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[Updated 2/4] On the return side: Spirovent and an expansion tank, question with pics

GannonGannon Posts: 15Member
edited February 4 in Radiant Heating
Greetings,

Moved in and became the owner of a fun hydronic heating system; baseboard heating on two floors and in-floor heating in two rooms, PEX, manifold, and all. All but baseboards installed around 2012.

Recently found water on floor. Boiler at 30 psi; diaphragm expansion tank is shot (no air). Was quoted an absurd amount to have it replaced, so doing it myself. In the process, would like to replace the air scoop I have with a Spirovent Jr.





Currently, my air scoop and exp. tank are on the return side. I see Spirovent is intended for supply side. Does it matter in the end? Likely won't get the best results, but I am thinking it is better than the scoop anyway and easier than redoing other parts of the system to retrofit.

Found a diagram of the system's piping and control logic. If not clear in picture, cold water supply for the system comes in via the tee above exp. tank.



Greatly appreciate any advice. Easiest to just replace exp. tank and leave scoop, but would like to improve system if possible--hence, the Spirovent addition.

Thank you!


Saw this post with some comments on the situation, but my pump is up against boiler and not between the Spirovent/air scoop and the boiler, as discussed. Perhaps there's more there that I'm missing?





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Comments

  • GroundUpGroundUp Posts: 815Member
    Air separators are mostly just a one-time deal. Fill and bleed once, as long as you're not adding water there will never be any air that needs removal after initial fill and bleed. I see no value in removing the scoop. As for the expansion tank, I'm betting it failed because of your ridiculous 30psi in the system; why is it so high? Is this a 7 story house? Tanks are typically precharged to 12psi and the water pressure should match that, unless the water column is higher than 27 feet, at which point the air pressure would need to be raised in addition to the water pressure. Where did this water on the floor come from? Relief valve perhaps? Also due to the high system pressure as your relief valve should be set to blow off at 30psi.

    Assuming this is just a regular 2 story house plus basement, I would simply replace the expansion tank (and add a shutoff valve with drain for future service). Test the air pressure in the tank prior to installation- it should be somewhere near 12psi. Screw it on, purge the system of air, raise the water pressure only to that same pressure, and go on with your day.
  • IronmanIronman Posts: 5,468Member
    The most important consideration is that the circulator is "pumping away" from the expansion tank connection (aka the Point Of No Pressure Change).

    The way that you're presently set up, that IS the case, so I'd leave it that way. Otherwise, you'd have to move the circulator to the supply too.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • STEVEusaPASTEVEusaPA Posts: 3,844Member
    edited February 3
    The air scoop is old technology, not very effective, and requires a minimum of 18" of straight pipe on the inlet side.
    The spirovent is better.
    You should be pumping away from the expansion tank (right after the tank).
    Your spirovent should be located where water is the hottest to be effective. Doesn't have to have the tank hanging from it.

    Edit for @GroundUp:
    The air scoop is old technology, not as effective, and requires a minimum of 18" of straight pipe on the inlet side.
    Better? lol.
    steve
  • GannonGannon Posts: 15Member
    Cheers, all. Pressure goes from 25 to 30 when heating, but resting even when we moved in was at about 22. Agreed it seems high but considered it could be because of the complexity of the system and understanding it less then. Doesn’t seem right so perhaps an issue there.

    Maybe path forward is to replace expansion tank only, as suggested. Let boiler cool down to see what its pressure is when cold. (How long are we talking for this if I only drain what’s needed to replace tank?)

    Challenge I’m seeing here is that it’s not clear what to pre-charge the expansion to. Two story house with boiler in the basement. Leave it at 12 and adjust the boiler to match, no matter what it is cold?

    If I have reason to suspect there’s a ton of buildup in the system—galvanized pipes were absurd when we moved in—benefit to replacing scoop, that air vent, and draining the boiler/entire piping system?

    Thank you!

    Check this picture out!
  • hot_rodhot_rod Posts: 12,584Member
    Those scoop type are old technology, any of the micro bubble type will do a better job, faster. It is best piped right out of the boiler, hotter fluid.

