# does my well pressure tank eliminate the need for an expansion tank on water heater ?



## RustyShackleford (Jun 22, 2020)

Title pretty much says it all.   Apparently the issue is whether or not there's a "check valve" between the house plumbing and the pressure tank proper; that's a one-way valve, and if it's in the whole place, it'd prevent pressure surges from being absorbed by the well pressure tank, and so an expansion tank _would_ be needed on the water heater.  

The thing is, I can't tell if I have a check valve, and if so, where it is.   Is there a way to test ?   Is it apparent from this photo ?   In the photo, the black pipe (leading off to the left) goes to the submersible well pump.   The copper pipe (leading off to the right) is the house water supply.    The green-handled faucet is the shutoff for the house water.    The crufty faucet is just a hose bib (especially for water access when the house supply is shutoff for repairs).   So the question is, do I have a check-valve, and if so, is it that bulge between the well pipe and the pressure gauge, or is in that pipe that tees off of the pipe between the pressure gauge and the pressure switch and leads to the pressure tank proper ?   Only in that last case would I need an expansion tank on the water heater, if I understand correctly.

EDIT: When I google "check valve for well" many of the results look almost exactly like the "bulge" that you see in my photo, between the well pipe and the pressure gauge.   So I'm pretty optimistic that is indeed my check valve, so there's a clear path between the water heater and the pressure tank, and so I don't need an expansion tank on the water heater.   Make sense ?    Of course there are two shutoff valves between the water heater and the pressure tank - the main house shutoff in my photo, and one I put on the cold water inlet to the water heater, so be able to isolate the hot water system.   I don't think these matter, as neither would be closed during normal operation.


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## blades (Jun 22, 2020)

Never had an expansion tank on a water heater with conventional ( Ng, LPg or electric)  heat source.


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## brenndatomu (Jun 22, 2020)

I've never seen an expansion tank on a well system unless someone had it installed to try and eliminate water hammer in their plumbing.
Your pressure tank is basically one  large expansion tank on the whole system.
As for the check valve...that "bulge to the left of the gauge" as you call it does appear to be one...


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## RustyShackleford (Jun 22, 2020)

blades said:


> Never had an expansion tank on a water heater with conventional ( Ng, LPg or electric)  heat source.


As opposed to solar ?    Is it more important for that ?


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## RustyShackleford (Jun 22, 2020)

brenndatomu said:


> Your pressure tank is basically one  large expansion tank on the whole system.


Exactly.   Unless there's a check valve in the way.


> As for the check valve...that "bulge to the left of the gauge" as you call it does appear to be one...


What I figured.   Thanks.


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## John Galt (Jun 23, 2020)

There is a check valve somewhere in your line or the water would drain back down to the pump. The brass bulge is it. The question sounds like you think you need another between the pressure tank and the house. No. If you do have another check valve then you would need an additional expansion tank also.  Code requires an expansion tank only if the system is closed, this absorbs excess pressure as the water heats. That second valve would make it a closed system and keep your well tank from absorbing that pressure.


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## zrock (Jun 23, 2020)

Where i live the expansion tank on the hot water is now in the building code.  everything has to have it they are cheap and easy to install


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## semipro (Jun 23, 2020)

Regardless of fuel source (electric, gas, etc.) any tank type water heater should have an external expansion tank unless the well pressure tank can act as one.  You don't appear to have a check valve between your WH and well tank so you should be okay.  There does appear to be a check valve in your photo but its located between the tank and well pump so it should not create a problem for the WH.


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## RustyShackleford (Jun 23, 2020)

zrock said:


> Where i live the expansion tank on the hot water is now in the building code.  everything has to have it they are cheap and easy to install


Actually there is one there now.   But a solder joint is leaking.    Gonna be very hard to re-solder it, so close to that big tank of water, and so close to the floor joists (it's in the crawl space).   So I was going to repair it with a Sharkbite fitting and prefer to just use a coupling - instead of a tee, with the weight of the expansion tank hanging from the press-in fitting.


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## Highbeam (Jun 24, 2020)

You can remote mount that little expansion tank away from the water heater. 

My home, on a well with 4 expansion tanks, also has the little one on the water heater because it is possible to shut a valve between the well expansion tanks and the water heater which would make it a closed system. Don’t you have a valve at your water heater on the cold line in?


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## sportbikerider78 (Jun 24, 2020)

That bulge is definitely a check valve.  There will also be at least one more in your well.

For plumbing...if there isn't a problem don't try to solve it.  
If you need to fix that leak, drain the entire system and sharkbite it and then put valves on the hot water heater at the same time.


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## RustyShackleford (Jun 24, 2020)

Highbeam said:


> You can remote mount that little expansion tank away from the water heater.
> 
> My home, on a well with 4 expansion tanks, also has the little one on the water heater because it is possible to shut a valve between the well expansion tanks and the water heater which would make it a closed system. Don’t you have a valve at your water heater on the cold line in?


