Well and Hot Water Expansion Tank

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Mr_Magoo

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I live where we are governed by UPC. I have a standard well system (not constant pressure) that operates between 30-50psi. The system is closed because there is a check valve where the water supply enters the house. Does my hot water heater need a small expansion tank? Isn't the well tank an expansion tank? The only way I could see needing the small expansion tank at the hot water heater is if there was a check valve on the cold water supply to the hot water heater. I recently rented a house with a similar standard well system and it had an expansion tank on the hot water heater. If I do need a small expansion tank on the HWH, what pressure do I set the expansion tank at 30 or 50psi?

Thanks,
Mike
 
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Yes, you need the expansion tank on the water heater. Where we're located, the check valve into the house is not required and the heated water can expand back into the well pressure tank. But, if you have a check valve on the water line as it enters the house, you're preventing any expansion back to the well pressure tank and you need the expansion tank at the heater. Most exp. tanks are pre-set at 40psi. I'm sure many here would change depending on the pressure switch settings at the well equipment but not me, I'd leave it at the 40, it'll do it's job.
 

Mr_Magoo

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But, if you have a check valve on the water line as it enters the house, you're preventing any expansion back to the well pressure tank and you need the expansion tank at the heater.

Thanks for your response. In my case, the well expansion tank is in my basement downstream from the check valve. So, the hot water heater is connected directly to the well tank.

Mike
 

Cass

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If the bladder tank is on the house side of the check valve it will take care of the expanded water...if the bladder tank is on the well side of the check valve then you would need an expansion tank...
 

Mr_Magoo

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If the bladder tank is on the house side of the check valve it will take care of the expanded water
The bladder tank is on the house side. Thanks for your help.
 

NHmaster

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The UPC and the IPC do not differentiate between a well system and city water supply where installation of a thermal expansion tank is required.
 

Mr_Magoo

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The UPC and the IPC do not differentiate between a well system and city water supply where installation of a thermal expansion tank is required.

My question is does my 120gallon bladder tank qualify as a thermal expansion tank? In my opinion it should, but I am not a plumber.
 

NHmaster

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Does your 120 gallon water tank say "thermal expansion tank" on it anywhere?
 

Mr_Magoo

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Does your 120 gallon water tank say "thermal expansion tank" on it anywhere?
No, it does not. It is a standard well bladder tank.

I am starting to get the feeling that there is not a consensus on this subject.

IMO, If I put a small expansion tank on my HWH and set it a 50psi, it is never going to do anything except take up space and rust. Any expansion of the HWH water is going to be absorbed by the 120 bladder tank. But, the code might dictate that I have this decoration in my system and that is the question I am trying to get answered.
 

NHmaster

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I believe that you did indeed answer your own question. However stupid some of these things seem (read my signature) they are still a requirement. It's a lot like spending the day at the DMV.:rolleyes:
 

Toolaholic

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He makes a good point Master. Expansion tanks arn't required everywhere!
I think they are in Wash state.
 

NHmaster

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The IPC requires them as does the UPC and the Nat Std code but after that I can't say. By the way your local jurisdiction may ammend the requirements of the state adopted code but only to the effect of making the requirement more stringent not less. So if your state code is ipc and the local inspector says he doesn't want an expansion tank, he's wrong and his ruling will not hold up in court. Doesn't happen very often because most towns and cities don't want to be bothered with the legal implications of implimenting their own codes.
 

MACPLUMB

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Hot Water Expansion Tank

I Disagree With Nh Master On This Issue,
I Think If You Want His 120 Gal. Well Tank To Be Approved As Thermal
Expansion All He Has To Do Is Get A Stencil Kit And Paint It On
The Side Of His Well Tank
The Point Is The Physical Construction Of Both Tanks Is The Same As
They Are Both Made For Potable Water To Expand Into
So As Long As There Is "no" Check Valve Between The Two I Think It Would Be Approved For That
 

NHmaster

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Hate to argue with you but I'll bet you can't find stencling the tank in the code book nor can you find an astm or any other approval for use as a thermal expansion tank on the well tank. It's all about liability baby.
 

Rotaris

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The pressure on the expansion tank Should be set to 50.
I would like to know "why set at 50psi" I set mine to 60 and pressure still climbs to 70? I am having a hard time figuring out the "why's" It does not make sense to me? Well pressure switch is set to 40-60psi. Check valve is in my iron filter head.
 

Reach4

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I would like to know "why set at 50psi" I set mine to 60 and pressure still climbs to 70? I am having a hard time figuring out the "why's" It does not make sense to me? Well pressure switch is set to 40-60psi. Check valve is in my iron filter head.
No big deal. It can climb to 100 and more without a problem for a dedicated thermal expansion tank.. You want it to not get close to the 150 where the pressure relief kicks in.

You get the maximum effect from the tank if you set it to the highest pressure for your water supply. So with 30/50, then 50 would be optimum. If 40/60 pressure switch setting, go 60.

If you have a softener, there is additional consideration.
1. You don't want hot water getting the softener hot. So having some length and volume of pipe between the softener and the WH can let the water cool before expanding into the softener.
2. Water expanding into the pressure tank due to thermal expansion will register as flow (phantom flow). I do that. Small amount of extra flow is recorded by the softener, if your calculations are that critical.

To avoid #1 and #2 totally, add a check valve at the output of the softener, and add a thermal expansion tank. I don't do that.
live where we are governed by UPC. I have a standard well system (not constant pressure) that operates between 30-50psi. The system is closed because there is a check valve where the water supply enters the house.
With a submersible pump, you don't normally want such an above-ground check valve. With a shallow well (suction) pump, you would like the check valve to be as close to the intake as practical. Ideally it would be down the well. A foot valve is a check valve and strainer combined.
 

Rotaris

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Thanks Reach, I started a new thread. Just to be more clear, I do have a Expansion tank installed. I also do not want my pressure going over 60psi or so on old Poly B lines in the house. Why does the Expansion tank not take up the Pressure over 60psi its hurting my brain! lol

Maybe I am staring at to much and it will be a difference in gauge pressures....likely just goes a few psi over because of this....wow over thinking as usual.
The check valve is in the clack valve body, came with the system
 

Reach4

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iuyiuy
Thanks Reach, I started a new thread. Just to be more clear, I do have a Expansion tank installed. I also do not want my pressure going over 60psi or so on old Poly B lines in the house. Why does the Expansion tank not take up the Pressure over 60psi its hurting my brain! lol
With no water heater at all, the pressure can go to 60, right? So at that point, the pressure has to go higher than 60 when the WH runs and you are not using water.

If you wanted to keep the pressure at 60 max, maybe adjust the pressure switch to 30/50, and get a bigger thermal expansion tank. Or if 30/5o is too low, how about 35/55. Adjust both precharges when you adjust the pressure switch.

Piping is supposed to take over 150 psi.

Poly B was supposed to have its problems when used with chlorinated water.
 
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