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I replaced the high pressure release valve last year because my old one was leaking. When I motor for extended periods of time the newer pressure release valve leaks as the engine warms up the water heater. Does anyone else have this issue? It was dripping every few seconds and actually put out quite a bit of water.

You can buy a replacement from any plumbing supply store. Take the original out and with you to match.

Aren't the boat ones at a lower pressure? Through home water heater ones operate at much higher pressure.

The relief valve in your marine water heater is the same as the one in your home water heater. It is designed to open with the rise in pressure caused by overheating. I think the boat valve fails more often than the home because of the higher water temp. My home water heater is set at 150 and my Westerbeake runs at 180. The domestic water pressure isn’t a factor. I replaced mine with one I bought at a local hardware store.

I believe the valves on a Raritan heater are at a much lower pressure. 75 psi vs 150 for a typical home water heater. See below article. Not sure I am comfortable using a. Home one since the pressure rating is almost double.

https://www.boats.com/how-to/water-heater-relief-valves/

Interesting...I had no idea. Unfortunately 210 is close enough to the 180 operating temp so I guess your valve is living on the edge.

Interesting...I had no idea. Unfortunately 210 is close enough to the 180 operating temp so I guess your valve is living on the edge.

My valve has continued to leak even after replacing it. Reading in the water heater replacement article they talk about adding an expansion tank to stop this.

1. Is the expansion tank the same as an accumulator?
2. It sounds like it plumbs into the cold water line.
3. Anyone have a recommended part number for an expansion tank?

I'm finally getting to this as I believe my pressure valve is failing again. When the water heater heats up after motoring for extended periods of time the Pressure relief valve opens and then the pressure water system pumps a bunch of water into the bilge. So it has stopped just dripping at higher temps it is pushing significant water out now.

I think I'm going to add a 2 gallon expansion tank based on what I see in some of the newer Raritan users manual.

Has anyone tried adding a gate valve to redirect the flow of water to the water heater or bypass it from the engine? This is supposed to keep the overall water temp in the tank lower.

I have a gate valve on the hot water system. I would not recommend that. I used to have a marine ball valve in the past and I think that was better--but I really have not found a reason to restrict the flow. I do not like gate valves on boats as the metals they are made of are often subject to internal corrosion (zinc, mostly). Having said that, i would think that you have some other issue if your hot water heater relief is blowing off water. Are you getting good flow through the salt side of your heat exchanger? Seems like it is possible you have too much heat from the engine going to the heater.