Shark bite Thermal Expansion Relief Valve, do I still need an expansion tank?

[Alucard]

Hello. This site is terrific. Anyway, the expansion tank I installed about 10 years ago sprung a leak so I needed to replace it. But, I saw that Sharkbite makes what they call a Thermal Expansion Relief Valve designed to reduce pressure from the expansion of water from the water heater, when pressure hits 125. The water just runs on the floor to the drain. It works okay. But, Sharkbite maintains that, if you have this valve, you don't need an expansion tank, so I purchased it and installed it. Now, without an expansion tank in our closed loop system, the water starts to heat up and expand, until it hits 125 or until someone turns on a faucet or shower. So, now, without the expansion tank, we get that initial high water pressure when someone turns on a faucet, just for fraction of a second. We do have a water pressure reducer about 10 feet from the water supply coming into the house, to reduce what comes from the street/water supply. But, this doesn't, nor is it supposed to reduce pressure from the water heater, as the water heats up. I have it set to about 70. It works as it should. I installed a water pressure meter to monitor this. Correct me if I'm wrong, and that happens often, but, with this sharkbite thermal expansion relief valve, pressure will build up into the system when the water heater does its thing until someone gets in the shower, or turns on a faucet or the pressure gets to 125. So, from the expansion of heated water, we will have anywhere from 70 psi to 125 psi, in our system without an expansion tank. So, we actually still do need an expansion tank. Is this correct?

 

[Reach4]

Without a tank, the drop from 125 to 70 should be nearly instantaneous, I would have thought that you should be ok without a thermal expansion tank. But if you are telling us that you do get a burst and it actually bothers you, then I guess you need a thermal expansion tank.

The downside of the 125 psi pressure relief method is that it consumes a bit of water. That is very important some places.

 

[Sponsor]

 

[Jeff H Young]

Without a tank, the drop from 125 to 70 should be nearly instantaneous, I would have thought that you should be ok without a thermal expansion tank. But if you are telling us that you do get a burst and it actually bothers you, then I guess you need a thermal expansion tank.

The downside of the 125 psi pressure relief method is that it consumes a bit of water. That is very important some places.

I think the amount of wasted water could be extremel minor like a gallon of water sometimes no water is wasted if water is used for any purpose when water is being heated it could be enough to prevent any water spitting out

 

[Alucard]

Thank you. I have considered the water wasted. I'll empty the bucket every day for a week and see how much I'm actually wasting. As far as the pressure goes, should I not be too concerned about the pressure oftentimes being between 70 and 125?

 

[Fitter30]

Most water devises are made for max 80 lbs working pressure. Yes they can handle more but putting undue stress on them and higher pressure can start to have water hammer.