{"product_id":"dometic-91604-water-heater-relief-valve-150-psi-1-2-npt","title":"Dometic 91604 Water Heater Relief Valve 150 PSI 1\/2 NPT","description":"\u003cp class=\"nvn-hero\"\u003eThe Dometic 91604 is the temperature and pressure relief valve that keeps your marine water heater safe. It's factory set to open at 150 PSI, threads in with standard 1\/2 inch NPT fittings, and uses an epoxy coated probe with no gaskets to shrug off corrosion. If your old relief valve is weeping or seized, this is the direct replacement.\u003c\/p\u003e\n\n\u003cdiv class=\"nvn-description\"\u003e\n\u003cp\u003eEvery pressurized water heater on a boat needs a safety valve, and the Dometic 91604 is the one that does that job. It's a temperature and pressure relief valve, factory set to open at 150 PSI. When the water inside a heater gets too hot or the system pressure climbs past that setpoint, this valve lifts and bleeds off the excess before anything ruptures. That's the whole point. A water heater is a sealed tank full of hot water under pressure, and without a working relief valve a failure gets dangerous fast.\u003c\/p\u003e\n\u003cp\u003eWhat you're getting is a straightforward temperature and pressure relief valve with a 1\/2 inch NPT threaded inlet. The 150 PSI setting is done at the factory, so there's nothing to calibrate or adjust. You thread it in, and it's ready. Dometic built this one to survive the marine environment too. The probe is epoxy coated to fight corrosion, and there are no gaskets to dry out, crack, or weep over time. On a boat that spends its life in humid, salty air, those two details matter more than they sound.\u003c\/p\u003e\n\u003cp\u003eInstallation is about as simple as marine plumbing gets. The 1\/2 inch NPT thread is the standard size for most onboard water heater relief ports, so in most cases it's a direct swap for a tired old valve. Wrap the male threads with a few turns of PTFE thread tape before you seat it, especially if you're threading into an aluminum tank port, since those ports can start to leak after a season of engine and hull vibration if the seal isn't clean. Snug it down, run the system back up to pressure, and check for weeping around the base. On tight installs, a small sailboat or a compact trawler galley where the heater is crammed against a bulkhead, a short threaded nipple extension gives you the clearance to get a wrench on it without the valve body fouling adjacent plumbing.\u003c\/p\u003e\n\u003cp\u003eHere's the honest truth about relief valves on saltwater boats. They're wear items. The valve stem can seize with corrosion, and a valve that can't lift is a valve that isn't protecting anything. We tell coastal boaters to test theirs at least once a season, and to plan on replacing it when it stops sealing cleanly or starts weeping. A valve that drips now and then isn't automatically bad, but a valve that drips constantly has usually lost its seat, and it's time for a fresh one. At this price, it's cheap insurance for an expensive water heater.\u003c\/p\u003e\n\u003cp\u003eWho's this for? Anyone servicing a marine water heater that uses a 1\/2 inch NPT relief port. It's a common maintenance part, and if your current relief valve is crusted over, chattering, or leaking, the 91604 drops right in. Match the thread size and the pressure rating to your heater before you order. The 150 PSI setpoint is meant for systems and tanks rated to handle it, so if you're running a lower pressure freshwater setup, confirm your tank and pump specs first. Some liveaboards prefer a lower relief setting to keep the pump from short cycling, and that's a legitimate choice, so know your system before you buy.\u003c\/p\u003e\n\u003cp\u003eOne more thing. This isn't a pressure regulator, and it isn't a shutoff valve. It's a last-line safety device, sized and set to protect a hot water tank from over temperature and over pressure. Treat it that way. Don't cap it, don't plug the discharge line, and don't thread a higher-rated valve into a tank that can't take the pressure. Used the way it's meant to be, the Dometic 91604 is the kind of part you install once and forget about, right up until the day it quietly saves your water heater.