    The scoops, even properly installed never get the tiny micro-bubbles, entrained air that comes out as the boiler warms. Your best heat exchange and highest efficiency comes from a high performance air separator.

    Get a new tank, check and confirm 12 psi, fill the boiler to 12psi, be sure the fill valve is not leaking thru and over pressuring the system.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • hot_rodhot_rod Posts: 12,584Member

    Who could've disagreed with my last post? It's 100% accurate.

    Not me :) I'd just change on word in it. You can probably guess which one.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GroundUpGroundUp Posts: 815Member
    The function of the expansion tank is to absorb expansion and maintain system pressure. So you do everything with the system cold, and if properly installed the pressure will remain at 12psi whether cold or hot. Doesn't look like you have much in the way of valving on either side of the scoop, so you'll need to drain quite a bit to avoid getting a bath swapping the tank. Personally I don't mind a little bath, what I'd do is only drain to a neutral pressure and have a new iso valve and nipple already taped and ready to screw, then spin off the tank (be careful, it will be HEAVY) quickly and thread in the nipple with the valve open until the threads start then close the valve. Then you can take your time installing the new tank. 2 people is very helpful for this- if one can be ready with the valve and the other remove the old tank, water loss can be minimized
  • GannonGannon Posts: 15Member
    You guys are great. I checked out the pressure reducing valve. It was set at 20 psi.

    Does that seem reasonable by any means? I reduced it to 12 to see how she proceeds. Obviously pressure will rise in my case until I get the new tank in, but now the tank is pre-charged to match reducing valve, so that’s a plus.

    So best practice is to add a ball valve right below that tee into the exp. tank and attach exp. tank to that?

    I am also going to replace the pressure relief valve. It’s not in good shape and has been getting a workout with the system at such a high psi and no working exp. tank. Agreed it’s a good idea?

    Thank you!
  • hot_rodhot_rod Posts: 12,584Member
    The tank pre charge needs to be checked before you pressurize the systems. Then the water fill pressure needs to match that 12 psi

    Expect 5, 10 psi increase as it heats up. Be sure it stays below 30, obviously 🙄
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GannonGannon Posts: 15Member
    To summarize, if I can, want to be sure I have it right. Winter is cold, so high stakes game here.

    Shut off boiler and allow to cool. Drain needed area to install exp. tank. Set exp. tank to 12 psi. Install ball valve and tank. Turn boiler back on. It will still be at 20 psi, so drain water and adjust reducing valve until at 12 psi on boiler.

    If tank working, pressure will remain at 12 psi and life is good.

    I’m also going to replace reducing valve, as it’s the next piece to fail, I’m sure.

    Appreciate any feedback!

    Thank you!
  • GroundUpGroundUp Posts: 815Member
    Webstone makes a ball valve with a drain that I use as tank isolation- it's got a 3 way ball design so it can either be straight through from system to tank, or you can isolate the tank from the system and use the drain either for the tank or the system depending which way you spin the ball. This way for tank service, all you have to do is rotate the valve and open the drain to relieve pressure from the tank, then remove the tank. You can often accomplish a tank swap without a drop of water on the floor and not have to drain any of the system. A regular old ball valve is fine too though.

    And yes if you're draining the system anyway, it would be a good time to replace the relief valve if it's weeping. 30# only, no higher
  • STEVEusaPASTEVEusaPA Posts: 3,844Member
    edited January 31
    @hot_rod I know, I should've used the C word for venting. Go Caleffi or go home! I just received the latest Idronics in the mail, no excuse!

    I've seen that gunk build up many times.
    Use this instead of just a ball valve.


    steve
  • IronmanIronman Posts: 5,468Member

    Who could've disagreed with my last post? It's 100% accurate.

    Steve, IDK who would disagree. For some reason, the HH staff has decided not to reveal those who disagree - maybe to try and avoid keyboard battles.

