Bubbling Noises in second floor air handler

Mer29

For the second time in 7 weeks, I've had to have my furnace company come out and purge the air from the system. The main air vent goes up from the basement and is located at the corner of the master bedroom. I heard a gurgling noise in the pipes which is why I called for service. The serviceman purged the system and replaced the air valves on the furnace but he he thinks that the problem has to do with the air handler, not the furnace. He told me that no pipes go through the vent but then what is the bubbling sound I hear and why all of a sudden is air getting into the pipes to cause the noise? I've lived in the house for 17 years and this is the first time I'm having this issue. The air handlers were replaced 5 years ago and if it makes any difference, the water heater was replaced in March 2017. I have a separate HVAC company that services the air handlers and I'm not sure if I should call them to take a look. Who can fix this issue and what exactly is causing it? I

Jamie Hall

What pressure is your system running at?

EBEBRATT-Ed

Post some pictures of the boiler and air handler if you can. Doesn't sound like your technician is top shelf

HVACNUT

The air handler is in the basement? There is a hydronic coil in the air handler or the ductwork being supplied by a boiler?
Is your bedroom directly above the air handler?
Typically, you wouldn't hear water from the zone through the duct vents. If anything, you'd only hear the fan.
Maybe call the A/C company and have them check the air handler for anything loose, vibration. Is the air filter clean?
Is there a humidifier on the system? You might hear water from that.

Mer29

Jamie, the furnace pressure was around 30 PSI. My furnace guy changed the air vents and now it's holding around 20 PSI.

Mer29

EBEBRATT-Ed The problem is that my furnace company and my HVAC company are two different outfits. I have a service contract for oil with the furnace company and they don't service air handlers. The HVAC company handles the two air handlers. I have two zones one for upstairs and one for downstairs. My furnace is 17 years old but in excellent condition. I have is serviced each year. The furnace guy heard bubbling in the return and had to drain the air out for the second time. In retrospect, I should have called the HVAC company to solve this mess.

Mer29

HVACNUT, I have two air handlers, the one with the issue is right over our bed but the vent that supplies the warm air is right next to the masterbath so I can hear the bubbling. I'm not entirely sure what the supply is from but I have Hydroair and I was told by the furnace guy that the return is attached to the boiler. I don't hear water bubbling in the vents, only in the main vent that comes up next to the bathroom. I must add that during the summer, I heard skips in the coolant that goes through the coils in the handler when the A/C was on. I recently had it serviced in late october (after the first bubbling incident which my furnace guy purged the system of air). HVAC changed the filter so it's clean. When I say I hear bubbling, it's loud. Right now it's fine because the air was purged but I have a feeling it's going to happen again. I can't keep paying for purging every six or seven weeks besides the fact that it's making me a nervous wreck to know it might happen again. What do you suggest?

Mer29

Mer29

Mer29

The air handler to the left is the one in the basement but it's the same exact one as the one in the attic. The one in the attic is not easy to get to. Thank you all for you comments and expertise.

hot_rod

The attic air handler is probably the high point in the system. it is good practice to have an automatic float type air vent at any high point in the piping of equipment.

You can add a safety cap or a discharge tube in case the float ever fails.

Mer29

Hot Rod, I'll mention that to the HVAC company. Everything was fine for 17 years until a few weeks ago. The only change was that I also got a new water heater in late March. The heat ran until almost late May (New York had a chilly spring) but I didn't seem to have any problem until I turned the heat on in late October. I need this issue solved before I lose my mind.

HVACNUT

I apologize @Mer29. I'm was under the assumption your bedroom was on the 1st floor, over the A/H. In any case, in my 30+ years, I've never had a complaint of bubble sounds from the vents with hydro air. I have however had calls due to hearing the heating water in the walls, in the piping going from the basement to the attic. Is it possible that's what you're hearing?
Also, is there antifreeze in the system for freeze protection for the attic coil and piping?

Mer29

HVACNUT, I don't hear the noise from the air vents themselves but rather the main vent (and maybe I'm using the wrong terminology) that goes up near the masterbath inside the walls. I hear the water without the bubbling now because my furnace company purged the system of air. This is the second time in 7 weeks it's happened so I have a feeling it will happen again. The coolant during the summer sounded like it was skipping also when the A/C was on but it wasn't bad enough to warrant a call to my HVAC company. 5 years ago I had the A/C units and air handlers replaced in the basement and attic because I had a leak and at that time I could really hear problems with the coolant in the pipes. I'm not sure if there is antifreeze in the piping but I imagine there would be since the attic gets very cold during the winter. I'm trying to absorb as much knowledge as I can before I call the HVAC company to examine this issue. Thank you.

hot_rod

It is tougher to get air out of glycol blends. Raise the temperature for a few hours and make sure there is a good quality, working, micro bubble air eliminator back at the outlet of the boiler. Also an accurate pressure gauge to determine fill pressure.

Mer29

Hot Rod,

It seems to be alright so far now that the heat is running continuously. As I said above, the PSI was 30 and my furnace company replaced the air vents which by the way were closed tight (is that what you mean by the air eliminators? The two gold vents above the gray tank in the pics above?) The PSI is now holding at 20 PSI, I've been checking each day. Also, that gray tank was full of water and not functioning properly so it was also replaced. (Sorry if I don't know the exact names). I'm crossing my fingers that the problem doesn't reoccur. Thanks.

hot_rod

30 psi seems high, most boilers have 30 psi safety relief valves, although 45 psi can be used on some applications.

You may want to make sure you relief valve is able to function, they have been known to stick shut. It is a pretty critical safety on pressurized vessels.

If you see a wide pressure swing from cold boiler to hot it may indicated an expansion tank that is waterlogged, or someone added 20- 30 psi fill pressure to try and handle a problematic air issue, without adjusting the air pre-charge in the tank

If the pressure at the tank, or boiler is 20 psi cold, then the tank needs to be pressurized to that psi also or you diminish the capacity, hence the 30 psi you may be seeing?

Mer29

Now that the HY-Vents (I looked on the bill) have been changed and the tank, the boiler sits at a steady 20 PSI. There is no fluctuation hot or cold and actually with this weather, it's running a lot so it's almost never cold. Everything seems to be alright at this point. I hope it continues. Thanks.