Here is the flushing nozzle I use. Make sure you have a good shutoff on the hose as if you turn on the pressure full blast out in the open, the tube will flex real heavy backwards. Once in the hole, not so much an issue. Once in the hole, go back and forth and spin it around too to blast all areas of the tank.
The saftey relief is 1/2 NPT pipe thread. A garden hose, is well what they call "garden hose" Totally different thread setup.
They sell adapters from 1/2" NPT to garden hose thread. Here is one I use when I screw in an air line to the city water connection to blow out that line.
That particular adapter is garden hose thread to 3/4 npt male with a 1/2" npt female thread inside. They have them in all kinds of configurations.
A heads up, if you have not drained and flushed the heater in that long of a time, there is a lot of sediment laying in the bottom. Flushing will help get a lot of it out. Do this first before any vinegar treatment. And then go take all the strainers out of the sink faucets. The left over will end up getting trapped in them and plug em. Once all flushed etc through the faucets, then put them back in.
Since the heater is stinky, this comes from bacteria. Your hot water line from the heater to every faucet also has a build up carried from the smelly water. It ma have migrated into the cols as well.
Suggest this verses the saftey relief valve. Flush the tank out good. Hook up the fresh water hose to the city water connection and flush the camper, sinks, toilet etc and hot water heater some more. If you have a winterizing kit at the water pump, After a long good flush, feed the vinegar in there like you feed the antifreeze and do the entire inside of the camper and a good soak time. Then flush again through the city water after the soak time. Or better, consider sanitizing the entire camper, fresh tank and all.
If you have never lifted the saftey relief lever in over 5 year, some times they can be finicky, have build up on the seat and not want to seal up again. This is not all the time, but it does happen. Some times letting it snap back down hard after a quick burp breaks free the offending piece of sediment on the seat.
Hope this helps
PS heads up, turn off the 120 VAC (breaker in power panel) to the heater so it does not get flipped on by accident during the draining etc. They burn out real quick with no water in the heater
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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