How do I know if my expansion tank is water logged?
 

The story begins when I dicovered that the relief valve (of my home's
heating system gas-based heater) discharges about 1/4 cup of water
daily.

A technician from the gas company (called for a different problem) that
saw this immediately pointed to the Amtrol expansion tank (Extrol model
#30) as the culprit. He said he could tell just by knocking on the tank
and listening whether it is a hollow sound or not.

After he went, I tried this myself but I actually noticed that the top
part (which should be filled with water) does not sound hollow, while
the bottom part (which should be filled with air only) sounds hollow.
Isn't this the way it is supposed to be? If so, what made him say this
is the expansion tank?

Also, while he said that the expansion tank should be replaced, I
noticed a threaded air valve at the bottom of the tank, which looks
like exactly the ones found in bicycle tubes. Is it possible that I can
get away with simply re-filling some air in the tank, instead of going
into the expense of replacing the tank?

It should be noted that I have no intention of replacing the tank
myself, but rather let a professional heating plubmer do that. However,
I feel that I need to gather as much information about the problem as
possible, before going ahead with ordering a repair. One plumber I
called said the expansion tank alone will cost me $250 (excluding
labor!). I found that same exact tank for sale on the Internet $43.55
....


Thanks!
Sam

How do I know if my expansion tank is water logged?
 

wrote:
The story begins when I dicovered that the relief valve (of my home's
heating system gas-based heater) discharges about 1/4 cup of water
daily.

A technician from the gas company (called for a different problem) that
saw this immediately pointed to the Amtrol expansion tank (Extrol model
#30) as the culprit. He said he could tell just by knocking on the tank
and listening whether it is a hollow sound or not.

After he went, I tried this myself but I actually noticed that the top
part (which should be filled with water) does not sound hollow, while
the bottom part (which should be filled with air only) sounds hollow.
Isn't this the way it is supposed to be? If so, what made him say this
is the expansion tank?

Also, while he said that the expansion tank should be replaced, I
noticed a threaded air valve at the bottom of the tank, which looks
like exactly the ones found in bicycle tubes. Is it possible that I can
get away with simply re-filling some air in the tank, instead of going
into the expense of replacing the tank?

It should be noted that I have no intention of replacing the tank
myself, but rather let a professional heating plubmer do that. However,
I feel that I need to gather as much information about the problem as
possible, before going ahead with ordering a repair. One plumber I
called said the expansion tank alone will cost me $250 (excluding
labor!). I found that same exact tank for sale on the Internet $43.55
...


Thanks!
Sam


put an auto tire pressure guage on the air valve and check the pressure
is still as specified in the owners manual.

If water comes out of the air valve you need a new tank , or a repair
kit.

How do I know if my expansion tank is water logged?
 

Also to small a tank will cause the boiler to overpressure as the water
heats. What pressure do you reach, could also be a bad pressure valve.

How do I know if my expansion tank is water logged?
 

m Ransley wrote:
Also to small a tank will cause the boiler to overpressure as the water
heats. What pressure do you reach, could also be a bad pressure valve.

does this model of tank have a bladder to seperate the air and the
water?

Mark

How do I know if my expansion tank is water logged?
 

Mark wrote:
does this model of tank have a bladder to seperate the air and the
water?

Yes, it does. Does this provide additional info that can help?

BTW, I followed marks542's suggestion: I put a bicycle air pump with
pressure gage (an auto tire one won't work because the threaded valve
on the tank fits a bicycle pump, not an auto tire one) and attempted to
measure.

My first observation was that **no water is leaking** (that's good,
right?)

However, the pressure gauge on my bicycle pump only starts to show
calibrated reading from 20 psi and above. The Extrol 30 needs only
12psi. I heard some air discharging in the process and so I was afraid
to depleat the air in the tank (which would exacerbate the problem -
not good on a Sunday morning...).

BTW, the air that came out of that valve was stinky (like dead fish or
something). Weird.

What do you suggest that I do next?

Thank you all for your help!
Sam

How do I know if my expansion tank is water logged?
 

wrote:
Mark wrote:
does this model of tank have a bladder to seperate the air and the
water?

Yes, it does. Does this provide additional info that can help?



if it has a bladder and significant amounts of water come out the air
valve, that means the bladder has ruptured.... time for a new tank....
a very small amount of water is prob just condensation

and I always thought a bike tire and car tire used that same fitting so
I don't undertand what you are saying about that.

Mark

How do I know if my expansion tank is water logged?
 

Mark wrote:
if it has a bladder and significant amounts of water come out the air
valve, that means the bladder has ruptured.... time for a new tank....
a very small amount of water is prob just condensation


and I always thought a bike tire and car tire used that same fitting so
I don't undertand what you are saying about that.

Mark, you are right. Thanks to your comment I double-checked... First,
I found this:

http://www.sheldonbrown.com/gloss_sa-o.html#schrader

Which confirmed that I actually have a pump for the Schrader type,
which is the standard automotive-style air valve.

That lead me to double-check why my first trial with the car tire gauge
did not succeed. It turns out that I was trying to be so cautious, that
I didn't press the gauge hard enough againt the valve.

So... I went ahead and used the gauge as recommended: The reading shows
something like 11.8 psi.

This is close enough to the optimal 12 psi (as specified by Amtrol), so
I must assume that the expansion tank's problem is a water-logging? The
stinky smell coming out of that valve suggests that indeed it may be
the result of water sitting there for a loooong time.

Comments? Suggestsion?

Thanks!
Sam