How do I purge a primary/secondary loop

[infinitymike]

I think I have air in my system. I have a primary/secondary loop. The oil burner and wood gun are tied into it.

By infinitymike at 2011-11-15

The two black pipes on the right are from the wood gun.

The returns tees of both units tap into the top of the loop with the supply tees only 4 inches below it.
The loop circ rotates the water counterclockwise.

There are bleeder valves all over the place.

This is the second day onliine.

Last night it was holding 190* at 18 psi.

It didnt fire all day, in the 60's here, but I lit a fire about an hour ago and it come up to temp quickly.
I raised the t-stat to call for heat and when I went to the wood gun there was rushing, bubbling, percolating water sounds .

I shut the return valve of the wood gun at the loop and opened the drain valve on the return line of the wood gun.
The pressure dropped to zero which I assume would be correct. the water was clear and I shut the drain valve.

But there is still alot of noise in the primary loop. Not bubbling or percolating sounds but just a sound of rushing water.

what do ya think

 

[in hot water]

I don't see an air purger anywhere in the piping? You have a float type air vent, that is intended to be a high point style vent. It really doesn't have a means to "grab" air from the fluid stream.

Those float type vents, on the suction side of a circ can sometimes allow air to be pulled into the system.

Looks like you could easily cut a purger into the piping just before that Taco primary pump. It's an ideal place to tie in the expansion tank also. And the boiler fill valve.

Here is some good reading on the How and Whys of air & dirt removal.

www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_2_usa.pdf


Consider a multi-purpose device that is both a air and dirt eliminator. Here is a clear display I built to show how a dirt and air purger works. The blue box is an aquarium pump that pushes lots of air into the piping. The Discal Dirt eliminator purges 90% of the air out on the first trip around. The lower chamber collects the particles of dirt that is dumped into the piping.

This type of air eliminator will remove the smallest micro bubbles and even clear up cloudy water that has dissolved air in solution.

Air in a system can not only cause noise and air locks, but the smallest bubbles will hamper the heat transfer in the boiler and heat emitters. Scrub it all out with one of these micro bubble resorbers.

Spirotherm, Taco, B&G are other good brands.

hr

 

[Clarkbug]

I think in hot water has it pegged.

The air vent will be great for air that settles out in your system, but not necessarily any that are/were in suspension in the water when you filled it up.

 

[ewdudley]

I think I have air in my system.

But there is still alot of noise in the primary loop. Not bubbling or percolating sounds but just a sound of rushing water.

Assuming all the new pumps are 007s and assuming the primary loop is 1.5", with just the primary loop pump running you would expect maybe 3.25 feet per second, which should be pretty quiet.

But if either or both of the load circs connected across the primary loop are running then you would be getting up into the 6 to 9 feet per second range, which you should expect to be fairly noisy, but otherwise harmless.

If it's 1.25" piping you could be well up over 10 feet per second, which would of course be even noisier and there would be some risk of wearing out certain piping fixtures over time.

All those automatic air vents should be adequate for removing air. The scrubbers have their uses, but normally aren't needed.

 

[Gasifier]

Mike,

How is the heat throughout the entire house? How many zones. Do they all seem to be heating well?

 

[infinitymike]

I think I have air in my system.

But there is still alot of noise in the primary loop. Not bubbling or percolating sounds but just a sound of rushing water.

Assuming all the new pumps are 007s and assuming the primary loop is 1.5", with just the primary loop pump running you would expect maybe 3.25 feet per second, which should be pretty quiet.

But if either or both of the load circs connected across the primary loop are running then you would be getting up into the 6 to 9 feet per second range, which you should expect to be fairly noisy, but otherwise harmless.

If it's 1.25" piping you could be well up over 10 feet per second, which would of course be even noisier and there would be some risk of wearing out certain piping fixtures over time.

All those automatic air vents should be adequate for removing air. The scrubbers have their uses, but normally aren't needed.

The primary loop is 1.25", the primary loop pump is a 007, the two zone pumps are also 007's, the pump that supplies from the OB is a 007 and the pump from that supplies from the WG is a 00R 3 speed set on medium.

It seems to have quieted down a bit. There is definitely a noticeable hum that was there before, but not as pronounced, with the OB and original piping. But is better than hearing the OB fire up :cheese:

P.S. I have city water, not well water. I don't know if that is better or worse.

 

[infinitymike]

Mike,

How is the heat throughout the entire house? How many zones. Do they all seem to be heating well?

It's good, but not great. I think there is still some air in the system. I purged it last night, and my installer is coming over tomorrow to purge it as well.
There really isn't a huge demand for heat yet. Highs have been in low 60's and lows have been in the high 50's.

