Hydronic baseboard heat is noisy

[Jeff7181]

I recently moved into a new home and had to replace the boiler immediately. Boiler seems to be working fine, but there's quite a bit of noise when it turns on from air bubbles passing through the baseboard heating. The installer says it's been bled properly and this is normal.

Can anyone with hydronic baseboard heating confirm or deny that it's normal to very clear hear the flow of water and gurgling when the heat kicks on?

 

[jmagg]

I hear no water, I do hear tapping which i'd assume is expansion. It was bled last year with a new circulator. I've had hot water baseboard in every house i've lived in, and they've all tapped. Did he replace the circulator with the boiler?

 

[herm0016]

ours is nearly silent. you can hear it turn on and off only when we are in bed reading or similar amount of background noise. it clicks and taps a tiny bit, and there is a very slight gurgle. a snoring dog drowns it out. our bedroom is the highest point in the house where all the air would accumulate. boiler and pump is about 2 years old, and we do have an air separator.

 

[paperfist]

You need to bleed it. I'd put auto bleeders on every radiator.

Is the heat uneven? That said, like has been mentioned they seldom are completely silent.

Side note, I recently put a fan behind one radiator. Holy cow it's like having unlimited heat sure to make you melt. I can't believe these things were never setup with one.

 

[Jeff7181]

Thanks for the feedback. So what I'm experiencing definitely isn't normal. Some work needs to be done on the lines anyway, so after the cold season is over I'll be draining the system, cleaning it, and replacing/rerouting some sections of the baseboard radiators. Seems like the perfect time to add bleeders, too, because I don't see any.

The guy who installed the boiler only flushed the system from the basement where the boiler is installed. Didn't bleed a single zone.

 

[paperfist]

You have slant/fin baseboard or cast iron radiators? What kind of boiler did you have and what was it switched to?

 

[Jeff7181]

You have slant/fin baseboard or cast iron radiators? What kind of boiler did you have and what was it switched to?

Yes, slat/fin baseboard. Seems to be a combination of materials depending on where in the house we're talking about (it's an old house - dates back to 1880 with the most recent addition being about 40 years ago.

The old boiler was a Munchkin that had leaks in the valve train. Replaced with a Navien NCB 240e combi-boiler.

(I'm on propane)

 

[herm0016]

fancy. we went with an 86%. that includes modern temperature controls, adjusts temperature of the water based on demand and actually works great. at elevation here, the 90+ stuff only runs a few points more efficient than a regular boiler, and costs more than double. payback time is way longer than ill be alive.

 

[Jeff7181]

fancy. we went with an 86%. that includes modern temperature controls, adjusts temperature of the water based on demand and actually works great. at elevation here, the 90+ stuff only runs a few points more efficient than a regular boiler, and costs more than double. payback time is way longer than ill be alive.

Yeah... I need to get the installer back out to install the outdoor temperature sensor so it adjusts the boiler temp automagically. Right now I have to set it manually, which is pretty inconvenient since I have a dirt floor basement with basically a ship ladder to get down there.

 

[Jeff7181]

I don't post on here a lot anymore so I'm doing this more often than I ever thought I would, but in case anyone was following this and could learn from my experience...

The Navien boiler apparently has an integrated air bleeder to get those last little bubbles out... and it certainly works.

Long story short, I actually discovered a leak - that's where the noise was coming from - tiny little pinhole pissing in the basement and allowing air to enter. So while the auto bleeder was doing its job, and the makeup valve was doing its job, it couldn't keep pace with a leak.

I paid the installer to come out and bypass the segment with the leak because all the joints looked like crap, and now everything is silent, even with the circulation pump on the higher setting.

I think my summer 2021 project is going to be to replace the hydronic baseboards in my "problem zone" with brand new high output ones. I've been thinking about doing a retrofit radiant floor system, but found some really ugly, corroded joints and so I think the whole system needs to go... I'll scrap the copper and hopefully get a few bucks back. But I'm going to put Pex everywhere I can get away with when plumbing in the new baseboards, and try to get a few more feet installed in the room since right now with an outdoor temp of 15 degrees and a supply temp of 160, it's losing ground in this 400 sq/ft room even with about 40 feet of fin-tube baseboard.

Initially my idea was to add retrofit radiant floor because that operates at a lower temp, and I could use the return water from the baseboards to feed the radiant floor and keep the boiler supply temps in the 140 range at most, and be in the condensing sweet spot for the best efficiency if my delta ended up being around 20 degrees between the two systems. However, because the rest of the home is baseboard and I don't really want to put radiant floor in the whole house, I think it's best to put brand new fin-tube in the problem zone and see if that helps in the 2021/2022 winter. If not, then I'll look at adding radiant floor and replacing the baseboard in the rest of the house with radiant floor... at least on the first floor where I have easy access from the basement.

Anyway... late-night ramblings are done...

 

[herm0016]

the original system was probably designed with a 180 degree water temp, that's why you are not getting the heat out of it. the new condensing boilers run at about the same efficiency as an old school one at those temps. they are designed for around 140 degree water. good find on the tiny leak. you can put a mix valve in the line that will recirc and cool the temp down for the radiant zone.