Expansion Tank Question


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Old 05-07-11, 06:17 AM
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Expansion Tank Question

Hi,

I currently have a Bock oil fired hot water heater. It's being replaced with a GE electric Hybrid unit (heat pump). Anyway, the Bock has been in operation for 20 years with no expansion tank. The relief valve has never leaked either or discharged. In GE's installation instructions it shows an expansion tank in the cold water line. Do I need to install one with the new unit? If the pressure became to great in the tank wouldn't the relief valve do its thing? I also have an expansion tank on my boiler, not sure that matters.

Thanks in advance.
 
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Old 05-07-11, 07:35 AM
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I also have an expansion tank on my boiler, not sure that matters.
Two seperate animals.

Anyway, the Bock has been in operation for 20 years with no expansion tank. The relief valve has never leaked either or discharged. In GE's installation instructions it shows an expansion tank in the cold water line. Do I need to install one with the new unit?
If you have a closed system you need a expansion tank. A closed systen is when you have a pressure reducing valve where your incoming water is. If this is installed the street pressure is high and needs to be reduced for the home. When the water heater heats up the water expands. Normally the expansion would push back out towards the street, but with a reducer on the main it cant. So a expansion tank takes up the expansion.

Now even with out a pressure reducing valve I recommend a expansion tank on all water heaters. Its easier to expand to the tank then to the street IMO.

Now if you do install the expansion tank make sure you set the air pressure to what your house pressure is. This is the proper way. Add the air to the tank befor you install it. They are preset to 40 psi I believe.

Example: If your home has 60 psi put 60 psi in the tank. You can do this with a bike pump. There is a schrader valve on the tank.

To check home pressure they sell a gauge that attaches to you outside hose bib. They sell them at the home stores in the irrigation, or plumbing dept.

Please post back when you install the unit. People would like to know how well they work. How quiet is it? etc.......

Its good to check the tank at the boiler once a yr also. You need to bleed of the pressure at the boiler. That tank should have 12-15 psi.


Good luck.

Mike NJ
 
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Old 05-07-11, 10:31 AM
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I will post about the install and operation. What size expansion tnak do you suggest?
 
 

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