Air Entering Boiler Plumbing

All,

My EFM has been running for a few months now and I have had no issues. Quick description of my setup: I have the coal boiler in parallel with the oil, and ball valves isolating the unused boiler. The expansion tank is an older model that looks like a small barrel hung between two of the floor joists. All of the original plumbing hasn't been touched, I just ran the coal boiler in parallel. My baseboard system has one main copper line that runs from the boiler to one end of the house. This main splits into two loops, one on the north side of the house and one on the south. The loops head back the opposite direction and then re-combine right before the two boilers. Each of the returns has a garden hose style drain valve before they merge into the single return. During the intial fill I ran water through the system with a garden hose hooked to each if these valves until it stopped sputtering air and hot water was coming out. I have an automatic bleeder on top of the boiler that was letting off occasionally after the initial fill. For a few days after the initial fill I would use the baseboard bleeders (I have one on every baseboard in the house) to get a little trapped air out of the system. This seemed to work well and all baseboards were getting hot, with no funky noises from the baseboards.

A few days ago I woke up the the "glugging" baseboard sound like there was an air pocket. I purged this air out as much as I could using the baseboard vents again. I turn the thermostat up to 80 or so when I'm doing this so the circulator is constantly circulating. After I finished purging put the thermostat back to 70 and the circulator stopped running. Within seconds I hear the glugging sound from some of the baseboards again!! I don't see how water could get into the system since it is pressurized. I also haven't heard any glugging sounds yet. Did I not purge the system correctly? There is no air scoop or air eliminator in the system at all.

Thanks,
Joe

I think it could be that the expansion tank needs draining. Those old type tanks do not have a bladder inside them to separate the air from the water. Given enough time the air disappears (it absorbs into the water & sneaks out) and now you have a full tank of water. When the system cools down it can suck air in, hence the gurgles. So.... shut off the boiler. Shut off the connection from the tank to the boiler system. Drain the water from the tank. Turn the valves back on from the system to the tank making sure the water inlet in turned on. Now the tank will partially fill with water and it will compress the air that's in the tank. Now you have air that will compress as the water expands. You will probably have to purge each baseboard one more time, then you'll be OK until the air in the tank once again disappears.

The cure? Get a modern expansion tank with a bladder.

1st

Never bleed off air with the circulator running --

Your old expansion tank is probably piped into a tapping on the top of the oil boiler? Is your EFM now piped in such a way that the flow is bypassing the oil boiler? One way or another, it sounds like the air is not going into the tank like it is supposed to. Perhaps it is due to the piping setup, or maybe that tank is full of water.

i had air problems all the time with my old system, I was a pain in the neck. I would start with a new expansion tank and an air seperator. also, try and lift one of the baseboards up higher than the rest making one bleeder higher than all of them. raise your system pressure to just below 30 psi (just enough to not pop the pressure relief valve) the wait a few minutes and most of the air in the system should find the highest point. that was the only method that worked for me. this time around I put an air seperator in line with the highest pipe run in my shop, once all the air is purged from that bleeder, im done, no more air! good luck.

Rob R. wrote:Your old expansion tank is probably piped into a tapping on the top of the oil boiler? Is your EFM now piped in such a way that the flow is bypassing the oil boiler? One way or another, it sounds like the air is not going into the tank like it is supposed to. Perhaps it is due to the piping setup, or maybe that tank is full of water.

The old expansion tank is not piped into the oil boiler. We made sure when we installed the coal boiler that we were only isolation the oil boiler and not the expansion tank, make up water, etc...

BUT....as Freddy and you suggested it very well could be a full expansion tank. I will check into that and possibly replacing it as well.

