Air Eliminator Problems in Radiant System

[00si2]

Last year I got my floor heating hooked up temporarily just to heat for that winter but had problems with the air eliminator all winter. I will soon be permanently installing it and want to try and get all the problems worked out. I don’t have any pictures of my actual set up (it’s now disassemble) but it’s very similar to the picture below asides from the air eliminator. I’m using a Spriovent jr.

The problem started out while trying to fill the system. No matter how long I pumped water through the system to fill it I couldn’t get rid of the air. I noticed the whole time the eliminator made a slight hissing noise and I thought it was doing its job removing the air but I later figured out it was doing the opposite and actually letting air in. By capping it I could fill the system to be almost air free. Once it was filled to around 15psi I closed the fill valves, removed the cap and would let it run. After a couple days running the pressure would drop back to zero and I would restart the process. I eventually discovered that every time the recirc pump would cycle off the air eliminator would let a tiny amount of air in and would drop the pressure down after a couple days. My fix for that was to just leave the eliminator capped and that’s how I ran it the remainder of the year. The problem with that is I was never able to completely get all the air out and it continued to be noisy while running.

I searched around to try and find a solution but I have come up empty. Anyone ever have any similar problems with these?

 

[Ron Lombardo]

The problem is you have no expansion tank ... add the tank and the air sperator you have will work fine ... i also dont see any sort of check valve or flow valve. Where is the feed make up water for the system ? and the purge valve and hose conenction needs to be moved from the supply pump area to the return ...because the feed make up water will be paipe to the supply on or near the ari seperator ?

Your best bet is to down load the piping diagram from the manufactuer of the boiler

Ron

 

[anthony666]

x2 with the expansion tank

also an air eliminator on it's own is never gonna get all the air out .. flush it out with a garden hose

 

[chickenhauler]

Is your air eliminator behind the pump?

 

[rlitman]

Air purge valves will allow air in if there is a vacuum condition (which is VERY bad for other reasons as well)
That can happen on the intake side of the pump. You should have a positive pressure on the system as a whole, and an expansion tank (such as an extrol, which must be sufficiently sized for the volume of heated water in your system) on the intake side of the pump (you MUST pump away from the expansion tank; google PONPC).
The iron pipe "tail" I see coming off of your air scoop is designed for placement of an expansion tank. Personally, I'm more a fan of a microbubble resorber than an air scoop (especially for radiant applications), but that's a different argument.

 

[00si2]

The problem is you have no expansion tank ... add the tank and the air sperator you have will work fine ... i also dont see any sort of check valve or flow valve. Where is the feed make up water for the system ? and the purge valve and hose conenction needs to be moved from the supply pump area to the return ...because the feed make up water will be paipe to the supply on or near the ari seperator ?

Your best bet is to down load the piping diagram from the manufactuer of the boiler


Ron

I do have an expansion tank on mine and its connected to the bottom of the air eliminator. I should have mentioned that in the original post. Im still looking for an actual picture of my setup but im having a hard time finding where i saved it.

There is a check valve built into the pump. Do i need to add an additional one to that?

I'm not sure what a flow valve is or are you calling it a flow or check valve?

Is your air eliminator behind the pump?

The eliminator is behind the pump on the suction side.

Air purge valves will allow air in if there is a vacuum condition (which is VERY bad for other reasons as well)
That can happen on the intake side of the pump. You should have a positive pressure on the system as a whole, and an expansion tank (such as an extrol, which must be sufficiently sized for the volume of heated water in your system) on the intake side of the pump (you MUST pump away from the expansion tank; google PONPC).
The iron pipe "tail" I see coming off of your air scoop is designed for placement of an expansion tank. Personally, I'm more a fan of a microbubble resorber than an air scoop (especially for radiant applications), but that's a different argument.

The vacuum condition seems to be the problem with my system but whats causing it? I have the eliminator installed at the highest location on the suction side of the pump and its connected to the expansion tank.

Do i need to add a check valve somewhere into the system?

What does PONPC stand for?

 

[chickenhauler]

I don't like to suggest throwing parts/money at a problem, but I would look at the air scoop and air eliminator as a possible replacement.
I have an Amtrol setup like this, and it's worked flawlessly:

An auto-fill/backflow preventer would be worthwhile too. Even purging my system with 40 psi one loop at a time left air in the system that took a few days or so to completely get rid of. Those little air bubbles hang on to every fitting they can, and seem to hang out in the manifolds a lot too.

 

[Jackfre]

I prefer the Spirovent system myself over the older Amtrol design as shown. I had a heck of a time with my system at home and upon replacing the Amtrol with the SV within 24 hrs the system completely settled down, and over 16 yrs never gave air problems again. You do need an expansion tank. There are about a bazillion of those Amtrol air eliminator systems out there that have done fine.

 

[rlitman]

The vacuum condition seems to be the problem with my system but whats causing it? I have the eliminator installed at the highest location on the suction side of the pump and its connected to the expansion tank.

Do i need to add a check valve somewhere into the system?

What does PONPC stand for?

If you have an extrol tank, it should be charged with pressure, and the system should be pressurized to match that (say about 15PSI in the tank, and 12PSI in the lines).

