Pressure tank help

[Huskurdu]

I would like to know what people are using for expansion tanks on their boiler systems with storage. I've got about 560-600 gallons total system water and need to figure out how to 'cost effectively' control my system pressure. In my previous thread I stated that the T/P valve leaks on my gas boiler when the system pressure exceeds 30 lbs (usually when system temp is over 170 degrees....obviously this is what it is supposed to do.....and obviously it is because my two pressure tanks only equate to ~10 gallons of pressurized storage....I need to get up around 44-50 gallons of storage. Should I put smaller tanks in series, if so, how? Should I spend the son's college money and by one single unit? Or is there another way?

 

[RJP Electric]

I remember your other post, you have a Extrol 60 screwed onto your airscoop on your wood boiler(way too small). It dosent make economic sense to have a bunch of these in series hanging from your ceiling because the cost will be equal or greater to just a larger floor model like a SX-60V or SX-90V, I would just pipe out of the airscoop to a floor model

 

[Huskurdu]

I remember your other post, you have a Extrol 60 screwed onto your airscoop on your wood boiler(way too small). It dosent make economic sense to have a bunch of these in series hanging from your ceiling because the cost will be equal or greater to just a larger floor model like a SX-60V or SX-90V, I would just pipe out of the airscoop to a floor model

The SX-60V is about $170 dollars cheaper than the SX-90V on Pexsupply.com....do you think that it would be ok for my system? It seems that people's opinions and calculations seem to vary....I suppose the worst case scenario would be that I might have to put the Extrol 60 back in the system in series if the SX-90V didn't work.....what do you think? Thanks for your input.

 

[leaddog]

I'm using a 250gal propane tank for an expansion tank for 2200gal of storage. It works very well. I just piped it into the bottem an the air is trapped inside like they used to do with water systems. I have a air valve in the top if I have to add air but so far it hasn't moved atall. I haven't even insulated it yet as very little hot water flows thru it.
leaddog

 

[2.beans]

i have two 90s ,3 60s , and one thirty. i did this in case one fails i can shut it off with the ball valve and change it without shutting down the system. ive hooked up two other systems with 500 gallons storage and used 2 90s and the original tank and have had no problems. two 90s gives about 28 gallons of expansion i believe.

 

[RJP Electric]

I do have a SX-60V, with 500 gallons storage. 35 gallons in the biomass plus whatever is in the pipes. Awfully similar to your setup. I used this calculator. 550G, 60º-180º=24.0 G diaphragm tank.

 

[Huskurdu]

I do have a SX-60V, with 500 gallons storage. 35 gallons in the biomass plus whatever is in the pipes. Awfully similar to your setup. I used this calculator. 550G, 60º-180º=24.0 G diaphragm tank.

I attempted to use a calculator on one of the web sites and came up with the SX-90V....but I don't have a ton money lying around to spend, so I'm going to try your set up. Worst case, I hook up the Extrol 60 again if the 90V is not enough. If yours works, probably mine will. Someone made a general statement long ago in one of the previous threads that "it will work, it's just a matter of how well it will work". I am finding those words very valuable. Thanks.

 

[Huskurdu]

I'm using a 250gal propane tank for an expansion tank for 2200gal of storage. It works very well. I just piped it into the bottem an the air is trapped inside like they used to do with water systems. I have a air valve in the top if I have to add air but so far it hasn't moved atall. I haven't even insulated it yet as very little hot water flows thru it.
leaddog

Money is tight, so I tried adding pressurized air to my 500 gallon storage and it worked perfectly. Obviously I'll have to put a pressure tank in in the future and take the air out of the storage tank, but I won't have to do it right now. I couldn't believe what a difference it made. @170 degrees it would have over 30 lbs of pressure and make my gas boiler's T/P valve leak. Now I've taken it to 195 degrees with no problems. Thanks for the idea.

 

[steam man]

I wonder how much adding air to a pressurized storage system affects the advantage of pressurized storage by not having to deal with the effects of O2 in the system. Surface area and temperature will affect how much the O2 degrades iron based system components. It made me wonder how using a bottle of nitrogen gas to displace the air would work as far as cost is concerned. Just thinking.

Mike

 

[Huskurdu]

Now that i've had a chance to install the SX-90V and remove the pocket of air out of the 500 gallon storage tank, here is my take on that. Putting an air pocket in the tank works, but it is certainly now ideal. I had to continually bleed air out of the system. I have 2 air scoops and several air purgers/eliminators/bleeders and they always had a little air hiding in them. With the expansion tank (with a bladder) this no longer occurs.
I see a lot of people using bladderless expansion tanks and wonder how often they have to replenish that air??? Maybe because the surface area between the water and air is less it makes a difference??? hmmm

 

[in hot water]

those bladder-less expansion tanks typically had a fitting like this B&G;. Follow a link that explains how the airtrol fitting works.

www.bellgossett.com/literature/files/599.pdf

 

[overshot]

I wonder how much adding air to a pressurized storage system affects the advantage of pressurized storage by not having to deal with the effects of O2 in the system. Surface area and temperature will affect how much the O2 degrades iron based system components. It made me wonder how using a bottle of nitrogen gas to displace the air would work as far as cost is concerned. Just thinking.

Mike

If I am following you correctly, you are talking about a air over water pressure system and replaceing it with nitrogen over water.

I think you would get seltzer water. :lol:

 

[sdrobertson]

I see a lot of people using bladderless expansion tanks and wonder how often they have to replenish that air??? Maybe because the surface area between the water and air is less it makes a difference??? hmmm

I haven't had to add any air yet but I'm using a 330 gallon tank and I have it filled about half way with water. I had to add air to my old well water tank before I replaced it with a bladder tank but it was only 40 gallons or so and the water flowed in and out many, many times but with the boiler, I seem to just move the water inches so I think this may also have an effect on air absorption.

 

[steam man]

I wonder how much adding air to a pressurized storage system affects the advantage of pressurized storage by not having to deal with the effects of O2 in the system. Surface area and temperature will affect how much the O2 degrades iron based system components. It made me wonder how using a bottle of nitrogen gas to displace the air would work as far as cost is concerned. Just thinking.

Mike

If I am following you correctly, you are talking about a air over water pressure system and replaceing it with nitrogen over water.

I think you would get seltzer water. :lol:

N2 or nitrogen is inert. Won't hurt anything. CO2 is used in carbonated water production. I made a carbonated beverage maker out of a CO2 fire extinguisher once. Worked good. CO2 will make things acidic though-carbonic acid would be bad for steel.

Mike

 

[overshot]

I wonder how much adding air to a pressurized storage system affects the advantage of pressurized storage by not having to deal with the effects of O2 in the system. Surface area and temperature will affect how much the O2 degrades iron based system components. It made me wonder how using a bottle of nitrogen gas to displace the air would work as far as cost is concerned. Just thinking.

Mike

If I am following you correctly, you are talking about a air over water pressure system and replaceing it with nitrogen over water.

I think you would get seltzer water. :lol:

N2 or nitrogen is inert. Won't hurt anything. CO2 is used in carbonated water production. I made a carbonated beverage maker out of a CO2 fire extinguisher once. Worked good. CO2 will make things acidic though-carbonic acid would be bad for steel.

Mike

Beverages get the fizz from being saturated with a gas under pressure. When the pressure is released it comes out of the beverage and creates bubbles. The trick is finding a gas that comes out of the solution fast. CO2 and Nitrogen both fall into that catagory. Air dosent.

I think the new "rage" in beer making is Nitrogen to replace the CO2.