    I personally don't believe in anonymity when you state something publicly.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • STEVEusaPASTEVEusaPA Posts: 3,844Member
    edited February 1
    Oh it's no big deal, just wondering if someone knew something I didn't regarding my post. Sometimes people may hit it inadvertently. Or someone doesn't like me...lol

    I've never disagreed with a post without stating my reason. I think it's important to point out if someone said something wrong, in case someone else stumbles upon the post and thinks it's good advice.
    steve
  • GannonGannon Posts: 15Member
    Today's the day for the repairs. Exp. tank, air scoop, Hy-Vent, pressure relief valve, and pressure reducing valve all going in. System is in such bad shape that I am going to replace the air scoop and air vent while at it; likely some sediment build-up.

    With that said, I already have the Spirovent Jr in hand. If there's any benefit to it, would like to install it today--on the supply side. Can I install it in one of the marked locations (A, B, or C) on the picture here? If not, is there somewhere else in the system that makes more sense?



    Thanks, as always!
  • STEVEusaPASTEVEusaPA Posts: 3,844Member
    edited February 1
    I'd flop the El over and I'd stick it right in at 'A'. If you're really ambitious, come out the bottom and over to the wall and mount your exp tank there with a bracket, & the above mentioned Webstone Expansion Tank Valve. Then put the circulator at 'B' with isolation valves.
    Now you're pumping away.
    After initial purge you'll never have to bleed again.
    Then you can easily eliminate the air scoop & repipe from the right side of the air scoop back to the boiler.

    steve
  • GannonGannon Posts: 15Member
    Oh man, that is ambitious! So circ pump (Grundfos Alpha) can sit on supply side at B and not be up against boiler? Does it pull water through boiler and through return as well then?

    Probably won’t make those more significant changes unless there’s some significant performance to be gained. Doesn’t seem that way based your comments and others’.

    Seems like “best” route for now is just to forego eliminating micro bubbles and just deal with what I have now in terms of air elimination.

    I’m pretty convinced that air vent is fully clogged, so thinking I’ll still swap out scoop and vent, just given how cheap they are.

    Thanks again. This help has been invaluable.
  • hot_rodhot_rod Posts: 12,584Member
    Spiro at A, circ at B. You could leave old purger in place with expansion tank, remove and plug the brass vent hole.

    The expansion tank is the point of no pressure change, thru the boiler to the new pump location, if that helps any.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • SuperTechSuperTech Posts: 1,164Member
    That's not exactly the best route, long term. Microbubble resorber air eliminators are superior to the old scoop and air vent in every way possible except cost. Air vents typically don't last long, you will be preventing future air problems if you follow the advice in the above posts. Circulator on the supply outlet side of the boiler, pumping away from the expansion tank is the best way to go.
  • GannonGannon Posts: 15Member
    Understood and thank you both for the wisdom.

    Short term, as in today, I will replace tank, scoop, air vent, reducing valve, and relief valve.

    Long term, likely in summer when I can drain the whole thing more easily, I’ll swap circulator (the Grundfos) to where hot_rod suggested and add in the Spirovent. Also gives some for me to time to look into whether Spirovent is the way to go, or a Caleffi instead. If I do this, I presume exp tank needs to be relocated, I understand.

    Does that seem like a reasonable path forward, in short and long term? Greatly appreciate all this advice. What I’m not fond of here is moving the tank again later, but it doesn’t seem wise to go all winter without a functioning tank, right?

    Thank you!
  • hot_rodhot_rod Posts: 12,584Member
    Any of the brands will do a good job of air separation.

    I think Caleffi is the easiest to service, remove the working part on top to clean or replace by hand. Large low velocity zone and polymer media inside that can handle most any fluid condition.

    With that Alpha I suggest a DiscalDirtMag, 3 functions in one, protects the ECM from any small magnetic particle.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • GroundUpGroundUp Posts: 815Member

    Who could've disagreed with my last post? It's 100% accurate.

