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Old 04-16-2012, 08:54 PM   #1
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Is 15psi on boiler too low?


After over a year, our new boiler started dripping in one of the open-ended vertical copper pipes and flooded our boiler room. We called the plumbing company that installed it and we were told that municipal water PSI was too high. He showed me that it went over the 100 psi limit of his PSI gauge attached to our outdoor faucet.

He recommended we have an expansion tank installed. So we did. They installed it for 1k+.

When they left and we started using the shower and laundry, we noticed the water too weak. The shower head does not sprinkle but instead water pours weakly in the middle. I looked at the boiler's psi meter and it showed under 15psi. I took a picture:



We complained to the plumbing company but were told on the phone our PSI was 50. They said our faucet and shower head had dirt which would explain the weak water coming out. When I said the laundry faucet is weak, too, we're told there's a screen in the hose and that might be clogged up, too.

We had none of these problems until right after the expansion tank was installed.

Any advice appreciated. Thank you.

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Old 04-16-2012, 09:26 PM   #2
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Is 15psi on boiler too low?


Boiler pressure is *rarely* more than 15psi
For water pressure, as in the whole house, 50PSI after your reducing valve is reasonable.
Many homes will have 100PSI *before* the reducing valve (mine is close to 120)
With 50PSI and clear lines valves and aerators... you should have good flow as well.

While the expansion tank is reasonable and prudent (if pricey at $1000!)...
the main thing you need is a good pressure reducing valve.
And maybe a second pressure gauge to see the before and after numbers.

hth


Last edited by TarheelTerp; 04-16-2012 at 09:30 PM.
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Old 04-17-2012, 10:55 AM   #3
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Is 15psi on boiler too low?


Thank you, TarheelTerp.

The price was $750 for the expansion tank. The rest was for whatever it was that got "popped" in our boiler by the high incoming pressure. (Is that still pricey? We picked them to install our boiler over a year ago after getting quotes from 3 major plumbing companies in the area, and since then I assumed their prices to be the lowest. Still, thanks to your comment, I should always do price comparison in case that isn't always true.)

I will try replacing the shower head tonight.

We actually have two baths, the other one has a different shower head and water seems to sprinkle out fine -- water is not focused in the middle like a faucet as with our other bathroom both on the same floor -- albeit weaker than before.

I'm beginning to suppose with your comment that what we're going through is probably normal(?). We're spoiled by the strong current before and after the expansion tank (installed between the city's main and our boiler, if that's what is meant by domestic) we miss that with the now more-or-less normal water pressure. I suppose the plumbing company installed things right and we'll just have to get used to the lower water pressure.

I'll pick up a psi gauge, too, just in case.

Quote:
Originally Posted by TarheelTerp View Post
Boiler pressure is *rarely* more than 15psi
For water pressure, as in the whole house, 50PSI after your reducing valve is reasonable.
Many homes will have 100PSI *before* the reducing valve (mine is close to 120)
With 50PSI and clear lines valves and aerators... you should have good flow as well.

While the expansion tank is reasonable and prudent (if pricey at $1000!)...
the main thing you need is a good pressure reducing valve.
And maybe a second pressure gauge to see the before and after numbers.

hth
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Old 04-17-2012, 11:13 AM   #4
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Is 15psi on boiler too low?


I am not certain you understand the plumbing setup in your house completely. The pressure on the city side of the reducing valve is apparently 100 psi, which is not uncommon for city water. There should be (and almost certainly is) a pressure reduction valve between the water meter and your domestic cold water supply. This valve is apparently set to 50 psi. You did not indicate that the boiler company replaced or adjusted the pressure reducing valve, so I assume it is the same as it was before they did the work on the boiler.

The boiler has a makeup water valve, which is designed to keep the boiler full of water in the event of water loss due to leakage, or from normal yearly draining of the water. The makeup water valve typically includes a pressure reducing valve, or sometimes the pressure reducing valve is separate from the makeup water shutoff valve. Regardless, the typical domestic boiler operates at about 15 psi, so the boiler pressure reducing valve is designed to reduce house pressure to 15 psi (the boiler pressure). Based on your gage, the boiler is now operating correctly at 15 psi, but this has NOTHING to do with the main pressure reducing valve on your city service, it is due to the boiler pressure reducing valve. The boiler valve, by the way, is supposed to include a backflow preventer to keep boiler water from entering the domestic water supply, which can happen if for some reason the city pressure drops below 15 psi, which can occur during fire hydrant tests, water main break etc.

