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Washing Machine Thuds

Sun Jun 22, 2014 10:15 am

I'm trying to figure out if this is normal or not as I remember way back in the day my parents had this same thing. I bought a brand new front loading washing machine and when it goes to take in water it sucks for about 2 seconds then stops with a thud. It then starts taking more in for about 2 seconds and thuds again. It does this a few times until it has enough water to begin the cycle. Is this normal to have the thud sound?
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Maximum Gerbil
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Re: Washing Machine Thuds

Sun Jun 22, 2014 2:33 pm

It's water hammer from it shutting off so quickly. ... /100069256 or similar from your local hardware or plumbing store may help.
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Re: Washing Machine Thuds

Sun Jun 22, 2014 8:11 pm

+1 for water hammer. Not good for your pipes.

If the hammer arrester doesn't help, you may need to get a plumber in to sort out the issue. There are a few tips online on ways to try to deal with it without calling a plumber (something to the effect of turning off the mains, turning on the taps that have the hammer problem, and letting the water drain and air pockets re-establish themselves - don't have time to google right now), but I've found them to be temporary at best for my pipes.
Maximum Gerbil
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Re: Washing Machine Thuds

Mon Jun 23, 2014 8:04 am

The problem with establishing air pockets in the plumbing to take the shock of the water hammer is that the air dissolves back in to the water over time. A friend of mine drains his house down every winter when shutting off the outside taps just to re-establish them. The water hammer arrestors have a piston in them between the air and the water to stop the air being absorbed. You can get other arrestors that are meant for T-ing in to the plumbing rather than going on the machine, but I don't think they will be as effective as the problem is with the washing machine valve shutoff. LG washers seem to be notorious for it.

One thing with the arrestors that go on the machine, they need to go on the back of the machine and not on the end of the hoses where they plug in to the taps. If the machine connections are a little recessed that can be tricky if not impossible if the arrestors don't have a long enough output on them. I've got mine sticking sideways as the top overhang is just a smidge too long to get them vertical. That's OK as they are designed to operate any way up.
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Re: Washing Machine Thuds

Mon Jun 23, 2014 4:36 pm

Basic problem with a washing machine is that the device wants either all water or no water and must reliably cycle between them many thousands of times using electrical control. Usually this means a relatively cheap and highly reliable solenoid valve. Unfortunately, solenoid valves also operate very fast unless intentionally damped (which has other consequences for complexity and reliability). So, when cycling off, all of the fast-flowing water mass in the pipe network is halted abruptly and 'slams' to a stop.

Most other household taps shut off in a progressive fashion and don't typically produce this effect.
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