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High water pressure; Moen cartridge

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Peabody

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Jun 22, 2022, 9:38:18 PM6/22/22
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I recently downsized into a condo, and sensing that the water pressure
might be a bit high, today I bought a water pressure gauge from Home
Despot, and got a reading of 90psi at an outside hose faucet. The condo was
built in 1980, and I assume the pressure has been high ever since, although
of course I don't know for sure.

I'm thinking about putting in a pressure regulator to bring it down to
about 60psi, which would give me low-to-mid 50s at the second floor
showers. Does anyone here have experience with these regulators? Is it
possible that reducing the pressure after all these years might actually
induce leaks? Are there any other downsides to these regulators?

I also need to replace a Moen 1200 cartridge that been there since 1980. I
understand that getting the old one out after all this time can be quite an
adventure, but what I haven't seen on Youtube is anyone using heat to help
with that - a hair dryer, or even a propane torch. Seems like heat would
help a lot. Has anyone here tried that?

Ed Pawlowski

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Jun 22, 2022, 10:25:02 PM6/22/22
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Regulators are common and work well. I miss the 110# we had where I
worked.. Curious why you want to reduce it after 40 years?

No idea about the cartridge.

Peabody

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Jun 22, 2022, 10:39:06 PM6/22/22
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Ed Pawlowski says...

> Regulators are common and work well. I miss the 110# we
> had where I worked.. Curious why you want to reduce it
> after 40 years?

Well, when I Google the issue, and watch relevant Youtube
videos, they all say that normal residential pressure is
40-60psi, and that maybe 70psi is acceptable, but that
higher values put strain on the plumbing system and
appliances connected to it, and that a pressure regulator
should be used. But I just wondered if there's another side
to this story.

> No idea about the cartridge.

It just seems the extra heat would expand the housing the
cartridge fits into, and that would make it easier to
remove.

Marilyn Manson

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Jun 23, 2022, 9:30:30 AM6/23/22
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On Wednesday, June 22, 2022 at 9:38:18 PM UTC-4, Peabody wrote:
> I recently downsized into a condo, and sensing that the water pressure
> might be a bit high, today I bought a water pressure gauge from Home
> Despot, and got a reading of 90psi at an outside hose faucet. The condo was
> built in 1980, and I assume the pressure has been high ever since, although
> of course I don't know for sure.
>
> I'm thinking about putting in a pressure regulator to bring it down to
> about 60psi, which would give me low-to-mid 50s at the second floor
> showers. Does anyone here have experience with these regulators? Is it
> possible that reducing the pressure after all these years might actually
> induce leaks? Are there any other downsides to these regulators?

I can't imagine how lowering the pressure could induce a leak.

The pressure from my water authority reads at 90-95 psi at my cold water
hose bibs.* I have a PRV set for about 55 PSI. Above 55 I tend to get some
water hammer when quick closing valves like on the dishwasher and washing
machine slam shut.

The common "wisdom" is that most household fixture aren't designed to
handle high pressure over the long term. OTOH, I've had licensed plumbers
tell me that that is a myth. In my case, I don't concern myself with that issue
because for me it's more about eliminating the water hammer.

* When I moved in 35+ years ago, the cold water hose bib at the front of the
house was (still is) plumbed before the PRV so that it is at full street pressure.
However, the rear hose bib was after the PRV, therefore at the lower pressure.
I tapped into the pipe to the front hose bib and provided street pressure to the
rear hose bib also. SWMBO was quite happy since it cut her watering time in
half. She loves her flower gardens.

I also added a hot water bib at the front. It's at the lower pressure of course,
but it's nice to have hot water available at the hose bib.

>
> I also need to replace a Moen 1200 cartridge that been there since 1980. I
> understand that getting the old one out after all this time can be quite an
> adventure, but what I haven't seen on Youtube is anyone using heat to help
> with that - a hair dryer, or even a propane torch. Seems like heat would
> help a lot. Has anyone here tried that?

A hair dryer sounds safe enough, a propane torch does not. I've never tried
either. I've always been able to get the cartridges out using the various tools
designed for that task. Granted, I've never had to deal with a Moen 1200. I
know that some of the shower cartridges have heavy duty pullers designed
specifically for them when the little plastic tool doesn't work.

I bought this the last I had to replace a 20 year old Moen shower cartridge. It
worked perfectly.

https://www.amazon.com/gp/product/B000DZH9I8

I thought you needed to use a licensed plumber for all repairs?

