04:10PM | 01/21/03
Member Since: 12/23/02
6 lifetime posts
we recently had a hot water tank expansion tank installed on the cold pipe coming into the hot water heater.
This expansion tank is mounted upside down, the print on the tank is upside down.
When i read the instructions that came with the expansion tank, it shows a picture to mount the tank right side up.
Does the mounting of the tank affect the operation of the expansion tank.
How do i know if the expansion tank is working ok.
How do i test the expansion tank


06:10PM | 01/21/03
Member Since: 01/13/03
50 lifetime posts
I had the same question on mine (plus I see this everywhere), so I contacted the manufacturer and they told me it really doesn't matter. The important things are the pressure (tested with a tire gauge on the end) and that it is located on the cold side (inlet) on the HW tank. The psi setting is on the tank, you fill it like a tire.



05:02PM | 01/31/03
Member Since: 01/26/03
5 lifetime posts
In reference to checking the psi on the expansion tank: I recently moved into a 35 yr old house. Decided to check the tank's psi as mentioned. The label on the tank said fill to 15 psi and it was at 12. So, I added some air with the trusty bicycle pump. However, when I put the pressure gauge and pump connection onto the valve stem some very bad smelling brown water leaked out. I mean it smelled like a dead fish might be rotting inside there. What's causing that? Should I drain it completely and refill it?
Also, can someone tell me exactly what the differences (to high or to low) in pressure will result in.


09:01AM | 10/23/06
Member Since: 10/22/06
1 lifetime posts
The tank is divided with in. One part is pressurized air and the other is water. When mounted if the in coming part is facing down that is the best way to install. When water enters there may be sediment. With the inlet on the bottom the sediment can drain out. To test take a tire pressure gage and check the air pressure to he specs on the tank.Add if needed.


09:36AM | 10/23/06
Member Since: 01/24/06
1626 lifetime posts
Me office1
CRASH Hydronic course

There are basically two types of expansion tanks used on hot water heating systems.

1- A tank filled with air and 1/3 water and has to be drained once the air is depleted

(absorbed into the system). Some do come with a sight glass

The other type is a bladder type sort of a balloon inside a steel tank.

The pressure settings are governed by the static head of your heating system.

Each system is different but the average is based on 12 -15 PSI setting

The static head is merely the cold fill of the water to the highest radiator and the gauge on the boiler will give the attitude reading .433 x the height

To prove this constant Lets assume your upper most radiator is 20 feet above the boiler the reading would be 8.66 on the altitude gauge marked with a red area along with the pressure settings. Now you have to add more pressure on the automatic feeder to make sure you have positive pressure on the system so one would add a total of 12 - 15 PSI

Now take the 8.66 PSI X 2.31 = 20 feet NOT enough pressure to keep the air out so we add a fudge factor of say 4 PSI more Here is how we get to the 12 PSI (simple huh)

We math figuring the pressure to have a system that is not air bound but yet low enough to not have the pressure relief valve opening every time the pressure approaches 30 PSI

The expansion tank takes up the expanding hot water as when water is heated it does expand and it a closed system the pressure does build.

People screw around constantly with the expansion tanks for no valid reason.

If it is not broken why try to fix it? Like the dummies who go around bleeding a system every year even when there is nothing air bound.

Al they are doing is killing their boiler as they are allowing fresh water in which contains oxygen which will in time rust out the boiler and other ferrous components

All one does is look at the Tri indicator (pressure, altitude, temperature)

The factory setting is set 12-15 PSI just like the automatic feeder.

If your getting water from a diaphragm type it is time to replace it as the bladder has given up the ghost

Just remember pressure temperature relationship
8157 s tieger plumbing  h


02:05PM | 11/02/06
Member Since: 11/01/06
2 lifetime posts
Hi all, new to this site, but love it already.

In response to your excellent explanation on hydronic systems I'd like to pose a question.

Just moved into a 50 year old house. It seems to be a system pretty much like what you describe. However, I do not see a pressure guage on the expansion tank.

Here is my problem. The heating system works fine. There is no knocking or any other problems associated with air in the system.

However, the domestic hot water is a different matter. I can turn on a faucet (all hot) and watch it go from normal flow, to nearly a trickle, normal, trickle...etc.

Showering is NUTS! I turn it on, first comes out of the spiggot normal flow and temp, then turn on the shower head, slows to a COLD trickle for a few minutes, then surges up to normal temp and flow and then varies throughout the whole shower. It seems like something simple and I'd hate to have to spend a fortune if it's something I can fix.

As a side note, I did notice that right off the main hot water output is a valve that supplies the house. It has the normal knob for on and off but then has a small "*****" below. Is this a flow adjust? Never seen anything like this before (not being a plumber). I tried to turn by hand but could not.

Thanks in advance!



02:06PM | 11/02/06
Member Since: 11/01/06
2 lifetime posts
Sorry, I meant "Hyrdonic" in my last post


06:22AM | 11/07/06
Member Since: 01/24/06
1626 lifetime posts
Me office1
If water flows and then starts to trickle you may have galvanized piping that is starting to corrode internally Or sedimewnt build up inside the piping.

Also remove the shower head and check the flow restrictor for sediment inside the flow restrictor.


07:04AM | 11/04/07
Member Since: 08/21/05
1 lifetime posts
I am on city water and my expansion tank has gone bad again. I replaced it in Jan 2003. The only issue I have is that my water pressure gets high I believe. It comes out of the faucets faster and harder.

The last time I also replaced the water pressure valve.

Before I had it fixed all my stop valves were leaking and I ruined my hot water heater and had to replace it also.

I guess what I would like to know now is it just my expansion tank. I do I know that the water pressure valve is functioning as it should? Can anyone assist me? My hot water stop valve to my washer is already leaking??

Thanks in advance.

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