Air gurgling in radiant heat system

moemah123

Hope you are well everyone.

3 months ago I lost heat in my radiant heat system due to lots of air in system. I called my radiant heat service and they came and flushed system. 2 weeks ago I heard the same noise again. This time not waiting for my heat to go out I called them and they said expansion tank failed. They replaced it and flushed system and loops. Yesterday and today again I hear the gurgling noise (sounds like someone flushing toilet) 

I am frustrated, i paid alot so far to get rid of this noise and in 3 months and 2 flushing air noise is still there. They guarantee labor for 90 days but at this point i am concerned they will start randomly blame parts. I also don't know if it makes sense to flush system 3rd time in 3 months. What could be the issue? I have a 1600sqft home and I keep temp at 67 so it won't kick often.

I welcome any advice on how to handle this.

kcopp

How is the system piped? Is there a working air separator in the system? Pix will help.

moemah123

Apologies for the late reply. My issue now is slightly different. I had someone else from that company come and they told me there is a leak in manifold which is why the system is building air and losing pressure. I attached a picture of said manifold. Yes it looks corroded, when I touched with my finger it was wet not dripping.

His suggestion is to replace this whole manifold and the other one upstairs (which is working) but stressed that this one at minimum needs to be replaced. I was quoted 1k parts price to just replace this 1 manifold with 3 loops (labor is excluded) and I am feeling that's a very big price for just the parts. To replace the 2 manifolds would cost 3k overall with labor I expect. I am not even sure this will fix main issue. Is this expected price for this job or should I look somewhere else? It feels huge and I don't know many companies in Washington that work with radiant heat

Appreciate the advice

Mad Dog_2

Take better pictures 📷   from a distance...too close  . We still wanna see all the boiler piping    mad dog

moemah123

moemah123

Let me know if those are good or I can take different photos for what you ask. I appreciate it

kcopp

Ok That explains a lot.
Its an open loop system. No air separation. Need to have one.
The water that you use for bathing is the same water that goes into your heating system.
Not an ideal set up IMO... but it is what you have.
Im not sure what the cost of running a business is there but it is what it is.
I don't think you need to replace the manifold just yet.
Is the circulator a bronze or a stainless steel one? It should be... looks like a cast iron one.

moemah123

The person told me the system is closed loop system and that my water and heat are separate. Is that not accurate? As I understood it the tank is sort of split into 2 where one is responsible for heat and other half is for domestic water.

Is there something I should be taking a picture of to confirm? As they assured me water and heat are separate

And as for manifold they blamed lost pressure and air on it. Is there a reason to hold off? Also anything I can do like caulk, or tape etc to make sure water doesn't leak? It's wet when I touch it but not dripping 

kcopp

Is that a combi-cor water heater?
What is the model number?
If it is... why did they install a potable water expansion tank on the heat side?

moemah123

I believe it is combi attaching model number. I don't know why it has expansion tank (though they say it has failed and needs replacing and that it being upside down wasn't an optimal design) attaching pic of model number 

kcopp

Ok then. It is a Combi core. They stopped making that according to the website. Still its Non O2 barrier pex and you still need an air separator.

moemah123

Does this mean I need a completely different tank? Or it's something to install in the tank? How can I tell if it is or isn't there already?

Also I think main issue I have is system loses pressure fast. It used to be every year I need to purge. Over last 3 months it was done twice. Do you suspect the rusted manifold is not the issue ?

What is your recommendations for me to do at this point?

kcopp

Sounds like a leak. It is possible you have a leak under your slab. You need to pressure test the piping and see if it holds.
The manifold is miniscule.

Mad Dog_2

Thats some extremely shoddy Craftsmanship.  An inspector would never pass this.  I'm not being cute, here.  Mad Dog

Mad Dog_2

I think it is safe to say, this installer "don't do"  black screw pipe for gas nor does he know how to or is able to solder.  Mad Dog 

moemah123

kcopp said:

Sounds like a leak. It is possible you have a leak under your slab. You need to pressure test the piping and see if it holds.
The manifold is miniscule.

So you think i should ignore this manifold rust and that it being wet is not what causes system to lose pressure? Is there anything i can do, like caulk or glue or something to stop the corrosion or rust?

