How do I adjust water pressure for our washer
July 1, 2010 8:46 AM Subscribe
We hooked up a clothes washer in our new condo, but my wife remembers the original home inspection indicating that the water pressure was too high for the washer, and that we would need to adjust it first before first using it.
How do I do this? Where is it done, and how? Any pointers?
How do I do this? Where is it done, and how? Any pointers?
With a condo this is going to be a little tricky. First, is your water individually metered or is part of your monthly assessments? If it is individually metered, you can have a plumber install a pressure regulator at or near the meter. If you are on a common meter and (as I suspect) all of your water lines are inside the wall, it is possible to get in-line pressure regulators that simply screw onto the water faucets ahead of the washer hoses. These are not as satisfactory as regulating the pressure for all sinks, toilets, etc., through doing it at the source.
You also might want to check with the maker of your washing machine as to the maximum recommended pressure for incoming water. They may tell you that there is nothing to worry about. Is there a history of washing machines blowing out due to high pressure in your building? Ask your new neighbors. The inspector may have simply been overly conservative in his judgment.
posted by Old Geezer at 9:59 AM on July 1, 2010
You also might want to check with the maker of your washing machine as to the maximum recommended pressure for incoming water. They may tell you that there is nothing to worry about. Is there a history of washing machines blowing out due to high pressure in your building? Ask your new neighbors. The inspector may have simply been overly conservative in his judgment.
posted by Old Geezer at 9:59 AM on July 1, 2010
For about $10 you can go to a big box or plumbing supply store and get a pressure gauge to tellyou what your pressure is and how it varies during the day. For years my pressure was always above 80 PSI (I think it got as high as 120 at times; it should have been about 50). I never had problems with appliances (washing machine, dishwasher) but had to deal with leaky faucets and running toilets a lot. I got a pressure reducing valve installed for about 300 dollars (he did some other work so by itself it would have been a little cheaper) and my fixtures have needed much less maintenance. Flabdablet described the procedure well. It is within the realm of an experienced handyman to do, but in my case I opted for a pro.
You may want to make sure your appliances are connected with steel braided tubing, as it is much more resistant to bursting.
posted by TedW at 11:00 AM on July 1, 2010
You may want to make sure your appliances are connected with steel braided tubing, as it is much more resistant to bursting.
posted by TedW at 11:00 AM on July 1, 2010
If you install a whole-house pressure limiter yourself, (which I was able to do fairly easily only because I could put it in place of an old, no longer used activated carbon filter) keep in mind that you will probably need to add an expansion tank to your water heater, or it will start leaking through the pressure relief valve on top, because the pressure limiter will almost certainly have a backflow prevention feature that will take away the previously available ability of your water system to cope with the thermal expansion of the heating water in your tank by pushing it back into the outside supply line.
posted by jamjam at 2:26 PM on July 1, 2010
posted by jamjam at 2:26 PM on July 1, 2010
Response by poster: It dawned on me that the previous owners had a washer hookup, and I'm guessing that they didn't have major issues. Perhaps this is something that is model specific? We have an old Maytag A512, but I can't find any specifications regarding water pressure limits.
posted by SpacemanStix at 3:33 PM on July 1, 2010
posted by SpacemanStix at 3:33 PM on July 1, 2010
keep in mind that you will probably need to add an expansion tank to your water heater, or it will start leaking through the pressure relief valve on top, because the pressure limiter will almost certainly have a backflow prevention feature that will take away the previously available ability of your water system to cope with the thermal expansion of the heating water in your tank by pushing it back into the outside supply line.
The way that works at my house is that the main regulator restricts incoming flow so that upstream can never pressurize the house plumbing to higher than 700kPa. There's a pressure relief outlet attached to the water heater's cold water supply line set to open at 850kPa, and a pressure/temperature relief valve on the hot side that will open at 90°C or 1000kPa, whichever happens first.
There is a separate backflow prevention valve upstream of the regulator, which was there before we got the regulator installed; plumbing regulations where I live make it illegal to push water back into the supply mains.
So as long as there's even a dribble of water flowing in the system, the main regulator keeps the internal plumbing below 700kPa. When all the taps are off and the heater is heating, thermal expansion in the heater tank can make it rise as high as 850kPa, at which point the relief valve cracks open and starts spilling a little cold water from the bottom of the tank. The only time the hot-side PTR valve opens is when I operate the easing lever.
Our friendly local plumber tells me he sees lots of houses that don't bother with the 850kPa pressure relief outlet, instead relying on the mandatory hot-side PTR valve. That works (although the maximum system pressure could then rise as high as 1000kPa) but it means that every time the water heater operates, it sends heat energy that you have paid for down the drain with the expansion water.
posted by flabdablet at 8:41 PM on July 1, 2010
The way that works at my house is that the main regulator restricts incoming flow so that upstream can never pressurize the house plumbing to higher than 700kPa. There's a pressure relief outlet attached to the water heater's cold water supply line set to open at 850kPa, and a pressure/temperature relief valve on the hot side that will open at 90°C or 1000kPa, whichever happens first.
There is a separate backflow prevention valve upstream of the regulator, which was there before we got the regulator installed; plumbing regulations where I live make it illegal to push water back into the supply mains.
So as long as there's even a dribble of water flowing in the system, the main regulator keeps the internal plumbing below 700kPa. When all the taps are off and the heater is heating, thermal expansion in the heater tank can make it rise as high as 850kPa, at which point the relief valve cracks open and starts spilling a little cold water from the bottom of the tank. The only time the hot-side PTR valve opens is when I operate the easing lever.
