Exploding water filter
This is the first year my wife and I have stayed in our 2008 Spree travel trailer through the winter. We are in the Seattle area, so usually mild winters. We don't like the taste of our water at the R...
Forum Discussion
Gdetrailer wrote:
Sorry, not fully true.
MOST (if not all) water heaters actually have a CHECK VALVE installed on the COLD WATER side of the heater.
There SHOULD be a check valve since it is a part of the safety of your water heater system. Without the check valve the T&P (Temp and Pressure relief) valve would never ever trip creating a dangerous situation to say the least..
Sort of, but not entirely.
The problem with check valves is they are not 100% reliable -- especially those which do not comply with one of the many ASSE standards, such as those you linked to. Check valves fail quite often which is why they, in most commercial and some residential applications, must be tested and certified on an annual basis. There are companies that do nothing but backflow testing and certification because of this requirement. Almost all backflow devices eventually fail and need to be repaired or replaced at some point. Many cheap check valves don't work as you would expect them to from the start.
A check valve on a water heater has nothing to do with safety. On a small system, such as an RV, it is there to keep the hot water from migrating to the cold side, but without one, you probably wouldn't get this mixing anyway. What I'm saying is, it doesn't hurt to have one, but it probably isn't necessary. When was the last time you saw a check valve on the cold side of your residential water heater? Some, but not most water heaters have what is called a heat trap either on the top of the dip tube or within a nipple on the cold side. The heat trap is a very weak type of check valve (doesn't completely stop backflow) that is supposed to help keep the hot water from moving from the tank and into the cold water. When these fail, they cause flow problems. They are not repaired or replaced -- simply removed.
As far as the T&P not working if you don't have a check valve goes, why do you think it would never trip? When the pressure reaches 150 psi, it will open to relieve the excess pressure. It will also open if the temperature exceeds it's set temperature (usually 210 degrees) limit. A check valve has nothing to do with this.
I believe the OP has installed a filter that cannot withstand the 150 psi that is bleeding past the check valve (if there is one) when the water heater heats and increases his system's pressure.
Bruce
