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    Having Trouble Refilling/Bleeding Radiant Heat System (23 Posts)

  • ipman ipman @ 10:49 PM
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    Having Trouble Refilling/Bleeding Radiant Heat System

    Hello all,

    I have a water boiler with radiant heat baseboards throughout a house I purchase and am renovating. There are 4 zones: 1st floor, 2nd floor, basement and addition. Most of the pipe is 1/2" pipe but some of the runs are 3/4" pipe. I recently replaced two ~4' 1/2" baseboard units in the 1st floor zone with Slantfin Baseline units. I put in manual taco coin bleeders on the return side of the units. After finishing the install I have been having trouble filling up/bleeding the system. There are no bleeders anywhere except the two I just installed and one that is installed in the basement ceiling on a first floor zone pipe.

    Currently i am getting heat to my first floor and addition. I have two auto vents, one right on top of the boiler on the supply pipe before the pump. There is another autovent a few few above the boiler. I forget exactly what pipe it is on. I have attached pictures of the two autovents. One looks clean and the other looks like it is corroded a little. I had the caps loose on both autovents for a few days with no luck. The corroded one started leaking after I pressed the valve stem looking thing under the cap. I tightened the cap but it is still leaking a little bit (hopefully I don't come back tomorrow to see the water heater blew up from that tiny leak).

    I have 3 drains, one right off the boiler on the return pipe, one on the return pipe a few feet up from the first drain I mentioned, and one drain no the return pipe of the addition. I've bled some air from these drains but now water just comes out.

    Can someone give me some advice on how to properly fill the system and bleed it, given that there are no bleeders in the second floor? I am less concerned with the basement zone not working but of course that should get corrected as well. I have attached some pictures to illustrate the setup.
  • Zman Zman @ 11:38 PM
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    Power purge

    You need to find a way to push water through your system, one zone at a time, from the boiler room. Ideally you can close a valve and use the fill valve on one side and a hose and drain on the other. I cannot see from your pics if this is possible.
  • ipman ipman @ 12:25 AM
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    I only have two shut off valves, one on the return pipe right before the boiler and one for the return pipe of the addition. I tried filling the system by turning all the thermostats down so the taco zone valves would close, then I forced the 2nd floor open. The second floor actually got heat and I tried filling one zone at a time but I think so much air was on the second floor that all the air bubbles got trapped somewhere and the upward pressure was no longer sufficient to push the water around that zone.

    Do you think it would be a better idea to start from the bottom up instead of the top down? First basement then first floor then addition then second floor?
  • Zman Zman @ 12:45 AM
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    Push through.

    You need to find a way to force water through the zones at high pressure. In one side and out through a hose. Take a picture from farther back.
  • ipman ipman @ 6:07 PM
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    Heater Working

    Hello Carl,

    I went to the house today and to my surprise the upstairs heat started working as well as the basement. I opened the drains at the boiler and bled some more air out. Things seem to be working now. I am still not completely confident that all of the air is out and I cannot prove it since i don't have bleeders at the baseboards. I have some questions:

    1) I want to buy several 90 degree elbows and install manual coin vent bleeders at some key locations around the house at the baseboards. How would you suggest I remove the current 90 degree elbows so that I can sweat in the new ones? If I cut the pipes I will not have enough pipe left above the floor to sweat the new elbows for the second floor since I don't have access underneath the floor.

    2) Would it be enough if I add a t fitting/bleeder in the middle of the runs since it would be more easily accessible?

    3) I do not have an auto fill valve. The water supply pipe is 1/2". Can you suggest a good auto fill valve that I can install to keep the system filled?

    4) Should I consider adding shut off valves to make it easier to fill each zone? If so, where should I place the shut off valves? Right before the taco thermostat controlled zone valves or somewhere else?

    5) My auto vent near my boiler is leaking when I remove the cap. Do you think I should replace it with another auto vent of the same technology or should I look for a better autovent? You can see the pictures I posted earlier to see the type it is. There are two autovents near the boiler, any advantage for keeping both? One is higher up and one is right on top of the boiler.

