{"product_id":"zilmet-hydro-pro-35-litre-potable-expansion-vessel-1-inch-bsp-floor-mounted","title":"Zilmet Hydro-Pro 35 Litre Potable Expansion Vessel 1 inch BSP Floor Mounted","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\u003eZilmet Hydro-Pro 35 L\u003c\/strong\u003e (MPN: 11A0003535) is a \u003cstrong\u003efloor-standing potable water expansion vessel\u003c\/strong\u003e with \u003cstrong\u003e1\" BSP connections\u003c\/strong\u003e, designed for domestic and light-commercial hot water systems including unvented cylinders, pressurised water heaters and pump systems. It features a \u003cstrong\u003efixed butyl membrane\u003c\/strong\u003e approved for contact with drinking water, an \u003cstrong\u003einternal epoxy coating\u003c\/strong\u003e to prevent corrosion, and an \u003cstrong\u003eexclusive MIG-welded carbon steel shell\u003c\/strong\u003e that eliminates sharp internal edges which could otherwise damage the membrane. Rated to \u003cstrong\u003e10 bar working pressure\u003c\/strong\u003e and an operating temperature range of \u003cstrong\u003e−10 °C to +99 °C\u003c\/strong\u003e, with a pre-charge of \u003cstrong\u003e2.0 bar\u003c\/strong\u003e. Approved to \u003cstrong\u003ePED 2014\/68\/EU, WRAS, ACS, IAPMO and NSF\u003c\/strong\u003e standards. The floor-standing 1\" BSP configuration (11A0003535) is suitable for high-demand installations where a wall-hung vessel would be undersized.\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;\"\u003e35 L\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eVolume\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;\"\u003e10 bar\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eMax working pressure\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;\"\u003e99 °C\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eMax temperature\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;\"\u003e2.0 bar\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003ePre-charge pressure\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;\"\u003eWRAS\u003c\/div\u003e\n\u003cdiv style=\"font-size:12px;margin-top:4px;\"\u003eApproved\u003c\/div\u003e\n\u003c\/div\u003e\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;\"\u003ePotable water rated:\u003c\/strong\u003e The Hydro-Pro uses a \u003cstrong\u003ebutyl membrane approved for drinking water contact\u003c\/strong\u003e. It must not be substituted with a heating expansion vessel, whose membrane is not food-safe. The two vessel types are not interchangeable.\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;\"\u003eSizing note:\u003c\/strong\u003e At 35 litres, the Hydro-Pro is suited to larger unvented cylinders (typically 210–300 L) or installations with higher incoming water pressure. Always size the vessel using the cylinder manufacturer's sizing table, based on cylinder volume, incoming pressure and T\u0026amp;P valve set pressure.\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\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;\"\u003eFixed Butyl Membrane — Potable Approved\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe \u003cstrong\u003efixed butyl membrane\u003c\/strong\u003e is specifically formulated and approved for \u003cstrong\u003epotable (drinking) water contact\u003c\/strong\u003e. It is seamless and non-stretching, with no bubbles or internal corners that could trap stagnant water and promote bacterial growth. The membrane's compact dome shape keeps it in permanent intimate contact with the vessel wall, maximising effective volume utilisation.\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;\"\u003eMIG-Welded Carbon Steel Shell\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eZilmet uses an \u003cstrong\u003eexclusive MIG welding process\u003c\/strong\u003e that eliminates sharp internal edges and rough weld profiles. This prevents abrasion damage to the butyl membrane, which is the primary cause of premature membrane failure in lower-quality vessels. The smooth internal profile also makes the vessel easier to clean during servicing.\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;\"\u003eInternal Epoxy Coating\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe interior of the carbon steel shell is protected by an \u003cstrong\u003eexclusive internal epoxy coating\u003c\/strong\u003e, preventing the steel from corroding in the presence of moisture. The exterior carries an \u003cstrong\u003eepoxy-polyester powder-coat finish\u003c\/strong\u003e for corrosion resistance in damp plant rooms. Together these coatings extend service life significantly compared to uncoated or single-coat vessels.\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;\"\u003eFloor-Standing — 1\" BSP Connection\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe 11A0003535 variant is \u003cstrong\u003efloor-standing with a 1\" BSP connection\u003c\/strong\u003e. The floor-standing design is ideal where wall space is limited or where the vessel weight (filled) makes wall hanging impractical. The \u003cstrong\u003e1\" BSP connection\u003c\/strong\u003e suits direct connection to the system pipework without the need for a reducer, simplifying installation on larger cylinder systems.\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;\"\u003eInternational Certifications\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe Hydro-Pro 35 carries \u003cstrong\u003ePED 2014\/68\/EU, WRAS, ACS, IAPMO and NSF approvals\u003c\/strong\u003e — confirming compliance with European and international pressure equipment and potable water contact regulations. WRAS approval is particularly significant for UK installations, confirming suitability for connection to the mains water supply.