I keep getting air in my indirect fire hot water system

chuchundra

I live in a 60 year old house in Long Island, New York. It's a two story house, 1400 sq ft house with a single zone and 13 cast-iron radiators for hot water heat.

When we bought the house in 2010, one of the first things I had done was to replace the old, oil-fired burner and cheap , gas hot water heater with a new Burnham Alpine Condensing Boiler and a Buderus S120w indirect hot water heater.

Now when the system works, it's great. The house stays nice and warm in the winter and my gas bills are low.

The problem is that during the transition from heating season to non-heating season and also from summer into heating season, I get a lot of air in the hot water system. The system gets air bound and I have to turn the system off, close a valve and open the water spigot and let water run through a hose into a bucket until all the air is out.

This obviously creates several problems. One, I have no hot water. Two, the circulator runs and runs until I fix it, which can't be good for it and third, when It's cold out I have no heat because the burner is programmed to heat the hot water before it heats the house.

The guys who installed the system don't seem to have a good solution for me. The added an air eliminator right above the hot water circulator, but that didn't seem to help.

The system was fine all summer, but then it got a bit chilly, the heat kicked on and now I'm down in the basement bleeding the system on a daily basis.

Today I tried running the heat and then opening the bleeder valves on the radiators to try and clean out some of the air. No joy there. The problem remains.

If anyone has any idea of how to either

1. Keep the air from getting into my system or
   
2. Have it be automatically eliminated or other wise dealt with
   

Gordy

Sounds like poor purging / bleeding of the radiation side of things, along with improper air elimination.

Piping arrangement could be some of the issue. Got Pics?

When bleeding the air out of the system you need to start at the farthest point from the boiler, and work your way to the closest point of bleeding devices with circ off.

Your discription sounds like your trying to do it all from the boiler.

If the DHW works fine al summer. then problems star in the heating seaon then air in the radiation side has been in the system when heating starts it gets every where.

You may have a leak, may have a bad auto vent sucking air into the system.

Pics please.

chuchundra

Here's some pics

http://imgur.com/a/hN3vA

Thanks for your help.

icesailor

You have a 2 story house. Is the boiler in the cellar? Do you have enough pressure in the system? If you don't, you will get all kinds of air. You should have 20# of pressure reading on the gauge when the system is cold. You can hit the fast fill over ride on the pressure reducing valve and add more pressure. But it will need to be adjusted. Many fill valves say they are set to 12# to 15" which isn't enough. They really keep the system filled at around 10#.

If you are trying to purge and not using the fast fill/purge feature of the pressure reducing valve, you are purging improperly. If the installers that came to help you and didn't do it like that, they don't understand what the cause of your problem is.

I have never in my many, many years of doing hydronic heating seen so many systems with air problems. They just don't happen with systems with proper pressures.

If there is an air vent at the top of the system and you don't get a heavy squirt of water out of it, the pressure isn't high enough to push it up there. Even if you get a good squirt of water, there can be an air bubble under pressure that will make it appear that there is pressure in the system.

Rich_49

I advise you to use the "find a contractor " feature here . Your near boiler piping is poorly done , I can't find anything on Burnham's manual that states this boiler should not be Primary / Secondary piped . Although you are encountering low gas bills , I would venture that they could be much lower if this near boiler piping was done properly and at that point you could also address your air issues .

Can you send a picture from right above , looking down at the piping leaving boiler and also one of where the 2 vertical pipes to the ceiling from the boiler piping go to , also one of the piping coming out of the boiler from the front , side and bask of the boiler? We can see what we really need to from these locations .

chuchundra

Here's some more pics. Let me me know if this helps.

http://imgur.com/a/EIkBw

The green circulator goes up into the heating system.

I only have a very basic understanding of this stuff.

RobG

What does the PSI on the pressure gauge read?

Gordy

It is P/S is it not Rich.

Cant tell from the glare but I think the PSI is at least 15. There is a lot of hardware hanging there. Some more support would be a good thing.

chuchundra

I just checked it and it reads 20 with the system in standby.

RobG

If you look at the two sets of photos, the gauge is low in the first photo and high in the second photo. Have you checked the expansion tank?

billtwocase

Try closing the Taco 400 on the return side of the indirect. Never was a fan of auto vents on a return. Sometimes enough of a pressure drop will suck in air. You have one on the supply side, assuming that it is pumping away

icesailor

If the expansion/pressure tank is equal to a #15 or #30 Extrol, it is too small if the pressure is bouncing around like that.

