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clogged zone

LenRLenR Member Posts: 13
I've got a 3 zone hydronic system. The first floor zone is clogged and nothing comes out the drain when I try to flush it in the normal direction. I tried unscrewing the mechanism of the check valve and running the water through backwards. In that case I get a trickle. There doesn't seem to be any crud in the check valve, and it looks to be in good shape.

In the past, I had a problem that was solved either by replacing the check valve (Taco 218) or by flushing. I don't remember which. Later, flushing helped. I recall the water was blackish at first when flushing. As I recall, last winter there was a slow deterioration that wasn't helped much by flushing, ending with no flow at all, and no heat. That's what I'm seeing now, when I went back to check it out again.

The first floor zone has, in addition to a long baseboard, three heaters with fans that are hooked up to it. The one in the hall has never worked, the one in the bathroom stopped working some time ago, and the one in the kitchen usually worked until the end of last winter. At least some of these seem to be hooked up with rubber hoses, which have been present at least since we bought the house a bit less than 10 years ago.

Wondering if the clog has something to do with the hoses and I need to replace them, or if there's some other likely approach. Suggestions welcome.



  • Larry WeingartenLarry Weingarten Member Posts: 1,912
    Hello @LenR , I've had some luck flushing clogged pipes by doing as you have been, flushing under pressure back and forth, repeatedly. Sometimes it has taken over an hour of this back and forth to get the blockage to finally move, break up, and come out. Of course, you need to have the flow path clear of any possible plugs, like check valves or strainers. Perhaps the baseboard heaters could be bypassed as well, so you're not trying to do this flush through them. Then, once the main lines are working, flush those one at a time. No doubt others will have some thoughts too!

    Yours, Larry
  • Jamie HallJamie Hall Member Posts: 13,412
    My thought is... ten year old rubber hose??? Replace them.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • mattmia2mattmia2 Member Posts: 1,872
    preferably with soft copper tubing or oxygen barrier pex
  • ZmanZman Member Posts: 6,002
    Do you have a picture of the rubber hose?
    It may be a type with known issues or recalled.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Big Ed_4Big Ed_4 Member Posts: 1,433
    Plugged hydronic zone , I would say a valve is shut along the line ...
    I have enough experience to know , that I dont know it all
  • hot_rodhot_rod Member Posts: 13,838
    Can you get to both ends of the loop or zone, that is where you can try and flush.
    If it is rubber tube they were prone to plugging with magnetite. That can be tough to flush out, it takes some serious pressure. if you have 45 psi or more in the house, that is what to try. You need to make sure the boiler is not in the circuit, most have 30 psi relief valves :)
    It end up being easiest to disconnect both ends at the manifold to flush, sometimes.
    In lower loops, like basements, that magnetite can plug the loops completely. If you can get any flow at all, usually they can be circulated clean.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,315
    I would suspect the rubber hoses. That would be the place to start
  • Alan WelchAlan Welch Member Posts: 222
    1.  What is the system pressure.                               2. Is this piped Monoflow or in series.  If in series , one kinked hose will stop flow, if in parallel I would open flo control valve and try purging 
  • LenRLenR Member Posts: 13
    Thanks, guys. Sorry for not getting back sooner. I don't really want to deal with this problem, so I've been procrastinating. But I should fix it before the cold. The house's other occupant gets cold sooner than I do.

    The pressure is around 15 psi. I suspect that the three heaters are in parallel, since one worked when the other two didn't, but I'm not sure. One is a Beacon Morris Twin Flow III, model K42, and I suspect the other two are wall mount versions of the same. I don't know what "Monoflow" is, though. THere's definitely a lot of baseboard heater in the circuit as well, and that's not working either. I'm not sure the hoses are in the direct line. Maybe they're just to a couple of the heaters. I might decide to replace the hoses with copper pipe, assuming I can reach. IF they're tough to reach, maybe that's why they're hoses instead of copper. I never know what to expect in this house. The previous owner, I think, was sometimes a bit sloppy.

    I think I'll see if I can get to the ends of the hoses and take them off to check for blockage. I was going to check the heaters, but that would be a little more trouble, I think, since I'd need to use a torch.

