Home Improvement → [Plumbing] Banging noise from 50G Ht Water tank...

This has been getting worse over the last -5-6 months or so, and I don't want the tank to burst. I have a "builders-brand-special" gas-fired 50G hot water heater from about ~1998. It's direct-draft (no air pump & no white PVC pipes coming out the top).


When the washing machine is washing on 'warm' cycle, both Hot and Cold is used at the same time. When the washer 'lets loose' and opens both up at the same time, the hot water tank makes this banging, rumbling noise for 2-3 seconds before subsiding. Some times it more ominous than others, but none the less, I doubt the tank should make this noise when the water flow opens quickly. any idea about what this is?

Sounds like water hammer.

Water is nearly incompressible if the valve shuts off quickly there is a fair amount of energy in the moving water with no place to go.

Need to add a water hammer suppressor to hot and cold lines.
»www.wattsindustries.com/ ··· M-UK.pdf

/tom

Ah! that's the trick -- you have it reversed... the rumbling / banging happens when the water *starts* suddenly, not when it shuts off suddenly. --Thus the reason for my posting. If it was hammering upon shutoff, then I know I'd need some sort of pressure-arrestor.

It wouldn't hurt to use a couple on the washer hoses. Home Depot carries a hammerstop that fits a hose connection.

Lowes does to, as seen here:

»www.lowes.com/pd_24696-1 ··· 327&Ntt=

I installed two. They stopped the water hammer.

Is the banging noise in the walls or the heater itself?

Sounds like high pressure due to thermal expansion, then low pressure due to the washer demanding hot and cold..

He said the heater makes the noise when the washer opens the fill valve, not closes it. Water hammer happens when the solenoid valve shuts off quickly, and the mass of flowing water slams against the valve.

If your heater is from 1998, you are on borrowed time. Should be budgeting for a new heater. Rumbling can also be caused by lime/calcium buildup on the bottom of the tank.

Also get a pressure gauge and put it on the drain valve of your heater, and watch the heater as it heats. if the pressure continues to rise, you have a thermal expansion problem. Check the pressure under load also, as you may have a failing water pressure regulator. Pressure swings greater than 20psi are very bad for a tank

-j

You might need a expansion tank for the water heater. It pretty easy to identify this problem. If you turn on the cold water, in the sink, first thing in the morning, does it come out really hard for a second or two, and then flows normal? If so your hot water heater has pressurized you water lines. This is not a good thing either. I know some utilities have replace water meters, with models that have backflow preventer. So when your hot water heater, heats the water, it pushes water expansion back on your cold water lines. The backflow prevention device prevents it from pushing back into the public utilities water lines. Luckily, my water company hasn't installed such a device, yet. I guess they are waiting for a cheap smart water meter first. My previous apartment suffered from this problem, and besides from the occasional banging pipes, my washing machine hated it. I actually had to turn the gate valves, where it was only partially on. The pressure would be so high, that it would start filling on its on, and the machine off. Later.

»www.lowes.com/pd_160680- ··· cetInfo=

OP here: Thanks for the assistance. The tank has otherwise been working well over the years. The hammer / rumble definitly inside the tank (tank in basement, sitting on slab) not the pipes. This has gradualy increased over the last number of months. I can also attach a hose to the lower drain valve, and just run some water thru it to wash out the tank a bit. Some interesting info.. the house I'm in was built by my grandparents in 1963. The original 50gal tank was an American Standard with a fiberglass tank, which was quite unusual for 1963. This tank lasted from 1963 till it sprung a leak in 1998!

Gas water heater with a fiberglass tank? uhhh.. dont think so...mebe electric, but thats pushin it..

Mebbe you meant stone-steel or Monel?

-j

This sounds more like the issue perhaps. Have you ever drained and flushed the heater?