Boiler / Baseboard hot water lines humming

SoupSandwich

Hello world!

So, we bought a place that has a year model 1988 boiler hot water baseboard heating system about a month ago. Been having issues.... water wasn't circulating properly, replaced the pump (that was the wrong direction and fried). Water circulating... great! Pressure wouldn't maintain, so it sounded like Niagara Falls in the mornings. I'd have to manually open the valve to add water a few times a day (different problem... need to replace some pipe that leaks if water is left on). Bucket under the pressure relief valve showed (+/-) 1 gallon per day leaking out. Checked the expansion tank and it was full of water. Ordered and replaced that tank and the pressure valve, now no leaks, holding steady at 12 psi, water is circulating, and the heat is fabulous..... BUT

Even with the pump speed on low, the pipes at the other end of the house humm. Of course, that's my bedroom. Tried putting pressure on the pipes to see if it is a vibration, but no significant difference. All the radiatores heat fine.

Any ideas? I'm at a loss, as this is not my area of expertise. Thanks in advance for the assistance.

Jolly Bodger

Pictures of the system, manifold, pump, and the humming pipes might help. What size is the house? What pump do you have? Are there zones? Where is the boiler in relation to the bedroom? I'm especially interested to see the pump placement that was in backwards.

SoupSandwich

Thanks for your reply. I am at work right now, so I can't provide pictures, but I can provide some information. The pump that was on the system was a horizontal flow pump and it is a vertical flow system. At least that's what the local HVAC guy said when he replaced it at no charge.It was green, that's about all I can say. Now, the pump is red, either Grundfos or AB Alfa (similar to https://www.amazon.com/AB-Heating-Circulation-3-Speed-Tankless/dp/B06WLJ3M3K ). The system is 3-zone with the boiler at the north end of the house and the bedroom is at the south end (about 50 feet away). So the pipes go up from the outflow, to the zone valves (3) and then up to the basement ceiling and throughout the house from there.

As far as the expansion tank and pressure valve replacement, I did those myself. The local HVAC guy, when asked about them, said they were fine and that I'd just have to keep adding water when the rushing river sound was present. I did my own troubleshooting and determined that the tank and valve were both not functioning properly. The boiler tank, burners, air bleeder, and all the valves seem to be working quite well. I have drained the system several times to try and clean some of the gunk out of the system. Seems like it hasn't been cleaned in 30 years. Lots of sediment in the water when I drain it. It's much better now. This just has to last through the winter.... I will replace the boiler in the summer (or have it replaced) and flush out all of the zones. Not sure if a steady hum in some of the lines is normal or not because I haven't had this type of heater before.

Jolly Bodger

Maybe someone else will chime in here because I have never heard of a horizontal flow and vertical flow hydronic system or different pumps for them.
I would be concerned that your HVAC guy said the tank fill and expansion tank were fine and to just keep filling it. I don't think you are dealing with a hydronics expert.
Hydronics are normally silent. I can't wait to see some pictures.
Also give us some more details about the noise. Is it constant, does it start and stop with heat in that zone, or heat in any zone?

mattmia2

The corrosion in the water is from adding make up water. When you add new water you add oxygen which is dissolved in the water which corrodes the system. As the water is heated, the air comes out of solution and is removed by the air elimination. The system has to be leak free for the longevity of all the components.

SoupSandwich

Best I can do for now. Old expansion tank, old relief valve, and the old pump. For the picture of the furnace, I was actually taking a picture of the old water softener and that just happened to make it in the picture. I will take some more and upload after I get home from work.

mattmia2

We need to see better pictures of the near boiler piping. What I am wondering is if whoever worked on it thought that the pump was backwards because of its relationship to the expansion tank and air elimination when in reality it is simply an older installation/installer from before it was common to pump away from the expansion tank.

SoupSandwich

Here are the full pics. The pump is a Hydra Smart 3 speed. I hope these pics clear things up. Thanks again for the assistance.

mattmia2

Where and what are the zone valves? Most are designed for flow in only one direction. can you take some pictures of those?

When do you hear the noise?
Only when the boiler is on? All the time? only when certain zones are on?

JUGHNE

The "vertical" and "horizontal" terms applied to the pump may refer to the pump shaft orientation. Your pump should be rotated 90 degrees so the electric box is on the top. The pump shaft should be horizontal and the J-box on the top.

Source of the humming?? IDK

Also the arrow on the pump should point towards the boiler, some have been installed backwards.....easy to do.

The electric connection at the pump should be corrected also.

