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1

Sunday, June 17th 2012, 4:41pm

Another Load thumping question

I figured this was different enough, plus I've asked numerous live folks with limited success. . . so here it goes:

The past two seasons I've had a thumping sound, not when the zone turns on or off, but the whole time the zone is running. The frequency of the thump as well as intensity varies with different different zones. Not all the zones are problematic.

I have been able to open an inside sink to diffuse some of the noise, but this seems to be a waste and isn't very effective. There is no expansion tank. The back flow preventor is a FebCo, which needs to be replaced due to a small leak in the copper (is it copper?) It follows zones, I have swapped the innards of the valves and it does not follow the valve but stays on the actual zone.

Any ideas? I'm going to replace the FebCo, but not sure that will solve the problem.

Wet_Boots

Supreme Member

Posts: 4,066

Location: Metro NYC

2

Sunday, June 17th 2012, 9:02pm

try restricting the flow on the noisy zones

hi.todd

Supreme Member

Posts: 417

Location: Houston, Texas

3

Sunday, June 17th 2012, 10:06pm

Diaphragms on The loud zones.

:thumbsup:
:thumbup: :thumbsup:

hi.todd

Supreme Member

Posts: 417

Location: Houston, Texas

4

Sunday, June 17th 2012, 10:09pm

I just read that you swapped the innards on the valves.

Do you have a master valve?
:thumbup: :thumbsup:

hi.todd

Supreme Member

Posts: 417

Location: Houston, Texas

5

Sunday, June 17th 2012, 10:10pm

The backflow should be before the valves.
:thumbup: :thumbsup:

6

Sunday, June 17th 2012, 10:16pm

From the house, there is the main supply, copper pipe from the house, with a ball valve and drain. Then the FebCo with ball valves on both sides of it. Then the manifold boxes with valves.

I'll try to restrict the flow tomorrow, not sure how to do that but I'll read a bit tonight.

When you say diaphragm on the load zone, is that an add on or a part of the valve that needs to be replaced?

Wet_Boots

Supreme Member

Posts: 4,066

Location: Metro NYC

7

Monday, June 18th 2012, 5:31am

Use the ball valves to restrict the flow - this is for diagnostic purposes only

8

Monday, June 18th 2012, 8:35pm

For the zones that are thumping, restricting the ball valve to ~25% (almost off) removes the sound. There is also not enough flow to properly water with it this restricted, but it does rectify the situation. Now does that mean it is a diaphragm? Or possibly the FebCo with the slight leak?

Wet_Boots

Supreme Member

Posts: 4,066

Location: Metro NYC

9

Tuesday, June 19th 2012, 6:22am

It confirms that the problem relates to flow, and that a solution might be as easy as reducing the flow in the affected zones, by way of replacing rotor nozzles with ones a size smaller.

This is not a rare problem in systems that have flows that are too high for the plumbing supply to handle smoothly. A zone valve opens up, and the rush of water through the supply pipe creates enough of a pressure drop to allow the zone valve to almost close, whereupon the pressure in the supply pipe goes back up, and the process repeats. Reducing the flows in the zones is key to solving this problem permanently.

10

Tuesday, June 19th 2012, 11:09am

Add some more troubleshooting that I have done recently. I turned off one head at a time in one trouble zone, until the noise/vibration stopped. This only occurred after 4 of the heads were stopped, removing 1/2 of the zone. These zones operated without trouble for years, no changes in the heads etc (don't know if there was a pressure change, but the interior hasn't observed one)

The physical vibration seems to be centered around the Back-flow preventor. Could my flow have increased by 2-4x without a noticeable increase inside?

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