Expansion Tanks

[jbraun (James E. Braun, CMI)]

The average pressure regulator has a diaphragm. If you run water backs through the valve, the diaphragm will open up.

[jbraun (James E. Braun, CMI)]

@jfunderburk

1. Use the term “an approved device for thermal expansion control.” That is how the code references it. “Expansion tank” is inappropriate as some valves have thermal expansion control built in.

2. Expansion control is not to prevent backflow. Instead, thermal expansion control is required whenever the house is a closed system (and the water cannot back up into the municipal water system).

1. We are not talking about code.

2. Expansion tees work for a closed loop systems. And expansion tanks do prevent backflow.

[gfarnsworth (Gary Farnsworth, CMI)]

I do not open hot water heater drain valves, as there is too much risk in getting them to turn off after they are opened.

[jjonas (Jeffrey Jonas)]

@gfarnsworth

I do not open hot water heater drain valves, as there is too much risk in getting them to turn off after they are opened.

I was curious about that myself. It sounded like at least a couple inspectors check pressure at the WH. I do not open the valves either.

Perhaps another poll is in order.

[mlarson (Michael Larson, WI Lic. # 1672-106)]

@jjonas

I was curious about that myself. It sounded like at least a couple inspectors check pressure at the WH. I do not open the valves either.

Perhaps another poll is in order.

I do not open water heater drain valves for a very good reason.

Hard water deposits buildup in a tank that has not been drained regularly and WILL cause the valve to not close again.

Do you have to ask why I know that?

Use and outside faucet, the end of a washing machine hose or another hose fitting like on a laundry tub faucet.

[jfunderburk (Joe Funderburk, CMI)]

@jbraun

1. We are not talking about code.

Then don’t call out their absence at all, as the only reason they exist is because of codes.

[jbraun (James E. Braun, CMI)]

I do not call out their absence.
Anyway, my local code authority says expansion tees are acceptable.

[jpope (Jeffrey Pope, CMI)]

@sstanczyk

After 20 minutes or so, the hot water should be replenished, check your reading again. If the pressure has increased more than 8-10 pounds or more, the unit is bad and should be replaced.

A failing regulator will give you similar results. So I would call that an indication, but inconclusive to determining that an expansion-tank has failed.

The water heater drain-valve was where I checked for pressure for many years. After ruining four or five pressure gauges (at $60 a pop) I stopped doing it, unless there’s absolutely no other place to check.

[mbeauchemin (Marc-Andre Beauchemin, MAB,(CMI), (CPI), interNACHI, interNACHI Quebec,A)]

Keith,

I believe the 2008 Plumbing code is when it was introduced. I have not come across such installations.
Personally, I do not believe that they are as necessary as TPRV.