Expansion tank - gravity system

Brad White_122

a diaphragm tank without pressurizing the system because by definition you are closing it off (you have to). Remember, for the diaphragm tank to work you have to have pressure against the captive gas volume. Open that tank line and that is the volume the expaning water will see: Not much and out onto the floor...

No pressure, no squishee. I think Boyle put it that way,

But any expansion tank that high in the system would be smaller than if in the basement. Take elevation into account and calculate it each way to see the difference.

Why not affirm the existing tank's inegrity? It worked for probably 100+ years already. Can you beat that? I have to ask. If the current tank over-flows it washes the roof. If any other tank goes, there is pressure above gravity with which to contend....

Randy Calvi

expansion tank - gravity system

Looking for advice... I have a client with a gravity, cast iron radiator system. Older boiler, but in good repair and everything works OK. System has an old riveted tank in the attic, vented through the roof. Unit looks OK, but has a little bit of corrosion and water scaling on one end. It doesn't look like a leak to me, more like maybe some condensation (it's not wet). Client would like to replace the existing expansion tank for peace of mind. Is there a proper way to add a modern, diaphragm type tank to this system without closing it up or pressurizing it? If so, is it possible to place it in the attic where the existing one is? It seems to me, that putting a new tank in, teed to the vent line and de-pressurized might work, but I'm a little hesitant of that being the right solution. Thoughts, ideas or suggestions? Thanks much.

ddlong1286@yahoo.com

Where at?

I don't know where you live, but go to the nearest "farm & home" supply and get a small plastic stock tank that would match your current capacity.

You would have to make fittings for it or maybe not, I have never bought a stock tank before, but have seen bigger ones used for swimming pools.

If someone knows this won't work, let me know!!

Don in Mo

Perry_2

I wouln't use a stock tank; but there are other options

A stock tank will have a very large surface area available for contamination. In addition they are not really that sturdy. If they crack and leak in a field - no problem. In a house - a major problem.

Substaintially more rugged plastic tanks are available from companies that sell chemical storage tanks.

Please note that you will have to have a proper supporting platform as the tank walls do not adequatly support it by resting on a brace here and there.

Personally, I'd do some more investigation of the existing tank. There is a good chance that there is nothing wrong with it - perhaps you need a new vent line. There is nothing wrong with rivited tanks. A lot of them are still in service to this day.

Perry

DanHolohan

That's what I would do.

What Brad said.