As for the expansion tank, the boiler typically has an expansion tank which is designed to maintain 15 psi pressure in the system when the boiler water heats up. You need an air tank because if the system were full of water only, with no air, the water pressure in the system would get dangerously high if there were no expansion tank. I do not understand whether the boiler people installed an expansion tank on your boiler, or on your hot water heater. Your boiler should have had an expansion tank when it was installed, and unless that tank went bad, there should have been no need to replace it. If you can explain exactly what the boiler folks did, it would help to understand your situation. In my house, we operate on well water, and we have an expansion tank for our boiler, and a separate expansion tank on the main cold water inlet, which provides expansion for the hot water tank. It is pretty typical to have two expansion tanks, and is necessary when you have a main pressure reducing valve which incorporates a backflow preventer.
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Old 04-17-2012, 11:24 AM   #5
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Is 15psi on boiler too low?


Thank you, Daniel. Sorry I wasn't so clear.

Our boiler already has an expansion tank. It is very modern (probably latest model) compared to our old 1980's boiler that was replaced.

They installed the new (second) expansion tank between the boiler and city mains. The new expansion tank is inside the house, in the enclosed space under our foyer stairs by the front door.

When we moved into the house 15+ years ago, there is a main spigot (under the foyer stairs) that I turn off whenever I am doing plumbing work (replacing faucets, rubber washers, etc.) I suppose this is the "reducing valve" (?).

A few years ago, the city came in and did work (for free), and installed a lever that turns 90-degrees to turn off the water. Not sure if this can be a "reducing valve" too...

The new expansion tank is installed between the lever and the spigot.

Sorry I'm just beginning to understand now. I appreciate all the info I'm getting. Thank you.

Last edited by vcsolit; 04-17-2012 at 11:26 AM. Reason: removed "the pipes" for clarity
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Old 04-17-2012, 11:29 AM   #6
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Is 15psi on boiler too low?


The plumbing company says the city pressure must have increased which damaged something in our boiler (I can look up the receipt to find out what specifically -- I don't have it with me now) and so recommended the new expansion tank. Having no hot water and trusting them for past work in our house, I went ahead with their recommendation.

Also, the plumbing company says our house pressure is 50psi but I wasn't there when (if) they did the measurements. This is why I posted the question under the title "is 15 psi too low" because I thought it's supposed to read 50. Now I know it's not.

Last edited by vcsolit; 04-17-2012 at 11:31 AM.
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Old 04-17-2012, 11:37 AM   #7
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Is 15psi on boiler too low?


The plumbing company explanation makes absolutely no sense to me. The boiler absolutely should have had a pressure reducing valve, which should have reduced home water pressure to 15 psi. The home water pressure should have been controlled by the pressure reducing valve that you are referring to as a "spigot", although a spigot usually means a place to attach a hose, I have never heard a pressure reducing valve called a spigot.

You really need to examine your entire plumbing system more closely, something is totally wrong with the plumbing explanation, at least as you relate it. There should be a meter outside your house, which should be obvious. There should be a shutoff valve on the street, which is for the use of the city only. There should be a shutoff valve inside your house, which is probably the lever you referred to. My guess is the thing you are calling a spigot is really a pressure reducing valve, and possibly a combination reducing valve and backflow preventer. You can tell if it is a backflow preventer because there will be an arrow on it, showing the flow directions.

The only thing I can think of that makes any sense is if the main pressure reducing valve failed, allowing you to run on 100 psi water, and the boiler pressure reducing valve was not capable of handling that high a pressure, so it too failed. This would account for your previously superior flow experience, although 100 psi is at the upper limit for most fixtures, and is capable of damaging them. 50 or 60 psi is a much more common pressure rating for domestic water.
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Old 04-17-2012, 12:22 PM   #8
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Is 15psi on boiler too low?


Thank you, Daniel.

To be honest I'm not sure if the reducing valve (which I called "spigot" -- I didn't want to call it "knob" so I googled for the proper term, incorrectly) is still there. I stopped using it when the city installed the lever. I'll check tonight.

Your last paragraph is closest to how I remember it was explained to us. The plumber also said homes should have the expansion tank as standard. (I don't remember him mentioning a reducing valve as an alternative.) At the time, I thought it was an improvement to our house (plus the trust I placed on them for truly commendable prior year's work) so I OK'ed the expansion tank on the spot.

If it turns out we only needed a reducing valve (which I'll find out if still there) then I'll just have to live with having been ill-advised. If the house psi turns out to be below 50, then I'll complain.
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Old 04-17-2012, 06:24 PM   #9
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Is 15psi on boiler too low?


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Originally Posted by vcsolit View Post
Thank you, Daniel.

To be honest I'm not sure if the reducing valve (which I called "spigot" -- I didn't want to call it "knob" so I googled for the proper term, incorrectly) is still there. I stopped using it when the city installed the lever. I'll check tonight.

Your last paragraph is closest to how I remember it was explained to us. The plumber also said homes should have the expansion tank as standard. (I don't remember him mentioning a reducing valve as an alternative.) At the time, I thought it was an improvement to our house (plus the trust I placed on them for truly commendable prior year's work) so I OK'ed the expansion tank on the spot.

