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Author Topic: Expansion tank on storage tank  (Read 125 times)

dukethebeagle

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Expansion tank on storage tank
« on: March 10, 2019, 03:58:54 PM »

Been a while since ive posted
But i have an issue
My 300 lbs storage tank seems to be building pressure
It is below the level of the boiler outside
I seem to think it looks ''bulkier'' then before
I changed out the tank this year for a new one
I batch burn twice a day
My boiler is vented outside
But my storage tank is not really vented
Just the line going out to boiler .
So do i need an expansion tank on the storage.
Or should i just vent it outdoors higher then the boiler
I had no problem with my old tank.
But like i said it seems to be bulkier
Thnx guys
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E Yoder

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Re: Expansion tank on storage tank
« Reply #1 on: March 11, 2019, 04:21:44 AM »

So it sounds like it basically has a water column above it. How high? What's the tank made of and what shape?
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dukethebeagle

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Re: Expansion tank on storage tank
« Reply #2 on: March 11, 2019, 04:56:28 AM »

Aboute 6 foot above and a repurposed 275 oil tank
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RSI

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Re: Expansion tank on storage tank
« Reply #3 on: March 11, 2019, 06:19:29 AM »

What model pump do you have and is it pushing towards the tank?

An expansion tank will do nothing on an open system. A large pump before the tank and restrictions after the tank could cause the pressure to bulge the tank.
I was not able to find pressure ratings on oil tanks other than to not test above 5 psi.
A large pump could get the pressure to near 20 psi if the system gets blocked completely after the tank. (close valve, plugged hx, etc)

If you have a small pump you are probably fine. If it is a larger pump, I would think about replacing it with two smaller pumps, one before and one after the tank.
Or just get rid of the tank if it isn't necessary.
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greasemonkoid

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Re: Expansion tank on storage tank
« Reply #4 on: March 11, 2019, 03:03:01 PM »

I would put a 0-15 psi gauge on there and move the pump after the tank if it maxes out. Take note of the static pressure (all pumps off) and pump running readings. Wouldn't want dynamic line pressure to be much less than static.
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dukethebeagle

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Re: Expansion tank on storage tank
« Reply #5 on: March 11, 2019, 06:27:09 PM »

Taco 009
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RSI

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Re: Expansion tank on storage tank
« Reply #6 on: March 11, 2019, 09:31:02 PM »

If you need to keep the tank, I would move the pump to after the tank and if you need a pump to get the water to the tank from the boiler, put a 007 in for that.

That 009 could possibly build enough pressure to rupture the tank if something downstream gets plugged. (this is assuming it is a regular oval type tank that is not meant for pressure)
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dukethebeagle

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Re: Expansion tank on storage tank
« Reply #7 on: March 12, 2019, 04:33:58 AM »

I got a bunch of pump lying around.one 007 before and one 007 after.
I can swap out the 009
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dukethebeagle

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Re: Expansion tank on storage tank
« Reply #8 on: March 12, 2019, 06:41:06 PM »

I put on a grundfos 15 58 before the tank tonite
Set it on 1st gear
Gotta get a flange to put a pump after the tank
Gotta put on a 007 after the tank
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RSI

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Re: Expansion tank on storage tank
« Reply #9 on: March 12, 2019, 08:48:58 PM »

If you are going to do 2 pumps, you would probably want the high head pump after the tank and a low head pump before. A 007 can only produce about 4 PSI which is why I suggest that before the tank. A Grundfos 15-58 can produce over 6psi on low which is still probably ok. Those pressures are assuming a complete blockage in the line after the pump.

Did you ever mention what else is in the system? Length of pipe, heat exchangers, etc?
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