The toe kick must be at a high point and the bubbles are ending up there instead of being vented.

I think eventually the noise will stop and be bled normally, because you say the noise stops when running the entire system. Give it some more time. Verify that the air is actually bleeding at the vent (cap open).

Thanks for your response baymee. I hope you are correct.

The gurggling had occured for months during last winter. This year, I have started using the heat about three weeks ago and it has been gurggling with no dissipation. I have run the heat every morning for at least an hour or two. I ran the heat all of last weekend, still with no change in the gurggling.

How much time should I give this to bleed? What do you think would be normal in this situation?
THanks again.

Are you sure your air vent is working? The air should have been out of your system by now. Your air vent will probably be brass, about the size of a plum and will have a chrome bicycle tire innertube type cap on it. It should be slightly loose. The air will escape through an innertube valve stem (Schraeder valve) and the cap keeps water from spraying out.

Look for this valve or take a picture of your piping above the boiler and we can look for it.

Kristi,
I have the exact same problem & for the same reason (toekick heater added when kitchen renovated). HVAC mechanic has been here twice. He emptied expansion tank, bled radiators etc. and I still hear this horrible noise in the pipes when the boiler comes on. I think I found the answer on This Old House web site. Looks like I need to have an air valve installed. The link to the TOH video is below. It looks just like my system, so I am hoping this is the answer. I suspect this may coincide with the advice Baymee gave above. I don't think my unit has an air vent. Good luck!

Here is a link that might be useful: This Old House Installing an Air Valve

It won't play for me, but the dialog states that you need an air vent.

Water traveling through the pipes needs a collector to capture the bubbles as they go by. If there wasn't room on your toe kick to install the purger, you could probably get away with a crude fix. A tee soldered in the line with a short upward pipe and an air vent. However, your vent at the boiler should be doing its job, especially since you indicated that the noise stopped when the full system in use pushed all the air out of the toe kick line.

What is your system pressure? 12# or more?

Baymee, I will check the system pressure tonight, where would I look to check this? I assume an air valve is the same as an air separater or air eliminator? After some web searching I found a few companies that produce these: Spirotherm, Bell & Gossett and TACO. Are you familiar with any of these and do you have any recommendations?

Mims, I don't have speakers now, but will watch the video this evening. Thank you for the link. let me know if the air valve works for your gurggling noise.

http://www.amtrol.com/airvent.htm

That link will show you the purger and air vent. The purger is probably green and the vent is probably gold or brass colored.

I doubt it's a system pressure problem, but that would be on the temperature gauge on the boiler. One scale is the pressure and the other is the temperature.

I think your air vent cap might be closed, or otherwise not working.

System pressure is 25psi. I took some pictures of my hydronics which can be viewed on the link below. The first picture I think is a very old TACO air vent. Do you think replacing or fixing this could fix the problem. The gurggling noise is primarily right at the toe kick heater unit itself, upstairs in the kitchen.
Thanks again.

Here is a link that might be useful: Hydronics

You found it !

Loosen the cap on the bleeder and listen for air. If no air, slightly depress the valve stem under the cap and see if water sprays out. Wear glasses. If water comes out, it means that air is trapped at the kitchen.

You were able to eliminate the gurggling in the kitchen when you ran the entire system, so run the entire system and listen for air to escape at the bleeder. It should come out if it's bleeding properly.

Otherwise, I think you'll have to add a bleeder in the kitchen.

Usually, with a hot water heat system, there is a vent, whether it be manual or automatic, at every elbow, where the water must go down again. In other words, every radiator, element or pipe exiting down, should have one. Once the water is free of air, they are only "there" 'till the next time of opening the system. Many times, due to the air, the radiator won't make any heat, depending on the plumbing arrangement.

Baymee, This morning I turned on the main system at 6:00am and the toe-kick heat at 6:30 or so. No gurggling. I then inspected the air vent. I did not hear any air. When I depressed the air vent stem, water came out. Does that mean that air is trapped in the kitchen?

I had to rush off to work, so did not have a chance to turn off the main heat and test again with just the toe-kick heat running. Will do so tonight.

Apparently the air isn't being pushed out of the kitchen heater. In that case I would install a vent in that location.

It seems that this may be an ongoing problem.

Another place to install a vent is at the top of the boiler. When the nipples are welded or placed into the top of the boiler, they extend inside about 1/2". This is a great place to trap air that won't necessarily be sent into the supply line where the other vent can eliminate it. But every once in awhile some air will escape and cause you problems.

So, I would have a vent put there and one at the toe kick at the same time.

why bubbles when only kitchen zone is active? A theory.

Kristi's most peculiar symptom is that the problem only occurs when the kitchen zone is working by itself. I have an idea of why that might be, and this could explain lots of troubling air bubble problems. This has to do with the pressure drop caused by the circulation pump. The pump's job is to generate pressure between its inlet where it is low and the outlet where it is high. The amount of pressure change depends on the resistance of the pipe system. When only one zone is open this resistance is high and the pressure drop is large. The pressure right at the inlet to the pump can then be very low if the pump is powerful and the pipes to the zone are small. If this pressure gets really low, bubbles of water vapor can form. The way to check for this problem would be to put a pressure gauge on the drain outlet on the return side of the system just ahead of the circulation pump. If this pressure is negative, the solution is to reduce the pressure drop by reducing the power of the pump.

Any thoughts, Baymee?