    It was me, and I disagree with the theory that air scoops are not effective. I disagree with spirovents not being effective unless placed on the supply side. Sure, a Spirovent style on the supply side is going to be the MOST effective but to say the other methods are ineffective is quite disagreeable and nowhere near 100% accurate as there are hundreds of thousands of systems around the globe with "ineffective" means of air removal that somehow manage to be air free. I didn't realize this function was anonymous or I'd have explained myself earlier. I apologize if my disagreement hurt your feelings but perhaps newcomers reading comments like that don't know what you actually meant (I hope, anyway) might get the wrong impression and think the ONLY way to remove air from a system is with a spirovent on the supply side. We all know this is not the case, but they may not.
  • STEVEusaPASTEVEusaPA Posts: 3,844Member
    @GroundUp It's ok to disagree. Gonna take a lot more than that to hurt my feeling. You seemed to make some assumptions in your post using words like 'MOST' and 'ONLY', words I didn't use.

    It's pretty much proven a micro absorber is much more effective than an air scoop. They just eliminate micro bubbles and an air scoop really doesn't do that great of a job.
    They are also recommended to be placed on the supply where the water is hottest.
    I think what I recommended was the best solution, based on my knowledge, the collective wisdom of others, and my experience.
    I've never had an air problem with modern air removal, tons with air scoops.

    I did notice @hot_rod said the same thing too, however you didn't disagree with him :)
    steve
  • GroundUpGroundUp Posts: 815Member
    @STEVEusaPA the term "not effective" means "not effective". Bob did not say that, under any stretch of the imagination.

    "More effective" as you now have changed your statement to, is exactly what I said. Air scoops are, in no way shape or form, "not effective" as a whole. Spirovents are not "not effective" if installed anywhere other than the supply side. The proper suggestion would have been that air scoops and Spirovents on the return side are less effective than a Spirovent installed on the supply side.

    We are on the same page, but my point is that the statements I'm disagreeing with are misleading to those who are trying to learn, as they may not already know what you know.
  • GannonGannon Posts: 15Member
    edited February 3
    I'm glad to see this post sparked some very civil discussion on effectiveness of air scoops, Spirovents, and so on. I have learned a lot from the back and forth, so thank you all.

    This weekend, I swapped out the following:
    • exp tank
    • Hy-vent
    • air scoop
    • pressure relief valve
    • pressure reducing valve
    Here's where I stand now. Not much change aside from cosmetics, really.


    Still no microbubble eliminator; no change in circ pump location; no valve added to isolate the tank or the boiler.

    All is not functioning quite right, however. Picture below is a diagram for the manifold for the baseboards on first and second floors (boiler in basement), along with temp. readings before and after running circ. at high fixed speed for a few minutes. Manifold outlets 1 and 3 aren't getting hot water (or any water, maybe filled with air?).


    Some other details that might help:

    Those 2F baseboards--Bedroom (#1) and Bathroom (#3)--do appear to have water. Bathroom isn't able to be bled; bedroom has a Taco coin vent. Have bled that coin vent a bunch; at first, a good 45 seconds of air came out and heard gurgling water below. Now, water comes out when I bleed it. The fin pipe feels very heavy on the return end but light on the supply end of it (about a 10 foot run).

    I ran the circulator this morning (Grundfos Alpha; typically set to "Auto Adapt" mode) at High Fixed Speed for a few minutes. The manual says this "Runs at a constant speed and consequently on a constant curve. In Speed III, the pump is set on the maximum curve under all operating conditions. Quick Vent of the pump can be obtained by setting the pump to Speed III for a short period." Did hear the Hy-vent spitting out a bunch during this time.

    Was able to get the 2F Master Suite heated by bleeding coin vent, running circulator and opening/closing balancing valves (by guesswork rather than logic), and did the same to get the Living Room baseboard heated back up.

    Have bled some air from the boiler drain valve also. Don't think that's the best way to do it, as not sure that rubber gasket is up to the task of opening/closing frequently.

    Struggling still to get 2F Bedroom and 2F Bath to cooperate. Greatly appreciate any advice!

    Thank you!




  • SuperTechSuperTech Posts: 1,164Member
    Hydronic heating systems don't bleed, service technicians do. 😉. You need to purge those zones, big difference from bleeding a coin vent. This is from the air you allowed in during the work you performed. Of course if you followed the advice given to you and had a microbubble resorber and you were pumping away from the expansion tank it's much more likely that your circulator would be able to push the air to the air eliminator.
  • GannonGannon Posts: 15Member
    I believe I am pumping away from exp tank, no? It’s on return side along with the tank but is attached to boiler itself. Not on supply side, granted.

