Dual pressure tank install on residential supply

Users who are viewing this thread

Infernoman

New Member
Messages
8
Reaction score
0
Points
1
Location
Ontario Canada
Hello everyone, currently my home is supplied by a 1/2” line which replacing it would require digging and the quotes we’ve gotten are just out of the budget. So we’re unable to upgrade the supply line currently.

The 1/2” lines goes into the meter at 3/4 and the back out at 3/4 into a pressure reducing valve and supplies a 3 bedroom 1.5 bath. 2 small 1 bedroom apartments, and a sink/toilet in the garage.

The 3/4 splits inside the main home to supply the apartment which is about 50-80 feet away. With about 15 feet of elevation.

The 1/2 supply line is capable of around 10gpm at 40-50psi so is already lacking flow rate.

This issue compounds when one or more taps are on. Especially inside the second story of the apartment.

From what I’ve gathered a pressurized tank will help regulate pressure and provide a buffer zone before it drops. And will regulate pressure between the two buildings.

Since the city is pressurized and I’m running at a lower psi than the city is providing the tanks should constantly fill as they’re depleted. The PRV will stop backflow once it reaches the desired psi.

One of the pressurized tanks will be placed in the apartment on the main line. And the other in the main house also on the main line.



What I’m trying to figure out is where is the best place to put the PRV(s)? Before or after the pressurized tanks?

Before the tanks would allow me to keep a single prv. After the tanks would require 2 PRV’s but would allow me to keep the pressurized tanks at a higher pressure. Since the static pressure at the city line is 65-70 psi

Since demand wasn’t very high to begin with and flow/pressure was the issue will these tanks be enough to supply a constant pressure without a pump and 10gpm from the city line?
 

Jeff H Young

In the Trades
Messages
5,369
Reaction score
1,183
Points
113
Location
92346
If your plumbing is in good condition 65 to 70 psi shouldn't hurt . omit the the PRV, I wouldn't run 2 PRV's in any case.
It really doesn't matter but you say 2 apartments? no plumbing just a sink and toilet in garage for the apartments to share?
or there is 5 toilets etc etc. no mention how long the 1/2 inch line runs underground again doesn't matter.
Tenants cant be too pickey these days.
Expansion tank will help as you suggest I've never attempted to fix a problem this way perhaps a pump.
Id like to run a new 1-1/4 " min line size
 

Valveman

Cary Austin
Staff member
Messages
13,346
Reaction score
951
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
I agree. if the pressure is low remove or increase the pressure of the pressure reducing valve. Adding pressure tanks only works as the pressure gets lower, and low pressure is the problem now.
 

Reach4

Well-Known Member
Messages
35,461
Reaction score
3,659
Points
113
Location
IL
Thinking about this, I might consider separate low-pressure-drop check valves feeding each user. Then each user would have a pressure tank, followed by a pressure reducing valve with bypass. The bypass feature would allow thermal expansion. Otherwise the water heaters would also need thermal expansion tanks.

I am not a pro, and what I propose may not be better than other ideas envisioned.
 

Infernoman

New Member
Messages
8
Reaction score
0
Points
1
Location
Ontario Canada
If your plumbing is in good condition 65 to 70 psi shouldnt hurt . omit the the prv, I wouldnt run 2 prvs in anycase.
It really doesnt matter but you say 2 apartments? no plumbing just a sink and toilet in garage for the apartments to share?
or there is 5 toilets etc etc. no mention how long the 1/2 inch line runs underground again dosent matter.
Tenants cant be too pickey these days.
Expansion tank will help as you suggest Ive never attempted to fix a problem this way perhaps a pump.
Id like to run a new 1 1/4 " min line size
Believe me I would love to run 1-1/4 line as well haha. There is a total of 5 toilets, 4 showerheads. 2 run simultaneously.

