Pressure / Expansion Tank

Users who are viewing this thread

Messages
51
Reaction score
1
Points
8
Location
Westchester, NY
Hi folks, I had a plumber in this morning looking at what it would take to run a dedicated cold line to feed my second floor. Right now it's a single line that feeds both floors. While he was there he said that I should have a small pressure/expansion tank on my water heater. It's a common 40 - 50 gal electric water heater. We don't have a hot water pressure issue.

My question is, - what is the function/purpose of this pressure tank on the water heater, and why would I need it? I don't believe I do, but don't want to overlook anything.

(I will be changing out my well tank soon as the bladder is leaking, and either putting in the same again or going with the Cycle stop system - have not decided yet)

thanks everyone.
 

John Gayewski

In the Trades
Messages
4,352
Reaction score
1,344
Points
113
Location
Iowa
If your water heater is isolated from your cold water supply line with any type of one way valve then when the water is heated it will expand. When it expands it needs a place to go. Whether you need one or not depends on the components piped into your system.
 

LLigetfa

DIYer, not in the trades
Messages
7,507
Reaction score
579
Points
113
Location
NW Ontario, Canada
Unless there is a check valve between the hot water tank and well pressure tank, the well pressure tank will absorb thermal expansion negating the need for an expansion tank.
 
Messages
51
Reaction score
1
Points
8
Location
Westchester, NY
If your water heater is isolated from your cold water supply line with any type of one way valve then when the water is heated it will expand. When it expands it needs a place to go. Whether you need one or not depends on the components piped into your system.
Thanks @John Gayewski. My only check valve is before the well tank. The cold water supply line comes from well tank supply line and does not have any valves of any type. SO i guess any expansion is forced back into the well tank?
 

John Gayewski

In the Trades
Messages
4,352
Reaction score
1,344
Points
113
Location
Iowa
Thanks @John Gayewski. My only check valve is before the well tank. The cold water supply line comes from well tank supply line and does not have any valves of any type. SO i guess any expansion is forced back into the well tank?
Yeah, so you don't need an expansion tank. He probably just got mixed up.

I also think it's incorrect to have one right before the pressure tank. You should have one down in the well at the pump.
 

LLigetfa

DIYer, not in the trades
Messages
7,507
Reaction score
579
Points
113
Location
NW Ontario, Canada
I also think it's incorrect to have one right before the pressure tank. You should have one down in the well at the pump.
I concur. There should not be any check valve above ground unless a snifter (airmaker) is used in conjunction with a HP tank. In fact it is illegal in many states (rightfully so) as it can facilitate drawing in contaminated surface water.
 
Messages
51
Reaction score
1
Points
8
Location
Westchester, NY
I concur. There should not be any check valve above ground unless a snifter (airmaker) is used in conjunction with a HP tank. In fact it is illegal in many states (rightfully so) as it can facilitate drawing in contaminated surface water.
@LLigetfa @John Gayewski That's interesting, this is how it's been installed for 20 years. How does the location of the check valve lead to drawing in surface water? My wellhead/cap is in my driveway, pretty sealed, and 185 ft deep, with a submersible pump. its not in a location that ever would have standing water. Is it something I need to change?
 

LLigetfa

DIYer, not in the trades
Messages
7,507
Reaction score
579
Points
113
Location
NW Ontario, Canada
@LLigetfa @John Gayewski That's interesting, this is how it's been installed for 20 years. How does the location of the check valve lead to drawing in surface water? My wellhead/cap is in my driveway, pretty sealed, and 185 ft deep, with a submersible pump. its not in a location that ever would have standing water. Is it something I need to change?
You might have a ticking time bomb. The lower check valve requires pressure against it for it to seal and the topside check valve prevents that. If the lower check doesn't seal, the water column can drop leaving a partial vacuum at the top. When the pump starts, the column slams into the top check creating water hammer which over time can cause a leak to develop in the pipe between the wellhead and the house. Contaminated ground water can then be sucked in through that leak.
 

Reach4

Well-Known Member
Messages
38,877
Reaction score
4,431
Points
113
Location
IL
@Reach4.. Lol.. are you saying it should go?
No. I had made a comment that I realized had already been covered by previous replies. So I wanted to delete my post, but there is no button to do that. I should probably decided on a different thing to edit my post to, such as "retracted post" .
 
Messages
51
Reaction score
1
Points
8
Location
Westchester, NY
No. I had made a comment that I realized had already been covered by previous replies. So I wanted to delete my post, but there is no button to do that. I should probably decided on a different thing to edit my post to, such as "retracted post" .
ha, no worries.. thanks
 
Messages
51
Reaction score
1
Points
8
Location
Westchester, NY
You might have a ticking time bomb. The lower check valve requires pressure against it for it to seal and the topside check valve prevents that. If the lower check doesn't seal, the water column can drop leaving a partial vacuum at the top. When the pump starts, the column slams into the top check creating water hammer which over time can cause a leak to develop in the pipe between the wellhead and the house. Contaminated ground water can then be sucked in through that leak.
@LLigetfa ...interesting. I have terrible water hammer. I replaced the check valve by the well, and it eased it a little, but not gone. I also have an issue with my well tank where the bladder is losing pressure. I am considering the CSV solution, as an alternative. But I guess I need to call my well guy to see how they originally installed this and to confirm there is a check valve down below also. He is trying to sell me a 6K new tank install so he may just blame that on the continuous water hammer ....
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks