Old gravity expansion tank and conversion to new closed system

Xander

First off, forgive me if my terminology is off.

OK, I had an original "gravity" boiler system. The old expansion tank was way up in the attic. The tank/leftover pipes are higher than any radiator. I'm concerned about the air trapped in these pipes without a radiator to bleed. Do I simply insert an air release valve like the Taco slimeline hy-vent model below. Please see diagrams.

[B][SIZE="4"]OLD SETUP[/SIZE][/B]

[IMG]http://www.xjmllc.com/images/old.jpg[/IMG]

[B][SIZE="4"]NEW SETUP??[/SIZE][/B]

Xander

Gravity System Conversion ...Old Expansion Tank, How to pipe?

First off, forgive me if my terminology is off.

OK, I had an original "gravity" boiler system. The old expansion tank was way up in the attic. The tank/leftover pipes are higher than any radiator. I'm concerned about the air trapped in these pipes without a radiator to bleed.

Do I:

1) Simply insert a 2 small air release valves on both ends (like a Taco slimeline hy-vent).

2) Just connect the pipes

3) Connect the pipes and add an air release in between them




Please see diagrams.

Xander

revised system setup



I'm now almost certain I need to connect the pipes (based on the picture directly above) it's a supply and return piping through the tank.

Still, how do I remove this air in the pipes above the highest radiator (1 floor below)????

1) Just connect the supply/return pipes

2) Connect the supply/return pipes and add an air release in between them

Paul Fredricks_3

I'm no expert...

... but it seems to me that it would be no different than a system that had a standard expansion set up to begin with. A standard type of vent makes sense in case someone needs to bleed it. An automatic type vent is only added if there is a big and consistent air problem. These pipes are not the supply or return, just a place to let the water rise and fall. They are in theory connected now since they both go into the tank, but I don't think that has anything to do with the flow. I'd cap them separately as close to the attic floor as possible with a coin vent of drain valve on top. If you use a drain put a cap on it.

My .02

JK_3

If you have added a new expansion tank at the boiler then thoese two pipes can be capped with no need for bleeders. the only concern i would have is water being trapped in the lines and freezing in the attic. so yes cap them as close to the heated area as possible.

Dave Stroman

There are 2 pipes going to the tank to allow for flow to keep the tank from freezing. Cap them in the attic and insulate. No need for an air vent. Better yet, fine where they connect to the systems piping. Very common for the 2 pipes to connect to the main in the basement. Sometimes they connect to the top and bottom of a radiator.

Dave Stroman, Denver

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bob young

down feed

Could be a down feed then you would twin piping after removing tank.

tim smith

Regarding tie together

I would tie together with a tee, install a Hoffman 79 auto vent off the tee and connect bleed line to overflow line to basement so if 79 starts tp leak, you will see it in basement. Good luck. remove and seal hole in roof also:)