Frank

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Jun 23, 2022, 9:44:37 AM6/23/22
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On 6/22/2022 9:38 PM, Peabody wrote:
> Moen 1200 cartridge

I have had problems with old Moen cartridges and I see that there is a
removal tool but I have not tried it:

https://www.homedepot.com/p/DANCO-Cartridge-Puller-for-MOEN-86712/100560034

My biggest concerns were removal from shower and tub where there are no
shut off valves and I have to turn off whole house.

Last time around I saved the job for a plumber when I needed two other
jobs done.

Dean Hoffman

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Jun 23, 2022, 9:53:50 AM6/23/22
to
I've used a torch many times over the years to help loosen plumbing. Outside, though.
Heat a small portion of the outside fitting. It's easy to overheat things and expand both
instead of just the outside one.
Another trick is to put a bigger hammer on the backside of the fitting. Hit the fitting on the
front side with a smaller one. The vibration shakes things loose. It also helps to alternate
loosing and tightening of the fitting.
I'd think that lowering pressure would decrease the chance of a leak.

Marilyn Manson

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Jun 23, 2022, 3:44:51 PM6/23/22
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On Thursday, June 23, 2022 at 9:44:37 AM UTC-4, Frank wrote:
> On 6/22/2022 9:38 PM, Peabody wrote:
> > Moen 1200 cartridge
>
> I have had problems with old Moen cartridges and I see that there is a
> removal tool but I have not tried it:
>
> https://www.homedepot.com/p/DANCO-Cartridge-Puller-for-MOEN-86712/100560034

I've used that tool for my shower cartridge. Worked great. You just have to be patient and
remove it very slowly. If you try to force it, you can break the cartridge into pieces. That
would suck. My cartridge had been in for over 20 years and had been leaking for a while*,
so there was considerable corrosion. The tool did it's job.

*Basement shower, leak wasn't evident until the sill plate of the wet wall got wet enough to
eventually soak through the drywall. Fun repair...

I ended up cutting out the sill plate and bottom of the studs because they were soaked.

https://i.imgur.com/zJnHED6.jpg

>
> My biggest concerns were removal from shower and tub where there are no
> shut off valves and I have to turn off whole house.

Over the years, every time I had to shut off the main valve to repair or replace a
fixture, the first thing I did was install shutoffs so I wouldn't have to do that the
next time.

>
> Last time around I saved the job for a plumber when I needed two other
> jobs done.

The only time I've call a plumber was when the main valve itself needed to be replaced.
Nope, not me. Wasn't going to touch it. Even he had trouble because of its age and
location.

As Dirty Harry once said "A man's got to know his limitations."

Peabody

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Jun 23, 2022, 7:26:42 PM6/23/22
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Marilyn Manson says...

> A hair dryer sounds safe enough, a propane torch does
> not. I've never tried either. I've always been able to
> get the cartridges out using the various tools designed
> for that task. Granted, I've never had to deal with a
> Moen 1200. I know that some of the shower cartridges
> have heavy duty pullers designed specifically for them
> when the little plastic tool doesn't work.

> I bought this the last I had to replace a 20 year old
> Moen shower cartridge. It worked perfectly.

> https://www.amazon.com/gp/product/B000DZH9I8

Yes, that's one of the standard Moen pullers, and apparently
they work most of the time. But in the worst case, the
puller pulls the inner shaft of the cartidge out, leaving
the copper housing behind. I'm just afraid that since mine
has been there for 42 years, the probability of that
happening isn't particularly low. And of course if that
happens, your pucker factor goes up considerably because
you can't turn the water back on till it's fixed. If that
does happen, the solution appears to be cutting 1/2" threads
into the remaining part with a tap, and using a bolt to pull
the remains out (essentially the same puller process as the
original puller, but with slightly different parts).

> I thought you needed to use a licensed plumber for all
> repairs?

That's the rule. But I had pretty much talked myself into
the idea that if no connection is broken or made, that would
be ok for me to do. But even if I get a plumber to do it -
since he will be installing the pressure regulator anyway -
I think I would like to try the hair dryer for about 10
minutes before he attempts the removal, just to give us the
best chance of success.

