Hello,
Is there an advantage to a thermal expansion tank over a thermal expansion valve on a new hot water heater? If I'm replacing a hot water heater, can I reuse an expansion valve or do I need a new one?
Thanks!
A thermal expansion tank allows the heated water to expand against the bladder in the tank to prevent thermal expansion from raising the pressure in the closed loop. I'm not sure what you mean by a thermal expansion valve, where would you use one? I don't suppose you mean a TP relief valve?
Thanks, CasualJoe.
I went down to take a better look at the expansion device that I currently have and took some pictures. Sorry for the confusion, it's actually called an Expansion Control Valve. Here are some pictures. It's the thing with the red lable on it.
Hi,
What that is is a additional relief valve. The reason that is added is code because you probably have that flo gaurd gold piping throughout the home. because of that piping a lower rating pressure relief valve is needed. The large one at the heater is rated 150psi. That red faced additional one is rated at 100psi. Thats because PVC piping cant take the higher pressure copper can.
Like I said thats code.
And replace all new parts when replacing the heater. You need that additional relief valve by code if you have PVC.
Additionally absolutly add a expansion tank to the new heater.
Mike NJ
Mike, that is good information. I have never seen that type valve in use here, and almost all houses built use cpvc flowguard. Not a plumber, of course, but I do notice things. Is it possible the water heaters have lower psi TP valves? I wouldn't think so.
Mike, that is good information. I have never seen that type valve in use here, and almost all houses built use cpvc flowguard. Not a plumber, of course, but I do notice things. Is it possible the water heaters have lower psi TP valves? I wouldn't think so.
I thought it was code everywhere. No the water heaters do not come with the 100 psi relief valve. It needs to be added by the plumber. Instead of adding an additional one the original can just be swapperd out. But most plumbers around here opt to add. Although I believe you may still need both by code in some municipalitys and could be why one is always added.
Ususally you could tell because it has a red face on the front.
IMO flo gard gold is the worst stuff ever made. I have seen many flooded homes from cracked and brittle piping. Usually always the hot lines. Why? Look it up....
Mike NJ
Oh, I know. I had a client who thought she had a drip from her toilet, which would be a simple fix. Water was off, finally, and I disconnected the toilet feed tube and pulled a shattered piece of cpvc from the floor. After pulling down soaked insulation (mobile home) and replacing over 100 lf of cpvc, we finally had no leaks. Largest piece of pipe we pulled down was probably a foot long. This was last winter, and they turned their water off, but didn't use the drain spigot I provided to drain the pipes. They turned their thermostat to 55 degrees but turned off the propane tank. Not the brightest bulbs in the pack, to say the least. Temp in house when we got there was 38 degrees in the middle of the day.
You guys aren't making me feel warm and fuzzy about my cpvc piped house...
Thanks for the information on the thermal expansion devices. When we replace the water heater, I'll be sure it has a thermal expansion tank installed with it.
It just so happens that I had the county plumbing inspector out today to inspect some gas work we recently had done so I asked him about it too. He said that the Expansion Control Valve I have now isn't used very often anymore and it is there for the water heater and not because of the cpvc.
He said something like yeah, I'd probably go ahead and install an expansion tank when you replace the water heater....... not like it was required but like it was a good idea... that was a little weird to me.
He said that the Expansion Control Valve I have now isn't used very often anymore and it is there for the water heater and not because of the cpvc.
That statement cant be any farther from the truth.
Here is the spec from charlette pipe.
FlowGuard Gold® Copper Tube Size (CTS) CPVC Pipe and Fittings are used for hot and cold domestic water distribution, where the operating temperature will not exceed 180 degrees F at 100 psi.
Mike NJ
I'm not arguing with you - that's just what he said.
So, it sounds like I need to keep this device and then add a thermal expansion tank, correct?
Mike, isn't Flow Guard just a trade name? Isn't pretty much all CPVC pipe the same? I am assuming from this thread that ALL CPVC pipe should be installed in systems that WILL NOT exceed 100 psi. I was never a fan of plastic potable water systems and don't know a lot about them.
Any plastic type piping needs a 100 psi relief valve from my understanding of the code. In NJ anyway. Pex. cpvc, etc....
CPVC has a high pressure rating I believe 230 psi at regular temps 73f . When you have high temps it gets derated. So say 150F water reduces the psi to 95psi. And I believe they state with no shock, or water hammer. I would guess it gets derated additionally.
Info on typical CPVC
http://www.harvel.com/downloads/spec-cpvc-pipe.pdf
This is why I say its always the hot line that breaks first. Flow guard is a trade name but they had a bad batch of pipe years ago and got a bad rap. They never owned up to it.
I could find the info on that. If I remember it was some time ago. 8yrs????
I swear by pex these days. I would not use copper unless needed.
Mike NJ
If you had 150F water going
Tags: thermal, expansion, tank, valve, relief valve, water heater, expansion tank, thermal expansion, thermal expansion tank, Control Valve, Expansion Control, Expansion Control Valve, expansion valve
