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Peety 02-05-2010 09:39 AM

Hot water pipes (closed system) vibrate very loudly.
How do I stop my hot water pipes from vibrating?

My secondary heat is a closed system hot water tank (separate from consumable hot water heater). It has a regular tank, gas heated, pressure regulator, expansion tank, flow control and electric circulator in the basement which lead to 2nd floor pipes in base board registers, with an air bleeder valve on the in pipe, and one on the return pipe.

Very simple set up (about 40 years old) but it just started vibrating very loudly when the pump comes on. The vibration appears from the circulator pump back up the pipes and back to the tank, that is to say, I don't hear it in the cold water pipes in to the tank.

I tried oiling the pump, but really it sounds very smooth. Plenty of heat. I can't anchor the pipes anymore than they are. I checked the air bled valves but only a little air came out. The pressure on the tank meter was about 8 this morning (I released some water as a troubleshooting attempt and now it reads 4 -5 but started to climb to around 7 before I stopped heating again). I don't know what it was about a week ago though.

No water leakage and the expansion tank is about 5 years old. It is the smaller version, attached to the tank, and does not get hot.

Any ideas? Thanks in advance!

Viper16 02-05-2010 04:34 PM

I would think about getting a water hammer arrestor. I wonder if the expansion tank has the correct preset air pressure on the air side of the diaphragm. Where was this tank pressure gauge located?

Peety 02-05-2010 05:29 PM

Question about arrestor
Thanks for replying.

Excuse my ignorance but I don't think this system has any quick-closing valves, like those on the hot water heater system for the house - does that matter? Actually I don't think there are any valves at all (except the shut off valve on the cold inlet pipe.

The water gauge is a dual gauge located on top of the tank itself for altitude and water pressure. It is set for thirty feet and about 6-8 psi at the moment.

I removed the cap on the expansion tank (it was dry) and was going to measure psi with a tire gauge, but I don't know what it should normally read - right now I have the system off and will check it when the temp comes down on the water.

This just happened after a very long time, would I need a certain type of arrestor?

JohnH1 02-05-2010 07:31 PM

If it only happens when the pump operates then it has to do with the pump not water psi or hammer. Is this a 3 piece pump with a spring coupling that joins the motor to the bearing assembly? Post a pic if you can.

Peety 02-06-2010 10:26 AM

4 Attachment(s)
ok thanks. Here's my artwork. I can feel a slight vibration nearer the pump, but it sounds like a rocket engine by the time it is transferred up stairs :eek:

edit: as I look at the pictures I note the corrosion on the flow regulator leading from the tank in the second picture, lower left (as posted). I'm going to drain the tank a bit and dissemble that puppy. Could it be a corroded flow valve is straining the pump? No idea.

JohnH1 02-06-2010 03:43 PM

I would guess that it is the spring coupling in the pump slightly out of alignment due to sagging motor mounts. At the ends of the motor part of the pump there are rubber rings. Eventially they will sag and cause the shaft of the motor not to line up / or be perfectly leval with the pump shaft. This can cause the spring coupling to make noise and eventually break and when that happens you will really here it. I would change out the ring set and coupling.

beenthere 02-06-2010 06:14 PM

And or minor cavitation from being slightly low on water for a 2 story house.

JohnH1 02-06-2010 07:08 PM

Yep I did not think of that. Especilly since the pump is on the return with the diaphram tank on the supply all the head is on the suction side it would definetly be in the negitave.

2 story aprox 15 to 20 ft height at the most. Say 6-8psi + 4 extra No more than 10-12 psi will be needed.

Peety 02-07-2010 09:53 AM

Ok thanks everyone for responding and info and thanks JohnH1 for the Service Manual and Guide link.

We've got some work ahead of us which will take us awhile and this thread may close so I'm going to say now THANKS!


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