Air Trap

[hiker88]

I didn't want to hijack the other thread that's going today about spirovents, but I am having an issue that is related. I actually have a sprirovent in my system, but air bubbles are being "diverted" before they can get to it.

Sorry for the crude drawing, but I'm at my second job and was hoping for some input on this in case there are some parts I can pick up on my way home tonight so I can work on it first thing tomorrow morning.

I bought my boiler with the "near boiler" piping option. The supply comes off the boiler with 2-3 inches of black pipe and enters an inverted T-fitting (supply side of T-Fitting goes straight up). The supply side of the T goes up about 6-8 inches I'd say, and then enters the supply side of another T fitting. One side of this upper T-fitting has a combination temp\pressure gauge on it, and the other side of the T is my pressure relief valve.

Recently, I will sometimes notice a difference between the temperature gauge in this T fitting, and the temperature gauge on the supply side of my loading unit. I haven't figured out the pattern yet, as this happens very erratically. I've recently figured out that if I give the pressure relief valve a little blip when this happens, the temperature on the upper gauge will shoot right up and mirror the temp on my loading unit. I've placed the drain from my pressure relief valve into a container with water, and when this is happening, I can ease the relief trigger up and get some air bubbles in the water.

So, I realize I've got two problems. 1) This setup appears to be making my spirovent which is a bit further down the supply side ineffective. 2) Where is air getting in the system?

So, what can I do about air getting trapped where it is? Is it a bad setup that I have? . I don't know if I should redesign the temp gauge\pressure relief setup or if I should concentrate my efforts on stopping air from getting in (or maybe both)?

On the few times I've had to refill the system, the spirovent really hisses and dumps some air so I know that is working. I'm also going to try and figure out where air is getting in, but it just seems like a bad design for air to be getting stuck where it is...

 

[BoilerMan]

I'd replace the t with the temp and relief valve with a cross and use a bushing in the top port to get to the 1/8" and just put an off the shelf auto ait vent there. I'd leave everything else alone. Like Maple1 said in my thread about the spirovent, wi you can get the air to come out of the system at any point then you are good!

TS

 

[hiker88]

Thanks for the quick reply. Do you mean something along this line?

Is the bushing you mention pretty common? I haven't had to do any work w\back pipe as that was all done for me. The bushing would have to be whatever the inside diameter of 1 1/4 black pipe is and then on the other end be threaded for 1/8 female?

I can stop by Lowes on my way home and maybe switch this all out in the AM before I need to do a burn.

 

[Clarkbug]

1 1/4" to 1/8" might be tricky to find at Lowes. But I think most autovents are 1/4". You just may have to use a bushing in a bushing to get to that size.

 

[ewdudley]

1 1/4" to 1/8" might be tricky to find at Lowes. But I think most autovents are 1/4". You just may have to use a bushing in a bushing to get to that size.

Around here the plumbing inventories at the big box places vary from poor to not-so-bad. For Sunday afternoon who-would-have-it where-can-I-get-to-before-closing I've been rescued by Ace Hardware a few times.

 

[Bob Rohr]

I didn't want to hijack the other thread that's going today about spirovents, but I am having an issue that is related. I actually have a sprirovent in my system, but air bubbles are being "diverted" before they can get to it.

Sorry for the crude drawing, but I'm at my second job and was hoping for some input on this in case there are some parts I can pick up on my way home tonight so I can work on it first thing tomorrow morning.

I bought my boiler with the "near boiler" piping option. The supply comes off the boiler with 2-3 inches of black pipe and enters an inverted T-fitting (supply side of T-Fitting goes straight up). The supply side of the T goes up about 6-8 inches I'd say, and then enters the supply side of another T fitting. One side of this upper T-fitting has a combination temp\pressure gauge on it, and the other side of the T is my pressure relief valve.

Recently, I will sometimes notice a difference between the temperature gauge in this T fitting, and the temperature gauge on the supply side of my loading unit. I haven't figured out the pattern yet, as this happens very erratically. I've recently figured out that if I give the pressure relief valve a little blip when this happens, the temperature on the upper gauge will shoot right up and mirror the temp on my loading unit. I've placed the drain from my pressure relief valve into a container with water, and when this is happening, I can ease the relief trigger up and get some air bubbles in the water.

So, I realize I've got two problems. 1) This setup appears to be making my spirovent which is a bit further down the supply side ineffective. 2) Where is air getting in the system?

So, what can I do about air getting trapped where it is? Is it a bad setup that I have? . I don't know if I should redesign the temp gauge\pressure relief setup or if I should concentrate my efforts on stopping air from getting in (or maybe both)?

On the few times I've had to refill the system, the spirovent really hisses and dumps some air so I know that is working. I'm also going to try and figure out where air is getting in, but it just seems like a bad design for air to be getting stuck where it is...

The temperature gauge would be better located in a place where the fluid flows across it, instead of a dead end leg like that. It is a good spot for an air vent however. I'd still wonder where the air is coming from. Usually you only need to burp that tee once or twice after a fill and start. Put a service valve under the air vent also, they ALL leak someday

Check any packing nuts around valve stems, bolts tight on all the pumps?. Unless the system is taking on fresh water, it should not have a chronic air problem.

For an air vent, buy a 1/2" if the have it, air finds it's way into them better. Also bush in a few steps if you need to, 1-1/4 10 1' 1" to 1/2 oe 1/8. It's easier to find bushings like that.

If all the system fluid goes through the Spiro, it will release all, even the micro bubbles and entrained air.

 

[hiker88]

Well, I didn't find anything on the way home - but when I did get home, I found that it's actually a 3/4' T. But I haven't been able to come across anyone that sells a cross in that size either. I'll have to go to the plumbing supply store when they open tomorrow I guess.

I may see if I can redesign it a little bit, because this gauge is always a few degrees less than the digital readout on the display, probably because it is in a dead end as was mentioned.

 

[hiker88]

I just wanted to update this post that I was able to find a cross in 3/4". So I have supply into the bottom, my temp\pressure gauge on the front, a taco air eliminator on the top, and my safety relieve valve on the back.

I also went looking for the leak and I think I found it on the back side of a mechanical union on the return side of the space heat exchanger in my storage tank. I have 1 1/4 copper throughout the system so this nut is a monster. Maybe 1 1/2 to 2"? I did the dope\tape\dope trick on the threads and got a bigger wrench. When in doubt get a bigger tool right ? Knock on wood - no more drip.

I added a new zone to my system Sunday, and tackled this project as well. I think the new vent made a big difference getting air out when I filled the system and got it back on line.

After refilling, I did the hose trick for a while, and then ran the oil furnace for a bit. Once I was sure I had most of the air out it was time for a fire. I wish I knew a way to run the Froling cirlculator pump without a fire going, but if there is, I haven't figured it out yet. No matter how much air I try to get out before starting a fire, I still seem to have a slug of air to get out of the boiler once the circulator pump kicks on. I just keep the hose hooked up to the lowest point in my return and keep an eye on the gpm's on my alpha pump. I run the pump on high and expect 6-7 gpms with all zones calling for heat. If it drops at all, I let some water out and then add water back in. I just repeat this a bit until I don't hear any air in the system. It's super quiet now.

There was one point after the fire had been going for a while when there were no zones calling for heat and just storage was being charged. Then, there was a call for heat and after a few seconds, I got a good long hiss of air out of the new air eliminator, so I'm pretty sure it will make a difference if any more air gets in.