My theory was that a pump wouldn’t be able to increase the flow rate and psi enough because of the compromised city line. And it would struggle trying to pull from the line possibly creating a negative pressure and causing damage to the main.

Now since I know the main will flow 10gpm/40-50 psi at the meter and has 60-75 psi static. The tanks should build pressure to the static. But have 52 gallons available between them. I’m hoping the pressurized tank will stop the psi droop on the city line, and at least hold the 10gpm/50psi when the line is in high demand.

Before the PRV was installed. The apartment under high usage was falling to 5-10 psi. And the house to 25 psi. Now the house holds pretty steady around 40-45 under high usage and the apartment 20-25. Which in turn increased my flow rate.
 

Infernoman

New Member
Messages
8
Reaction score
0
Points
1
Location
Ontario Canada
Thinking about this, I might consider separate low-pressure-drop check valves feeding each user. Then each user would have a pressure tank, followed by a pressure reducing valve with bypass. The bypass feature would allow thermal expansion. Otherwise the water heaters would also need thermal expansion tanks.

I am not a pro, and what I propose may not be better than other ideas envisioned.
This is pretty much what I was thinking as well but instead of 3 tanks, a single tank in each location at municipal pressure then a PRV after each of the tanks. Before the water is introduced back into the system.
 

Valveman

Cary Austin
Staff member
Messages
13,346
Reaction score
951
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
Before the PRV was installed. The apartment under high usage was falling to 5-10 psi. And the house to 25 psi. Now the house holds pretty steady around 40-45 under high usage and the apartment 20-25. Which in turn increased my flow rate.
This makes no sense. The PRV is a pressure reducing valve and the pressure should be lower after it was installed. Is the pressure at the meter when flowing only 50 PSI because that is all the city is supplying, or is that the setting of the PRV?
 

Infernoman

New Member
Messages
8
Reaction score
0
Points
1
Location
Ontario Canada
This makes no sense. The PRV is a pressure reducing valve and the pressure should be lower after it was installed. Is the pressure at the meter when flowing only 50 PSI because that is all the city is supplying, or is that the setting of the PRV?
the only sense of it I can make is that the flow rate or velocity? of the service is too low and causing excessive pressure loss upon a tap opening. The PRV I’m using isn’t a restriction based PRV it’s spring based so the restriction size alters based on flow rate. Currently the setting of the PRV is at 50 psi. The PRV I’m using also has a check valve and pressure relief for the hot water heater.

“Bernoulli's Principle states that as the speed of a moving fluid increases, the pressure within the fluid decreases.” - So this would make me assume the velocity was too low to make it to the required fixtures fast enough causing excess load?
 

Reach4

Well-Known Member
Messages
35,461
Reaction score
3,659
Points
113
Location
IL
This makes no sense. The PRV is a pressure reducing valve and the pressure should be lower after it was installed. Is the pressure at the meter when flowing only 50 PSI because that is all the city is supplying, or is that the setting of the PRV?
I was picturing 30 psi or some such for the PRV, with the thought to make the pressure more constant. I would think that variable pressure down to 30, because another unit flushed the toilet, would be more irritating than one with constant 30 psi.
 

Valveman

Cary Austin
Staff member
Messages
13,346
Reaction score
951
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
the only sense of it I can make is that the flow rate or velocity? of the service is too low and causing excessive pressure loss upon a tap opening. The PRV I’m using isn’t a restriction based PRV it’s spring based so the restriction size alters based on flow rate. Currently the setting of the PRV is at 50 psi. The PRV I’m using also has a check valve and pressure relief for the hot water heater.

“Bernoulli's Principle states that as the speed of a moving fluid increases, the pressure within the fluid decreases.” - So this would make me assume the velocity was too low to make it to the required fixtures fast enough causing excess load?
Tighten the adjustment bolt on the PRV all the way down before you do anything else. I think that is limiting the pressure. I kind of know how those things work. Lol! Set at 50 PSI, 50 PSI is what you get. Even tightened all the way down it will have some restriction, depending on brand and size.
 

