Water rushing sounds in radiant floor heating

gmnorml

I moved in to a 3 year old half duplex a year ago with a hydronic radiant floor heating system and was hearing water rushing sounds in the walls in the master bedroom at night. It is not extremely loud but in the quiet of the night, both my wife and myself hear it - similar to the sound of water through the pipes when a bathtub down the hall is being filled but there is no one in the bathroom (kind of scary at first).

After a year of trying to figure out where and when the sound occurs, I have determined that the sound happens whenever the thermostat in the bedroom is requesting heat with the "Heat On" displayed. When the room is warm enough and the "Heat On" disappears, the water rushing sound abruptly stops. Now that I know the source, I can cause the rushing sound to occur by increasing the setting on the thermostat high enough that the "Heat On" appears and a few seconds later, the rushing water sound begins. Similarly, I can stop the sound by turning down the thermostat to the point the "Heat On" disappears.

Note that this house has four separate zones but the rushing water sound only occurs in the one zone the master bedroom is in on the second floor. I have tested the other 3 zones and they all are mostly quiet (a few creaking and pop sounds when first turned on but silent after that).

I would appreciate any suggestions on what could be causing that one zone to circulate the hot water so noisily and what, if anything can be done about it. Thanks.

Derheatmeister

Is this bedroom on the highest level of your unit ?
This sounds like you may have to pump purge the system..
Can you post some pictures of the mechanical room/Boiler/Manifolds.

JMWHVAC

Must have air in the floor heating pipes. If you think it sounds like the sound is in the wall, is there a manifold in the wall where the floor tubes come together? Behind an access panel?

hot_rod

Is there a manifold on the upper level for the bedroom loops? If so, usually that is where you would have a float type auto vent.

There should be an air purger or air separator at the boiler, that does most of the air elimination work, see if you have one and that it is working.

Also check the boiler pressure 12- 15 psi for a two story building.

Dave Carpentier

I had a bit of air circulating around my system, when my air vent was clogged up. I would describe it as waves crashing on a beach. Not sure why the air bubbles would travel in a group, but it certainly had a rhythm to it.

Intplm.

@gmnorml

The way you describe this could it also sound like a piggy bank full of coins sloshing around.
Sounds like you have air mixed with the water in your system.
Locate a manual purge set up on your system as well as what @hot_rod mentions above.

The system should quiet down a lot when the air is purged out of the system.

gmnorml

Derheatmeister said:

Is this bedroom on the highest level of your unit ?
This sounds like you may have to pump purge the system..
Can you post some pictures of the mechanical room/Boiler/Manifolds.

Yes, bedroom is on second floor of two story unit. I have attached photos of the boiler and related piping.

gmnorml

hot_rod said:

Is there a manifold on the upper level for the bedroom loops? If so, usually that is where you would have a float type auto vent.

There should be an air purger or air separator at the boiler, that does most of the air elimination work, see if you have one and that it is working.

Also check the boiler pressure 12- 15 psi for a two story building.

I'm not sure if there is a manifold on the upper floor. Presumably it's not out in the open so I'd have to look for an access panel to it. I'm new to all this so I'm hoping the manifold I'm looking for looks like the ones I googled online. If I find it, I'll try to see if venting the air will help. Thanks.

As for checking the boiler pressure, I don't know if I want to go there.

neilc

gmnorml said:

As for checking the boiler pressure, I don't know if I want to go there.

this could be your whole problem,
pressure should be in the boiler display cycle

HomerJSmith

You have four zones and the piping from the ZVs is Pex. The thermostat only governs the master bedroom which is on the top flr. There may not be a manifold if the radiant is a single loop serving only the master bedroom. The rushing sound may be because the flow thru the loop is too great because that loop is the shortest of the four loops and has the highest pump pressure.
I would turn up the thermostat in the master bedroom and then turn up the thermostat on one of the other three zones and see if the rushing sound goes away. If it goes away, I would suspect that the flow is too great and a balancing valve on that loop would be needed to bring the flow down to less than four GPM. I would also check to see if there is a shut off valve that is partially closed in the bedroom area, probably not.
If none of the above addresses the problem, I would suspect air in the loop which sound more like gurgling. Air in the loop is more difficult to deal with as you have no valves on that loop to close the flow and open to purge that loop

hot_rod

I think you would be better off with a primary secondary piping as the manual shows. Then use a delta P type circulator for the zones. That way the flow rate modulates as zone valves open and close. It helps prevent over-pumping the smaller zones when they are flowing.