I checked with the City today about the pressure, and they
said they would fix low pressure, but not high pressure. So
it's my problem. And I think I will have the regulator
installed if I can find a place for it. That's going to be
the hard part - finding where the feed comes up out of the
slab. I have no documentation of how that might have been
done. I assume it wouldn't be legal to put it outside in
the meter box, but I'll ask that question. That's really
the best place for it if it would fit.

Marilyn Manson

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Jun 23, 2022, 9:04:51 PM6/23/22
to
On Thursday, June 23, 2022 at 7:26:42 PM UTC-4, Peabody wrote:
> Marilyn Manson says...
> > A hair dryer sounds safe enough, a propane torch does
> > not. I've never tried either. I've always been able to
> > get the cartridges out using the various tools designed
> > for that task. Granted, I've never had to deal with a
> > Moen 1200. I know that some of the shower cartridges
> > have heavy duty pullers designed specifically for them
> > when the little plastic tool doesn't work.
>
> > I bought this the last I had to replace a 20 year old
> > Moen shower cartridge. It worked perfectly.
>
> > https://www.amazon.com/gp/product/B000DZH9I8
> Yes, that's one of the standard Moen pullers, and apparently
> they work most of the time. But in the worst case, the
> puller pulls the inner shaft of the cartidge out, leaving
> the copper housing behind. I'm just afraid that since mine
> has been there for 42 years, the probability of that
> happening isn't particularly low. And of course if that
> happens, your pucker factor goes up considerably because
> you can't turn the water back on till it's fixed.

Can't turn what water back on? The water to the fixture or the
water for the whole house?

If that happened to me, only that single fixture would be out
of commission because I have shut offs for every fixture.


> If that
> does happen, the solution appears to be cutting 1/2" threads
> into the remaining part with a tap, and using a bolt to pull
> the remains out (essentially the same puller process as the
> original puller, but with slightly different parts).
> > I thought you needed to use a licensed plumber for all
> > repairs?
> That's the rule. But I had pretty much talked myself into
> the idea that if no connection is broken or made, that would
> be ok for me to do. But even if I get a plumber to do it -
> since he will be installing the pressure regulator anyway -
> I think I would like to try the hair dryer for about 10
> minutes before he attempts the removal, just to give us the
> best chance of success.
>
> I checked with the City today about the pressure, and they
> said they would fix low pressure, but not high pressure. So
> it's my problem. And I think I will have the regulator
> installed if I can find a place for it. That's going to be
> the hard part - finding where the feed comes up out of the
> slab.

> I have no documentation of how that might have been
> done. I assume it wouldn't be legal to put it outside in
> the meter box, but I'll ask that question. That's really
> the best place for it if it would fit.

I'm assuming you live in a warm climate. My meter is inside
the house immediately (and I mean like 1 inch) after the main
shut off which is just inside the block foundation. The water
authority doesn't want to make it easy for a homeowner to tap
into the system before the meter. Since they own the meter, we
are not allowed to take it off and move it. My regulator is about
10' downstream from the meter. The only "branch connection"
between the meter and the regulator is the pipe that feeds
the hose bibs so that they are at street pressure.

Isn't there any place between where the service enters the building
and the first fitting where the system begins to branch off to the
various fixtures? All you need is about 6" of space.

Peabody

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Jun 24, 2022, 7:50:49 PM6/24/22
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Marilyn Manson says...

> Can't turn what water back on? The water to the fixture
> or the water for the whole house?

The water to the whole house. There's no shutoff between
the shutoff for the whole house and the shower faucet. I
wouldn't have built it that way, but it wasn't my decision.

And on the other side of the faucet is the standup tiled
shower in the second bathrooom. So I can't even get to it
from behind.

> If that happened to me, only that single fixture would
> be out of commission because I have shut offs for every
> fixture.

i have shutoffs for toilets, sinks, the water heater, the
ice maker and the dishwasher. But not the shower faucet. or
the outside hydrants.

> I'm assuming you live in a warm climate. My meter is
> inside the house immediately (and I mean like 1 inch)
> after the main shut off which is just inside the block
> foundation.

> Isn't there any place between where the service enters
> the building and the first fitting where the system
> begins to branch off to the various fixtures? All you
> need is about 6" of space.

Not particularly warm. We get below zero temps most
winters. But pretty much all the houses are slab. No
basements.

So the water comes into the house out of the slab. There's a
shutoff valve there, but above that it immediately branches
off three ways. So all of that would have to be re-done.
And this is all inside an interior wall. It would not be
cheap.