Now, for main issue you suspect that there is a leak under floor, is there an easy way to verify? What exactly should i ask them since they seemed so confident it is the manifold they wanted to charge me 3k for replacing both manifolds (upstairs and downstairs)

moemah123

Mad Dog_2 said:

Thats some extremely shoddy Craftsmanship.  An inspector would never pass this.  I'm not being cute, here.  Mad Dog

I agree with you, I was told the whole piping was not done well. I am at a loss what to do now to stop the leaks that happens as I cannot see any point of leak other than manifold, what do you think?

Mad Dog_2

Are u still in touch w the installer ?   How did u find him?  He owes you  $ back sir.  Feel for ya .  Unless he's willing to clean the mess up, I would get a Pro from here out to assess for u  mad Dog

moemah123

Mad Dog_2 said:

Are u still in touch w the installer ?   How did u find him?  He owes you  $ back sir.  Feel for ya .  Unless he's willing to clean the mess up, I would get a Pro from here out to assess for u  mad Dog

No unfortunately, I dont know who installer is. I bought house from previous owners. The pro came and said that manifolds need to be replaced as the pictures show one of them is rusted. But otherwise system looks fine for now (he wanted me to reconsider redoing the piping in future) kcopp mentions that maybe there is a leak under slaps so i am hoping to see if manifolds look bad or they are not the issue at the moment

Mad Dog_2

Your home inspection didn't pick up on. this?  That's  their sole purpose:  To protect a Home buyer from inheriting problems like this..  well,, Hopefully this Guy you have now gets it working right again  good luck and keep us posted  Mad Dog 

hot_rod

an air separator before the circulator with the expansion tank located there also would probably solve the air issues 

moemah123

I am attaching location on picture and let me know if this is where air separator is suggested. 

I have 2 questions for you.

The 2 manifolds on both floors have air relief on them, is air separator different?

Also since yesterday my pressure dropped from 35 psi to 25 psi. Is it possible that rusted manifold is the issue? Or something else is causing this huge drop? I don't see manifolds dripping and I am very suspicious they are the root cause but clearly the house is losing pressure fast and this was first thing identified

hot_rod

moemah123 said:

I am attaching location on picture and let me know if this is where air separator is suggested. 

I have 2 questions for you.

The 2 manifolds on both floors have air relief on them, is air separator different?

Also since yesterday my pressure dropped from 35 psi to 25 psi. Is it possible that rusted manifold is the issue? Or something else is causing this huge drop? I don't see manifolds dripping and I am very suspicious they are the root cause but clearly the house is losing pressure fast and this was first thing identified

The air purger should be at the piping as it comes off the tank, as per the drawing I attached above

You have air vents on the manifolds, they are not intended to do the “heavy lifting” you want a central air separator ideally.

The marking on the expansion tank? Does it say 12 psi? If so your system should run 12- maybe 15 psi. Not sure how it is getting to 35? Typically there is a 30 psi relief valve on the hydronics loop.

kcopp

This whole set up is really strange.
Why is it run at so high a pressure?
Should be 15-20 psi... not 35.
No air separator. Potable water expansion tank. Does it have a pressure relief valve on the heating side? How do you fill it?
Does it have an auto fill or are you doing it by hand?
Looks like the WH is vented in ABS. Not sure that is kosher.

I will say it again...I do think you have a leak bigger than just the drip on the manifold.
Need to pressure test it w/ air and start to isolate each loop.

moemah123

hot_rod said:

I am attaching location on picture and let me know if this is where air separator is suggested. 

I have 2 questions for you.

The 2 manifolds on both floors have air relief on them, is air separator different?

Also since yesterday my pressure dropped from 35 psi to 25 psi. Is it possible that rusted manifold is the issue? Or something else is causing this huge drop? I don't see manifolds dripping and I am very suspicious they are the root cause but clearly the house is losing pressure fast and this was first thing identified

The air purger should be at the piping as it comes off the tank, as per the drawing I attached above You have air vents on the manifolds, they are not intended to do the “heavy lifting” you want a central air separator ideally. The marking on the expansion tank? Does it say 12 psi? If so your system should run 12- maybe 15 psi. Not sure how it is getting to 35? Typically there is a 30 psi relief valve on the hydronics loop.