Does anyone read installation instructions anymore? I've never read Burnham Install instructions, but I'm quite sure that they don't suggest piping the boiler like that.

icesailor

chuchundra said:

I just checked it and it reads 20 with the system in standby.

What does it read when you fire up the boiler and the whole system gets hot? If it starts to rise over 25#, you need bigger expansion tanks.

Gordy

This is what I see as far as piping.

The Boiler loop is P/S per alpines manual. It is pumping into the boiler per IO manual pg. 48

Min. boiler psi 20

The Indirect should be piped supply return from the Primary loop (loop with the X Tank). Its plumbed off the boiler loop (secondary). Im calling primary where ever the x tank is. seems to be differing opinions on what is the primary, and what is the secondary loop.

Plumbing the indirect off the boiler loop like it is could it cause the issue.

This is of course IF the xtank was properly charged. Xtank is not bad seems pretty new. And is large enough for the system.

Gordy

Also when purging is done is the ( boiler loop) being done then isolated. Then the system (primary loop)? I cant see good purging from one point in the setup.

icesailor

DId I miss something about the P/S piping? I don't see photos showing the connections of the primary loop into the secondary loop.

Even if you pipe the Indirect like Munchkin and make the indirect as part of the primary loop, it doesn't end up looking like that. Or at least from the photos I saw. Maybe there's more.


https://file.ac/0bGDQ0i2X3E/Alpine I&O.pdf

RobG

Off topic, that looks like the same Landis treadmill that I bought for my wife and currently sits in my basement collecting dust.

Rob

Gordy

ICE first photo of first set of pics. Up top is that not closley spced T's with return coming in from Right, and supply leaving to the left with xtank and circ PONC?

http://i.imgur.com/zPugUo1.jpg

http://i.imgur.com/1UYhRi1.jpg

http://i.imgur.com/kKVyRk0.jpg

http://i.imgur.com/9xnwMuO.jpg

Maybe we are both seeing, or not seeing something.

icesailor

The new pictures didn't load for me before. I see it now.

I think that there is something terribly wrong with that piping. In a narrow way, it might conform to Figure 22 on the Install instructions. But it shows the Indirect connecting to the secondary with the supply to the indirect on the supply side and the return on the return of the secondary. BETWEEN the closely spaced tees. The photos look like the indirect is connected at the boiler on the primary. Why so many circulators? Does the primary pump run at the same time as the indirect pump? If it doesn't, is there enough flow through the boiler to keep it from making steam bubbles like when water starts to boil in a pot?

I'm not there. I can't put my big paw and feel for something wrong.
You have to think like water and how it would want to go. For some reason, my gut tells me that if I was water, I might not like going that way.

With Munchkins and their vision controller, the primary flows through the indirect. Full flow. When there is a call for DHW, it has priority. When there is no DHW call, all the flow is through the boiler. Somehow, I feel like there are multiplying circulators in the piping. Is that primary pump set to run no matter what is happening? It should.

RobG

That doesn't look like any primary / secondary piping that I have ever seen. Were missing a pump! It's tough to decipher much from the mess of piping. I see one system pump and one indirect pump.

Rob

icesailor

@Rob:

There's a secondary pump in another photo just after an Amtrol air scoop with the Extrol tank and the boiler fill connected to it. There IS a closely spaced tee connection. The indirect doesn't connect on the secondary. It is connected to the Primary at the boiler. One of those two circulators is the primary pump. I can't tell which one it is.

There must be a serious air issue judging by the large square container with the purge hose in it. I've never purged a system that I couldn't do a complete job of it into one 5 gallon bucket. But then, I would never EVER fill a boiler like that because it makes it almost impossible to purge the system.

Gordy

There is three pumps. Primary which is the Taco. Secondary which is a grundfoss after the xtank, and indirect which is another grundfoss.

And yes the indirect piping is not off the secondary loop per alpines I/O manual.

Gordy

I believe the indirect piping is causing issues. There has to be a reason the alpine wants it plumbed off the secondary loop.

chuchundra

Thanks for all your help.

I'm off on Tuesday, so I'll try to take some better pictures and maybe mark them up so as to explain how everything seems to work for me. If anyone has anything they'd like me to test or try, I'd more than willing.

Just FYI, I keep the big green bucket because I have to bleed the system a lot and it's easier to use that and then empty it with a five gallon Lowe's bucket. When I bleed it, it's rarely more than a couple gallons worth.

