Do I need an expansion tank?

Dear Readers,
I've a new oil-fired boiler with an indirect water heater. The boiler loop has an expansion tank. The domestic hot water does not. I have well water (bladder tank located 50+ft away from the boiler). Do I need an expansion tank on my domestic hot water? The plumber who installed said I don't need one, but I'm concerned.
All comments appreciated. Thank you. Anthony M. Falcone
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I think people started needing expansion tanks on water heaters when muncipal water supplies added check valves to stop contanimation of the water system. Since you don't have a check valve to prevent backflow, I don't see why you would need one.

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Don't you think his water system has a check valve?
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It probably has at least one at the well, but if he has a bladder tank between the hot water tank and the well, that should allow for all the expansion necessary.
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There is no existing check valve between the bladder tank and the indirect water heater domestic intake. You confirmed my suspicion that the house bladder tank acts as an expansion tank for the domestic water system.
Thank you all very much for your comments.
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I don't know of many that do. Mine certainly does not. Not in my last house either. Or the one before that. Why do you think he has one?
Backflow preventers are relatively new in residential applications also. I have four in my commercial/industrial buildings, none in residential.
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Yes & in some areas, backflow prevention is handled only at hose bibs & dishwashers via individual devices.
My neighbor had a city permitted / inspected re-pipe & now has vacuum breakers at the hose bibs.............no check valve & thus no need for an expansion tank.
cheers Bob
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Perhaps because he is on a well and I have never seen or heard of a well system without one. The footvalve _is_ a checkvalve and if it is a submersible, the checkvalve is built in. If there wasn't one, the pressure tank would empty back into the well every time the pump shut off.
Harry K
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:-)
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The check valve in a well system would be between the punp and the bladder tank. Not the bladder tank and house water pipes. So he doesn't need an expansion tank for the water heater.

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I believe that was explained earlier.
Harry K
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He indeed doesn't need one, but that's not the reason.
He doesn't need one because the pressure tank for the well serves the same purpose.

--
Regards,
Doug Miller (alphageek at milmac dot com)
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snipped-for-privacy@yahoo.com wrote:

Trust the plumber.
You don't need one for the domestic hot water because the pressure tank for the well will accomodate any expansion from the water heater.
You *do* need one for the boiler, even though you have a well, because there's a check valve between the boiler and the pressure tank. You may not be aware that you have a check valve, but you do: the pressure reducing fill valve at the boiler is a one-way valve, to prevent the possibilty of contaminating the potable water supply with a backflow from the heating system (e.g. in the event of a catastrophic loss of pressure in the potable supply).
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Regards,
Doug Miller (alphageek at milmac dot com)
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wrote:

Or if you shut the water off to make repairs...
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