Marilyn Manson

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Jun 24, 2022, 9:26:57 PM6/24/22
to
Define "immediately". How much distance before or after the shut off.

If it's inside an interior wall, how do you know how it branches?

Can you post an image?

How is your meter in an outside box if temps get below zero?

Peabody

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Jun 25, 2022, 11:07:11 AM6/25/22
to
Marilyn Manson says...

> Define "immediately". How much distance before or after
> the shut off.

The shutoff body starts about an inch above the slab, What
I can't see yet is what's above the shutoff. However, I can
see two vertical pipes on either side of the shutoff going
back down into the slab. So what I believe must be above
the cutoff is a four-way equal cross fitting, with the
fourth going up to the second floor. But I can't see that
yet.

> If it's inside an interior wall, how do you know how it
> branches?

There's an opening where the shutoff handle sticks out of
the wall.

> Can you post an image?

I'm working on rigging up my 808 keyfob camera so I can
stick it into the opening and take pictures. Film at 11.

> How is your meter in an outside box if temps get below
> zero?

The meter wells are about 18 inches deep, with cast iron
covers. I've never understood why they don't freeze up if
water isn't moving through them, but they don't. Maybe it's
just that there's enough thermal conduction to the pipes
that go straight down much deeper. We got through the big
freeze of February, 2021, with no problem. Well, the water
main broke, but none of the neighborhood meters did, or the
lines coming into the houses.

Marilyn Manson

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Jun 25, 2022, 1:46:11 PM6/25/22
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What's the frost line depth for your area? Just curious.

https://www.decks.com/how-to/articles/deck-footing-frost-depth-map

When my main shut off needed to be replaced, the water authority sent out
a guy to turn the water off at the "street". (it's actually in my front lawn) The
valve box (tube) was rusted shut so he couldn't get his 4'+ wrench down to the
valve. I brought out a cup of coffee to warm him up as he worked on gaining
access.

https://i.imgur.com/ljj2qNq.jpg

Peabody

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Jun 25, 2022, 5:23:50 PM6/25/22
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Marilyn Manson says...

> What's the frost line depth for your area? Just curious.

> https://www.decks.com/how-to/articles/deck-footing-frost
> -depth-map

I'm right on the 20" line.

> When my main shut off needed to be replaced, the water
> authority sent out a guy to turn the water off at the
> "street". (it's actually in my front lawn) The valve box
> (tube) was rusted shut so he couldn't get his 4'+ wrench
> down to the valve. I brought out a cup of coffee to warm
> him up as he worked on gaining access.

Here the meters for all the slab homes are out at the
street. I don't know about the older homes with basements.
In my condo, there are about 10 meters in a raised island
surrounded by concrete parking lot. And there's a shut off
just downstream of the meter. I suspect that in my case
the shutoff in the house is redundant. Anybody who wants
to shut off their water does that at the meter.

No luck with the camera today. Will try again tomorrow if
the covid booster this afternoon doesn't kill me.

Marilyn Manson

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Jun 25, 2022, 6:39:49 PM6/25/22
to
On Saturday, June 25, 2022 at 5:23:50 PM UTC-4, Peabody wrote:
> Marilyn Manson says...
> > What's the frost line depth for your area? Just curious.
>
> > https://www.decks.com/how-to/articles/deck-footing-frost
> > -depth-map
> I'm right on the 20" line.
> > When my main shut off needed to be replaced, the water
> > authority sent out a guy to turn the water off at the
> > "street". (it's actually in my front lawn) The valve box
> > (tube) was rusted shut so he couldn't get his 4'+ wrench
> > down to the valve. I brought out a cup of coffee to warm
> > him up as he worked on gaining access.
> Here the meters for all the slab homes are out at the
> street. I don't know about the older homes with basements.
> In my condo, there are about 10 meters in a raised island
> surrounded by concrete parking lot. And there's a shut off
> just downstream of the meter. I suspect that in my case
> the shutoff in the house is redundant. Anybody who wants
> to shut off their water does that at the meter.

Seems strange to:

1 - Have above ground meters in an area that gets down to 0°
(assuming °F) or even 0°C.

2: Have exposed shut-offs. Seems ripe for pranking.

I don't get why you suspect your shut off is redundant if your meter
isn't out in the parking lot like the others. What other shut do you
have that makes the inside one redundant?

Peabody

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Jun 26, 2022, 3:50:59 PM6/26/22
to
Marilyn Manson says...