    I tried flushing the pipes again, both ways. Forward was completely stopped, or almost. Backwards there was a trickle. Maybe I'll try doing that again, as well. Especially if I can find my thread dope. I don't like tape as much, even the stuff that DOESN'T come from the dollar store. (I got that for a non-plumbing project anyway.)
  • mattmia2mattmia2 Member Posts: 1,872
    Pex with an oxygen barrier would be a great replacement for whatever that rubber like product is. If you can get some flow, you could try a system cleaner or vinegar or citric acid in to the system to see if that will break up whatever is blocking it.
  • LenRLenR Member Posts: 13
    Any advantage of Pex over sweated copper pipe, other than faster installation?
    I may have to try vinegar, but I don't have a pump unless I can adapt a sump pump I have around here someplace.
    I'll probably start with replacing the rubber first, though.
  • mattmia2mattmia2 Member Posts: 1,872
    You could put the sump pump in a bucket or a heavy trash can and adapt it to hose thread and make a purge cart.

    The main advantage of pex is that you can get it in to places you wouldn't be able to get copper pipe in to. I assumed that the reason they used the rubber hose type material was that they were fishing it through some concealed space or using it to hook up something that needed to move a little or would have been difficult to fit rigid pipe to.
  • LenRLenR Member Posts: 13
    I took a look at the hose. I can't see all the markings, but they include:
    "Max Temp 180 F Max Press 100 PSIG" and
    "and Snowmelting ASTM D 380.395.412 1/13/1999"
    They are black and feel supple. They're slipped over copper pipe and attached with hose clamps. I haven't actually measured the pipe, but it looks to be 1/2 inch.

    I've tracked down where the hose goes. As I thought, it's snaked up to 1 of the heaters. The path is fairly circuitous, so if I'm going to replace it, I guess Pex is in order.

    I'm kind of pessimistic that the heaters are where the clog is, but it won't be hard to test the one with rubber hoses. Hypothetically, they're supposed to be in parallel with the heating pipes, but I suppose they might be parallel to each other, but with no other pipe.

    I've tried flushing the pipes back and forth again. I can get a trickle going forwards, and somewhat more going backwards, coming out of the check valve housing after unscrewing the mechanism.

    I'm thinking of pumping vinegar or system cleaner through. I'll need something to adapt a hose to the check valve housing, or else I need to install some other fitting to attach the hose to. The male threads on the check valve mechanism are around 1.05 in diameter. I'm hoping they're NPT. If so, I guess they're nominally 3/4.
  • mattmia2mattmia2 Member Posts: 1,872
    Add some boiler drains or purge stations. use a f-f hose like a washing machine hose or even better make a bigger id hose with 3/4' vinyl tubing and 3/4" female hose to hose barb adapters.

    If that hose isn't an effective oxygen barrier it will allow oxygen to diffuse in to the system and corrode the ferrous components of the system which might be what is plugging the system up.
  • Alan WelchAlan Welch Member Posts: 222
    Where are you located, and can you post some pictures?  I would think it more likely to be a problem  with a  valve ( isolation, check  or flow control )than a clog. Why do the other zones not clog as well, what is different about them,
  • LenRLenR Member Posts: 13
    The big differences I'm aware of are the three heaters and the rubber hoses. In the past, I think I had a problem with the check valve, which went away when I replaced it. Also, as I recall, the other zones didn't produce black water when purged, assuming I remember correctly. The zone in question has responded to purging before, but last winter it didn't. The current problem started with slow deterioration, which is one reason why I suspect a clog.

  • Alan WelchAlan Welch Member Posts: 222
    It might be time to call a heating professional. I wouldn't be surprised if you have numerous problems.   The primary one, poor flow shouldn't be too hard to diagnose. The individual units might have other problems,  airbound, bad blower motors or electrical. The one time I saw
     one hooked up with rubber hoses was because there was no access hole above the unit,and when it was pushed into the cabinet kickspace the hoses kinked.   If you have flow control valves, you are probably zoned with circulators . Does it run when you turn up the thermostat?
  • LenRLenR Member Posts: 13
    The circulators run, there's just no place for the water to go! I don't think the hoses are kinked. They're pretty thick.

    BTW, I'm in the Boston area.
  • Alan WelchAlan Welch Member Posts: 222
    I am as well. Pictures would help. You can try rapping the flow control valve,  its possible its stuck closed, though you did say you opened it up, How are you trying to purge the zone, any chance your on the wrong return?
  • LenRLenR Member Posts: 13
    Nothing seems to stick in the check valve, and it's really easy to put back in.

    I probably don't have the wrong return, since the other two returns work with the other two supplies. I have made that mistake, at least for a minute or two, before. I've successfully purged all three in the past.

    I tried bypassing one of the heaters. No luck. So that's not the problem, or at least not the whole problem.

