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 Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

My new house has Grundfos X MQ3-45. water pressure pump.
City water pressure to my house is about 30 psi (after I turned off the pump). and Once this pump is on, my water pressure jump to 90 psi. I liked the water pressure when shower and everything
now, bit of water coming from temperature pressure relief valve on water heater (75 gallon).
I replaced TPV but same thing happened.
I realized water expansion tank is the problem. When I press the air charge valve, water was coming out from the expansion tank (Watts 5 gallon tank). It means the rubber is ruptured and the tank is not good.
I bought new 5 gallon tank different brand from Lowes.
the air pre-charge should be equal to house water pressure.
Unfortunately, I don't have pressure reducing Valve
Can I air charge 90 PSI into new thermal water expansion tank?



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

My opinion, anything over about 60-70 psi is too much water pressure. I'd think about getting a pressure reducing valve installed and setting it correctly. Then you can get the expansion tank adjusted to match.

With sustained high pressure you could have other leaks develop. And that high pressure may be what happened to damage your old expansion tank. Your plumbing was originally installed and checked with a lower water pressure than 90psi.



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: Wheelchair (IL)

As a homeowner, in your state you can. But I would suggest that you not for so many reasons. Your home owners insurance policy may not cover that, in the event of a physical loss.

Best Wishes

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

Thank you for the response.
So, I should install PRV.
One question.
with water pump, the pressure is 90 psi.
so to make 60 psi, I need to reduce 30 psi. city pressure is 30 psi. basically, I need to reduce the city pressure to 0 psi?

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

Ha! I think your pump takes the 30 psi water coming in from city and boosts it to 90 psi. If you could take the city pressure to 0 psi your boost pump would also go to 0 psi. The PRV gets installed "downstream" of the boost pump (I believe).

There may be a way to adjust your boost pump so it puts out less pressure, you'd need to read the paperwork that came with it or contact the pump maker.

A properly installed PRV will solve the high water pressure problem. And it will be able to handle the 90 psi from your boost pump. If your new house came with the boost pump due to low city water pressure why didn't it also have a PRV installed by the same person/company?



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

builder's warranty is 1 year and I lived 1 year and half.
I already research and the pump's pressure is not adjustable.

I am wondering same thing here. why builder didn't install PRV???
Is it in state law?

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: packy (MA)

yes..

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

Is it possible you have a PRV and don't recognize it? I'm not sure where they are typically installed but I believe it should be in plain sight and easily found.

If you don't have one do you know if your neighbors have one or not? If they do then your home may have been an oversight and all it takes is a call to the builder, even though it is out of homeowner's warranty I'd think they'd want to make their mistake right. If not you can call whoever issues their building permit license or the BBB, local homebuilder's association or somebody and lodge a complaint. Find out if you next door neighbors have a PRV.

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: hj (AZ)

Regardless of WHAT air pressure you put into the tank, as soon as you turn the water on the pressure will be the same as the water pressure.

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: packy (MA)

hj, exactly.. totally different function than a well tank.
one is to absorb excess pressure and one is to give additional volume to a well system.

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

Here is the pipe map in my house







I am pretty sure I don't have PRV right?

PRV should be installed between main valve and pump right?



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: Paul48 (CT)

Yes....If you read the install instructions, it states that the inlet pressure is added to the pump pressure.

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: packy (MA)

metal clips holding plastic pipes ??

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

dear packy,
metal clips holding plastic pipes ??? where are you talking about?
You are saying this plumbing was not done properly?
What should I do?

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: steve_g (CA)

Watts states that max pressure for their expansion tank is 150 psi.

[www.watts.com]

Back when dinosaurs roamed the earth, I was required to install a PRV for anything over 100 psi. A few millenium later that was dropped to 80 PSI. It's too bad the pump isn't adjustable. Perhaps you should just replace it, or live with the 90 psi.



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

I'd have a pressure reducing valve installed, set it for something like 60psi. The PRV's are not that costly, it will solve the problem and probably prevent others from developing down the road.