Supposed to get cooler this weekend.

I can really see the need for storage in this kind of weather.

 

[in hot water]

If you have air vents all over the place, and still have air problems.. guess what. You need a central air purger inn the system. Or plan on a lot of manual bleeding.

I don't think you have a true primary seconday piping. The boilers tie into the loop as secondarys, closely spaced tees, but your loads are taken off as parallell zones. So when the primary circ runs, and either or both of the load circs run you have put those pumps in series. You are doubling the head and doubling the velocity. This compounds the air removal problem. Fluid moving in excess of 4 fpm is tough to get air eliminated from. Yet another reason to add a central purger. The purger presents a "wide spot" in the piping. At this wide spot velocity decreases and air can rise up and out.

Here is a drawing of how I think you are piped, and a drawing with all them inputs and loads as secondaries. it looks like it may at one time been piped with the loads a secondaries looking at those caped nipples?

I'd do some re-piping to get all the ins and outs connected via closely spaced tees. Add a purger at the suction of the primary loop pump, and tie the expansion tank into that purger. You need to establish a point of nom pressure change that all pumps "pump away" from. Then air, noise and all your other problems will go away.

hr

 

[infinitymike]

If you have air vents all over the place, and still have air problems.. guess what. You need a central air purger inn the system. Or plan on a lot of manual bleeding.

I don't think you have a true primary seconday piping. The boilers tie into the loop as secondarys, closely spaced tees, but your loads are taken off as parallell zones. So when the primary circ runs, and either or both of the load circs run you have put those pumps in series. You are doubling the head and doubling the velocity. This compounds the air removal problem. Fluid moving in excess of 4 fpm is tough to get air eliminated from. Yet another reason to add a central purger. The purger presents a "wide spot" in the piping. At this wide spot velocity decreases and air can rise up and out.

Here is a drawing of how I think you are piped, and a drawing with all them inputs and loads as secondaries. it looks like it may at one time been piped with the loads a secondaries looking at those caped nipples?

I'd do some re-piping to get all the ins and outs connected via closely spaced tees. Add a purger at the suction of the primary loop pump, and tie the expansion tank into that purger. You need to establish a point of nom pressure change that all pumps "pump away" from. Then air, noise and all your other problems will go away.

hr

The black horizontal pipes in the center of the top and bottom of the loop are factory made manifolds. The capped nipples are for future zones. The top manifold has the supply lines to both zones and the bottom manifold has the returns of both zones. And Actually I just noticed and don't know if it matters but the OB return is teed in below the supply and the WG return is teed in above the supply.

When a zone calls for heat BOTH the zone pump and the primary loop pump turn at the same time. They both shut off when the zone is satisfied.
So it is possible to have the heat source supply pump, the primary pump and the two zone pumps running all at once.

On the top of the OB I have one pipe that is teed and has the blow off pipe and the expansion tank. The WG is set up the same.

What problems could I have if I left everything the way it is?
Is it wrong and Should I tell my installer to redo it?
I am getting heat but could I get more?

Should I have the supply and returns of each zone on the same manifold?
And if so, does it matter if it is top or bottom?
And if so,does that mean that one manifold is really not useable?
Should I have the supply and returns of the 2 units in the same relation, supply on top tee and return on bottom and/or visa versa.
Does the rotation of the primary loop matter. either clockwise or counterclockwise with the placement of the supply and returns of the heat source.

Should I be pissed at him or myself or nobody?

Again will it work as is or can it be better.
Is it like driving on 2 tires with very little air, with a nail in the third and no treads on the fourth, without a spare.

 

[Gasifier]

Should I be pissed at him or myself or nobody?
Again will it work as is or can it be better.

Mike,

No need to be pissed. Be pissed at no one. It is all a learning experience. And everything will work out.
It is working right now. And it will work as is. When I asked you how the heat was you said it was good, but not great.
Can it be better? Almost everything can be improved. And I am sure these folks know what they are talking about. The only problem that I see is they are not there and everyone is relying on communication beween you and them. Why not wait and see how things go. You said you have not had much heat demand yet. But when you did you had heat. Good heat. Not great? I think you are also considering adding storage. So you have time to see how the heat goes when you start to get some real demand. And you can do what one or two of these very knoledgable people say when that time comes.

 

[infinitymike]

Thanks Gasifier,

I never really get pissed. But Like to think I would.

But really, maybe I am driving around on a flat. I could do it but it wont be great, and when the time comes for me to speed up, I may not be able to.
Know what I mean? Its hidden in the sarcasm. Yeah the heat is good, not great, right now,but come dead of winter maybe it will suck.

