This past winter we stayed in one place for 4 months, the longest without moving so far in 10 years. About 3 months into our stay our relief valve opened spewing scalding hot water everywhere. First thought was the heating element was stuck on however I verified it was not, so I my thoughts went to a defective relief valve and I replaced it. A vacationing RV tech was staying in the resort that we made friends with and he described that the water heater is built to have an air space at the top of the tank for expansion. He also said that when staying that long the water heater can loose this air space and to just turn off the water and carefully open the relief to reestablish the air pocket from time to time. So was it a relief valve failure, I don’t know, however no issues since!
The air space is exactly the issue when the relief valve is not failed and the water heater is working properly. I have been an RV camper for 40-years and when there is no air space, a relief valve will tend to expel a small amount of water each heating cycle. The reason tends to be we use a lot of hot water from these tiny water heaters showering, and with no air space, the cold water coming can expand a lot over a residential 40 or 50-gallon water heater. It tends not to be a problem when traveling and air from the water hose connection is introduced. That is one reason I open my hot water tap first when connecting to the hose bib in the RV park, to replenish that air space in the water heater if needed.
We have expansion tanks in all our residential water heaters. My plumber buddy says it’s to prevent pipes from bursting due to water pressure buildup due to heat expansion. Makes sense.
In my Atwood water heater, the water temperature is factory set and not easily adjustable. And set much hotter than a residential heater, as there is a mixing valve at the hot water outlet that bleeds in some cold water to reduce the delivery temperature at the taps. So it appears to deliver more hot water than one would expect for its size.
This past winter we stayed in one place for 4 months, the longest without moving so far in 10 years. About 3 months into our stay our relief valve opened spewing scalding hot water everywhere. First thought was the heating element was stuck on however I verified it was not, so I my thoughts went to a defective relief valve and I replaced it. A vacationing RV tech was staying in the resort that we made friends with and he described that the water heater is built to have an air space at the top of the tank for expansion. He also said that when staying that long the water heater can loose this air space and to just turn off the water and carefully open the relief to reestablish the air pocket from time to time. So was it a relief valve failure, I don’t know, however no issues since!
The air space is exactly the issue when the relief valve is not failed and the water heater is working properly. I have been an RV camper for 40-years and when there is no air space, a relief valve will tend to expel a small amount of water each heating cycle. The reason tends to be we use a lot of hot water from these tiny water heaters showering, and with no air space, the cold water coming can expand a lot over a residential 40 or 50-gallon water heater. It tends not to be a problem when traveling and air from the water hose connection is introduced. That is one reason I open my hot water tap first when connecting to the hose bib in the RV park, to replenish that air space in the water heater if needed.
We have expansion tanks in all our residential water heaters. My plumber buddy says it’s to prevent pipes from bursting due to water pressure buildup due to heat expansion. Makes sense.
Mike, those values tend to stick with dirt in them. Just want to remind people to flush them when water is cool.
Good idea. And I’ve seen several residential water heaters that no amount of flushing would make them stop dripping.
In my Atwood water heater, the water temperature is factory set and not easily adjustable. And set much hotter than a residential heater, as there is a mixing valve at the hot water outlet that bleeds in some cold water to reduce the delivery temperature at the taps. So it appears to deliver more hot water than one would expect for its size.
That is an Atwood water heater and does NOT have an anode rod. Please ignore Mike’s
Comment about the anode rod. That only applies to a Suburban water heater.
Yes, not all RV water heaters have anode rods.
Which is why I said “And while you’re at it, check to see if you have an anode rod and replace it.”