Water sloshing in baseboard heaters

ts004i · January 6

Hello, I have 3 zone hydronic baseboard heat without bleeder valves, so I need to flush the water near the boiler when it sounds like air has gotten in.

For some reason this year I flushed the zones like I normally do but afterwards it sounds horrible - loud banging and water sloshing in all zones throughout the house.

When I flush out the zones again there are lots of air bubbles, even though I just flushed them out a few minutes earlier.

I feel like I must be doing something wrong at the very end of the flushing process but I have no idea what. Or maybe a valve is broken somewhere and is letting air back in at the end? I am isolating each zone and flushing out all the water using the high pressure fill value.

Is this a common problem? Any tips? It's very frustrating to go through the entire flushing process and then hear the same sloshing sound afterwards.

Thanks for your advice!

Intplm. · January 6

First off why are you flushing out your zones and from what I can tell, you are doing it often?

As it is now you will need to purge your zones of air. Once you have done that you should not have to do anything else.

Questions:

Do you have an air purger/air scoop on your system? If so replace it with a micro bubble air separator.

Do you have a place to purge each of your three zone?. If not you will need to add that to your zones.

If you are hearing that tell tale sign as if you are shaking an old style piggy bank full of coins sound in your rads, that means air and you have a leak somewhere and you need to find it and correct it.

Any time you add fresh water to a heating system you are also introducing air. Cold make up water has air in it. And when you add water to the system you are inadvertently adding this air that can only be eliminated by the previously mentioned air seperator as the systems zones are put into operation.

Jamie Hall · January 6

to which may I add, what is the static pressure of your system (pumps off, boiler off)?

hot_rod · January 6

It's almost impossible to get 100% of the air out on a manual purge. As the water warms more air comes out of solution.

So you really need an auto air purger or air separator to finish off the job.

If you manual purge again, you add more air, so that may not be the next step.

Post a pic of the boiler piping. Maybe you have an air purger and it needs a cleaning?

mattmia2 · January 6

https://forum.heatinghelp.com/discussion/comment/1832440#Comment_1832440

or is closed because it is leaking.

ts004i · January 7

Thanks for the responses.

I try to purge the zones of air when they become unbearably loud with sloshing or banging sounds. It doesn’t seem to be especially effective though.

We don’t have bleeder valves on any of the radiators and I don’t think that there is an air purger or separator in the system, so perhaps this is the problem? The static pressure is about 20 psi.

neilc · January 7

why don't you post a wide angle view of the boiler, circ(s), expansion tank, any zone valves, all in one wide shot, from a couple angles,

someone will see something,

are you sure your gage is accurate? and that the 20psi is true?

Intplm. · January 7

https://forum.heatinghelp.com/discussion/comment/1832522#Comment_1832522

Ok. This shouldn't be happening. Please send pics as @neilc asks. This can be corrected.

ts004i · January 8

Thanks, here is a photo of the whole system and close up of above the expansion tank and the feed valve. Seems like I should have an air purger installed above the expansion tank, correct?

tcassano87 · January 8

First thing I noticed is there is no Air Eliminator on your main header allowing air to escape from the system properly, it also appears you don't have an expansion tank installed. Those two things are essential for the system to run properly, google the Lochnivar Noble Install manual and you will see it shown, those are incredibly good boilers and it should be working efficiently

How are you bleeding the air out? Are you closing the valve under the drain on the line you are bleeding, also I've experienced those high efficient combi pulling water in very slowly through the feed. As long as you have the drain open, open the fast fill to feed more pressure and push the air out faster and more efficiently.

Grallert · January 8

It looks like a zone has been added with out a purge station. I see new propress fittings. Is there a purge station out of frame somewhere? I also see a vertical pipe closest to the expansion tank. That might be a good location for a vertically mounted air and sediment separator. One more thing, That circulator should be mounted with the motor in the horizontal position, not hard to do while installing the air eliminator.

Mad Dog_2 · January 8

Yeah..where's your Spirovent or Caleffi Air Elminator? You need one. Mad Dog

hmemerson · January 8

https://forum.heatinghelp.com/discussion/comment/1832803#Comment_1832803

That thing on the side is an expansion tank, made by Zilmet. I don't do boilers, but it looked strange to me too, so I enlarged the picture and googled Zilmet Expansion tank on Lochnivar boiler, and saw a picture.

HE

tcassano87 · January 8

https://forum.heatinghelp.com/discussion/comment/1832808#Comment_1832808

you are correct I didn’t realize that in the picture

hot_rod · January 8

The very best spot would be on the supply under the boiler. That is the hottest point in the system. Next best on the horizontal piping before the pump.

Which is mounted incorrectly, turn it so the pump shaft is horizontal.

Screenshot 2025-01-08 at 10.04.25 AM.png

Screenshot 2025-01-08 at 10.02.09 AM.png

ts004i · January 9

Understood, thank you all for the advice! This is a great forum.

Water sloshing in baseboard heaters

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