The boost pump manufacturer can be contacted, there may be a part on the pump that can be changed to adjust the outlet pressure downward. Not sure why someone would install a 90psi pump like that and not install a PRV. Piping and fixtures in the home are really not made with that high pressure in mind, you are more likely to have leaks develop and it puts extra stress on everything, such as the water heater expansion cycle, any plastic water supply lines, the inexpensive plastic builder stop valves, fill valves on the washing machine and dishwasher, your garden water hose when it is charged with water pressure but the spray nozzle is closed down and you leave the hose in the sun, etc.



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: steve_g (CA)

That got me curious so I started looking around to see what the max pressure is for various fixtures. Not all that easy to find and I had to make a few calls. Fluidmaster states that the max incoming water pressure for a 400 fill valve is 230 psi. Delta told me that all their faucets are tested to 100 psi. I found this on Uponer [www.uponor-usa.com]:

Uponor PEX tubing carries the following hydrostatic temperature and pressure ratings.

200°F (93.3°C) at 80 psi
180°F (82.2°C) at 100 psi
120°F (48.9°C) at 130 psi (½" piping only)
73.4°F (23°C) at 160 psi

The burst pressure of copper piping is much higher[www.copper.org] page 75 (it's thousands of pounds)

I suspect that lower water pressures are preferred as a conservation measure, and there's nothing wrong with that.



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

If it is ok to have water pressure of 90psi how would you solve the original poster's problem without reducing the water pressure? His leaking water heater is just one of several potential leaks in the water supply system in a home with pressure that high.


This is from the Watts website concerning pressure reducing valves. Granted they sell PRV's, but I don't think they'd put this out there and subject themselves to industry criticism just to sell PRV's:

"Most plumbing codes require water pressure reducing valves on domestic systems where the municipal water main's pressure exceeds 80psi. Higher pressures could rupture pipes, damage fixtures,and injure the people using them."



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: steve_g (CA)

Just reporting what I see. Long time ago, 100 psi was the magic PRV number. I would wonder if pumping into a PRV is going to shorten the life of the pump, but I'm not sure. That would be a question (among other questions, like can the pump be set lower) for the pump mfg.

But to solve his problem immediately I would go ahead and charge the expansion tank to 90 psi, then think about dealing with the pump.

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: Paul48 (CT)

Reduce the inlet pressure. Adjust it until you get the outlet pressure desired.

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

Could the inlet pressure to the boost pump be reduced simply by partially closing the house's main shutoff valve and monitoring the outlet pressure for the desired level?



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: steve_g (CA)

Unless they were shooting for 90 psi, the pump wasn't sized correctly:

[us.grundfos.com]

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: packy (MA)

I would leave the inlet alone. DECREASING the volume by restriction either thru a PRV or a partially closed valve will hurt rather than help.
the pressure in the house when the pump is running will only last as long as the pump can adequately pull water from the street.

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

thank you all for post and recommendation.

One that I bought from Lowes (Utilitech 5-Gallon Expansion Pressure Tank). warranty card said AO Smith brand, I charged 90 psi. but couldn't hold pressure, precharged air was "0" after two days and of course, leaked from TPV. just don't buy that!

I ended up bought Falcon 4.8 G Potable Water Expansion Tank for up to 120-Gallon Water Heaters 5 Year Warranty from amazon.
charged 90 PSI. This one is holding 3 days now. will see how it goes.
Honestly, I liked water pressure now(30 psi from city + 60 psi from pump = 90 psi) when shower and everything but I don't want to have problem later, pipes might blow up or something!!.

I will try to contact city inspector or someone and see what's going on my house terms of water pressure and absence of PRV.

either way, I will install the PRV for sure to prevent from high pressure.
Thank you all again

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

Not to malign but sometimes I feel like Utilitech plumbing items are like Harbor Freight tools. Some are ok for the cost but others just don't work out like they should. Maybe just me.....

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: steve_g (CA)

Just for the heck of it, contact Grundfos tech help before installing a PRV:

Contact Grundfos Service
Phone: 630-719-7433
Email: serviceus@grundfos.com

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

I just find out MA plumbing code :
"(g) Excessive Water Pressure.