I attached this picture because I could not find which picture i uploaded of my system corresponded to your drawing. Your drawing shows expansion tank to right of pump and close to tank. While my expansion tank is on left of pump and further from tank. The black arrow was just to ask if air separator should be installed there or where exactly?

Expansion tank doesn't show psi. The main gauge in system shows 30 now

hot_rod

The expansion tank by the pump is a domestic water type, generally pressurized to 45 or 50 psi. Looks like someone adjusted the pressure and wrote on it with a marker, what does it say? They may have lowered it to 12 psi which is what the fill valve is commonly set to.

moemah123

The expansion tank here is not for domestic water. There is another one in post with pictures thats upside down that I was told is for domestic water. I was told this one is for the heating system. 

I don't know to be honest why there is 2 expansion tanks. 

As for pressure, I don't know if it's related to expansion tank (there is one left to.pump that's for heater and one on tank for domestic) but I was told whole system should be 40psi. So that I don't hear air bubbles in system.

I am not sure what to do anymore. I feel they will keep proposing fixes not related to the problem and making me pay 5x parts prices until they "fix" the problem.

I am not sure why my system is losing pressure fast. I didn't do any floor work. Their claim is if manifolds don't fix leak. Then they will look under slabs because maybe there is a nail that rusted and exposing leak.

At this point I don't think that makes sense and need guidance on what to do next. Again main issues seem to be system loses pressure 40 to 20psi and air bubbles and the only thing identified is one loop of manifolds is in pretty bad shape

hot_rod

If the pressure drops to 20 and stays there for hours, days, why not just run the system at 20 psi?

You need and air purger, period. Running 40 psi to eliminate air noise doesn't make any sense? I'm thinking if you had an air purger before the pump, with an expansion tank connected to it, all your problems may disappear. 10- 15 psi is plenty adequate.

Assuming there is not a hole in a tube allowing water pressure to drop to 0. Figure that out first. Does the system ever drop to 0 psi. If so I would agree with a possible leak in the slab, the lowest point in your piping.

You have two expansion tanks, one for the domestic water, one for the hydronic system. The tank they used on the heating loop happens to be a domestic water model, not a problem. Looks like they adjusted it to 40 psi according to the date and writing on it, yes?

It doesn't take much of a leak to drop pressure 20 psi, how quickly depends on how much fluid is in the system. So any visible leaks could in fact be causing the drop.

moemah123

I will monitor how many days it takes to drop to 0. If it takes a week or 2 to drop to 0 does this mean a definite leak?

I will discuss with them air purger. To be clear is this different from air separator? 

Also my last question if the pressure does drop to 0 and the bad manifold isn't dripping but wet. Would it be the likely culprit or I should ask them to look under slabs first for possible leak? 

hot_rod

My thought would be to turnoff the red and blue handle valves near the pump. Remove that expansion tank and install this type of pressure gauge, available at any online or box store. Pump it to 60, 80, even 100 psi if you can. If there is a leak in the Pex you will know with minutes, maybe seconds with high pressure. I think most codes require a 100 psi test on Pex in a slab pour.

Screw the black cap closed on the air vent at the manifold, of course.

If it drops, spray soap, or mix some dish soap in a glass paint the manifolds and Pex connections. Find and fix any leaks there, retest.

While the manifold/ tube test is under way watch the pressure gauge near the pump, left of it. Does it drop? If so there is a leak in the piping in the room, should be obvious.

You need to break the system in bite size pieces to quickly determine where the leak is. Pretty basic troubleshooting suggestion.

moemah123

I started contacting some companies, I was disappointed to know there is only basically 2 companies in my area that work with radiant heating.

I have a question couple questions. Is there a recommended brand for air separator/ purger to buy? And would it be straightforward for technicians to install or it needs considerations? Like size of pipe / distance from boiler etc

The other question is, they seem persistent that rusted manifolds should be replaced. I feel this won't fix the issue but I am keeping an open mind. I am not convinced that the manifolds in picture are worth 1000 dollars. Is there anyway I can buy item myself from somewhere else and they install or i should just accept cost.