    The inside of the rubber hose seems to be in rough shape, though the outside looks fine. I bought a piece of oxygen barrier pex, but it seems very stiff, so I'll probably be looking up ways to bend it. I've turned grey PVC into a wet noodle with heat before, but I don't know if that would work in this case, whether it would damage the oxygen barrier, or whether it would stay floppy long enough to thread it through. I may need elbows to make it work. Is there another kind of oxygen barrier tube that's more flexible? I have a piece of white PEX (didn't know it was PEX) in a smaller size from an old project, but it's quite stiff as well and is a little smaller. I bent it almost 180 degrees with a heat gun, but it's hard to do without adding partial kinks.

    Next step is to flush with vinegar, but if the blockages are made of rubber particles, I don't know how much that will help.
  • Alan WelchAlan Welch Member Posts: 222
    If you have isolation valves on both supply and return you can try to narrow down where the blockage is.  Shut the valves and cut the zone in the middle.   See if the water flows from either direction when you open supply and return valves. Without pictures it's difficult to give better advice. At least we know its not frozen. 
  • mattmia2mattmia2 Member Posts: 1,872
    My suspicion is that tubing isn't keeping the oxygen out and the clog is from rusting ferrous components of the system and it has settled there.

    if you need tight bends you might need to use fittings. Or use copper fittings to get it heading in the right direction and run the pex straight. there is a plastic or metal piece that snaps over the pex and holds it in a bend but it is a fairly wide radius. Another option is to use smaller pex if that will provide enough flow for the heater (and an adjustable bypass if they are in series with the rest of the circuit)
  • LenRLenR Member Posts: 13
    Per Larry's suggestion, I just tried purging back and forth a dozen or two times. It's easier because I've screwed in an adapter for a hose into the housing of the check valve. Not much luck yet, though it seems possible that I'm getting a tiny trickle forwards. Maybe that's just the pipe draining. Backwards I get a larger trickle.

    I was going to flush with vinegar, but it turns out that the pump needs an adapter to hook up a hose. I assumed it was hose threads when I bought it. Seems to be 1/2" pipe thread.

    I probably ought to check if the rubber hoses are clogged since that's easy to do. Here are a few picks of them.

    It's hard to show pics of the whole system, because some of the pipes run in the finished part of the basement and are covered up.
  • LenRLenR Member Posts: 13
    I just checked the hoses, which, at the bottom end, are much too large for the barbed fittings. Of course, that give me tremendous confidence in whoever put this mess together.

    As it turns out, the hoses are not clogged, though a bunch of rusty crud poured out, suggesting that nothing has flowed in there for a while.

    Tomorrow I'll pick up a fitting or two and try the vinegar purge.

    If that doesn't work, I may have to trace the system somehow and track down the clog per Alan's suggestion. Not so easy with the finished ceiling covering some of the pipes and making it hard to tell what goes with which.

    I'm planning on replacing the hoses eventually, but that's not my priority until I get rid of the clog.
  • Alan WelchAlan Welch Member Posts: 222
    With isolation valves on both ends of zone closed, disconnect both hoses on one of the units and hold them in a bucket while a helper opens isolation valves one at a time  and see if you have flow in either direction. 
  • hot_rodhot_rod Member Posts: 13,838
    Vinegar is not much of a cleaner for hydronics. It works on limescale in plumbing fairly well.
    If in fact you suspect a hydronic sludge formation, get a cleaner from Fernox or Rhomar that is specifically designed for common hydronics. They have it available in aerosol cans now, connect to a hose thread and squirt it in. A 12 oz can will do about a 35 gallon system.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • LenRLenR Member Posts: 13
    Thanks for that tip. I may have to try some of that cleaner. I suppose I should replace the rubber hoses with PEX before I do that? (I was already planning to.)

    Through pumping various combinations of air, water, and vinegar, through various kluged up plumbing arrangements, I've got the flow up to 1 gallon per minute using the system pressure. I think that's considerably less than the other zones, but I think this zone has everything but the kitchen sink. If those kickspace heaters are all in series, maybe 1 gallon per minute is all it can get when it's clean. Lots of heavy black stuff came out.

    The pump I have is a bit weak and I don't think it goes quite as high as it's supposed to, so, once I had a bunch of vinegar in the pipe, I had to push it through with air. Years ago, I had a sump pump. That certainly would do the job, but I think it has vanished in some kind of macro manifistation of a quantum mechanical phenomenon. The kind that are more likely the more often you move.

    I'm such a cheap skate. Trying to figure out how I can fake a PEX clamp tool.

    Anyway, thanks again for all the advice. At this rate, I may wrap it all up by the end of the month!

