Air noise in closed heating system? 1

[palanaruva]

Dear colleagues,

I have closed heating system in my apartment and since the first day of installation there is all day air noise presence. Can someone suggest what would I need to do in order to remove these noisy noise?

I have a closed heating system with double speed wilo pump with lower speed setting. The pump is installed 1 m bellow the bathroom dryer, if this is important at all. When filling the system with water, all the air is removed and the system is starting to produce the noise. After some few days of working, air is accumulated in the highest part of the bathroom dryer, while the pressure at the electrical heater increased to 2.7 bars (was around 2 bars when starting without air presence). The temperature in the heater is being kept 65 degrees celsius constant. After removing the air, the system starts to collect air again at the same place and so on.

Is there any solution for removing this noise?

Thanks
P

 

[MikeHalloran]

Even if there are no leaks, it may take several tries to remove all the air that's dissolved/entrained in the water.
Was the system evacuated before filling?
I'm guessing it was at most just vented at the top and filled from the bottom.





Mike Halloran
Pembroke Pines, FL, USA

 

[palanaruva]

Hello Mike,

thank you for your reply. I have been removing the air since last heating season, like 1 year ago, and since that time every 5-10 days I am releasing the air from the top of bathroom dryer, so I can not count how much time I did this, a dozen. After releasing the air, only water is coming, so I am pretty sure, there was no air in the system anymore. After few days, the air is coming again. I believe the pump produced it.

What did you mean by "Was the system evacuated before filling?" I filled the water till some 1 bar pressure, after that, release the air from each heating body in my apartment. Then again filled the water and release the air and so on, till all the air released. After that, by foot air pump, I added more air to the expansion tank till I reach some 1.5 bar.

Eventually, the system is operated second season with the air accumulating on the top of bathroom dryer with non-stop noise production. I can hear the air noise inside the pump and through the heating bodies. Very annoying.

Inside the pump manual it says "if you hear the air noise and bubbles inside the system, put the lower speed on the pump", but this was already done before.

P.

 

[Compositepro]

Install an automatic air vent valve.

 

[hydtools]

The pump may be drawing air past the shaft seal.
Air may be drawn in when the system cools and enclosed pressure drops below atmospheric.
Is water being lost from the system, indicating a leak somewhere through which air may enter when the system cools.

Ted

 

[bimr]

Do you have an expansion tank on the system. If you don't have an expansion tank, the system may be pulling air in as the system is cooling.

 

[palanaruva]

Thank you for your replies.

Compositepro, installing automatic air valve will release the air from the system for sure, but the accumulation of air and air noise inside the system will never stop though, which is my main problem. I will for sure install automatic air valve once I fix the problem. Thank you for your suggestion.

Hydtools, I have already checked the pump, there is a screw in the center of the pump, when I unscrew it the water from the system is coming out. It is tightend very well. Anyway, I think the air could not go inside the system through the shaft seal, because the pressure of the the pressurized system is higher then the atmosphere pressure, so the water could only comes out. Correct me if I am wrong please. I don't know, if the pressure at the pump goes bellow atmosphere, going vapor, then there could be air bubbles formation anyhow. Your second suggestion, water does not cool at all, it keeps being 60-65 degrees Celsius. The pressure may go bellow atmospheric. But why it goes under? Should I install a lower flow pump? There is no water loss at all from the system.

Bimr, there is an expansion tank with bladder inside. Shoul I increase the pressure inside?

I will upload the photes of the system tomorrow.

Thank you again for your participation on this.

 

[MikeHalloran]

I have owned a few automobiles whose cooling systems had unvented high points, and they performed best if all the air was removed from the system, with a vacuum pump, before water was admitted, just like evacuating a refrigeration system.

If you have a vacuum pump that isn't bothered by water (e.g. a faucet driven eductor), or one that you don't care about that much anyway, you could pull a vacuum on the high point you have. Put the pump above the high point connection, use some large diameter transparent tubing, and throttle the flow so the water doesn't burp too high as the air comes out. If the air flow doesn't stop, you have a leak.

