Can't find out what causses that noise in hydronic pipes

Luc

Thanks Tim for your reply.

The zone valves on the manifolds are the Wirsbo slow-opening thermal actuator. I did check the backward zone valve option. The zone valves are installed on the supply manifold. Could this be really the problem?

When I cut off the water to one manifold(it has 9 valve actuators)the noise stops. When I turned it back on it start again. 20 minutes later there is no noise anywhere even if I play with the cut off valve on the same manifold.

Tom Hopkins

I got a constant hammering noise coming from the supply pipes of a zone at its highest points. It sounds like a the noise of a washing machine in the wash cycle. The zone is made up of several manifolds. Each manifold has several zone valves.

Changed the circulator on this zone recently. Thought it was coming from the circulator that was pumping too much. Lowered the speed of the circulator without any change.

I then checked to see if it was air in the pipes. There is a float type air vent on each return manifold of the radiant tubing. It just happen that in noisy area there is little demand from the thermostats. Most of them are turned off. I turned several of the thermostat on and all of the sudden the noise stopped. One thermostat was then kept on for a few hours and then turned off. I then thought the problem was solved, but the next day it came back.

Any idea what could cause this constant hammering noise? Is it because there is still some air in the system? Could it be a bad zone valve? For the moment, I told one of the resident to keep some thermostats running so that it would evacuate any air that could cause this.

Thanks for all your help.

EMC PLUMBING

could be a few different problems,if its run out in copper, the holes that were drilled for the pipes to run through may be too small, when the copper heats up and expands it has no where to go but against the wood.How is the boiler set up one pump on the return and zone valves on the feeds, if so if a few zones are calling and the pump is running,and one zone valve closes, it can cause a hammering sound, but should not be a constant thing only one zone shuts down? thats a couple of ideas.
good luck
ed

Tom Hopkins

Thanks Ed for the answer.

The building is seven years old and the problem has only been noticed after we changed the circulator weeks back. The circulator is an UPS 32-160/2 from Grundfos. It is pomping 30 USGPM @ 30' of head. The water temperature in the lines are between 110F and 130F. The supply and return pipes are copper 1 1/2''. The building structure is all metal.

Luc

tim smith

I would bet on backwards zone valves

Or maybe pump flow reversed? What type of zone valves do you have?

Brstr

Flow

Is the replacement circ an exact replacement, or is it a different make/model. It may be possible that you will need to incorporate a pressure differential bypass valve if the noise only appears under low load conditions.

Luc

The circulator comes from another manufacturer but it has the same pump curve. The manufacturer recommends it as a replacement in the cross reference table. I checked the pressure that the pump is giving me and it gives 30 head feet. I also called the manufacturer and he told me that the pump was size ok.

I am looking more towards a problem with the zone valves or the manifolds.

Dave Yates (GrandPAH)_8

we had a similar sound

with a manifold system. The manifold with adjustable valves was on the suction side of the pump and its tiny little valve stems were fluttering closed/open/closed......

Reminded me of Edgar Allen Poe's "The Telltale Heart" story.

Luc

Dave,
How did you fix the problem? Change the manifold? I have located the noise to one manifold. The manifold with the actuators are all on the supply side. Do you think that it would depend of the high flow? Would it occur when a specific actuator is closed or open because it does not happen all the time? Might also be depending on the demand of the other manifolds because like I said above, it stopped when I turned on several thermostats.

Dave Yates (GrandPAH)_8

injection loop

flipped the circ as it was an injection loop

With your high-flow high-head, I'd be suspicious of anything that can close/open - especially with your noting the noise dies off with more zones active.

With the pump sized for all zones active and then restricting flow to a single zone, I'd suggest adding a by-pass PRV or get a delta-p model pump.

Tom Hopkins

Thanks Dave.

I don't think that it will be possible to flip the circulator. With this circulator, there are two other circulators that get their input from the same three way motorized valve that controls the water temperature of the radiant floors. This is a big system with 7 hydrotherm modular boilers for a capacity of about 2 million BTU.

I attached a diagram. The pump is P2 and it heat radiant Bloc 2.

There is no-bypass PRV valve, but they have installed a manual cutoff valve on 3/4'' pipes between the supply and return. This valve is wide open.

Dave Yates (GrandPAH)_8

P-3

Looks like the P-3 supply governs the 3-way mix vlv? Do the other two pumps run at the same time with all three on/off via a single relay?

[Deleted User]

BINGA!!!

That particular valve assembly was designed to close off AGAINST flow. When applied to shut of WITH flow, as the disc approaches the seat, it gets sucked into the seat causing a solid THUNK. Under certain conditions, it can be a thunk thunk thunk ad naseum. Same principle applies to non electric TRV's. You WILL know when you have it installed backards...

They thump.

Now, how to correct it... Are there more than one manifolds running backwards? If so, would it be better to reverse the pump serving the system? Or flip flop the S&R pipes.

Field judgement call..

ME

Tom Hopkins

Thanks Dave for the reply. I appreciate it. I am new to hydronics and the more I look into this system the more I see different problems.

I am going on site today to check out the manifold. I will look over the installation to see if the temperature sensor is really installed on the exit of the P3 circulator. The system was designed to run all the time but I know that someone afterwards installed some controls on the P3 pump so that it runs only on demand.

Tom Hopkins

The temperature sensor is installed differently then on the diagram. It is on the main pipe right after the 3 way valve. This main pipe feeds the three ciculators.