Loud banging from heating system

17 posts in this topic

We live in the top-floor flat, in an old apartment building in Munich, which has communal heating.  Every year around the start of 'autumn' (i.e., now) the heating system gets really noisy and starts emitting loud bangs/clunks throughout the day, and into the night.  The noise comes from some (but not all) of the radiators, and in the walls (we assume heating pipes are there). 

 

We assume the noise is caused by air in the heating system, but have never had this confirmed by the building owners.  Last year the building management sent maintenance personnel round to us, after we complained (we had to wear ear plugs every night to sleep), but we were never told what the reason was.  Eventually the noise went away by the time winter rolled round properly.

 

Does anyone know if:

1) this noise is normal for old heating systems, and we just have to put up with it? (I really hope not; we're again having to wear ear plugs to sleep)

2) if it's not normal, how do we get it fixed/improved?

 

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My parents in law own an older house with radiators and a oil heating system, and I can sympathise as the noises you describe sound very familiar. It doesn't bother me that much (only there to visit) so I never tried to figure out whether it is normal or preventable, or not. It may be that you have it worse as the heating system is bigger (apartment block vs house).

 

 

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It is normal at the start of the heating season. Bleeding the radiators should stop the noises. That's probably what the maintenance personnel did. It's an easy job and there are plenty of videos online.

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11 hours ago, skinnypuppy said:

It is normal at the start of the heating season. Bleeding the radiators should stop the noises. That's probably what the maintenance personnel did. It's an easy job and there are plenty of videos online.

 

That's fine, but we cannot do it ourselves because don't have access to the apparatus in the basement to refill the system.

 

We can ask the Hausverwaltung, but doesn't the entire heating system need to be bled to fix this issue? I assume the building has a single shared heating system. Every time we've asked for radiators to be bled in the past they've just come to our flat to do it.

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AberMiranda,

 

You don't bleed the air from the heating system in the Keller, you bleed each radiator.  Since you're on the top floor, any air in the system will make it's way to your radiators.  There should be a air bleed valve on the top side, opposite the temperature/flow valve.  Usually there is a "key" used to open the valve and let the air out of the radiator. When the heating system is on, you should open the valve slightly until you hear the air escaping. Once water flows out, close the valve and you should be good to go. 

 

You might search YouTube for "how to bleed radiators" to see what need to be done.  Keep in mind, you may have to do this on a regular basis since you are at the top of the system. 

 

S. 

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21 hours ago, skinnypuppy said:

 Bleeding the radiators should stop the noises.

Not necessarily though. I rememberthat 20 years or so ago in our multifamily house there was a valve causing the problem. There was a distant heating system installed (hot steam).

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3 hours ago, jeba said:

Not necessarily though. I rememberthat 20 years or so ago in our multifamily house there was a valve causing the problem. There was a distant heating system installed (hot steam).

Agreed. Same happened to us in a previous apartment where a valve had been installed backwards (!?!?). I would still start with the simplest, cheapest option (i.e. the €2 key from a hardware store and a few minutes of radiator bleeding) before moving to the more complicated.

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On 07/09/2021, 01:01:46, Shenandoah said:

AberMiranda,

 

You don't bleed the air from the heating system in the Keller, you bleed each radiator.  Since you're on the top floor, any air in the system will make it's way to your radiators.  There should be a air bleed valve on the top side, opposite the temperature/flow valve.  Usually there is a "key" used to open the valve and let the air out of the radiator. When the heating system is on, you should open the valve slightly until you hear the air escaping. Once water flows out, close the valve and you should be good to go. 

 

You might search YouTube for "how to bleed radiators" to see what need to be done.  Keep in mind, you may have to do this on a regular basis since you are at the top of the system. 

 

S. 

 

Well, maybe it's different in the UK, but my experience with bleeding radiators has involved first letting the air out with a bleed key, like you said, and then refilling the system using a valve typically somewhere underneath the boiler. Otherwise the pressure drops and the heating doesn't work properly, and this is corroborated by the YouTube videos I've watched. In a sealed system you need to replace the air with water, after all.

 

Or does a typical German apartment building heating system work in a way that makes this step unnecessary?

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8 hours ago, HH_Sailor said:

Air out, water in.

Sounds a good plan to me.

 

TBH unless vast amounts of air get vented, you'll get away without topping up. 

 

 

(Replying as OP's other half)

 

When we've had the radiators bled in previous years (the Hausverwaltung sent someone round) some of the radiators had almost no water left in them. And they aren't small radiators, either. The amount of gurgling and whooshing going on in the radiators at the moment leads me to think there'll be a similar amount of air in them this year, too.

 

So yes, vast amounts of air!

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13 hours ago, AberMiranda said:

and then refilling the system using a valve typically somewhere underneath the boiler

 

only if necessary - the 'green zone' on the water level in a heating system is quite wide - only if yours is right on the bottom margin will there be a problem, and then people will complain and the building management will send someone round anyway, and they will top it up. 

 

They are likely to keep it at the higher margin, assuming that residents will be bleeding their radiators as required.

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AberMiranda,

 

There should be an auto fill valve for the boiler/heating system that would keep the system full and under pressure during operation.  

 

S.

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27 minutes ago, Shenandoah said:

AberMiranda,

 

There should be an auto fill valve for the boiler/heating system that would keep the system full and under pressure during operation.  

 

S.

Sorry, but that kind of setup is illegal in Germany, to prevent contamination of the drinking water pipes by the water in the heating system. If the system needs topping up, it always has to be done manually.

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36 minutes ago, Shenandoah said:

AberMiranda,

 

There should be an auto fill valve for the boiler/heating system that would keep the system full and under pressure during operation.  

 

S.

That's what the ausdehnungsgefäß (expansion vessel) is for. If you had an auto fill system you'd never notice even a major leak in your heating system's plumbing!

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Folks,

 

Normally an auto-fill valve has a backflow preventer (to prevent supply water contamination).  It also does not allow "over pressurizing" the boiler.  The water supply pressure is higher than the boiler system pressure.

 

The expansion vessel/tanks (in a boiler system) prevents the boiler system from over pressurizing when the water is heated.  The expansion tank usually has a rubber diaphragm with air/nitrogen on one side and water from the boiler on the other side. 

 

You also have a water meter located before the auto-fill valve to monitor how much water is being added to the boiler.  

 

S.  

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That's all well and good, but in my more than 30 years in Germany dealing with various Gasetagenheizungen and living on the top floor of several buildings, I've had multiple Sanitärinstallature and bog standard Klempner in several German states explain to me that even a permanent hose between the water line and the heating circulation system is strictly forbidden by the binding regulations, to say nothing of an auto-fill, always-on system.

 

For whatever historical reason, Germans take their potential potable water contamination very seriously. Fuck with that belief at your peril or risk finding out.

 

No offense, Shenandoah, but do you have any experience living in Germany? Or are your comments based on what you imagine living in Germany might be, based on the local regulations you know?

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El Jeffo,

 

No offense taken.  I'm in the US but have a couple of rented apartments in Berlin in an "old building".  I spend a month or so in Germany every year (if I can).  I am very familiar with the house and the heating system (in Germany).  I will take another look at the boiler when I'm in Berlin next month and post.  

 

S.

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