The suction side of a pump will be at a lower pressure than the output side. If the system is not pressurized, it will draw some vacuum. Aside from air entering (and the issues related to that), this can cause cavitation and ruin your pump.
This is a good location for the expansion tank, but the air eliminator is better placed out the pump outlet (where it will never experience vacuum). Automatic air vents on inlet manifolds may be good for removing bubbles for an initial fill, but should be closed when the pump is running. A bleed screw is cheaper and just as good here.

As I said, google PONPC and read up. There's way more to understand then I can write in one post, but it means "point of no pressure change".

A check valve can stop gravity flow (when the system is off), or prevent reverse flow if you have multiple loops. It won't hurt, but it's not the source of your problem.

 

[BadgerBoilerMN]

Confusing advice, all a little bit off.

The people who sell these systems should provide accurate heat loads, CAD tube layouts, near piping diagrams and complete installation instructions.

The pump (properly called a circulator) should pump to the radiant floor and away from the micro-bubble re-absorber which, will take all of the air out of the system. The common air scoop was designed for high temperature system and is inadequate for most radiant floor application. The check valve is likely unnecessary, I wouldn't add another.

The typical static (circulator off) fill pressure is 12psi.

It is best to get a little professional help before starting any DIY project.

 

[anthony666]

so badger dude, you're saying he doesn't need an expansion tank ?? you're saying that air doesn't need to be flushed out and that boiler instruction manuals don't come with near boiler piping diagrams ??

quit trolling forums looking for business

 

[00si2]

What about when the problem i was having while trying to fill the system with the breather cap open on the air eliminator and it letting air in? Only once it was capped i was able to purge most of the air out.

 

[pstnbly]

Step 1 close all the valves at the pex manifold (I'm assuming there are valves on 1 side of each pex loop). Step 2 close the ball valve on the return pex manifold (lower in picture). Step 3 connect a hose to the lower manifold boiler drain, run the hose outside or to a drain, open the valve. Step 4 open 1 pex loop isolation valve at a time and purge until air is no longer present, do 1loop at a time until you are sure all air has been removed. Loops are now purged. (I'm not sure what the schrader valve and gauge are for on the upper pex manifold but they are not needed and I would replace them with a boiler **** so I could purge the loops with street water pressure from a hose.

Isolate the pex manifolds from the system with the 2 ball valves, close the circulator isoflange valves, place a bucket under 1 isoflange bleeder a open it, bleed out all air. repeat for other isoflange. All air that is not in suspension should now be out of the system. Open isoflange valves.

Close system water supply valve and relieve system pressure (crack open a flange bleeder until system pressure is 0. Pressurize the expansion tank with air at its schrader valve to system pressure (15 I assume). Open all valves on loops and manifolds (except drains) and operate system.

Technically there should be 18" between the first elbow and the air scoop but I've seen them work without 18" Also a spiravent (MBR micro bubble resorber) is far superior in this application to an air scoop. air scoops work better at high temps (180) MBR's work better at low loop temps.

 

[Fastback]

Your system sounds a bit like mine (Pictured). It sounds like you have a fill valve system problem that is not allowing the air to be pushed out while filling it.

Take a look at the valves on the bottom of my setup, I turn the center valve OFF and push fluid in through the blue valve, and then I let the red valve dump back into the bucket that the portable pump is drawing from. The check valve in my pump also helps keep things moving on the proper direction.

Once I get the air out as best I can I let the heat do the rest as it causes expansion that can apply pressure to the bubble and move it to my spirovent.

I hope I did not confuse things...

 

[danski0224]

The discharge pipe on the pressure relief valve is (1) supposed to be the same diameter as the valve outlet and (2) terminate within 6" of the floor.

 

[danski0224]

so badger dude, you're saying he doesn't need an expansion tank ?? you're saying that air doesn't need to be flushed out and that boiler instruction manuals don't come with near boiler piping diagrams ??

quit trolling forums looking for business

You should re-read the reply, as there is no mention of eliminating the expansion tank.

I also doubt any business would happen- look at the locations of the posters.

There is nothing wrong with mentioning getting some professional advice. Why? Apparently, very few people read the instructions that come with HVAC equipment... or do even the slightest amount of legwork on their own.

 

[anthony666]

You should re-read the reply, as there is no mention of eliminating the expansion tank.

I also doubt any business would happen- look at the locations of the posters.

There is nothing wrong with mentioning getting some professional advice. Why? Apparently, very few people read the instructions that come with HVAC equipment... or do even the slightest amount of legwork on their own.

you should read the OP, there is no expansion tank

and you should read some his other posts where he say's he'll help folks for a fee

i do hydronics for a living, so i guess what i say is professional advice too

these type of forums are meant for people to share information with other people, yes ??? not to drum up business, right ??

 

[Ron Lombardo]

Not to be critical but check out what we call in the trade a primary / secondary loop system ... it utilizes 1 pump to circulate water thru the Heat source and another pump thru the system. It works better because in a heating system you only maintain heat loss once the system is maintaining temperature ... piped as a supply and return system your heating it to a high temperature every pass thru the heat source ...much more costly.

 

[Highbeam]

you should read the OP, there is no expansion tank

and you should read some his other posts where he say's he'll help folks for a fee

i do hydronics for a living, so i guess what i say is professional advice too

these type of forums are meant for people to share information with other people, yes ??? not to drum up business, right ??

I don't come here to pay for professional advice. Or to be told to seek professional advice. That's a cop out in my opinion to be reserved for only the most dense, dangerous/unsafe, and unable to be helped type of member.

Most forums have rules against trolling for jobs like that.