Hopefully I am communicating well enough for the very knowledgable guys (which includes you) to help me.

 

[ewdudley]

The black horizontal pipes in the center of the top and bottom of the loop are factory made manifolds. The capped nipples are for future zones. The top manifold has the supply lines to both zones and the bottom manifold has the returns of both zones.

Right

And Actually I just noticed and don't know if it matters but the OB return is teed in below the supply and the WG return is teed in above the supply.

Don't know what you mean.

When a zone calls for heat BOTH the zone pump and the primary loop pump turn at the same time. They both shut off when the zone is satisfied.
So it is possible to have the heat source supply pump, the primary pump and the two zone pumps running all at once.

This not orthodox primary-secondary. Normally you'd have closely-spaced tees for everything connecting to the primary loop, but you have loads connected across the loop so the load pump flow is added to the primary loop pump flow. The only problem I see with this is flow velocity and noise. With all three pumps you could be getting up close to 10 feet per second with 1.25" pipe, which is pushing it, but should be fine as long as the noise doesn't bother living space occupants, although there is some risk of erosion corrosion of the copper in the primary loop.

Does the rotation of the primary loop matter. either clockwise or counterclockwise with the placement of the supply and returns of the heat source.

It looks like the loop is going counter-clockwise. So your loads are returning to the bottom, which is fine. Your heat sources should be pulling from upstream and returning to downstream. For your oil boiler this does not appear to be the case, which would need to be corrected. Likewise need to confirm the the wood boiler is pulling from upstream and returning to downstream. If the wood boiler tees are wrong it would really cut down on how much heat you can inject into the primary loop.

Most likely the 00R should be on high speed.

Ideally your load pumps would be 'pumping away' from the primary loop. What system pressure are you running at? If it is high enough you can side-step the pumping away problem.

 

[in hot water]

I think you came here with two problems that you wanted to correct. 1, hard to bleed air, 2 rushing water sounds.

Unless you make some adjustments neither of those problems will go away. Unless your system can defy thermodynamics and and basic hydraulic principles.

The rushing is caused by excessive velocity, which is created when you have the two pumps running in series. I'll include a slide that shows how two pumps in series doubles the head, and the speed the fluid is moving in your pipes. Pumps in series is sometimes desired for filling tall drainback collectors, for example.

For the air to come out of the fluid stream easily, you need to be below 4 fps (feet per second) velocity. Above that velocity the air just moves along with the fluid. The float vents you have are probably 1/8 pipe size, it's nearly impossible for an air bubble to slow and find that tiny opening. They may vent a bit when everything shuts down, but it needs to be at a high point in the system where air seeks to be. putting a tall nipple doesn't create that condition really.

The purgers I mentioned above will work well up to 6 fps, not as well at 8, but they will eventually scrub air even at high velocities. That's why they are sold a "problem solvers" Systems with chronic air problems are quickly fixed when you add micro bubble resorbers. That's why engineers developed them to replace float vents and the cast iron scoop vents. It's critical with todays small passage, low water content, high efficiency boilers that ALL the air, even the micro bubbles are eliminated.

Excessive velocity will also cause un-necessary wear in all the piping components. I have seen copper tube and fittings develop pin hole leaks from oversized pumps on DHW recirc systems, sometimes in a few years time. Un-reamned copper adds to that wear potential. Here is a fitting with pin holes from an oversized circ.

The fix is fairly simple, you have the tees in place to move the returns next to the pump that supplys them. Then every device inn the system will get exactly the flow required under any condition, even if the pumps were all different sizes. ideally you would know how many gpm every zone required and adjust the pump speed to that. If those are multiple speed circs, start on low speed, if that supplies enough heat, you are all set.

If you don't have closely spaced tees, you don't have a true primary secondary piping. You're 1/2 way there.

No need to blame anyone. This site wouldn't exist is all systems were installed and operating perfectly. The folks that hang here do so to help others with the experiences they have learned. Nobody I know is born with this information pre-programed in their head. Hydronics can be very forgiving to some minor mistakes, but a few basic rules need to be followed.


hr

 

[Gasifier]

Thanks Gasifier,
I never really get pissed. But Like to think I would.
But really, maybe I am driving around on a flat. I could do it but it wont be great, and when the time comes for me to speed up, I may not be able to.
Know what I mean? Its hidden in the sarcasm. Yeah the heat is good, not great, right now,but come dead of winter maybe it will suck.
Hopefully I am communicating well enough for the very knowledgable guys (which includes you) to help me.

