Originally Posted by Borrego Dave
John, after reading all these posts, it seems to me that folks have a different idea of pressurized. Just MHO but to me in RVs, the house water pump is just that, a pump. It sucks water from the fresh tank and pushes it to keep the water heater full and to the faucets at very low pressure, around 45PSI. That pressure is only in the system when the pump is running, then becomes static. If you're connected to city water that's a different kettle of fish. Now you have constant pressure on your TTs water system. No one I've seen/read has stated if they are talking city or on board water. I've never hooked up to city water in over 30 years in any RV but all I've ever done is run the hot side of a faucet after filling the tank until it runs without popping air. Once that happens the heater is full and heating by 110V or LP is moot. As we don't use much hot water, I only turn the heater on about 10 minutes before wanting hot water. I've never had an element burn out or heard of any of my camping buds have that happen either, lucky on our part????
That's right. The pump comes on and pressurizes the system up to the switch cut off point. About 30-45 psi or so. Then the pump goes off as controlled by it's pressure switch. At that point the whole system is pressurized and waiting for a faucet to open. When a faucet opens, water comes out, the pressure drops and the pump comes back on. Then the faucet shuts off and the pressure climbs to the cut off point again. That process continues until the tank runs out of water or the pump is turned off. The affect in the trailer is the same as if connected to shore water. It is standing by under pressure and water comes out of the faucet when it's opened. The tank can be held at pressure from city water or the on-board pressure pump. The element is much more likely to survive when the trailer is either connected to shore water or the pressure pump is switched on because then the pressure is higher. I don't have any occasion to run the electric element when disconnected from shore power, or with the water shut off from shore or with the pressure pump off. Mine is not a tank style electric heater, but a propane/electric that I only run on propane
when camping. I will run the electric element when plugged in to shore power and connected to shore water.
The small 2-6 gallon tank style water heaters are designed primarily as point-of- use, under sink water heaters that are constantly connected to household pressure. They run on 120 volts and are plugged in. Some have gone into RVs.
I have also adapted them to other uses that are much lower pressure, so I've seen their weaknesses. I've also had several snap switches fail on the propane/electric units. The result is the same. No hot water even though there is power. Then you have to check the element and the snap switch independently.
None of this is designed to be a big debate. I'm simply saying it's better to run the electric element when the water pressure is on. If not, it can burn out.