Also, that's a Landice 8700 treadmill. I bought it along with an eliptical and five hundred pounds of olympic weights off Craigslist when I bought the house in 2010.

j a_2

Thinking you should find a competent,installer to come look..Not much you are going to do with it…Condensate tube appears dirty, meaning burner dirty…Is there a dirt separator installed…FYI boiler pump runs anytime there is a call for the boiler to come on...

icesailor

Just for the sake of discussion, I don't know who, but it appears to me that someone tried to fix the problem. There's the check valve in the boiler loop that doesn't appear to have been there when first piped. All the other fittings have Teflon pipe tale and some form of gray dope on them. The nipples on the check valve have only tape. With the two circulators so close together by the boiler in the primary loop, I can understand that you could get pump multiplication, one makes the other become a second stage pump.
IMO, that primary pump should be on not just when the boiler is running but whenever there is any kind of a call on any of the secondary circulators.

That's the perfect application for a hydraulic separator. Connect the primary/boiler side only to it and then any and all else to the secondary side and you can never have a problem. There's probably a wiring issue. If they house has 22 Cast Iron Radiators, the beauty of the Mod Con so that you can use cooler ODR water set to the OAT. But you don't want ODR water being piped through the indirect when it is calling. In what sequence do the pumps run? It may have piping issues, and it might work better if the secondary/indirect was changed. But it has been working except for the Spring/Fall air issue. If the flow and pressure is too high, you can get cavitation and air.

chuchundra

For the people who are following this.

I read through this discussion a few times, did some more research and looked at the installation manual helpfully provided by @icesailor‌

If I'm understanding the terminology correctly, it looks like the hot water heater is connected to the primary loop. If you look at this picture

http://i.imgur.com/Uiab0Lk.jpg

The red circulator is for the hot water loop. Those pipes are connected right to the primary boiler loop just as it comes out of the boiler. The green circulator in that picture is for the primary boiler loop.

If you look at this picture

http://i.imgur.com/1UYhRi1.jpg

The two pipes in the center of the image are the primary loop as it connects to the secondary loop and my one heating zone.

Looking at the manual page 48, it seems like the indirect should be connected to the secondary loop, not the primary as it currently is. Although the only picture I've been able to find online of a similar install has the indirect hooked up to the primary loop.




I think I have a basic understanding of how everything works now and maybe how it should work.

The thing is, as usually happens, the system has reached some kind of stasis and I haven't had to bleed the system for nearly 48 hours.

What I'm going to do next it call the original installers and have them come in and discuss this. They're actually good guys with a very decent reputation locally and I have another business relationship with them, so if we can figure out how to fix it, I feel that they'll fix it.

I partially blame myself for this. When I was looking to convert from oil to gas, none of the installers I called wanted to deal with the high efficiency system I wanted. When these guys said that they could do it, I didn't do my due diligence. Turns out that they'd never done a system like this. Live and learn.

Rich_49

Burnham does address this in their manual . We dealt with a similar situation this past winter in Mass (baseboardheathelp). That circ can be placed where it is but the boiler pump must be off during a call for domestic and only the DHW pump should engage .

icesailor

Rich said what I was trying to say. That the primary pump for the P/S system MUST not be running when the Indirect pump is running because of a call. Strange things can happen unintentionally. And the Indirect pump can NOT be running when the Primary Pump is running. The Primary and Secondary pump must ALWAYS be running when the Indirect pump is off. If the Indirect pump is on, the Primary and Secondary pump Must be off. But that might be causing the air problem is the Indirect pump isn't jamming enough water through the boiler.

As I understand it and how P/S came to be, was that there were two sources, a power plant and satellite locations and that the flow rates for the two were so vastly different that the water wouldn't flow. Someone figured out that of you took the flow of the power plant and circulated within itself as a loop, and then connected the other buildings into the first (primary) loop with closely spaced tees (as a loop), you ended up with locally operating circulation systems within the two loops. What has been done there is technically correct but prone to problems. The #1 issue and requirement for hot rod beer cooler boilers is high unrestricted water flow through the heat exchanger. That's why hydraulic separators work so well. Closely spaced tees in a P/S systems act as small hydraulic separators.

There's another thing I have run into that I read about but never expected to ever find it and understand it. If you have those tees so close together, one flow into the main can interfere with the flow from another source. The article was covering the subject of "Hydraulic Jump". Which in the article, described how water flowing in a horizontal plane, had laminar flow, traveling horizontally in the horizontal pipe. When it traveling in a vertical pipe, it is "circular flow" where it flows around the inside of the pipe. Like water down a sink drain. When water flows from the Horizontal to the vertical, it must make a transition laminar to circular or the other way around. There is a suggested length of free pipe that is needed to make this transition. Known as the Hydraulic Jump. I looked for the article for years and never found it. Google searches don't turn up the phrase.