> I don't get why you suspect your shut off is redundant
> if your meter isn't out in the parking lot like the
> others. What other shut do you have that makes the
> inside one redundant?

No, my meter IS out there with the others. So I have the
shutoff in the meter well, and the master shutoff inside the
house, with nothing between but a run of copper pipe. So
either will shut off all the water to the house. What I
don't have is a way to separately shut off the water to the
shower.

One possibility, depending on what's behind the wall, is to
replace the master shutoff with a pressure regulator. But
I'm still trying to get pictures so I can tell what's in
there. Do you suppose they make pressure regulators with a
built-in shutoff? That might be the ideal, lowest cost
solution for me.

I also need to investigate whether the PRV will prevent
backflow. I don't want one that does that.

Marilyn Manson

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Jun 26, 2022, 4:14:11 PM6/26/22
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Peabody

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Jun 26, 2022, 5:36:21 PM6/26/22
to
Marilyn Manson says...

>> I also need to investigate whether the PRV will prevent
>> backflow. I don't want one that does that.

> https://www.physicsforums.com/threads/why-pressure-reduc
> ing-valve-doesnt-prevent -backflow.822366/

Yes, but the backflow occurs only when the pressure in the
house exceeeds the city pressure by enough to allow the
backflow to happen. If as in my case the city pressure is
90psi, and the regulator is set to 60psi, when the water
heater heats up, the pressure can go back up above 90psi,
which is worse than having no regulator.

Of course that's without an expansion tank installed, which
I also don't have. I see all kinds of explanations of how
they work, but none with any numbers. So lets say you have
a two-gallon tank which is pressurized to 60psi when the
water is cold, and the tank is all air at that point. If
the water heating up causes the tank to become half filled
with water, what is the pressure at that point? Is it
120psi because the air now occupies half the volume it did
before? Well, it's just not clear to me what actually goes
on inside these tanks, and what the resulting water pressure
is.

Also, I think you have to depressurize the system to ckeck
the expansion tank pressure. Otherwise, you don't know
where the bladder is.

I think things work in this complex even with high pressure
because the meters are still two-way - no anti-siphon valves
or backflow preventers. So it's an open system.

Marilyn Manson

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Jun 26, 2022, 7:01:36 PM6/26/22
to
On Sunday, June 26, 2022 at 5:36:21 PM UTC-4, Peabody wrote:
> Marilyn Manson says...
> >> I also need to investigate whether the PRV will prevent
> >> backflow. I don't want one that does that.
>
> > https://www.physicsforums.com/threads/why-pressure-reduc
> > ing-valve-doesnt-prevent -backflow.822366/
> Yes, but the backflow occurs only when the pressure in the
> house exceeeds the city pressure by enough to allow the
> backflow to happen. If as in my case the city pressure is
> 90psi, and the regulator is set to 60psi, when the water
> heater heats up, the pressure can go back up above 90psi,
> which is worse than having no regulator.
>
> Of course that's without an expansion tank installed, which
> I also don't have. I see all kinds of explanations of how
> they work, but none with any numbers. So lets say you have
> a two-gallon tank which is pressurized to 60psi when the
> water is cold, and the tank is all air at that point. If
> the water heating up causes the tank to become half filled
> with water, what is the pressure at that point? Is it
> 120psi because the air now occupies half the volume it did
> before? Well, it's just not clear to me what actually goes
> on inside these tanks, and what the resulting water pressure
> is.

What goes on inside the tank - physically - is easily explainable.

https://www.youtube.com/watch?v=G2kRC-mETM4

As far as the "numbers" inside the tank, assuming that you have
closed system (check valve at meter, perhaps) the pressure
will basically be the same as the then-current system pressure.

But I'm not sure why you are concerned with those numbers.
I trust what the tank manufactures tell me and use their tables
to determine the correct size tank for the system in question.

e.g.

http://www.americanwaterheater.com/media/22209/exptank.pdf

>
> Also, I think you have to depressurize the system to ckeck
> the expansion tank pressure. Otherwise, you don't know
> where the bladder is.

Checking the tank pre-charge is easy. AFAIC that's the only
important number. Here's how to pre-charge and then check
the pre-charge annually.

https://www.youtube.com/watch?v=MT1MTEZREQk

>
> I think things work in this complex even with high pressure
> because the meters are still two-way - no anti-siphon valves
> or backflow preventers. So it's an open system.