    So sounds like an airbound system is the problem. I bled a lot myself this weekend, I swear.

    In current setup, can I cool off boiler, hook up drain hose (to the boiler drain valve above tank, not the boiler itself?), and use fast fill feature of reducing valve to force water in?

    Should I have circulator on or off at this time? Presuming it and all other pumps should be off when doing the above, if it makes sense.

    Thanks again!
  • STEVEusaPASTEVEusaPA Posts: 3,844Member
    Can you show a picture from a little farther back on the manifold?
    They make fittings for the end caps to bleed/purge. Much easier to get an initial purge at the manifolds.
    You'll want to get the pressure up in the 25psi range while purging. Then when you're done, bleed off a little water to drop it back down to 12 psi.
    I'll think maybe your air scoop isn't doing much, especially because it doesn't have the required 18" of straight pipe on the inlet side.
    steve
  • GannonGannon Posts: 15Member
    Here’s the further out picture.

    Thinking it’s that bottom cap on right, of supply or return side, right? Looks like garden hose connects to it. Close all and just leave open one of the problem outlets?

    Use fast fill to hit 25 psi mark, I presume. Cold water still going to boiler (I can’t isolate it), so presume I should cool it down.

    Thanks again!
  • GannonGannon Posts: 15Member
    Utilized the circulator at high speed, closed 2-9, and that was enough to get water moving through 1. That baseboard has heat.

    Opened 4 and closed 1. That was enough to get the water moving through 4. That baseboard has heat.

    Took a few minutes to do this, then put circ back to auto adapt setting.

    1-9 all heated, fast forward one hour, check in while boiler running, and the circulator has developed a chirp/whirr that increases with fan speed.

    Reheat the circ pump maybe? Still value in going back to purge and refill any lines? Or did I get lucky in that regard? (At the expense of a happy circ pump, maybe?)
  • SuperTechSuperTech Posts: 1,164Member
    I usually don't run the circulator pump while purging. It sounds like you did everything else correctly. Running the circulator temporarily at its highest speed is usually only done for a few minutes after the initial purge. I hope your Alpha is ok, that's a fine circulator.
  • SuperJSuperJ Posts: 575Member
    edited February 3
    I think you're likely going to get best results with one of the constant speed settings (or maybe constant pressure) on your primary pump.

    The noise might be the check valve (if it's installed), or junk in the impeller, or air that will clear. You don't need the internal check valve in your application.

    I'm not familiar with your boiler, but can tell it's not a modcon. You may want to think about some sort of protection against low return temps and flue gas condensation. Especially with your cascading loads which pulls extra heat out of the return water.
  • GannonGannon Posts: 15Member
    Is there a difference—in terms of effect—between purging via a garden hose to a drain and having the circulator on, compared to what I did—which maybe isn’t purging or correct—which was set the circulator to high speed and restrict flow to just the problematic outlets on the manifold.

    I just now did garden hose to boiler drain and fast filled the system with all the manifolds open. Circulator happier but still a noise. Now I’d say it sounds like a rattle. Leads me to think it’s air or some build up, a la junk in the impeller. I’ll monitor that and see how we develop. No need for immediate action, it seems.

    Don’t know anything about why one setting—fixed speed or fixed pressure—would be best for the circulator, so will have a look into that. Any suggestions with this setup?

    What I find odd is that my psi on the boiler is about 25, and it’s 19.5 on the exp tank. Didn’t change anything on reducing valve, and it was factory set to 12. The whole system has been around 20-25 psi since before I started all this (and replaced the reducing valve), so it’s intriguing that even with all this new stuff, that psi is still super high. I’m going to drain it to 12 again and see what happens.

    Appreciate any thoughts!

