{"product_id":"tjernlund-products-ps1503-switch","title":"Tjernlund Products PS1503 Switch","description":"\u003cp\u003eThe \u003cstrong\u003eTjernlund Products PS1503\u003c\/strong\u003e is a high-sensitivity \u003cstrong\u003educt pressure switch\u003c\/strong\u003e engineered to automate HVAC accessories by detecting positive air pressure within the supply plenum or trunk lines. As the \u003cstrong\u003edirect replacement for DFS-221-227\u003c\/strong\u003e, this \u003cstrong\u003eSPST normally open switch\u003c\/strong\u003e simplifies field installations by eliminating the need for complex interlock wiring with the furnace blower. The \u003cstrong\u003ePS1503 duct airstat\u003c\/strong\u003e features a snap-acting mechanism triggered by a precise \u003cstrong\u003epressure rise of +0.05 +\/- 0.02\" W.C.\u003c\/strong\u003e, ensuring consistent activation of auxiliary equipment such as \u003cstrong\u003educt booster fans\u003c\/strong\u003e, humidifiers, and UV air purifiers. Housed in a durable enclosure with an integral sampling tube, this \u003cstrong\u003epositive pressure switch\u003c\/strong\u003e supports electrical ratings up to 15 Amps non-inductive at 277 VAC or 300 VA pilot duty. Field technicians must ensure the \u003cstrong\u003ediaphragm is mounted vertically\u003c\/strong\u003e to maintain set-point accuracy and prevent gravity-induced switching errors, providing a reliable control solution for high-performance airflow management systems.\u003c\/p\u003e\n\n\u003cstrong\u003eKey Benefits\u003c\/strong\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUniversal Compatibility:\u003c\/strong\u003e Serves as a \u003cstrong\u003edrop-in replacement for DFS-221-227\u003c\/strong\u003e pressure switches.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrecision Sensing:\u003c\/strong\u003e Actuates at a low-threshold \u003cstrong\u003epositive pressure rise\u003c\/strong\u003e for sensitive air detection.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHigh Electrical Capacity:\u003c\/strong\u003e Rated for \u003cstrong\u003e15 Amps non-inductive\u003c\/strong\u003e and \u003cstrong\u003e300 VA pilot duty\u003c\/strong\u003e circuits.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlexible Application:\u003c\/strong\u003e Ideal for triggering \u003cstrong\u003eelectronic air cleaners\u003c\/strong\u003e, humidifiers, and \u003cstrong\u003ein-line booster fans\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSimplified Integration:\u003c\/strong\u003e Eliminates the requirement to find a 24V or 120V tap on the blower motor.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cstrong\u003eCommon Questions\u003c\/strong\u003e\n\u003cp\u003e\u003cstrong\u003eCan I install the PS1503 on the return air side?\u003c\/strong\u003e\u003cbr\u003e\nNo, the \u003cstrong\u003ePS1503\u003c\/strong\u003e is specifically designed to sense \u003cstrong\u003epositive pressure\u003c\/strong\u003e. For return air applications where negative pressure is present, a vacuum-sensing or differential pressure switch is required.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eWhy is the mounting orientation critical for this airstat?\u003c\/strong\u003e\u003cbr\u003e\nThe internal diaphragm is calibrated for \u003cstrong\u003evertical mounting\u003c\/strong\u003e. Installing the switch horizontally can result in shifting the set-point or failing to reset properly due to the physical weight of the diaphragm mechanism.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eDoes this switch require a separate power source?\u003c\/strong\u003e\u003cbr\u003e\nThe \u003cstrong\u003ePS1503\u003c\/strong\u003e is a \u003cstrong\u003enon-adjustable mechanical switch\u003c\/strong\u003e that acts as a dry contact. It breaks or makes the \"hot\" leg of the circuit assigned to the accessory it is controlling, adhering to local \u003cstrong\u003eHVAC electrical code\u003c\/strong\u003e requirements.\u003c\/p\u003e\n\n\u003cp\u003eDisclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.\u003c\/p\u003e","brand":"Tjernlund Products","offers":[{"title":"Default Title","offer_id":41659660599474,"sku":"PS1503","price":118.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1838\/2375\/products\/Pic_da363620-e662-4c72-a716-5ce1f43f6885.jpg?v=1645227589","url":"https:\/\/www.gsistore.com\/en-ca\/products\/tjernlund-products-ps1503-switch","provider":"GSIstore","version":"1.0","type":"link"}