I recently installed a new water heater. With the pressure set at
60psi, my pressure would spike to 90+ psi after the heater fully
recovered. I installed an expansion tank, pre-charged to 60psi.
Now my pressure never goes above 75 and that's right after
the WH fully recovers.

I'm fine with that since it only stays that way until any fixture is
opened or a toilet is flushed. Worst case is the pressure is at
75 psi for a few hours. I'm not going to stress over that.

Peabody

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Jun 26, 2022, 7:27:21 PM6/26/22
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Marilyn Manson says...

> As far as the "numbers" inside the tank, assuming that
> you have closed system (check valve at meter, perhaps)
> the pressure will basically be the same as the
> then-current system pressure.

Well, I'm not sure about that. I found this link that does
go through the numbers.

https://rogergriffith.com/thermal-expansion-tanks-part-2/

The size of the expansion tank affects how much the pressure
increases when the water is fully hot. But it's not going
to be the same as normal system pressure. It will be higher
that that, depending on the precharge pressure and the size
of the expansion tank.

The thing is, in an open system with no regulator, an
expansion tank provides no benefit. The pressure will
always be at the City pressure. I think the regulator
changes that, and I suspect requires an expansion tank.

Marilyn Manson

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Jun 27, 2022, 11:23:00 AM6/27/22
to
On Sunday, June 26, 2022 at 7:27:21 PM UTC-4, Peabody wrote:
> Marilyn Manson says...
> > As far as the "numbers" inside the tank, assuming that
> > you have closed system (check valve at meter, perhaps)
> > the pressure will basically be the same as the
> > then-current system pressure.
> Well, I'm not sure about that. I found this link that does
> go through the numbers.
>
> https://rogergriffith.com/thermal-expansion-tanks-part-2/
>
> The size of the expansion tank affects how much the pressure
> increases when the water is fully hot. But it's not going
> to be the same as normal system pressure. It will be higher
> that that, depending on the precharge pressure and the size
> of the expansion tank.

I didn't say that it would be the same as the "normal system
pressure". I said the "then-current system pressure".

You seemed to have been wondering what the internal pressure of
the tank might be after the WH recovers. You said "If the water
heating up causes the tank to become half filled with water,
what is the pressure at that point? Is it 120psi because the
air now occupies half the volume it did before?"

What I am saying is that the pressure in the tank will always be the
same as the *current* pressure throughout the system. You can test
that at any fixture within the system. I test at my utility sink since it
has faucet with hose threads, making it easy to put a pressure tester
on it.

That's the whole point of an expansion tank and the importance of
proper pre-charging. The expanding water causes the baffle to
compress the air, thereby essentially "enlarging" the system. The
same amount of water in a larger system means lower pressure
throughout.

Can I tell you how/if it will work with your system? No. All I can tell
you that the addition of the tank in my house reduced the increase
in pressure from 90+ after recovery to about 75. That's good enough
for me.

>
> The thing is, in an open system with no regulator, an
> expansion tank provides no benefit. The pressure will
> always be at the City pressure. I think the regulator
> changes that, and I suspect requires an expansion tank.

It may or it may not. You can only determine that by testing the
pressure. There are other ways to eliminate excess pressure, such
as air chambers - vertical stubs of standard copper pipe that are
filled with air. Unfortunately, they do not have baffles and can get
filled with water over time, eliminating their effectiveness. Draining
and refilling the entire system can often solve the waterlogging
issue.

BTW...just as an aside, the Watts gauge that is shown in the expansion
tank video that I linked to can be somewhat deceiving. You'll notice the
red needle that is supposed to retain the highest pressure that the system
reached. That needle can show a ridiculously high false reading if you
have any water hammer. Here's the issue:

The red needle is "freewheeling" meaning that it is pretty loose on the shaft.
That allows it to be pushed up by the black needle. There is just enough
resistance to hold it in position after the black needle "recedes". However,
there is not enough resistance to stop it from being *thrown* upwards
when water hammer causes the black needle to swing violently. IOW, the
black needle may jump from 60 to 80 when water hammer occurs. When
the black needle hits the red needle, the red needle keeps going past 80
like a ball off of a bat. I watched my black needle jump to 80 psi and the
red needle shot to over 110. That can be very deceiving if you aren't
watching (like I wasn't) when the water hammer occurs. You walk up to
the gauge and see a max pressure of 110+ and think that system is
as spiking to 110+ which can be quite concerning.



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