Thanks,
Joe

Sting wrote:1st

Never bleed off air with the circulator running --

if the expansion tank were to be water logged there would be no place for expansion and the EFM and the Oil boiler would be blowing off from the relief valve as either came up in temperature. I would suggest that you may not have done as well venting the system as you may have thought and the fresh water that you have purged into the system is now allowing the free oxygen to be dissipated combining with the air still trapped in the piping and magnifying the problem just a bit.
Modern expansion tanks with a bladder just do not require the attention of conventional style tanks without the bladder, don't waste your money they do the same thing, allow room for expansion. unless the conventional tank is leaking. I could also add depending on the location of your circ pump you could be creating mico bubbles from a lower pressure area at the suction side of the circ pump, however this issue will eventually cause a more costly problem than just air in the heating system.

JRDepew wrote: I don't see how water could get into the system since it is pressurized.

Air should not get into the system, but when you boil new water, undisolved oxygen in the system will separate from the water as you heat it. It sounds like you are flushing the system from the return hose fauchet. Do you have a auto fill valve ? The auto fill valves should have a bypass lever to flush the system with full pressure. Isolate all the zone ball valves, and flush 1 zone at a time.

JRDepew wrote:There is no air scoop or air eliminator in the system at all.

That is a problem.

Bell & Gossett makes a nice air separator with a large tapping for steel expansion tanks. "IAS" is the product name.

AA130FIREMAN wrote:

JRDepew wrote:There is no air scoop or air eliminator in the system at all.

That is a problem.

Is that really a problem?

It Depends

The heating system keeping me warm tonight was built without an air scoop -- yet it appears be working just fine - but I am more focused on the snow tonight watching the ball game in Green Bay - maybe that's why it works

Let me get back to you on that

Okay,

I closed the gate valve that isolates the compression style expansion tank and drained it. I'm guessing that it was maybe 1/3 full. I did notice that there is a fitting similar to this (the L-shaped one with a brass stick top extend to the top of the tank:

http://www.pexsupply.com/Bell-Gossett-112010-1-2- ... -8624000-p

What is the second cast iron device next to this? I don't have one of those and finding good literature on these seems to be difficult.

This is screwed into the bottom of the tank. In the description of this product it says: "Airtrol Tank Fittings must be used with the appropriately sized In-Line Airtrol or Rolairtrol air separator." Does this mean that a regular air separator like this should be used?:

http://www.pexsupply.com/Bell-Gossett-112119-1-1- ... -8601000-p

The top fitting of this air separator would then be plumbed to the style compression tank that I have? Reading the Bell and Gosset .pdf it says:

"The IAS-1½ and IAS-3 have a ¾” NPT tapping to accept a high capacity air vent or can be piped to a plain steel compression tank. The IAS-1 and IAS-1¼” have a 1/8” vent tapping to accept an air vent. All models have a ½” NPT bottom tank connection."

Another thing I am reading is that the auto air vent that I have on the top of the EFM is a big no-no with a conventional style expansion tank? I am reading that this will lead to a waterlogged expansion tank but I didn't seem to have an issue with that.

Thanks,
Joe

Joe,

You really need an air separator and I don't think the one you linked is right. It also sounds like you may need a new fill/pressure valve set at 12-15lbs.(watts brand is good) If you don't already have one then that as well as not enough expansion tank capacity are your problem. When you add the volume of water of the efm the old expansion capacity is not enough, especially if the one you have is the old type.below is an air separator that I believe to be the best and when you install that make sure that it is on the pressure side of the circulator. Hope that helps....

Best,

Waldo

http://www.pexsupply.com/Honeywell-Sparco-PV125S- ... 4AodkA8Aaw

That B&G Inline-air-separator would work fine, that is why it has the big tapping in the top...so you can pipe it right into the steel tank. The Spirovent that Waldo listed is intended to be used with a diaphragm style tank.

Joe ,

I forgot to mention you should add another expansion tank and it would hang from the spirovent. But if Rob likes the other vent and its easy to do Im sure its fine , just be sure to add more expansion capacity as well The efm almost doubled my water volume and I have a radiant floor.more water = more expansion

Waldo