Yeah, there are two valves between the well pressure tank and the water heater: the main shutoff valve (shown in my photo) and the one on the cold line into the water heater.   I would never close either during normal conditions though.  I always make a point of turning off the water heater breaker when I turn off the well pump breaker (before a long trip), and don't actually close the main shutoff at all.   I'd only close the valve AT the water heater when I'm going to work on the water heater or the hot water pipes.  Would it still be a problem ?  I guess one could imagine a scenario where I need to work on hot-water pipes, turn off the valve, don't bother turning off the water heater, and don't start cutting into the hot-water pipes right away, and ...  An actual safety issue ?  I imagine the P&T valve would take care of any serious overpressure.   Googling, it looks like it's more an issue like high blood pressure, that it can cause chronic damage to valves and such; if that's the case, then I imagine my well pressure tank is good enough (and I could remove the one at the water heater).

But that's a good point that the expansion tank doesn't need to be right AT the water heater.   Anywhere in the hot-water pipes could suffice, I imagine, as long as there's no valve between there and the water heater.


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## RustyShackleford (Jun 24, 2020)

sportbikerider78 said:


> That bulge is definitely a check valve.  There will also be at least one more in your well.


Thanks.



> For plumbing...if there isn't a problem don't try to solve it.


Are you saying that a leaky solder joint is NOT a solder joint that's more likely to fail ?   Because it's a VERY slow leak, I wouldn't be worrying about it just because of that.


> If you need to fix that leak, drain the entire system and sharkbite it and then put valves on the hot water heater at the same time.


There's already a valve on the cold-water line coming in to the water heater, just before the expansion tank and the water-heater itself - so that's good.  Sharbkbite can be installed without things being dry, right ?   Can a Sharkbite "tee" be trusted to hold the weight of the expansion tank ?


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## brenndatomu (Jun 24, 2020)

RustyShackleford said:


> Can a Sharkbite "tee" be trusted to hold the weight of the expansion tank ?


Many people think that SharkBite fittings can't be trusted at all...only use them for temporary repairs, or somewhere that failure would not be catastrophic.
Only time I personally have ever used one was in a place where once everything was assembled, the line could not blow apart because of a nearby floor joist...and that is how they fail, they let the pipe come out.
As far as small leaks with them, if you prep the pipe and install the SB fitting correctly, it won't leak...so coming apart is your only possible failure then.


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## RustyShackleford (Jun 25, 2020)

brenndatomu said:


> Many people think that SharkBite fittings can't be trusted at all...


Well, I've got one on my main water line (you can AMOST see it in the photo above).

But the weight-bearing thing is troubling - actively TRYING to pull it apart.    I realized I can buy one of those adapters that's NPT at one end and PEX at the other, and solve the problem that way (that I was stuck with copper coming out of the water heater that I couldn't solder onto, and couldn't even really screw in a new "L", the hot water pipe being in the way).


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## maple1 (Jun 29, 2020)

John Galt said:


> There is a check valve somewhere in your line or the water would drain back down to the pump. The brass bulge is it. The question sounds like you think you need another between the pressure tank and the house. No. If you do have another check valve then you would need an additional expansion tank also.  Code requires an expansion tank only if the system is closed, this absorbs excess pressure as the water heats. That second valve would make it a closed system and keep your well tank from absorbing that pressure.



My check valve is down my well. The foot valve.


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## sportbikerider78 (Jun 29, 2020)

RustyShackleford said:


> Well, I've got one on my main water line (you can AMOST see it in the photo above).
> 
> But the weight-bearing thing is troubling - actively TRYING to pull it apart.    I realized I can buy one of those adapters that's NPT at one end and PEX at the other, and solve the problem that way (that I was stuck with copper coming out of the water heater that I couldn't solder onto, and couldn't even really screw in a new "L", the hot water pipe being in the way).


I'm with you...doesn't seem like a great idea to hang a tank with a sharkbite tee.  Personally, I wouldn't have any problem doing it with a vertical peice of tubing, but not horizontally mounted tank.  
What I was saying about don't fixing plumbing if there isn't an issue...was this.  Fix the leak, but unless there is a need for the expansion tank, why install one?


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## RustyShackleford (Jun 29, 2020)

sportbikerider78 said:


> What I was saying about don't fixing plumbing if there isn't an issue...was this.  Fix the leak, but unless there is a need for the expansion tank, why install one?


Oh ok.   Yeah, I think I'm with you.  I'm convinced that, under normal operating conditions, pressure spikes in my water heater can be absorbed by the well's pressure tank (which sits in the crawlspace, only about 10ft of piping removed from the water heater, and with no check valve in the way).   Yes, with the shutoff for hot water closed, or the main shutoff valve closed, the water heater is isolated from the well pressure tank; but that's obviously abnormal conditions, and in particular I'm going to turn the water heater circuit-breaker off in any of those modes (working on the hot water system, or going out of town, respectively).   And if for some reason I don't, I don't expect catastrophic results; if it went on for awhile, it'd be like high blood pressure, causing gradual damage to faucets and such.   Also, the house being completely plumbed with PEX (and some old polybutylene in the walls, yikes !!) I think its flexibility (compared to copper) might absorb some pressure spikes as well.

So I'm going to eliminate the expansion tank, and just fix the leak, using one of those adapters that has NPT threads at one end and a PE barb at the other end.


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