Expansion Tanks

[Joe Funderburk, CMI]

Originally Posted by bkelly2

When they put a Back Flow device and or Regulator on the water supply to the house, and you have Copper or CPVC Piping then yes they are needed.

The type of piping is irrelevant. The code doesn't specify a piping exception.

[Joe Funderburk, CMI]

Originally Posted by krunquist

Good article Nick. All correct. But what I'm asking is the expansion tank really a needed item or is it code overkill? I'll continue with code etc. for inspections but personally I see overkill and wonder what others have seen in the field. I'm especially interested if ther are any plumbers out there with field experience with expansion tanks or lack of them.

How do you define "code overkill"? There is no way to know what occurs without dissecting the water heater to see if damage is present. I always assume people smarter than I am wrote the codes and don't question it, as I'm not privy to the information they used in deciding to promulgate it.

[Brian A. MacNeish]

Originally Posted by jfunderburk

How do you define "code overkill"? There is no way to know what occurs without dissecting the water heater to see if damage is present. I always assume people smarter than I am wrote the codes and don't question it, as I'm not privy to the information they used in deciding to promulgate it.

Wasn't the expansion tank for DHW systems brought in when some codes/municipalities required a backflow/check valve on the municipal water supply line? We don't have the backflow/check valve requirement here, hence, no expansion tanks on the DHW system.

[Joe Funderburk, CMI]

Originally Posted by Brian A. MacNeish

Wasn't the expansion tank for DHW systems brought in when some codes/municipalities required a backflow/check valve on the municipal water supply line? We don't have the backflow/check valve requirement here, hence, no expansion tanks on the DHW system.

Do you have pressure regulators? Those valves create a closed system at the house and would meet the criteria for requiring an expansion control device.

[James E. Braun, CMI]

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

[James E. Braun, CMI]

Originally Posted by 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.

[Gary Farnsworth]

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.

[Jeffrey R. Jonas]

Originally Posted by 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.

[Michael Larson]

Originally Posted by 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.

[Joe Funderburk, CMI]

Originally Posted by 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.

[James E. Braun, CMI]

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

[Jeffrey R. Pope]

Originally Posted by 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.

[Marc-Andre Beauchemin]

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.