High Pressure Water from Street

10 years ago

We are plumbing a very old house and have two issues we need to address: The brand new hot water heater and the awfully old boiler for the radiators.

Our water pressure at our hose outside measured at 97psi. I do not want to reduce the water pressure, because the house is a large three-story structure and I don't want the water in my most remote shower to feel like I'm hanging out in a sprinkler. I LIKE high pressure!

But the 40 gal HW heater needs an expansion tank and the one the guy at Lowes told me to get is too small (2 gal) according to its own chart. I currently have the HW off because the minute it heats up the TPV starts dripping and I'm not interested in an explosion thank you very much.

How large of an expansion tank should I have, and is this water pressure ok? The guy at Lowes acted like this was an absolutely insane pressure and recommended no more than 65 psi. Is this a modern, eco-friendly pressure only, or is it actually unsafe to have 100 psi coming into the house? He said my faucets would leak at that pressure but the cold water has been hooked up for months with zero problems.

Also, I have no idea how many gallons of water will go into the boiler and I would need that to size the expansion tank for it, correct? There's an existing tank there, but it's rusted out and hanging by a thread so I want to replace it. The boiler runs a mono-flow HW Radiator system that we want to use for heating and we know it isn't leaking, it's holding water, but I don't know how many gallons to account for. All of the gallons in the entire house? Do the radiators completely fill with water? That seems like a LOT of gallons, it's approximately 90-100 4-foot tall fins.

Sort by:Oldest

Comments (6)

rwiegand
10 years ago
We used to have a house with 90+ psi coming from the street. I had a whole second career replacing faucet washers-- we had to screw down on them so tight to turn them off that the washes would get shredded. Adding a pressure regulator that allowed us to drop the pressure to 50-55 still gave plenty of oomph to the system but with much less hassle. Depending on your setup (eg if there is only one riser to the upper levels) you could feed the upper floors with higher pressure than the lower ones.
User
10 years ago
IIRC correctly code sets a max of 80 psi for residential.

The T&P valve on your WH is a safety device and repeatedly tripping it compromises it's reliability as such

A PRV (pressure regulating valve) is a MUST. Get your water pressure down to about 60-65 psi.

You'll find all you want and need to know about thermal expansion here... http://www.watts.com/pages/learnabout/thermalExpansion.asp

This post was edited by justalurker on Fri, Aug 9, 13 at 16:10
Related Professionals
Worcester Plumbers · Miller Place Plumbers · Athens Kitchen & Bathroom Remodelers · Beverly Hills Kitchen & Bathroom Remodelers · Champlin Kitchen & Bathroom Remodelers · Eagle Kitchen & Bathroom Remodelers · Glen Allen Kitchen & Bathroom Remodelers · Lynn Haven Kitchen & Bathroom Remodelers · Manassas Kitchen & Bathroom Remodelers · Oklahoma City Kitchen & Bathroom Remodelers · Rolling Hills Estates Kitchen & Bathroom Remodelers · Spanish Springs Kitchen & Bathroom Remodelers · York Kitchen & Bathroom Remodelers · Phillipsburg Kitchen & Bathroom Remodelers · Gibsonton Kitchen & Bathroom Remodelers
kirkhall
10 years ago
Justalurker,
This is us too. Apparently our whole city has about 100psi to houses. We discovered this when we had someone come to replace an element in our WH. Our house measures just over 100

I called my plumber, who still has work to be done for us and I still owe him money (he hasn't invoiced it yet) for earlier work this spring, back in JUNE about this issue. I am still waiting. He said he'd get to me in July...

How long is realistic to "let this go" given that we've lived in this house 9 yrs without knowing about the issue. Everyone seems to say "TOO HIGH!" but then when the city supplies it at that... I bet 90% of the houses have no idea their water pressure is too high.

Also, how much should it cost to have a PRV installed?
User
10 years ago
As long as your T&P valve on the WH is repeatedly bleeding off excess pressure then nothing bad should happen BUT I'd want the problem corrected sooner than your plumber seems to want to get around to it cause if your T&P valve sticks closed then possible BOOM and it is now August.

When a PRV is installed and adjusted the plumbing system in your home becomes a CLOSED system and that necessitates the installation of a thermal expansion tank. I'd also replace the T&P valve in the WH at the same time BUT make sure the new T&P is an exact replacement in length and temp and pressure for the one that is installed in the WH from the factory. The aproned ones at the box stores think T&P valves are all the same and whatever is on the shelf fits all but it doesn't. In my experience you might have to really search to find an exact replacement T&P valve and don't let ANYONE, including plumbers, tell you it doesn't matter.

As far as cost, I've learned that plumbing always costs more than you expected, but it has to be done. Call a couple other plumbers and ask for a free quote.

With the proper water pressure faucets, fixtures, appliances, hoses, and toilet flappers will last a lot longer before needing attention.

This post was edited by justalurker on Sat, Aug 10, 13 at 17:54
kirkhall
10 years ago
Thanks! We have an expansion tank, but know it has failed (water will come out at the top "bicycle valve" if you push in the pin).

Time to give the plumber some sort of ultimatum, I guess...
Thanks!
User
10 years ago
Expansion tank failed because you pressure is TOO HIGH. Cure the disease instead of treating the symptom... you need a PRV installed and now you need a new thermal expansion tank because the plumber isn't doing his/her job. I'd find a new plumber..

Here are the installation instructions. Make note of what is says about max system pressure... http://media.wattswater.com/2915054.pdf

It should be easy to replace. The tank should simply screw into the 3/4" female fitting when you unscrew the old one. A few clockwise wraps (looking down at the top of the tank) of Teflon tape on the tank threads should do the job.

You can buy the expansion tanks at HD and Lowes. Just get the same size and set the air charge to plumbing static system pressure with the tank EMPTY.