\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;\"\u003eProtected Pre-Charge Valve\u003c\/div\u003e\n    \u003cp style=\"margin:0;font-size:15px;\"\u003eThe air pre-charge valve is \u003cstrong\u003eprotected by a tamper-resistant cap\u003c\/strong\u003e to prevent accidental interference and contamination during installation and service. The pre-charge of \u003cstrong\u003e2.0 bar\u003c\/strong\u003e should be verified at commissioning and checked at each service with the water side de-pressurised.\u003c\/p\u003e\n  \u003c\/div\u003e\n\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;\"\u003eTechnical Specifications\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\u003eMPN \/ Part number\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e11A0003535\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eVolume\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e35 litres\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\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:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eOperating temperature range\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e−10 °C to +99 °C\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003ePre-charge pressure\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e2.0 bar\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eConnection size\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e1\" BSP\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eMounting type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eFloor standing\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eApplication\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003ePotable water (DHW unvented systems, pressurised water heaters)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eMembrane type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eFixed butyl — potable water approved, non-replaceable\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eShell material\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eCarbon steel, MIG welded\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eInternal coating\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eExclusive epoxy coating\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eExternal coating\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eEpoxy-polyester powder coat\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#f0faf9;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eApprovals\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003ePED 2014\/68\/EU, WRAS, ACS, IAPMO, NSF\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr style=\"background:#fff;\"\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003e\u003cstrong\u003eManufacturer\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd style=\"padding:9px 12px;\"\u003eZilmet SpA, Limena, Italy\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\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;\"\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;\"\u003eWhy choose the Zilmet Hydro-Pro over a standard expansion vessel?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eThe Hydro-Pro is a \u003cstrong\u003epremium potable-rated vessel\u003c\/strong\u003e with several engineering advantages over budget alternatives: the \u003cstrong\u003eMIG-welded smooth interior\u003c\/strong\u003e prevents membrane abrasion; the \u003cstrong\u003einternal epoxy coating\u003c\/strong\u003e prevents corrosion that can contaminate water; and the \u003cstrong\u003eseamless butyl membrane\u003c\/strong\u003e geometry prevents stagnant water pockets. WRAS approval confirms it meets UK Water Regulations for connection to the mains supply — not all vessels on the market carry this approval.\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;\"\u003eCan this vessel be used on a central heating circuit?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eNo. The Hydro-Pro is designed exclusively for \u003cstrong\u003epotable (drinking water) circuits\u003c\/strong\u003e. Central heating systems require a \u003cstrong\u003eheating expansion vessel\u003c\/strong\u003e (such as the Zilmet Cal-Pro range) with an SBR rubber diaphragm suitable for glycol solutions and heating water. Using a potable vessel on a heating circuit may cause premature membrane failure.\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;\"\u003eWhere should the Hydro-Pro 35 be installed?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eThe vessel should be connected to the \u003cstrong\u003ecold water inlet pipework downstream of the PRV and upstream of the non-return valve\u003c\/strong\u003e — or in the dedicated expansion vessel port on the cylinder's inlet control group. Floor-standing models should be positioned \u003cstrong\u003eupright\u003c\/strong\u003e with the connection at the top (as supplied). Ensure the connection point is accessible for annual pre-charge pressure checks.\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;\"\u003eHow do I check and adjust the pre-charge pressure?\u003c\/summary\u003e\n  \u003cdiv style=\"padding:14px 16px;background:#f9fefe;\"\u003eAt each \u003cstrong\u003eannual service\u003c\/strong\u003e: isolate the vessel from the system and depressurise the water side completely before checking. Use a standard tyre-type pressure gauge on the air valve (after removing the protective cap). The correct pre-charge for the Hydro-Pro 35 is \u003cstrong\u003e2.0 bar\u003c\/strong\u003e. Top up with dry nitrogen or clean, dry compressed air if the pressure has dropped. Never check pre-charge with the water side pressurised — the reading will be inaccurate.\u003c\/div\u003e\n\u003c\/details\u003e\n\n\u003c\/div\u003e","brand":"Zilmet","offers":[{"title":"Default Title","offer_id":64644418404701,"sku":"11A0003535","price":127.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0958\/2051\/3629\/files\/ZilmetHydro-Pro35LitrePotableExpansionVessel1inchBSPFloorMounted11A0003535.webp?v=1778253398","url":"https:\/\/qualityheating.co.uk\/products\/zilmet-hydro-pro-35-litre-potable-expansion-vessel-1-inch-bsp-floor-mounted","provider":"AIZO Quality Heating","version":"1.0","type":"link"}