I feel I fully agree I needed concrete proof that manifolds are issue (my system now is at 10psi from 40 on 14th march) I also have to add that I keep house temp low (65) so radiant loops are not running often. And the rusted manifold is very dry (I assume because loops don't run as much) so I don't know for certain why it is losing pressure.

Thanks for guiding me so far

GroundUp

Whoever installed that expansion tank for you, owes you a refund and an apology. It's a potable tank and if my eyes don't deceive me, it says 50 psi on it. It needs to be a hydronic tank and should be 15 psi or less- typically 12. You have no means of air elimination which should have been addressed right away by the "technician", and you don't have a lot of system volume so yes if that manifold is wet to the touch, it's leaking fairly significantly and should be replaced. At the bare minimum, you should add an air eliminator where the current expansion tank is located, and replace that tank with a hydronic tank like an Extrol #15. Those manifolds are dirt cheap and would take a competent technician a couple hours to replace, $3k is highway robbery. What is your location? Perhaps someone here can point you toward an actual heating company to take care of this for you.

hot_rod

actually, I would stick with that tank, since you have non barrier tube a standard hydronic tank would rust quickly. As long as the pressure is adjusted properly it will work. The tank is lined inside to be used for domestic water, so it will not rust. It is rated to 200 and 150 psi.

moemah123

I live in Washington. If someone does know of good radiant heat companies that would be great. I want to recap suggestions so I can take it to this company next week.

It seems there is an agreement that I should get air eliminator. Should I buy the parts and ask them to install it? And is there credible website and parts you recommend for this system?

Same for manifolds. Is there anyway I can buy the above part or similar for less than 1k? They will charge fees to install (240/hr) making replacing a single manifold 1.5k job, hoping I can minimize the cost somehow. Any recommendations welcome for manifold that would work with system.

Finally, I am not sure if we have consensus now on keeping / replacing expansion tank and if it is actually doing anything

hot_rod

Yes you need an air purger.

Yes the tank you have is fine if pre charged and installed properly.

A knowledgable hydronics guy could clean that up in a day. New manifolds, air purger, probably 3- 400 bucks worth of parts.

SupplyHouse.com has those copper manifolds.

You need someone that understands hydronics and has some pride in their work. What city are you near?

Screenshot 2023-03-24 at 11.55.50 AM.png

Screenshot 2023-03-24 at 11.42.58 AM.png

moemah123

Thanks so much hot_rod for your continued support. I am near Seattle, WA. Let me know if there is a site you recommend or way to find experts to help.

was taking a look at my piping in pictures and didn't see enough space to install air purger. Do you expect the system would need to be reconfigured to make space? Or can it be installed in current system (despite tank and valves, pump being so close together?

hot_rod

if it were me I'd move that assembly to the right a foot or so, clean up the piping from the tank connections. @Paul Pollets lives in that area, private message him by clicking on his contact. He may help or know another competent hydronic company

moemah123

One more question.

I noticed that system now stabilized at 10psi. I attached two pictures showing a pattern that I am seeing for last week.

The picture with almost 0 psi was taken yesterday. This was system calling for heat and it dropped from 10 psi to 0-5 psi.

The picture with 10 psi was taken today. This was the system being on stand by.

I Have seen and taken pictures of this pattern everyday for past 5 days. When system calls for heat it goes as low as 0 and when it goes to standby it goes back to 10

What does this all mean? My expectation was if there is a leak it goes and stays at 0 not go up and down during past week. What do you think

hot_rod

The circulator pump, which direction is it pumping? Should be an direction arrow cast into the body of the pump down under the motor.

GroundUp

https://forum.heatinghelp.com/discussion/comment/1744181#Comment_1744181

Can you show us an example of a "rusted" hydronic tank caused solely by non-barrier tube? Cutting 80% of the pressure from a potable tank bladder will shorten the tank's lifespan a whole lot more than non-barrier tube will do to a hydronic tank.

hot_rod

how does lowering the pressure have anything to do with it?

If the potable tank is the same size as the non potable and pressure is the same in both, the tanks perform, accept, the same.

The potable tank has a 3/4 stainless connection, coated inside, butyl diaphram