Infernoman

New Member
Messages
8
Reaction score
0
Points
1
Location
Ontario Canada
Tighten the adjustment bolt on the PRV all the way down before you do anything else. I think that is limiting the pressure. I kind of know how those things work. Lol! Set at 50 PSI, 50 PSI is what you get. Even tightened all the way down it will have some restriction, depending on brand and size.
Played around with pressures tonight. There seems to be a sweet spot, where the 100 foot run doesn’t load down the whole system, but the house has a bit lower psi. Increase the psi and the 100 foot run progressively gets worse after around 60 psi. I did make a mistake by using clamp based pex fittings on the PRV and I also replaced those tonight which increased the flow considerably. But still having issues under load.

I’m hoping the pressure tanks arrive tomorrow. And I’ve recently seen a few pictures of manifold based setups with a loop to help maintain pressure? The person who did the plumbing originally doesn’t seem to have had very much experience. Not that I have much more. But I do have the internet at my disposal now.

I found this today haha
05F90D70-0525-4E1C-93BC-0B3FDD35F196.jpeg



Here is a photo of the branch line inside the house after the PRV.
EAE11210-2125-40AF-A0D7-E45B124DF678.jpeg



The service line splits before the shutoff valve for the house. To the right goes to the apartments. From right to left after the shutoff there’s, second story, first story, on demand water heater then hose.
 

Infernoman

New Member
Messages
8
Reaction score
0
Points
1
Location
Ontario Canada
Let’s suggest that friction loss is my issue combined with a decreased flow rate. This would cause the issues I’m having… low usage is okay because friction loss is lower at a lower flow rate. When usage increases so does friction, which causes a psi drop and a decreased flow rate from the supply.


This would also make sense why the PRV helped. Because it helped regulate the issue.

If that is the case, the best place to put the PRV would be on the apartment side. With one tank at full pressure in the house and moving the PRV to the apartment after the pressure tank in there. This should regulate the friction loss and have the pressure tanks available for high usage.

If I wanted to get really fancy I could also put a PRV after the tank inside the house and only keep the 100’ line and tanks pressurized.

Sound about right?
 
Last edited:

Infernoman

New Member
Messages
8
Reaction score
0
Points
1
Location
Ontario Canada
Tighten the adjustment bolt on the PRV all the way down before you do anything else. I think that is limiting the pressure. I kind of know how those things work. Lol! Set at 50 PSI, 50 PSI is what you get. Even tightened all the way down it will have some restriction, depending on brand and size.

I removed some of the flow restrictions earlier, the strainer on the PRV, 4 elbows and about 5 feet of 3/4”.

I have some more accurate numbers now. I’ve added a Pressure gauge in the bottom apartment which has about 10 feet of elevation.
With the PRV at 70 psi(160 ft) When you run the cold water on the bathtub in the bottom apartment there’s a 40 ft head loss, add the hot and there’s another 30 foot. For a total of 70ft.

Switch to the shower and there’s 30-40ft of head loss.
 

CountryBoy19

New Member
Messages
21
Reaction score
1
Points
3
Location
Indiana
It would seem to me that if your issue is getting enough supply through the 1/2" line then you need to add storage after that line but before a PRV. Keep in mind that water also has inertia so when a tap opens, without a pressure tank to buffer the differential between supply volume and consumption volume, there will be a pressure drop. If you add a pressure tank at full city pressure then put a PRV after the tank but before any other service lines the pressure should remain very stable.

Sometimes just adding the tank will do the trick but you already have the PRV so as long as it's sized properly it shouldn't be restricting flow.

My well is 1200 feet from my house. It used to be that the only pressure tank was near the well. When a tap was opened at the house there would be a significant pressure drop because 1200 feet of water all of the sudden had to start moving faster. I added a 2nd tank at the house and the problem has been solved.
 
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