Location of Expansion Tanks

[velvetfoot]

I am in planning stage. Looks like I'll try to fit a 1000 gallon tank in the basement. The tank will likely be 25 away from the boiler on the other side of the basement. Mr. Dudley noted in another thread that a good loacation for the tanks would be on top of the storage tank, which should be possible because of the relatively low profile of the tank (compared with two stacked 500s). Anyway, is this location sill the ideal since the boiler is pretty far away? Could they be located somewhere else without penalty?

 

[ewdudley]

Dudley noted in another thread that a good loacation for the tanks would be on top of the storage tank, which should be possible because of the relatively low profile of the tank (compared with two stacked 500s).

Above storage (and adjacent to boiler) would be ideal for a non-bladder tank, a bladder tank can go most anywhere as long as it is tied-in at an appropriate point.

 

[kuribo]

My boiler is at a higher elevation than my storage tanks (above grade, storage below grade in basement). I wonder if it would be best in my situation to have the expansion tank at the same elevation as my boiler? I plan to use a non-bladder tank....

 

[velvetfoot]

Above storage is ideal for a non-bladder tank, a bladder tanks can go most anywhere as long as it is tied-in at an appropriate point.

Thanks, I forgot that I think the subject was about bladderless tanks. Could they perhaps go on the floor next to the boiler?

 

[ewdudley]

My boiler is at a higher elevation than my storage tanks (above grade, storage below grade in basement). I wonder if it would be best in my situation to have the expansion tank at the same elevation as my boiler? I plan to use a non-bladder tank....

I believe ideal for non-bladder tank in your situation would be to place the expansion tank completely above the boiler.

On supply pipe leaving boiler would be an air-eliminator vented not to atmosphere but plumbed to a pipe that goes to the top of the expansion tank, followed by the near-boiler circulator, followed by the tee that feeds storage on one leg, and that feeds the return temperature protection thermostatic valve on the other leg. Then a small pipe going up from the return-from-storage line to the bottom of the expansion tank. This is essentially the same as the non-bladder tank above storage configuration, the key goal being to take any gas that comes out of solution when boiler water is heated and letting that gas rise up directly into the top of the non-bladder expansion tank.

Near-boiler circulator is moved up to boiler supply side to lower the pressure at air separator, and to tie the expansion device in on the suction side of the circulator.

[Edit:] Note that putting the pump on the supply line is the ideal pump location for this kind of setup, the normal location on the return side would probably be just fine so long as the air separator vents to the expansion tank.

 

[kuribo]

Thank you!

The biggest difficulty may be getting a large expansion tank above the boiler. With a system water capacity of 1200 or so gallons, I think I will need in excess of 100 gallons of expansion. That's a lot of tank....

 

[velvetfoot]

Maybe you could use two.

 

[velvetfoot]

Thanks.

 

[woodsmaster]

Ewdudley has it right. I originally had my non bladder tank on the floor and didn't have a line hooked from air separator to top of the tank. I had to add air every month or so. I since raised the exp. tank and added a line from the separator to the top of the tank and I haven't had to add air since.

 

[goosegunner]

Ewdudley has it right. I originally had my non bladder tank on the floor and didn't have a line hooked from air separator to top of the tank. I had to add air every month or so. I since raised the exp. tank and added a line from the separator to the top of the tank and I haven't had to add air since.

I have my vertical 120 gallon lp tank on the floor in my boiler room. I also have the problem of adding air occasionally.

My room isn't tall enough to get the tank completely above my boiler. I do not have a line connected to the top of my expansion tank to my air separator.

How much water do I need in the bottom of the tank if I lay it horizontal?

I am thinking I could build a metal stand and incorporate shelves under it to store kindling or wood.

I have actually considered getting rid of the non bladder tank, I can hear air at my pump at times and I think it is related to the non bladder tank set up.

gg

 

[kuribo]

Wouldn't a 120 gal bladder tank cost about 10X what the propane tank cost?

 

[goosegunner]

Wouldn't a 120 gal bladder tank cost about 10X what the propane tank cost?

The 120 gallon propane tank has proved to be more capacity than I need.

I just have a hunch that a bladder tank would be a lot more consistent once the initial air is removed from the system. I think it might be worth the extra expense. The 120 gallon propane tank would then be moved to my basement for a buffer tank right near my forced air furnace. It would also allow me to use it for DHW as remote storage makes it tough to use for DHW.

gg

 

[webie]

I guess my system shouldnt work at all . I have my boiler in my garage and storage in my garage , ran out of room there , so my expansion tank ( old water heater ) sits on the floor in my basement . I have no idea what the water height is in it . I just capped the hot and cold inlets , pulled out the drain and plumbed the expansion line in there . My sytem is about 7-8 lbs of pressure cold and about 15 fully hot . It works and thats good enough for me .

 

[maple1]

I believe ideal for non-bladder tank in your situation would be to place the expansion tank completely above the boiler.

On supply pipe leaving boiler would be an air-eliminator vented not to atmosphere but plumbed to a pipe that goes to the top of the expansion tank, followed by the near-boiler circulator, followed by the tee that feeds storage on one leg, and that feeds the return temperature protection thermostatic valve on the other leg. Then a small pipe going up from the return-from-storage line to the bottom of the expansion tank. This is essentially the same as the non-bladder tank above storage configuration, the key goal being to take any gas that comes out of solution when boiler water is heated and letting that gas rise up directly into the top of the non-bladder expansion tank.

Near-boiler circulator is moved up to boiler supply side to lower the pressure at air separator, and to tie the expansion device in on the suction side of the circulator.

[Edit:] Note that putting the pump on the supply line is the ideal pump location for this kind of setup, the normal location on the return side would probably be just fine so long as the air separator vents to the expansion tank.

I was thinking about this.

If the air eliminator is now not vented to atmosphere but now vented instead to what is basically system pressure on the air escape side - would it still work right?

 

[ewdudley]

I was thinking about this.

If the air eliminator is now not vented to atmosphere but now vented instead to what is basically system pressure on the air escape side - would it still work right?

Good point. According to the Bell & Gossett sheets on these types of systems, the diameter of the pipe that takes the bubbles away has to be large enough so that the bubbles will rise freely and not bridge the pipe.

 

[webie]

This may be right or wrong but this is how I plumbed mine with storage in the back of my garage and my expansion tank ( old water heater ) is sitting on the basement floor . From my boiler in the back of the garage my supply rises to ceiling height . About 6 feet from my boiler the 1-1/4 tees to two 1-1/4 one feeding my zones and the other to storage . Shortly after the line goes to storage I have a 1-1/4 x1-1/4 x 1/2 T with the 1/2 going up about 1 inch then running directly under my up stairs floor joists . This line is about 1 inch higher than my supply line . From there it runs down my one wall across part of my basement ceiling and then down to the bottom of my expansion tank in the basement . All of my pressurized storage is on the same level as my boiler . I just was out of room there , and the expansion tank fit perfect in a dead spot right in the corner by my sump pump . I did not do anything special , capped the hot and cold inlets , pulled the water heater drain and teed into that and retained the drain for it . I figured I didnt need no water height sight tube thingy . If the pressure goes up I will just drain it . So far everything has been running perfect 7-8 lbs of pressure cold and about 15 hot .
I see no reason that a non bladder expansion tank has to be above your storage in a pressurized system .