The pump inside the boiler should have an air vent also, is that open?

gmnorml

neilc said:

gmnorml said:

As for checking the boiler pressure, I don't know if I want to go there.

this could be your whole problem,
pressure should be in the boiler display cycle

I see. I thought I had to get a pressure guage and somehow insert it in the piping to get a reading but I looked at the boiler display again and can see it rotating through various values including one showing 19.2 psi. I assume that's the boiler pressure which looks to be high. I'll try to figure out if I can lower the pressure myself and see if that makes a difference.

neilc

19 is ok, not your problem then,
gonna need to purge that top floor,

neilc

have you found your manifolds ?

gmnorml

neilc said:

have you found your manifolds ?

I don't think so. I only found this pipe access in the walk-in closet but I don't think that's the manifolds.
I don't even know what these shut off valves are for because they're not even close to any faucets. Anyway, is it possible there is no separate manifolds, just the one in the boiler room?

I'm disappointed to hear 19.2 psi is not high because I tried what @HomerJSmith suggested about turning up the thermostat on all 4 zones and it did seem to lower the water rushing sound significantly in the master bedroom zone. At the same time, the zone below the master bedroom seemed to have the water rushing sound when I did that. I was planning to lower the boiler pressure until I saw your post...I may still try.

hot_rod

Those are Dahl mini ball/ balance valves. They are intended to balance flow in different loops. But it will be a trial  and error procedure without some data

gmnorml

HomerJSmith said:

You have four zones and the piping from the ZVs is Pex. The thermostat only governs the master bedroom which is on the top flr. There may not be a manifold if the radiant is a single loop serving only the master bedroom. The rushing sound may be because the flow thru the loop is too great because that loop is the shortest of the four loops and has the highest pump pressure.
I would turn up the thermostat in the master bedroom and then turn up the thermostat on one of the other three zones and see if the rushing sound goes away. If it goes away, I would suspect that the flow is too great and a balancing valve on that loop would be needed to bring the flow down to less than four GPM. I would also check to see if there is a shut off valve that is partially closed in the bedroom area, probably not.
If none of the above addresses the problem, I would suspect air in the loop which sound more like gurgling. Air in the loop is more difficult to deal with as you have no valves on that loop to close the flow and open to purge that loop

I turned up the thermostat on all 4 zones and the rushing water sound in the master bedroom diminished significantly as far as I can tell with ambient noise during the day. I also noticed the zone below the master bedroom seems to now have the rushing water sound more noticeable than the master bedroom zone - have to put my ear to the wall to notice. I later systematically turned down the the thermostat of the three zones except the master bedroom zone and the rushing water sound returned to that zone. So it looks like my setup needs a balancing valve and I'm assuming this is probably something best left for a professional to do?

BTW, I don't think it sounds like gurgling, simply water rushing sound (like when you flush a toilet) so would you say air in the pipe is less likely?

hot_rod

With 4 or more zone valves it would be good to have a pressure bypass valve.
with a single circulator the bypass allows excessive flow to bypass back to the boiler. Which in turn reduces the flow velocity when only one zone is open

HomerJSmith

You would probably benefit from a primary/secondary configuration. You appear to be pumping into your expansion tank, not good. If a change in configuration is made an ECM pump between the expansion tank and the zone valves would be beneficial. With the Dahl valves, it is difficult to determine the flow in GPM. It may be a mal-adjusted Dahl balancing valve that is creating the noise. Having two balancing valves on one loop seems improbable. So your pic of the Dahl valves shows that there are two loops that are being fed. It may be different rooms. Tell me where your four thermostats are located that control your four zone valves.

gmnorml

The four zones are roughly divided into the front/back and first/second level parts of the house. Here is a (very) rough layout of the zones (Z) and thermostat (T) locations at my house (Z4 is the master bedroom):

I don't fully comprehend what you and @hot_rod are trying to tell me (again, this is all new to me) but it sounds like to solve my problem, I probably can't do it myself and will need to get a professional?