Steam heat boiler expansion tank replacement

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Raminee

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Hello All,

This is my 1st post on this forum so I am hoping to get some good advice from some of you professionals out there.

I have an old steam heat boiler with an old (diaphragm less) expansion tank that I wish to replace with a modern 14 Gallon capacity one.
I am attaching a drawing of my boiler system for your viewing.

I have an idea as how to go about doing this but want to make sure I am taking the right steps.

Can you advise if I am missing any steps in the following list to replace the expansion tank ?

1) Shut the boiler off
2) Close the Input supply valve
3) Open the Drain valve to drain the water in the system.
(Now one question I have here is do I drain all the water or just enough to ease the pressure in the system?
My thought is to allow gravity to drain all the water in the system)
4) Replace the expansion tank.
(Next question on this is which way should the expansion tank be? Water side up / Air side down or vice versa )
5) Close the drain valve
6) Open the supply valve and wait a few minutes to let the pressure build up.
7) Turn the boiler back ON
8) set the thermostat to run the pump and circulate the water around the system
(Which brings me into my next question: How to get rid of the air in the system?
Do I simply vent it from each Radiator ??)

Many thanks for any pointers on this.

Raminee
 

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Breplum

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Actual 'steam' boilers with gravity drain on condensing lines are quite rare in California.
They usually have steam traps.
shopping

You more likely have a radiant heat boiler. Is that what you have?
I am not a specialist in hydronics so won't answer further.
 

Fitter30

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Steam doesn't have a expansion tank. Take some pics of boiler , piping and any pumps. Bladder tank doesn't care what position its in. Water fill pressure under 100° with all pumps and boiler off matches ex tank pressure. Extank replacing like for like?
 
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John Gayewski

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You have a hot water boiler, not steam.

The expansion tank should have the schrader valve pointed down. This is the primary orientation shown by the manufacturer and its the best way to test the tank in the future to see if it's leaking as the water will settle to the bottom and near the valve opening.
 

Jeff H Young

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You have a hot water boiler, not steam.

The expansion tank should have the schrader valve pointed down. This is the primary orientation shown by the manufacturer and its the best way to test the tank in the future to see if it's leaking as the water will settle to the bottom and near the valve opening.
Good point on pointing the schrader valve down as far as the theory . If manufacture says any position though I could see a slight advantage to that being somewhat prefered.
I worked a bit in Pipefitting but never learned that much about the workings in Heating and cooling and almost zero refridgeration mainly just following prints and running pipe which I loved but wish Id gotten more deep into it
 

Raminee

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You have a hot water boiler, not steam.

The expansion tank should have the schrader valve pointed down. This is the primary orientation shown by the manufacturer and its the best way to test the tank in the future to see if it's leaking as the water will settle to the bottom and near the valve opening.

You are all right I do not have a steam boiler. It is a Hot Water Boiler !!!! My bad.

Good point about the position and testing .

Thx
 
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