Or, install a compound pressure/vacuum gage at the connection, pull a good vacuum, close the connection, and see how long the vacuum remains.
CAUTION: Vacuum may damage the bellows of some designs of pump shaft seals, so there is some risk to this procedure, but there's a fair chance that your shaft seal is leaking anyway. I don't know if vacuum will bother the expansion chamber; isolate it for the test if you can.



Mike Halloran
Pembroke Pines, FL, USA

 

[palanaruva]

I tried again. I removed the air completely from the system by hand air valves at each heating body and the one at the electric heater. The air is somehow still emerging from nowhere, I can here it right now, it goes directly to my brain .

Please see the installation photos:

Maybe someone will think of something.

Thanks.
P.

 

[Compositepro]

"Compositepro, installing automatic air valve will release the air from the system for sure, but the accumulation of air and air noise inside the system will never stop though, which is my main problem."

An automatic air vent at the highest point in your system, which appears to be your dryer rack, will prevent accumulation of air because the air will be vented. Do you have an expansion tank in your system? Do you have a make-up water line with pressure regulator? Your system is not at constant temperature. The heaters cycle on and off. Water expands and contracts. Your dryer is the perfect design for an air separator to capture any air in your loop. What is the elevation change from lowest to highest point?

Any fresh water entering the loop will contain dissolved air.

 

[bimr]

It would appear that your Mikoterm unit is incorrectly specified. The heater that you have is primarily used for underfloor heating and as such is piped so that air is not easily released when used for above floor applications like you have.

To affect the most effcient purging, each zone and loop should be purged individually. The key to purging is to create a high-velocity flow through the piping/tubing to force air out of the system. Circulation pumps are generally low flow and may not provide the needed velocity.

The system must have at least one air vent device and, for large-scale systems, there may be several air vents at key points in the system. The primary air-vent should be located between the water heating device and the circulator pump. This should be the point of lowest pressure in the system. Open the vent to the atmosphere while flling/purging the system to allow free escape of air. When fluid begins to escape from the air vent, close it and continue filling/purging the system. Note that the preferred air venting location is not possible with the Mikoterm unit that you have.

See the attached mikoterm installation drawing showing showing suggested air release points 4 & 5. A link to the technical document is listed below:

http://www.mikoterm.com/blok-kotlovi-donji-razvod.html

http://vanguardproductsolutions.com/Vanguard_Radiant_Manual.pdf

An automatic air release may help when it is installed at the high point in the system. (On the heated towel bar.)


Good luck.

 

[palanaruva]

Hi all,

thank you again for your replies.

Compositepro, I have an expansion tank in the system, it is located above the pump, please see the images. I have the pressure regulating valve, it located below the water heater, it act for the pressure higher then 3 bars and the water is then being released to the atmosphere. It is located at the water intake pipe as by pass, please have a look at images 456. The distance between lowest point to the highest is around 1.8 m (bottom of the room heating body and the top of bathroom dryer). Distance between the pump and top of dryer is 1.3 m.

Bimr, take a look at the image number 3, there is a manual air valve on the top of the water heater (small white button on the left). Would there be any chance to install automatic air valve in there? But this does not look very safe to me. Anyway, without a some system reconstruction, it would be not possible to install air valve in a proposed location (position 4 or 5), although this could be done on manifold (the place where all lines gather, it some 40 cm below the pump). What do you think? I will certainly install automatic air valve at the top of the dryer then.

 

[bimr]

This is a self contained heating unit including expansion tank and the directions seem to be in the Serbgian language. It is difficult to completely understand.

However, in reviewing the operating instructions:

http://www.mikoterm.com/uploads/file/compact-6-18kw-donji-izvodi-ce.pdf

there should be an automatic air vent in that location. See the sketch. The text says "Automatska odzra~na
slavina" - translation is Automatic vent-term tap.

See the attachment.

 

[palanaruva]

Thanks Bimr, yes it's Serbian. I already have all this documents, but it is not automatic, is only a classic tap that you unscrew till all the air comes out and then crew it back. Should I try to install one?

Thank you all again for taking part in this thread. I will appreciate if anyone has something to add.

Have nice holidays.
P.

 

[bimr]

I think that is your best solution. The installation manual is calling for an automatic vent, not a manual vent.