Street side / House side shutoff valves for house water main

MikeSpeed6030

I believe residential backflow preventers are typically just installed on outdoor sill cocks and heating boilers - because they could be sources of contamination of the city water supply in the event that pressure is lost on the public water system. Hot-water heating boilers invariably have an expansion tank and a relief valve. Sill cocks, when the valve is open, are usually exposed to atmospheric pressure or just a short nipple downstream of the backflow preventer. Putting a backflow preventer on the whole-house supply from the city would be a horse of a different color, risking over-pressurizing all the home's water system due to thermal expansion.

I lived in one urban area that required an expansion tank on residential plumbing systems (but no relief valve or whole-house backflow preventer was required).

JUGHNE

Some 30 years ago our small town with maybe 250 water customers applied for a grant from the state for an additional muni water well. The EPA water police were close at hand, so in order to get that we had to install meters, (yes, previously all existing meters had been removed and we had an exorbitant flat rate of $6.00 a month )

But with the meters came double check back flow valves....no drain or vent type. Our low 30 to 40 PSI dropped about 10 PSI.
I replaced some 50+ year old water heaters that had the temp only relief valves....I saw at least 2 PRV with plugs installed or a drain hose going to the floor drain. Remote read out were included. Today most of the meters don't work well and parts are not available. The guts were removed from the back flow valves. Vac breakers added to all outside hydrants. Testable back flow valves are required for boilers, ice machines and UG lawn sprinklers. (And now if your meter isn't recording well the flat rate is 18.00 per month...if it is obvious that you have UG sprinklers then you will get a new meter ).

Note: here we own the curb stop and even this non licensed plumber (but licensed electrician) has his own stop key. FWIW

jumper

Won't heater's T&P relief valve relieve pressure? A working expansion tank can absorb shocks. But who checks expansion tanks?

JUGHNE

T&P will just barely open and dribble or drip. Eventually it will become corroded shut and be stuck, maybe to never open again.
You check the expansion tank when the T&P starts to drip, that's how you know.

Squidstro

Wouldn't the easiest for a plumber be to replace my main valve exactly where the current one sits?

Looks like a threaded FIP connection on the right side of the valve and then a threaded connection to a compression connection to the meter on the left side of the valve. That should be a can of corn for a plumber to swap for a ball valve with no sweating necessary.

I'm also assuming that's a 3/4" valve too.

Can you guys comment on what type of connection ball valve I should target? FIP? FTP? Compression adaptors? Etc.

Here's a closeup of the current gate valve

SWEI

Squidstro said:

Looks like a threaded FIP connection on the right side of the valve and then a threaded connection to a compression connection to the meter on the left side of the valve.

It's a meter coupling (half-union), and they're standardized. No shortage of supplier options there, e.g. http://www.aymcdonald.com/en-US/No-lead-Meter-valves-meter-couplings-y-and-u-branches.html

The Town water department here will deliver an adapter (like yours, with a 3/4" MNPT end) to a jobsite if we call and ask.

JUGHNE

Looks like you have a 1" valve with a 1 X 3/4" reducing bushing for the meter spud. The large nut on the meter is in effect a union, the spud uses a rubber washer under that nut. The spud would have to be unscrewed from the valve. The reducing bushing should be brass as the rest of the components are. With the curb stop shut off this should be the typical "10 minute job" .

A new ball valve may be a little longer than the old gate, however your service line is soft copper and may shift as needed.

Squidstro

SWEI said:

It's a meter coupling (half-union), and they're standardized. No shortage of supplier options there

Thank you SWEI. So when JUGHNE said...

JUGHNE said:

A new ball valve may be a little longer than the old gate, however your service line is soft copper and may shift as needed.

Can these meter couplings be custom sized depending on how far a connection is from them?

SWEI

Squidstro said:

Can these meter couplings be custom sized depending on how far a connection is from them?

Not that I know of. The most common version is what you have there, with a male NPT spud end. The majority of those in residential applications will be a 5/8" meter nut with a 3/4" MNPT end.

Squidstro

But if the threads of the meter are under that nut, what's the length of pipe going to the threads on the left side of the valve? That pipe can't be cut to size on the meter-side?

SWEI

The tailpiece is cast. You might be able to cut and re-thread it if you need it shorter, but it would take a fair bit of work. I'd just bend the service riser as @JUGHNE suggested above.

JUGHNE

Both risers out of the floor will bend slightly. Just plan on replacing the bad valve going to the hose bib. You can cut that 1/2" line and have a lot of flexibility. Then any adjustment could made in the 1/2" line as needed if the larger piping is done first.

Plumber should figure it out pretty quick.

Squidstro

Good call on replacing the hose bibb shutoff valve at the same time for added flexibility

Here's another curiosity question. How do you unscrew the gate valve from the threaded pipe with the drywall behind it in the way of that valve rotating counter clockwise to the threads?

JUGHNE

Unscrew the guts out of it or cut the stem off.....cut the 1/2" first...pull away from the wall a little......unscrew the meter spud....loosen the flare nut on the 1" riser and rotate the valve out 90 degrees. (and the last thing is cut the SR).

IIWM I would loosen the meter spud nut and then unscrew the bushing out of old valve, the spud would turn with bushing....this is easier to do with the old valve firmly held in place.....2 wrenches for sure!...........then follow options above.

Are you DIY or hiring? If he cuts SR then he didn't think about it much.

Squidstro

I'm probably going to hire - but I'm no doubt a DIYer and like to learn. That's why I ask all these questions and I can sense some of the guys thinking "just let the plumber do it and it will be fine" which is fine. But I still want to learn.

MikeSpeed6030

Remove the bonnet from the gate valve. Use two pipe wrenches - but of course the water will have to be shut off. But, if you intend to hire a plumber (which I think you should), why not let him figure all this out?

Squidstro said:

Good call on replacing the hose bibb shutoff valve at the same time for added flexibility



Here's another curiosity question. How do you unscrew the gate valve from the threaded pipe with the drywall behind it in the way of that valve rotating counter clockwise to the threads?

Squidstro

Squidstro said:

I'm probably going to hire - but I'm no doubt a DIYer and like to learn. That's why I ask all these questions and I can sense some of the guys thinking "just let the plumber do it and it will be fine" which is fine. But I still want to learn.

This is why