{"product_id":"hydronic-expansion-tank-2-1-gallon-1-2-mnpt-closed-loop-heating-system-expansion-tank-etx-15-replacement","title":"Hydronic Expansion Tank – 2.1 Gallon, 1\/2\" MNPT – Closed-Loop Heating System Expansion Tank – ETX-15 Replacement","description":"\u003ch3\u003eKey features\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003eDesigned for Closed-Loop Hydronic Heating Systems - Engineered for boilers, radiant heat, and other closed-loop systems where thermal expansion must be controlled. Not for domestic potable water.\u003c\/li\u003e\n\u003cli\u003e2.1-Gallon Capacity with Pre-Charge at 12 PSI - Ships factory-pre-charged to 12 PSI for standard hydronic setups. Pressure can be adjusted on-site using the included Schrader valve.\u003c\/li\u003e\n\u003cli\u003e1\/2\" MNPT Connection – Direct ETX-15 Replacement - Features a standard 1\/2\" MNPT system connection commonly used in residential and light commercial heating systems. Compatible as a replacement for ETX-15-type expansion tanks.\u003c\/li\u003e\n\u003cli\u003eDurable Steel Construction with Butyl Diaphragm - Heavy-gauge steel shell and a long-life butyl rubber diaphragm keep water separated from air, preventing corrosion and providing consistent system pressure control.\u003c\/li\u003e\n\u003cli\u003eVertical or Horizontal Mounting Options - Compact 8\" diameter x 12.5\" height size allows easy installation in tight mechanical rooms or equipment areas.\u003c\/li\u003e\n\u003c\/ul\u003e\u003cp\u003eThis 2.1-gallon hydronic expansion tank is built for closed-loop boiler and radiant heating systems, where thermal expansion must be managed to maintain safe, stable system pressure. The tank arrives pre-charged to 12 PSI, the standard setting for most residential hydronic systems, and includes a Schrader valve for pressure adjustment when needed. The interior butyl rubber diaphragm separates the air charge from system water, preventing internal corrosion and preserving long-term performance. With a 1\/2\" MNPT connection, this tank is a direct replacement for ETX-15-style expansion tanks and is compatible with most residential hydronic boilers. Not for potable water use. This model is intended for closed-loop heating applications only.\u003c\/p\u003e\u003cp\u003eFree shipping included. 30-day hassle-free returns.\u003c\/p\u003e","brand":"Belmont Warehouse","offers":[{"title":"Default Title","offer_id":43244004114641,"sku":"BW-B0DWB7LCXH","price":125.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0674\/3123\/5793\/files\/41FVyMn9cJL._AC_SL1000.jpg?v=1786647582","url":"https:\/\/belmontwarehouse.com\/products\/hydronic-expansion-tank-2-1-gallon-1-2-mnpt-closed-loop-heating-system-expansion-tank-etx-15-replacement","provider":"Belmont Warehouse","version":"1.0","type":"link"}