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eKey Features\u003c\/h2\u003e\n\u003cul class=\"nvn-features\"\u003e\n  \u003cli\u003eFactory set at 150 PSI, so there's no calibration or adjustment needed on install\u003c\/li\u003e\n  \u003cli\u003eCombined temperature and pressure relief in one valve, guarding against both over-heat and over-pressure\u003c\/li\u003e\n  \u003cli\u003e1\/2 inch NPT threaded inlet fits the standard marine water heater relief port for a direct swap\u003c\/li\u003e\n  \u003cli\u003eEpoxy coated probe resists corrosion in humid, salty marine air\u003c\/li\u003e\n  \u003cli\u003eGasketless design means nothing to dry out, crack, or weep over time\u003c\/li\u003e\n  \u003cli\u003e210 degree F temperature setpoint suited to marine hot water tanks rated for the load\u003c\/li\u003e\n  \u003cli\u003eCompact body threads into tight heater installs, with room for a short nipple extension where clearance is short\u003c\/li\u003e\n  \u003cli\u003eGenuine Dometic replacement part, MPN 91604\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cdiv class=\"nvn-trust\"\u003e\n  \u003ch2\u003eWhy Buy from NVN Marine\u003c\/h2\u003e\n  \u003cul\u003e\n    \u003cli\u003eAuthorized Dometic reseller, full manufacturer warranty\u003c\/li\u003e\n    \u003cli\u003eNMEA member and ABYC certified, advice from real boat techs\u003c\/li\u003e\n    \u003cli\u003eSame-day shipping before 3 PM ET on in-stock items\u003c\/li\u003e\n    \u003cli\u003eNY headquarters and Fort Lauderdale flagship retail store\u003c\/li\u003e\n  \u003c\/ul\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eFrequently Asked Questions\u003c\/h2\u003e\n\u003cdiv class=\"nvn-faq\"\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat pressure does the Dometic 91604 relieve at?\u003c\/summary\u003e\n    \u003cp\u003eIt's factory set to open at 150 PSI. The setting is fixed at the factory, so there's nothing to adjust. When system pressure reaches that point, the valve lifts and bleeds off the excess.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat thread size is on the 91604?\u003c\/summary\u003e\n    \u003cp\u003eIt has a 1\/2 inch NPT threaded inlet, the standard size for most onboard water heater relief ports. Wrap the male threads with PTFE tape before you seat it.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eIs this a temperature and pressure valve or pressure only?\u003c\/summary\u003e\n    \u003cp\u003eIt's a combination temperature and pressure relief valve. It protects against both an over temperature condition and over pressure, which is exactly what a hot water tank needs.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWill it hold up to saltwater?\u003c\/summary\u003e\n    \u003cp\u003eDometic uses an epoxy coated probe and a no-gasket design to fight corrosion. That said, relief valves are wear items on coastal boats. Test yours each season and replace it if the stem seizes or it weeps constantly.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eDoes it need any adjustment before use?\u003c\/summary\u003e\n    \u003cp\u003eNo. The 150 PSI setpoint is factory set. You thread it in, bring the system up to pressure, and check for leaks around the base.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWhat if the valve drips after install?\u003c\/summary\u003e\n    \u003cp\u003eA little weeping right after install usually means the thread seal needs another wrap of PTFE tape or a firmer snug. A valve that drips constantly has typically lost its seat and should be replaced.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eWill it fit a tight water heater install?\u003c\/summary\u003e\n    \u003cp\u003eThe body is compact enough for most installs. On cramped setups where the heater sits against a bulkhead, add a short threaded nipple extension so the valve body clears adjacent plumbing and you can get a wrench on it.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eIs this a genuine Dometic part?\u003c\/summary\u003e\n    \u003cp\u003eYes. This is Dometic part number 91604, UPC 692931916040, a direct replacement relief valve.\u003c\/p\u003e\n  \u003c\/details\u003e\n  \u003cdetails\u003e\n    \u003csummary\u003eCan I use it on a lower pressure freshwater system?\u003c\/summary\u003e\n    \u003cp\u003eThe valve relieves at 150 PSI, so it's matched to systems and tanks rated for that. If you run a lower pressure setup, confirm your tank and pump ratings first. Some liveaboards choose a lower relief setting to reduce pump cycling.