SoupSandwich

Thanks all. The humming is coming from the pump and the verticle pipe connected to it. It's vibrating which resonates through the rest of the pipes. Starting to think that the "HVAC guy" did a poor job on that. That's too far out of my comfort zone, so I'll have to call someone to fix it.

SoupSandwich

Oh, and the vibration is constant because he said the pump is supposed to run 24/7.

mattmia2

get a better pump?

Or if the motor isn't oriented in a direction recommended by the manufacturer, fix that.

mattmia2

Wait, how does the zoning work? There must be a path for water to flow, either a zone or a bypass if the pump is constant.

hot_rod

when a circulator is installed with the motor in a vertical orientation, but can trap air at the bering up top and ruin them within hours. If nothing else has changed, rotate the circ, or change it and see if the noise stops.

The water falls sound is an indication that it has not been purged adequately.

If it is a zone valve system with no bypass and the pump runs constantly, a ∆ P circulator would be a better choose, Grundfos Alpha or any of the other pump brands have them.

Jolly Bodger

There is no reason that the pump should run 24/7. From what I can see here you are lacking on controls. Does you house have zones? Multiple thermostats?
@hot_rod is right. The motor should not be in that orientation. It should be horizontal. With any pump.

SoupSandwich

Update... it was the pump being installed with the shaft vertical. Rotated the pump to put the control box on top and no more vibration.

Intplm.

Your system does not show any purge ports. There is no location pictured that shows where to get the air out. At least one of the noises that you are hearing is air mixed in with the water. This is the "waterfall noise" and is a clear indication that the system needs to be manually purged.

The humming can be a few different things, You may need to support your pipes better. Adding some more hangers may help.
With that new circulator running all of the time that noise is surely a big nuisance. The pipes might be directly rubbing where there is a penetration through the floor or through a floor joist on another pipe etc. Look for something like that to help eliminate the noise resonation in the house.
Great that the vibration has been found by rotating the circulators motor. Hopefully that noise does not return.

Try these things.
New or more hangers
Eliminate possible rubbing
Eliminate any leaks (So you don't have to continue adding water. The cold make up water is oxygenated water that has a lot of air in it. This is a source of additional added air)
Maybe install a micro bubble air separator, like a Spirovent.

And find out why the circulator needs to always be running? It shouldn't from what I can see.

EdTheHeaterMan

I always told my customers that your heater is humming ’cause it forgot the words

EdTheHeaterMan

The control box on the right side of the heater where the thermostat wires attach, Has a place to connect the circulator. If that control box failed to operate the circulator in the past, a temporary fix would be to operate the circulator constantly until the control could be replaced. Maybe that temporary repair was never reconciled by the previous owner

SoupSandwich

EdTheHeaterMan said:

The control box on the right side of the heater where the thermostat wires attach, Has a place to connect the circulator. If that control box failed to operate the circulator in the past, a temporary fix would be to operate the circulator constantly until the control could be replaced. Maybe that temporary repair was never reconciled by the previous owner

I will look at that after Christmas. Thank you.

Zman

Thanks for reporting back on the cause of the noise, I would have expected premature failure with that orientation but not the noticeable noise downstream. Always good to learn new things .

I assume you have zone valves on the returns. If this is the case, you absolutely should not be running the circ all the time. A circ that is "deadheaded" like that will waste energy and fail prematurely. I have seen the "delay off" relays in the slant fin fail and cause the symptom you are seeing. It might be cheaper to install a separate pump relay rather than a new board in the boiler. This one would be a simple replacement https://www.supplyhouse.com/Taco-SR501-4-1-Zone-Switching-Relay.
Something like this would clean up the zone wiring at the same time https://www.supplyhouse.com/Taco-ZVC404-4-4-Zone-Valve-Control-Module-with-Priority

It probably is not worth repiping, but your system is pumping into rather than away from the expansion tank. This can contribute to the air and noise issues you are experiencing as well.

Who sized the new circ? It looks pretty robust for a simple zoned baseboard system. Probably not worth tossing the one you have, next time you are replacing you may want to take a closer look. http://www.walrusamerica.com/Files/GPD_Cat.pdf

BTW, the picture of the original circ was pumping correctly into the boiler return. If you reversed the new one, you are now pumping backwards through the boiler.

Gman66

I suspect the OP has mistaken the ball valves as "zone valves" and in fact this is a single zone system with 3 branches and that is why the circ is always on.

Soup - how many thermostats do you have?

SoupSandwich

1 thermostat. You are correct.... it is single zone with 3 branches. Working perfectly now.