In the case of the problem system, the ells turning into the black main part of the primary are so short that the water never has a chance to get back into the proper orientation or even decide where it is going to go.

In your case, if someone understood what they were looking for, you could probably correct it and make it work. Someone needs to lay hands and eyes upon it to see and feel it.

unclejohn

It seems to me that the extrol tank is not in the right spot and when you call for DHW the relief valve may open and air lock the system

SWEI

The fins on the Taco circulator were a red flag for me, so I zoomed in a bit to read the label. A 0014 has more grunt than the majority of residential applications need. Time for a bit of math.

icesailor

@Swei:

Look at Figure 21 and Fig.22 in the Alpine Manual. They show the indirect connected to the Secondary, on either side of the closely spaced tees.

It hasn't been mentioned what model that Alpine is, but a 0014 puts out almost 10 PSI (23' Head) and is trying to stuff 1400 Gallons Per Hour's worth of water through that boiler. Its not the biggest boiler or it would be 1 1/4 pipe.

I can imagine it now if the Alpine Rep comes to cast his eye upon the problem. He'll open the I/O manual to figure 21 and 22, look back and forth a few times and finally declare "Its not piped like in this drawing.". And it isn't.

Both those boilers shown, the one under discussion, and the one with the SuperStor look to be piped the same. They aren't.

That problem needs someone that has been around the race track for a lot of laps. It will take a serious hands on approach. You'll never understand combustion until you have a digital combustion analyzer and you use it always. You'll never understand pumping and piping until you start putting Tri-Dicator gauges on the supply and returns of boilers and circuits. That's how "Circuit Setters" work in large installations that you balance out for maximum efficiency.

Gordy

If you look at pg. 44 of I/O manual they love a big circ for the primary boiler loop. They are sizing for a 25* delta on all models except the 80 which is 20* delta per note (1). Don't think the math was done like SWEI stated in his post.

Gordy

Also page 55 look at,recommended circ sizes for an alliance indirect. Huge.

Rich_49

Seems to me that this installer likes to pump right into the bottom of air vents . Look at the vent right above the Grundfos and then again on the return out of the top of the Indirect . Could this be a part of the problem ?
The 0014 is a bit heavy handed for that boiler loop huh . What size Alpine is this ? Betting a like for like replacement w/o a heat loss being done .

bsln

Look at Figure 21 and Fig.22 in the Alpine Manual. They show the indirect connected to the Secondary, on either side of the closely spaced tees.

Older versions of the Alpine I/O manual permitted piping the indirect to the near-boiler piping for certain models. The 0014 was recommended for the smaller boilers & tanks, and the boiler software allows the DHW pump to be set as either "Boiler Piped IWH" or "Primary Loop Piped IHW". In the 2/10 I/O manual see figures 32A/B for near boiler piping with indirect, and table 12B for the circulator. The newer manuals do not show this as an option except for multiple boiler installations (fig 25B of the 8/14 manual).

That said, I have an ALP105 and AL50SL piped in this manner (as was per the manual at the time), and it's problematic - constantly overshoots the DHW setpoint and cycles, even with max mod turned down.

icesailor

bsln said:

That said, I have an ALP105 and AL50SL piped in this manner (as was per the manual at the time), and it's problematic - constantly overshoots the DHW setpoint and cycles, even with max mod turned down.

ANd when that overshoot happens, there's no possibility of that Placer Mining Pump cavitating in the hot water and making air?

If Burnham changed the diagrams, there had to be a problem.

Gordy

Read page 50 of the I/O.
If that in directs flow rate is less than the required min. Flow rate of the alpine it needs to be plumbed in the secondary.

Gordy

So you got a 15-58 on the indirect, and a 0014 on the primary.

Seems to me some people are worried less about HX errosion, and more about over heating the HX.

chuchundra

bsln said:

Older versions of the Alpine I/O manual permitted piping the indirect to the near-boiler piping for certain models. The 0014 was recommended for the smaller boilers & tanks, and the boiler software allows the DHW pump to be set as either "Boiler Piped IWH" or "Primary Loop Piped IHW". In the 2/10 I/O manual see figures 32A/B for near boiler piping with indirect, and table 12B for the circulator. The newer manuals do not show this as an option except for multiple boiler installations (fig 25B of the 8/14 manual).

That said, I have an ALP105 and AL50SL piped in this manner (as was per the manual at the time), and it's problematic - constantly overshoots the DHW setpoint and cycles, even with max mod turned down.

Any idea when this might have been changed? The install was done in spring of 2010.