    Thanks!
  • STEVEusaPASTEVEusaPA Posts: 3,844Member
    edited February 4
    Your circulator moves water by pressure differential. Because you’re pumping away from the expansion tank your circulator is adding pressure to the system. Your gauge is on the boiler, so it’s showing more pressure, which is fine.
    If you had gauges on both sides or your circulator you would see the differential as an increase. You may see the gauge bounce if you cycle the circulator on and off.
    I never purge with the circulator on. I purge, then run the circulator thru all the zones. Then if need be, turn off circ, and purge again.

    I still say, spirovent type air elimination at 'A', circ at 'B', all your problems go away. Scoop on the scrap heap.
    steve
  • GordyGordy Posts: 9,482Member
    The key to the pressure differential is it never falls below the set system pressure on the suction side of the circulator when pumping away from the expansion tank. When you pump into the ponpc the suction side will drop below the system fill pressure.

    This all works on the return side of the boiler, but there are certain instances where high head circulators could increase the pressure differential enough to pop the relief valve when piped on the return side of boiler.
  • GannonGannon Posts: 15Member
    Thanks for the insights. Didn't know the effects of the circulator's location. Thought it was just a pump, but I understand now after some reading what the difference is between the two. In my system, the Grundfos Alpha is the circulator, whereas the B&G and Taco 007 are pumps. The diagram I found shows the Taco labeled as an injection circulator?

    Any opinions what setting to enable on the Grundfos Alpha 15-55f? Literature suggests auto adapt, but that's not specific to this system, of course.

    I purged and refilled the baseboard lines* last night, using garden hose on supply and a garden hose on the return to the drain. A lot of what came out of the lines was closer to motor oil than water. Suspecting the system hadn't been purged since it had been installed.

    Did some homework on condensation. Looks like this boiler is a conventional boiler, intended to operate as a non-condensing boiler. I understand that all boilers can be condensing boilers, so curious on inlet temperature now. Is that influenced by the circ setting? That is, can the right circ setting keep water moving, therefore keep the system closer to an average temperature?

    Potential issue, I see, though, is that the normally closed Taco zone valve will block circulation through the baseboards. Am I right? Or is there not a case where circ would run without boiler running (and therefore the valve would be open)?

    Thank you!

    * Turns out my previous purge was not very effective. It was just going through the in-floor heating system. That's because the Taco valve to the manifold for the baseboards is in a normally closed position. When I shut down power to the pumps, I can't manually open it because the handle is broken off. May be there's a way to trip it open but didn't see it in a quick Google search. Perhaps the pump will die before I need to purge lines again.
  • STEVEusaPASTEVEusaPA Posts: 3,844Member
    edited February 4
    Turn power off. Remove wire from C1 in aquastat. Turn power on. Call one zone at a time, and when the zone valve opens, purge.
    C1, energizing the circulator, should only happen when an end switch in any zone valve makes.
    I've posted this a number of times, but still fun to watch (and learn):
    steve
  • GannonGannon Posts: 15Member
    Helpful video and will keep those notes. He made a comment about a vacuum around the 3 minute mark that made me think of something.

    The highest baseboard in the house is hot, but it doesn't bleed water or air. Open the coin vent and nothing. Could it really be air in there still? Bad coin vent? Don't want to remove the thing itself, as I'm not sure I'll be able to recap without draining that line.

    To summarize another point he made and I think others have made, circulator should be on supply side, and microbubble eliminator after that. Exp. tank should stay on the suction side of the system; is it OK if boiler is between the tank and the circulator?

    Thank you!
  • SuperTechSuperTech Posts: 1,164Member
    It's not the best practice to have the boiler between the tank and the circulator, but it's not the worst either. You are still pumping away from the point of no pressure change. Ideally the configuration should go boiler - microbubble resorber/expansion tank - circulator.
    As far as the coin vent that nothing comes out of, you don't have to remove it to find out what is going on. I would slowly start unscrewing it while the boiler is off to see if there is any water pressure behind it. If you have 12-15 PSI of water in the boiler you won't have to unscrew it much before it starts to leak.
    In a closed hydronic heating system everything is a circulator, because it's all loops. A pump has a much different job to perform than a circulator.
    As far as what each circulator and zone valves purpose is in your system and if you have an injection pumping setup, I would need to see better pictures of your boiler and all the near boiler piping to determine what is going on.
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