Expansion Tank on water heater

Mikb1957

I have a small condo with all electric heat and electric hot water heater. It doesn't have an expansion tank on it. Is there any set up where this would be ok? It's a closed system as far as I know.

EdTheHeaterMan

Electric heat can be a fan blowing across electric elements. the fan can be connected to duct work or not. No expansion tank required
Electric heat can be electric elements inside a metal enclosure called baseboard heaters. No expansion tank required.
Electric heat can be a boiler that is connected to pipes. The electric elements in the boiler heat up the water and a pump moves the heated water thru the pipes, to hot water radiators of some type. The colder water from the radiators returns to the boiler thru other pipes, to be reheated. This is a closed system and would require an expansion tank.

An electric water heater that connects to your kitchen sink faucet, washing machine, bathtub, or shower would be an open system (because the water goes down the drain when you open the faucet) and they do not require an expansion tank in every situation. More and more water systems may require expansion tanks because there may be a backflow preventer at the water meter.

What type of electric heat do you have?
What does your water heater look like?

Pictures will help us answer your query

hot_rod

Mist water heaters need an expansion tank or device if you are on public water

EBEBRATT-Ed

@Mikb1957

You probably don't need an expansion tank on an electric tank type water heater in your application.

When cold water in a water heater expands when heated some jobs require an expansion tank especially if the incoming city water has a pressure reducing valve or a check valve.

Most water heater do not require an expansion tank. When the pressure rises due to the heated water a small amount will flow backwards into the city water main. In addition, the pressure is reduced when someone draws hot water. Also, you mentioned you are in a condo, so I assume there are many condos attached to the same water line.

Mikb1957

I should have been clearer in my description. I have electric baseboard heating, nothing to do with my water heater or any water at all..There are many condos attached to the same line, my building has 12 units. This is a weekend place in rural upstate NY and trying to get information from the town about water is challenging at best, but I guess that should be my next move, if there is a check valve they probably require the ET, if not, I'm good as is. Thanks for the info..

EBEBRATT-Ed

Some states require a vacuum breaker on the cold water line between the last shut off valve and the tank. Your state probably doesn't. With 12 units you shouldn't will not have an issue without an expansion tank.

If your concerned get a pressure gauge at the big box store or at supply house.com.


Water Test Gauge, 3/4" Hose Thread, Top Mount (0 - 200 PSI)
Brand:
Bluefin
SKU:
GW25-200-TM

This is one at supply house.

EdTheHeaterMan

That water heater is designed for DHW open systems.

When the water in that tank expands there is a small air cushion at the top of that tank that will absorb some of the expansion. If there is more expansion than that small space can absorb, the water just backs up past the water meter to the street main. At some point in time, if your utility starts to upgrade the meters / water services with BackFlow preventers, then you relief valve will start to release water pressure…. Then you must have an expansion tank designed for DHW. If your utility does not require one, and your relief valve is not discharging, then I would not worry about it .

If however you would feel more comfortable adding an expansion tank, there is no harm in doing so. Just purchase the correct model designed for DHW like this one.
https://www.supplyhouse.com/Amtrol-140N43-THERM-X-TROL-ST-5-Expansion-Tank-3714000-p?_br_psugg_q=water+heater+expansion+tank
This is the gauge mentioned above
https://www.supplyhouse.com/Bluefin-GW25-200-TM-Water-Test-Gauge-3-4-Hose-Thread-Top-Mount-0-200-PSI?_br_psugg_q=bluefin+gauge

realliveplumber

Mikb1957

Very helpful information, glad I inquired. Thank you all.

EBEBRATT-Ed

Of Course "Bradford White" recommends that expansion be allowed for" I am sure every water manufacturer does as well.

It's called CYA.

Never see expansion tanks on WH around here Very rare.

hot_rod

Plumbing codes require expansion devices if there is a check valve or backflow device. A gauge like this will capture the high pressure in your system
80 psi is also the maximum pressure based on code and the rating on faucets and toilets. The gauge will give you some data on your homes pressure.