If it turns out we only needed a reducing valve (which I'll find out if still there) then I'll just have to live with having been ill-advised. If the house psi turns out to be below 50, then I'll complain.
I am so sorry to say also... this makes no sense at all ... a boiler has an expanison tank and reducing valve from the start at install.... capable of reducing city water line pressure..... if 100psi was present at boiler and reducer failed... relief valved should have opened and flooded the area protecting boiler from major damage...just my 2 cents...

Last edited by ben's plumbing; 04-17-2012 at 06:28 PM.
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Old 04-17-2012, 06:58 PM   #10
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Is 15psi on boiler too low?


Something else to consider in regards to your shower head- It's possible that pipe scale has now clogged the head and aerator. It can happen when pipes are cut into to install things like PRV's, etc.
Also, if you have a pressure regulating valve on the house line, you also need an expansion tank.
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Old 04-17-2012, 08:45 PM   #11
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Is 15psi on boiler too low?


Water started dripping out here and flooded our laundry/boiler room:

#1)


This is our heater installed 1 year 4 mos ago:

#2)


This is the expansion tank installed:

#3)


The receipt says:

"Installed new main water pressure regulator w/ dual check backflow prevention and expansion tank w/ relief valve. Also replaced temp/pressure relief valve for boiler."

On the other receipt (where I gave downpayment), it says:

"Install one pressure domestic system pressure absorption and backflow domestic. Also one pressure relief system for Triangle Tube. 1 yr warranty."

Pricing was $265.92 for I think the boiler's pressure relief system and $750 for the rest.

Our old boiler was replaced over a year ago because of water (muck, actually) started pouring out of one of the copper pipes.

I'm wondering if what the city did when they came in a few years ago to do free work caused the damage to our old boiler -- and now to our new one.

Today, I bought a psi gauge at HomeDepot and it reads about 43-44 psi. I also installed a new shower head and water sprinkles out better.
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Old 04-17-2012, 09:23 PM   #12
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Is 15psi on boiler too low?


Quote:
Originally Posted by vcsolit View Post
Water started dripping out here and flooded our laundry/boiler room:

#1)


This is our heater installed 1 year 4 mos ago:

#2)


This is the expansion tank installed:

#3)


The receipt says:

"Installed new main water pressure regulator w/ dual check backflow prevention and expansion tank w/ relief valve. Also replaced temp/pressure relief valve for boiler."

On the other receipt (where I gave downpayment), it says:

"Install one pressure domestic system pressure absorption and backflow domestic. Also one pressure relief system for Triangle Tube. 1 yr warranty."

Pricing was $265.92 for I think the boiler's pressure relief system and $750 for the rest.

Our old boiler was replaced over a year ago because of water (muck, actually) started pouring out of one of the copper pipes.

I'm wondering if what the city did when they came in a few years ago to do free work caused the damage to our old boiler -- and now to our new one.

Today, I bought a psi gauge at HomeDepot and it reads about 43-44 psi. I also installed a new shower head and water sprinkles out better.
makes all the sense in the world now.....not just for boiler....thanks...
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Old 04-18-2012, 12:40 AM   #13
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Is 15psi on boiler too low?


Id say they should have pulled/cleaned the aerators on faucets and shower heads when they worked on your supply lines
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Old 04-18-2012, 10:34 AM   #14
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Is 15psi on boiler too low?


getting back to the original issue of the pressure relief valve leaking water...Which they will do under one or both of two conditions.

first condition Over pressuring of the boiler system. This can be caused by too high of a static boiler pressure. If this is too high (normal would be in the 12-15 psi range) it would over pressure when heating and cause the pressure relief to vent pressure... ie: leak water. This is usually caused by a faulty pressure regulator. As these do not self repair the condition would still be present untill someone replaced the regulator. Another culprit in a over pressure condition is a saturated bladder/expansion tank. The tank below your boiler is a bladder tank. If the bladder is ruptured it will no longer contain air on one side of the bladder. This will cause a rapid increase in pressure within the system when the system is heating water. since air is compressible and water is not the air in the bladder will compress to make room for the increase in water volume when it is heated.

The second condition is usually a defective Pressure relief valve. This is pretty common and will cause water to leak out like you saw. Generaly these are set to release at 30PSI so do not confuse these with a hot water tank pressure release valve. When they changed that it solved the problem.
I doubt that any spike in the city water pressure contributed to your problem and 100+ PSi is not all that uncommon in some areas. I have measured anywhere from 90-125 PSi in my own house with no issues at all. Generaly it is 90-95 PSI. I also do not need a pressure tank on my domestic system as we do not use backflow preventers in our area on our municipal water supply

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