\u003c\/p\u003e\n  \u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003ctable class=\"nvn-specs\"\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003cth\u003eTitle\u003c\/th\u003e\n\u003ctd\u003eDometic 91604 Water Heater Pressure Relief Valve\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eBrand\u003c\/th\u003e\n\u003ctd\u003eDometic\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eManufacturer Part Number\u003c\/th\u003e\n\u003ctd\u003e91604\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eUPC\u003c\/th\u003e\n\u003ctd\u003e692931916040\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eKeystone Part Number\u003c\/th\u003e\n\u003ctd\u003eD7E91604\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eValve Type\u003c\/th\u003e\n\u003ctd\u003eTemperature \u0026amp; Pressure Relief Valve\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003ePressure Setting\u003c\/th\u003e\n\u003ctd\u003e150 PSI (factory set)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eTemperature Setting\u003c\/th\u003e\n\u003ctd\u003e210 degrees F\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eThread Size\u003c\/th\u003e\n\u003ctd\u003e1\/2 inch\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eThread Type\u003c\/th\u003e\n\u003ctd\u003eNPT\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eProbe Construction\u003c\/th\u003e\n\u003ctd\u003eEpoxy coated\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eGasket\u003c\/th\u003e\n\u003ctd\u003eGasketless design\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003cth\u003eAdjustment\u003c\/th\u003e\n\u003ctd\u003eFactory set, non-adjustable\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cscript type=\"application\/ld+json\"\u003e\n{\n    \"@context\": \"https:\/\/schema.org\",\n    \"@type\": \"FAQPage\",\n    \"mainEntity\": [\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What pressure does the Dometic 91604 relieve at?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It's factory set to open at 150 PSI. The setting is fixed at the factory, so there's nothing to adjust. When system pressure reaches that point, the valve lifts and bleeds off the excess.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What thread size is on the 91604?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It has a 1\/2 inch NPT threaded inlet, the standard size for most onboard water heater relief ports. Wrap the male threads with PTFE tape before you seat it.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Is this a temperature and pressure valve or pressure only?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"It's a combination temperature and pressure relief valve. It protects against both an over temperature condition and over pressure, which is exactly what a hot water tank needs.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Will it hold up to saltwater?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Dometic uses an epoxy coated probe and a no-gasket design to fight corrosion. That said, relief valves are wear items on coastal boats. Test yours each season and replace it if the stem seizes or it weeps constantly.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Does it need any adjustment before use?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"No. The 150 PSI setpoint is factory set. You thread it in, bring the system up to pressure, and check for leaks around the base.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"What if the valve drips after install?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"A little weeping right after install usually means the thread seal needs another wrap of PTFE tape or a firmer snug. A valve that drips constantly has typically lost its seat and should be replaced.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Will it fit a tight water heater install?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The body is compact enough for most installs. On cramped setups where the heater sits against a bulkhead, add a short threaded nipple extension so the valve body clears adjacent plumbing and you can get a wrench on it.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Is this a genuine Dometic part?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"Yes. This is Dometic part number 91604, UPC 692931916040, a direct replacement relief valve.\"\n            }\n        },\n        {\n            \"@type\": \"Question\",\n            \"name\": \"Can I use it on a lower pressure freshwater system?\",\n            \"acceptedAnswer\": {\n                \"@type\": \"Answer\",\n                \"text\": \"The valve relieves at 150 PSI, so it's matched to systems and tanks rated for that. If you run a lower pressure setup, confirm your tank and pump ratings first. Some liveaboards choose a lower relief setting to reduce pump cycling.\"\n            }\n        }\n    ]\n}\n\u003c\/script\u003e\n","brand":"Dometic","offers":[{"title":"Default Title","offer_id":45074777276509,"sku":"2009472","price":34.19,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0299\/7266\/0317\/files\/ImageServerAPI_b4fc6f89-b5ab-4120-b070-2e9ab111a7c6.png?v=1789821331","url":"https:\/\/nvnmarine.com\/products\/dometic-91604-water-heater-relief-valve-150-psi-1-2-npt","provider":"NVN Marine","version":"1.0","type":"link"}