Another Expansion Tank Installation Question?

[JK60]

All expansion tank installation illustrations that I've seen show installation of an expansion tank on the cold water side in the immediate vicinity of the water heater. In looking at my water heater there is a location about 8 inches from the heater that is ideal for this install. Ideal that is in terms of available space and ability to support the expansion tank. However this section of pipe gets hot when the heater turns on, I assume due to the backflow of hot water from the heater. Is that a problem for the expansion tank? Should I look for a different location? Obstructions from vents, heater ducts, etc above do not allow for installation anywhere else in the immediate vicinity of the water heater. Can the tank be installed anywhere else or does it have to be close to the water heater? Thank you for any information you can give me.

Jerry

 

[Gary Swart]

The expansion tank must be located in the supply line between the water heater and the PRV or backflow preventer. Those are the devices that cause a closed system and make the expansion tank necessary. The tank can be located anywhere on the supply line as long as it meets the above requirements. The place you describe will be fine.

 

[Sponsor]

 

[JK60]

The place you describe will be fine.

Thank you for the information. Am I correct in assuming then from your response that the fact that the pipe gets hot and subsequently the water entering the expansion tank will also be at a somewhat elevated temperature, is not an issue for the expansion tank and will not cause premature failure?

 

[Gary Swart]

That's correct!

 

[Jadnashua]

When you're doing the install, if you don't have them, consider installing heat traps on the hot water heater. It will help keep the heat from escaping. Does anyone know if it will change the effectiveness of the expansion tank with the heat traps installed?

 

[JK60]

I could be completely wrong but I thought the heat traps prevent water from backflowing which is good for energy conservation but by doing so create a closed loop system within the water heater. It seems that at this point with the expansion tank outside this closed loop the tank would have no effectiveness in reducing the buildup in pressure. Just my inexperienced analysis.

 

[Cass]

No they prevent the heat from escaping / raidiating from the tank through the water in the open pipe. Expanded water flows from the tank and will flow through a heat trap nipple.

 

[JK60]

I have a Rheem 50 gallon water heater. I just looked at the installation instructions in the provided Use & Care Manual and they are showing two different locations for installation of heat traps depending on whether it is an open or closed loop water system. If I interpret their instructions correctly then for an open system the heat traps are attached directly to the water heater, however for a closed system where an expansion tank is utilized the heat trap is shown to be between the expansion tank and the cold water supply. Doesn't this imply that a heat trap does act as a backflow preventer?

 

[hj]

tank

That is correct for some heat traps. Others are not that tight and will allow the pressure to escape. But the way the expansion tanks works there would be very little of the hot water that would enter the tank anyway, and if it did the existing water in the tank would cool it down immediately.