Our friendly local plumber tells me he sees lots of houses that don't bother with the 850kPa pressure relief outlet, instead relying on the mandatory hot-side PTR valve. That works (although the maximum system pressure could then rise as high as 1000kPa) but it means that every time the water heater operates, it sends heat energy that you have paid for down the drain with the expansion water.
posted by flabdablet at 8:41 PM on July 1, 2010
Ok, fladablet, very interesting, it's a pleasure to hear from someone with your knowledge and understanding; I'd hate you to know how much time I've devoted to thinking about water heaters and how little there is to show, but perhaps you won't be too put out, and the OP may gain more of a sense of these things, if we work it around another time or two.
There's a pressure relief outlet attached to the water heater's cold water supply line ...When all the taps are off and the heater is heating, thermal expansion in the heater tank can make it rise as high as 850kPa, at which point the relief valve cracks open and starts spilling a little cold water from the bottom of the tank.
It's true that the water which backs out of the tank as it heats up to the thermostat's set point does come from the bottom of the tank where the water is coolest, yet this is a slow process, and that water has probably heated up somewhat before it begins to come out, and more as time goes on-- but the real issue seems to me to be that as the water comes from the bottom of the tank, it must travel up the length of the internal fill tube, passing slowly through the entire rising temperature gradient in the tank.
I think that means that the water coming back out of the cold water inlet is very close to the temperature of the hottest water in the tank. Once it gets out of the water heater it pretty quickly reaches equilibrium with ambient temperature, too.
Therefore, I would argue that in energy terms you are no better off than those who let the expansion come out of the "hot side PTR"-- nor am I any better off with my uninsulated expansion tank.
But if my water heater manual is correct in asserting that the water heater pressure relief valve is not robust enough to stand up to such repeated operation, we can look forward to saving the expense of replacing it, as well as avoiding a potentially much, much greater cost if its failure were to make for a flood.
Modern water heaters should probably have an internal expansion tank.
posted by jamjam at 11:14 PM on July 1, 2010
There's a pressure relief outlet attached to the water heater's cold water supply line ...When all the taps are off and the heater is heating, thermal expansion in the heater tank can make it rise as high as 850kPa, at which point the relief valve cracks open and starts spilling a little cold water from the bottom of the tank.
It's true that the water which backs out of the tank as it heats up to the thermostat's set point does come from the bottom of the tank where the water is coolest, yet this is a slow process, and that water has probably heated up somewhat before it begins to come out, and more as time goes on-- but the real issue seems to me to be that as the water comes from the bottom of the tank, it must travel up the length of the internal fill tube, passing slowly through the entire rising temperature gradient in the tank.
I think that means that the water coming back out of the cold water inlet is very close to the temperature of the hottest water in the tank. Once it gets out of the water heater it pretty quickly reaches equilibrium with ambient temperature, too.
Therefore, I would argue that in energy terms you are no better off than those who let the expansion come out of the "hot side PTR"-- nor am I any better off with my uninsulated expansion tank.
But if my water heater manual is correct in asserting that the water heater pressure relief valve is not robust enough to stand up to such repeated operation, we can look forward to saving the expense of replacing it, as well as avoiding a potentially much, much greater cost if its failure were to make for a flood.
Modern water heaters should probably have an internal expansion tank.
posted by jamjam at 11:14 PM on July 1, 2010
Well, we could argue theory back and forth, or we could just go and feel the thing. I've gone and felt the thing on numerous occasions, and I can assure you that what dribbles out of the pressure relief valve on the cold side of my heater's tank while either the solar loop or the electric booster is operating remains quite cool for most of a heating cycle. In contrast, when I operate the PTR valve easing lever, what comes out is always stinking hot (as was the dribble that used to come out of there before I got the bottom relief valve fitted). Therefore, the expansion overflow is surely not dumping as much heat energy as the PTR valve would if left to operate alone.
I don't know what kind of heater you have, but mine has a heating element near the bottom of the tank, just a little above the cold water inlet. There's no "internal fill tube", just a diffuser to spread and slow incoming cold water so as to minimize loss of stratification. The solar loop does have an internal tube for water returning from the collector, and that tube's outlet is also well above the cold water inlet.
posted by flabdablet at 4:50 AM on July 2, 2010
I don't know what kind of heater you have, but mine has a heating element near the bottom of the tank, just a little above the cold water inlet. There's no "internal fill tube", just a diffuser to spread and slow incoming cold water so as to minimize loss of stratification. The solar loop does have an internal tube for water returning from the collector, and that tube's outlet is also well above the cold water inlet.
posted by flabdablet at 4:50 AM on July 2, 2010
Best answer: Seconding buying new water hoses that are strongly reinforced. With higher than normal water pressure, your old rubber hoses are just waiting to burst, flooding not only your condo, but the one below you, and probably at night or while you are away. That's major headache! When the washer isn't washing, the hoses must continually withstand the full water pressure, day and night, because the water valves are, of course, inside the washer.
posted by exphysicist345 at 12:36 PM on July 3, 2010
posted by exphysicist345 at 12:36 PM on July 3, 2010
Best answer: ...which is exactly why every washing machine ever made comes with instructions that tell you to turn off the taps when you're not using the machine.
Not that anybody ever does.
posted by flabdablet at 7:16 PM on July 3, 2010
Not that anybody ever does.
posted by flabdablet at 7:16 PM on July 3, 2010
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posted by flabdablet at 9:13 AM on July 1, 2010 [1 favorite]