  • ethicalpaulethicalpaul Member Posts: 1,865
    My pex tool was at my mother’s so I tried a pair of channel-locks for a temporary situation. No dice!
    1 pipe Peerless 63-03L in Cedar Grove, NJ, coal > oil > NG
  • hot_rodhot_rod Member Posts: 13,838
    The rubber sure is handy for jamming in kickspace heaters, but I would scrap the rest for pex. Those are not the best clamps for rubber tube and you can see signs of seeping around the ends of them tube. Some feel that is where O2 may enter the system that keeps the corrosion ongoing?
    Are you positive you have a blockage, not just high pressure drop in the loop? Although if it has worked in the past, something is reducing flow. if it has been a gradual decline, it does present like sludging.
    I know of jobs that have sludged closed, beyond cleaning or repair, so it has happened to others.
    In some cases you need a lot of pressure to move the sludge more like a pressure washer psi, but be careful of exceeding the tube ratings and blowing connections apart.
    Big solids like rust need high flow rates like 5 fps to move, but sludge that is stuck to the tube walls needs psi to scrub.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • mattmia2mattmia2 Member Posts: 1,872
    Maybe throw a dirtmag on there to collect what stuff breaks loose as well.
  • Larry WeingartenLarry Weingarten Member Posts: 1,912
    Hi @LenR , "I'm such a cheap skate. Trying to figure out how I can fake a PEX clamp tool. " How about having a look on Ebay and searching for "PEX tool"? Seems you can have both cheap and the right tool! ;)

    Yours, Larry
  • mattmia2mattmia2 Member Posts: 1,872
    I used propex fittings and type a pex and bought a cheap knockoff expander tool but bought milwaukee heads for the sizes i needed. Propex has a distinct advantage in that you can expand the tubing somewhere out in the open then quickly shove it on a fitting in some dark difficult to access corner.
  • Larry WeingartenLarry Weingarten Member Posts: 1,912
    Hi, Absolutely agree with @mattmia2 . If you've ever compared the actual fitting ID of expansion and insert fittings, you'll see a big difference in them.

    Yours, Larry
  • LenRLenR Member Posts: 13
    I'm not positive I have blockage. Sludge build up is just as good an explanation. I intend to rinse it out some more with some kind of cleaner or more vinegar, which did in fact seem to improve things. So far, I'm up to a gallon a minute under system pressure to a drain. That's less than the other lines, though.

    I was trying to figure out how the hoses run. They seem to be on some circuitous path which is too deep past obstacles for me to reach with my arm. I don't want to tear up everything. Maybe if I just pull the heater I can see better what's going on.

    I haven't been buying stuff off eBay, because I keep telling myself I'm going to have it all fixed in a day or two.
  • motoguy128motoguy128 Member Posts: 182
    A company that installs geothermal systems will often have a purge cart. They can deliver almost 100psi and you can circulate any solution to clear the plug. Something strong like Rydlyme most almost be guaranteed to clear it. But you need good ventilation and PPE.
  • LenRLenR Member Posts: 13
    Judging by the quality of some of the plumbing I'm seeing, I'd be very hesitant to go to 100 psi!
    At system pressure of, I forget, 15 or 20 psi, I'm getting about a gallon a minute. That's considerably less than other zones, but maybe they just hooked up too much stuff in line to this one. I managed to flush out a lot of crud with vinegar, pumped through with one of those cheesy little drill pumps.

    Tomorrow I'll put the return valve back, which I had removed for back flushing, and see if it all works.

    That still leaves me with replacing those rubber hoses. Conveniently, there is only one isolation valve, so I'll have to shut off that whole zone when I replace those hoses. Maybe I'll add a 2nd shutoff while I'm at it.
  • Tom_133Tom_133 Member Posts: 702
    In the past I fought with a system that sounded like yours. The air separator and the water inlet that was piped into the bottom of the air separator were plugged, I mean PLUGGED, with the brown sludge. Of course the whole system was pretty sludge but after I found the blockage I was able to clean system and roll. Hope that helps
    Montpelier Vt
  • LenRLenR Member Posts: 13
    Tried the heat today. It works. At least two of the kick space heaters are getting warm, though their fans don't work. The baseboard, of course, doesn't need a fan. I've shut off the flow to the one with the rubber hoses and I guess those hoses are the next thing to tackle. Ugh!
    Then it would be fixing the fans. I don't know if the fans themselves are dead or if there's something else wrong. I may not get that far this year.
  • mattmia2mattmia2 Member Posts: 1,872
    The fans likely are controlled by an aquastat at the heater and if you have restricted flow they may not be getting hot enough to trip the aquastat on.
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