First, I will tell you I am not, very knowledgable, with these systems. I do have some good general "life" experience though. Second, I understand what you mean, and only you know what it sounds like and how it is behaving. And if you need to do something right now. One of the things that my install guys told me is this. That even though we added air seperation and purge equipment, maybe the best air seperator/purger is my vertical storage tank. At the very top of the tank was a port, I think 1/2" and we piped in one of those bleeders (if that is the correct name) right at the top of the tank. And you were close to buying a storage tank at one time. Good decision in my opinion, by the way, to not go with one of those that you were looking at. But I think one of the absolute best things that you could look at doing is adding that storage. I see the T you have next to the controller with the air bleeder on there and that made me think about how you are set up to add your storage in. That tank could be a great air seperator/purger. And you would have much less idling of your boiler. I am heating my house with the E100. Your house is smaller than mine. I have 400 gallons of storage and my Wood Gun is shutting down on a regular basis right now. Even with our temps being in the 20s at night time last night and tonight. I can imagine that your boiler is going to be shutting down quite a bit. If you find a storage tank and add it, when you do you could take the advice of the guys who are knowledgeable with these systems and maybe change a few things to improve with the pumps, etc. Something for you to think about Mike. Maybe in hot water and some of the other guys could add to this thought.

 

[infinitymike]

[/quote]It looks like the loop is going counter-clockwise. So your loads are returning to the bottom, which is fine. Your heat sources should be pulling from upstream and returning to downstream. For your oil boiler this does not appear to be the case, which would need to be corrected. Likewise need to confirm the the wood boiler is pulling from upstream and returning to downstream. If the wood boiler tees are wrong it would really cut down on how much heat you can inject into the primary loop.

Most likely the 00R should be on high speed.

Ideally your load pumps would be 'pumping away' from the primary loop. What system pressure are you running at? If it is high enough you can side-step the pumping away problem.[/quote]

I'm not much of a fishermen so I don't think I get the upstream downstream thing. Nor do I under stand the pumping away thing.
The more I stare at it I see that the pump is counter clockwise and the first tee of the oil burner is the supply followed by the return as the water goes around the first tee of the wood gun is the supply followed by the return. Is that up stream down stream? The same thing for the zones, although they are not closely spaced tees, the supply is first in the loop and the return second.

What do you mean pumping away? oh wait , because I have the pumps on the return side I am pulling towards the loop. So they should be on the supply side pushing away.
Ding Ding I think I got that one!

Still tryin to figure out upstream downstream :red:

 

[infinitymike]

Thanks Gasifier,

Always good encouraging words.

U DA MAN

 

[ewdudley]

It looks like the loop is going counter-clockwise. So your loads are returning to the bottom, which is fine. Your heat sources should be pulling from upstream and returning to downstream. For your oil boiler this does not appear to be the case, which would need to be corrected. Likewise need to confirm the the wood boiler is pulling from upstream and returning to downstream. If the wood boiler tees are wrong it would really cut down on how much heat you can inject into the primary loop.

Most likely the 00R should be on high speed.

Ideally your load pumps would be 'pumping away' from the primary loop. What system pressure are you running at? If it is high enough you can side-step the pumping away problem.

I'm not much of a fishermen so I don't think I get the upstream downstream thing. .

Like you're standing on the bank of a creek, upstream is where the water is coming from above you and downstream is where the water is going to below you. For your counter-clockwise loop, if you're looking at nine o'clock upstream is ten o'clock and downstream is eight o'clock.

The more I stare at it I see that the pump is counter clockwise and the first tee of the oil burner is the supply followed by the return as the water goes around the first tee of the wood gun is the supply followed by the return.

Which looks like it is wrong to me. The oil burner should be pulling water from 9:30 where the water is coming from and returning to 8:30 where the water is going to. I think this needs to be fixed.

The same thing for the zones, although they are not closely spaced tees, the supply is first in the loop and the return second.

Likewise not good.

What do you mean pumping away? oh wait , because I have the pumps on the return side I am pulling towards the loop. So they should be on the supply side pushing away.
Ding Ding I think I got that one!

With high enough system pressure and some analysis of your system it's possible this doesn't need to be fixed, but simply pumping away to begin with means you don't have to worry about it.

Likewise with the load circs pumping across the primary loop. It's possible you can get away with it, but if they were simply plumbed in with closely-spaced tees you wouldn't have to worry about the noise and excess velocity either.

 

[infinitymike]

Thanks EWD,

I see what you are saying. I appreciate your insight and knowledge.

And thank you as well In Hot Water,

Both you guys are helpful.

Now comes the fun part of having to talk to my installer. :-S