienic \u0026amp; Compliant\u003c\/strong\u003e — Butyl membrane (WRAS 1501305) safe for potable systems; meets UK water regulations.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eNo Noise Ever\u003c\/strong\u003e — Completely silent (0 dB) — ideal for residential or noise-sensitive commercial settings.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cdiv class=\"dw-grid\"\u003e\n\u003cdiv class=\"dw-card\"\u003e\n\u003cstrong\u003eHigh-Capacity Boost\u003c\/strong\u003eUp to ~80 l\/min extra flow — supports 4+ simultaneous high-demand outlets.\u003c\/div\u003e\n\u003cdiv class=\"dw-card\"\u003e\n\u003cstrong\u003eZero Energy \u0026amp; Silent\u003c\/strong\u003ePassive — 0 W, 0 dB, performs in power failures.\u003c\/div\u003e\n\u003cdiv class=\"dw-card\"\u003e\n\u003cstrong\u003eVery Large Usable Volume\u003c\/strong\u003e~175 L effective — extended powerful performance.\u003c\/div\u003e\n\u003cdiv class=\"dw-card\"\u003e\n\u003cstrong\u003eWRAS-Approved Membrane\u003c\/strong\u003eButyl rubber (ref 1501305) — hygienic \u0026amp; potable-safe.\u003c\/div\u003e\n\u003cdiv class=\"dw-card\"\u003e\n\u003cstrong\u003eComposite Construction\u003c\/strong\u003eLightweight (35 kg empty), corrosion-free, 5-year warranty.\u003c\/div\u003e\n\u003cdiv class=\"dw-card\"\u003e\n\u003cstrong\u003ePre-Charge Adjustable\u003c\/strong\u003e1.4 bar factory — site-optimised for best results.\u003c\/div\u003e\n\u003cdiv class=\"dw-card\"\u003e\n\u003cstrong\u003eExpandable System\u003c\/strong\u003eLink multiple units with add-on kits for commercial-scale flow.\u003c\/div\u003e\n\u003c\/div\u003e\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"dw-spec-table\"\u003e\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number\u003c\/td\u003e\n\u003ctd\u003e11007353\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTotal Vessel Volume\u003c\/td\u003e\n\u003ctd\u003e350 litres\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eUsable Water Volume\u003c\/td\u003e\n\u003ctd\u003e~175 litres (at 1.5 bar differential)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions (Ø × Height – vertical only)\u003c\/td\u003e\n\u003ctd\u003e614 × 1448 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eEmpty Weight\u003c\/td\u003e\n\u003ctd\u003e35 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFull Weight (approx.)\u003c\/td\u003e\n\u003ctd\u003e210 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eConnections\u003c\/td\u003e\n\u003ctd\u003e1¼\" BSP male × 28 mm compression\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax Working Pressure\u003c\/td\u003e\n\u003ctd\u003e8.6 bar (860 kPa)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePre-charge Pressure\u003c\/td\u003e\n\u003ctd\u003e1.4 bar (factory — adjustable)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMax Boost Head (closed valve)\u003c\/td\u003e\n\u003ctd\u003e4.3 bar\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWater Temperature Range\u003c\/td\u003e\n\u003ctd\u003e4 °C to 35 °C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAmbient Temperature Max\u003c\/td\u003e\n\u003ctd\u003e40 °C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMembrane Material\u003c\/td\u003e\n\u003ctd\u003eButyl rubber (WRAS 1501305)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTank Construction\u003c\/td\u003e\n\u003ctd\u003eContinuous strand fibreglass + epoxy resin\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWarranty\u003c\/td\u003e\n\u003ctd\u003e5 years (vessel \u0026amp; diaphragm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\u003c\/table\u003e\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cdiv class=\"dw-contents-grid\"\u003e\n\u003cdiv class=\"dw-contents-item\"\u003e✔ 1 × Acc350 SuperStream Accumulator Vessel\u003c\/div\u003e\n\u003cdiv class=\"dw-contents-item\"\u003e✔ 1¼\" BSP male to 28 mm compression fittings\u003c\/div\u003e\n\u003cdiv class=\"dw-contents-item\"\u003e✔ Pre-charge adjustment guide\u003c\/div\u003e\n\u003cdiv class=\"dw-contents-item\"\u003e✔ Full installation \u0026amp; commissioning manual\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"dw-info-box\"\u003e\u003cp\u003e✅ Must-have accessories: Upstream Kit 22\/28 mm (11007380) for first unit + Add-on Kit (11007327) per extra accumulator. For very low incoming pressure add Charger Pump (11007348). Vertical mount only — no horizontal cradle available for this model.\u003c\/p\u003e\u003c\/div\u003e\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eDoes the Acc350 need power or annual servicing?\u003c\/strong\u003eNo — 100% passive, silent (0 dB), zero electricity and zero maintenance for the full 5-year warranty and beyond.\u003c\/div\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eHow much extra flow does it deliver?\u003c\/strong\u003eSupplements mains by up to ~80 litres per minute — ideal for 4+ simultaneous high-flow outlets without noticeable pressure loss.\u003c\/div\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eIs horizontal installation possible?\u003c\/strong\u003eNo — vertical mount only. For horizontal capability choose Acc200 or Acc250 with cradle.\u003c\/div\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eIs it safe for potable\/drinking water?\u003c\/strong\u003eYes — WRAS-approved butyl membrane (ref 1501305) ensures hygienic storage of wholesome water.\u003c\/div\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eCan I connect multiple Acc350 units?\u003c\/strong\u003eYes — parallel installation is straightforward. Use one Upstream Kit for the first + Add-on Kits for each additional accumulator.\u003c\/div\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eWill it benefit my unvented system or combi boiler?\u003c\/strong\u003eYes — dramatically improves hot \u0026amp; cold performance on restricted or low-pressure mains supplies.\u003c\/div\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eWhat if incoming pressure is consistently very low?\u003c\/strong\u003eFor dynamic pressure below ~2 bar, combine with the SuperStream Charger Pump (11007348) to raise supply pressure before the accumulator.\u003c\/div\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eHow durable is the composite construction?\u003c\/strong\u003eExtremely — fibreglass\/epoxy resists corrosion indefinitely and is much lighter\/stronger than traditional steel vessels.\u003c\/div\u003e\n\u003cdiv class=\"dw-faq-item\"\u003e\n\u003cstrong\u003eDoes the pre-charge need regular adjustment?\u003c\/strong\u003eFactory-set at 1.4 bar and sealed for life; simple checks possible but rarely necessary in normal operation.\u003c\/div\u003e\n\u003c\/div\u003e","brand":"OSO Hotwater","offers":[{"title":"Default Title","offer_id":63734017524061,"sku":"Acc350","price":1350.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0958\/2051\/3629\/files\/OSOSuperStreamColdWaterAccumulatorTank.jpg?v=1772780702","url":"https:\/\/qualityheating.co.uk\/products\/oso-acc350-superstream-350l-cold-water-accumulator-tank","provider":"AIZO Quality Heating","version":"1.0","type":"link"}