When the municipal service or other water service source provides water to a building that exceeds 80 P.S.I.G., a pressure reducing valve shall be installed in the water main pipe at the point of water service entrance to the building. This is to reduce the water pressure to a maximum of 80 P.S.I.G. or less. This requirement does not apply where the water service pipe supplies water directly to a water pressure booster system, an elevated water gravity tank, or to pumps provided in connection with a hydro-pneumatic or elevated gravity water supply tank system."

It looks like PRV requirement doesn't apply to my house since I have water pressure booster.
hm....

I will try to call Grundfos and see I can lower the pressure down from the pump

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

yes, your pressure from the city if much lower at 30 psi. But the implication of the plumbing code is that 80 psi is too much pressure for residential use. With your boost pump on you measured 90 psi. There's a reason behind the plumbing code limit of 80 psi max water pressure so I'd get it below that if I were you. My experience is that 55-60 psi is fine and you'll no longer have to worry about getting your freckles or tats removed by the water pressure when showering. And you don't have to tell anyone your "stream" is not as strong as it used to be. <grin>

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

Do I need permit to put PRV? plumber has to pull the permit?
How can I know what size is PRV? 3/4 or 1"?
Can you tell by looking at the photo I posted?
Do you know what kind of pipe I have? CPVC? PEX? what's the the white plastic pipe?



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

In your case since the city water pressure coming into your house is only 30 psi I would think a PRV would get installed after your boost pump. But I will defer to the experienced plumbers.

In MASS I'm going to guess that legally you can't install the PRV yourself, they have some strict plumbing codes there. But it is inside your home, you can do it yourself and no one will know, so that is up to you. Did you find out if any of your neighbors that also have low incoming water pressure and have boost pumps have a PRV or not?

The size of the PRV would depend on the size of the pipes it will get connected to. I don't know what that white plastic pipe is, builders used a lot of poly pipe back in the day but I thought it was usually black.

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

talked to Grundfos tech guy and confirmed the pump pressure is fixed.
He told me to put PRV prior (inlet) to the pump.

I found out the pipe info as well.
Uponor AquaPEX 1". watched and got info from youtube and the pipe looks pretty good.
to use this system to connect PRV, I need pipe expander which is about $175.

So, my plan
cut pipe and use two SharkBite U140LFA 1" adapter (push fitting) to connect 1" Pressure reducing Valve.
what do you think?

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

"talked to Grundfos tech guy and confirmed the pump pressure is fixed.
He told me to put PRV prior (inlet) to the pump."
------------------------------------------------------------------------------------------------------------
Ha! that shows how much I don't know about boost pumps and PRV's!


Probably not going to happen, but is there a tool rental place in your area that might have the pex pipe expander?



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

Uponor aquarPEX system looks like special and i don't think I can rent the expander.
I can buy an expander from amazon and return after use. but I feel like I am a liar.

Why? you don't like Sharkbite adapter?

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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: steve_g (CA)

A lot of folks will buy PEX tools on ebay, then sell them on ebay when they're finished. Sharkbite in an exposed location should be OK though.

I'm not sure what PRV you would install to drop the pressure from 30 psi to 20, if you want to drop the psi downstream of your pump to 80 psi. Watts has some low-pressure PRVs but only up to 3/4". The number for Watts is 1-978-689-6066.



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: stuckinlodi (MO)

Nope, I have nothing against sharkbite fittings. When I read your posting about how expensive the pex expander is the thought of maybe being able to rent the tool came to mind since you probably only need to make 2 expanded connections, and I stopped reading the rest of your comment as I thought about that. The sharkbites might be just the thing to make the job easier and less costly.

Before you go too far I'd get the correct PRV in hand.

I'm curious about this 30 psi water pressure, is your entire city water supply like that? What about the fire hydrants in your neighborhood? Pardon me, but this seems goofy for a city to do.



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 Re: Can I air charge 90 PSI into thermal water expansion tank?
Author: kivfer (MA)

I bought Wilkins 1-NR3XLDU 1" Pressure Reducing Valve
it said it can reduce to 15 - 75 psi

just talked to city water department guy and confirmed 30 psi is the right pressure for my house (one of the highest ground level in town so water pressure is the lowest)



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