    6) Please let me know if there are any other upgrades I should consider when I go through this process.

  • McMaster McMaster @ 9:43 PM
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    My system has a couple water valves (spigots) at the manifolds, somewhat like you would have on the outside of your house one would hook a hose to. This is where I hook my transfer pump hoses to.

    1) I take a 5gal bucket of soft water and stick my transfer pump suction hose into the bucket. The pump discharge hose goes from my pump to the valve/spigot (which I then crack open). I use a 1/3 hp transfer pump from Harbor Freight. It moves a LOT of water.

    2) I connect a hose from another valve (spigot) in a different part of the HW system that I run into the bucket (the return water line).

    3) I engage the pump and 'push' water through the system until all the air bubbles are purged. The pump draws water from the bucket and the return water goes back into the bucket. I can see the air bubbles as they come through. It usually takes about a minute or so to purge a line. Of course, I do this with the water cold, not hot.

    4) I have multiple circuits so I start with each valve closed and do one at a time. When finished, I shut the valves and remove the hoses.
    This post was edited by an admin on November 7, 2012 9:53 PM.
  • Zman Zman @ 10:50 PM
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    It is hard to tell much from the pictures you posted. More would be helpful.

    I don't think you need bleeders on the baseboards. If you pipe the boiler room correctly you don't need them.

    Watts makes a good valve fill valve/ backflow preventer.

    McMaster does a nice job of describing the purging process. You should be able to use your zone valves to isolate the zones. A common configuration is to install a boiler drain then a ball valve then another boiler drain. The ball valve is only closed to purge. You can then pump (or use your fill valve) in either direction.

    The air vent installed on the Tee in your picture is not effective in removing air.  You need an air eliminator.A good eliminator is designed to slow the water and pull the air out of solution.Spirovent makes a nice one.
    The location of the eliminator is also important.

    More Pics?

  • ipman ipman @ 11:02 PM
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    Also, I believe I have the configuration you mentioned. There is a drain at the bottom which you can see next to the heater. on the same pipe there is a shutoff valve in the middle and then another drain above it.

    When I fill the system, should I be closing that valve?
  • ipman ipman @ 10:58 PM
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    McMaster - Why do you use the pump system vs opening the water supply that is already connected to your water heater? Is it because you can connect the hose to all of the different drains on your water heater whereas the water supply is only connected at one place?

    Carl - I posted more pictures.

    Thank you.
  • Zman Zman @ 11:22 PM
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    Does the arrow stamped in the casting on the black pump point up?
    If you follow the pipe from the pump, does it go to the zone valves?And the expansion tank?
    How is the tank connected? With a Tee? Where does the 1/2" pipe behind the tank go?
  • ipman ipman @ 11:58 PM
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    I will have to verify (not at the house right now) but I think the answers to all of your questions are yes.

    Which 1/2" pipe behind the tank are you referring to?
  • Zman Zman @ 12:06 AM
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    It looks

    Your expansion tank is attached to a black tee. There is a 1/2" black pipe going forward and a 1/2" copper going back. Where do the pipes go?
  • ipman ipman @ 9:41 AM
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    I believe the copper end is capped off but I will try to verify later today.
  • Slimpickins Slimpickins @ 12:21 PM
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    Looking like a piping job from a graduate of the Rube Goldberg School of Plumbing. I would call a local company that specialized in hydronics and install a micro air absorber, redo the expansion tank and pump to "pump away", add some isolating and purge valves. Otherwise you'll be fighting the air problem for ever. Even if Zman help you get it purged, you're still fighting an up hill battle Also that yellow CSST gas line concerns me, not sure the size of boiler but I bet its undersized.
    This post was edited by an admin on November 8, 2012 12:22 PM.
  • ipman ipman @ 5:49 PM
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    reply to wow

    Hello Slimpickins,

    What do you mean a pump to pump away?
    What information can I get you about the boiler/yellow CSST gas line so you can let me know if its truly undersized? What is the consequence of an undersized line?

    I posted some more pics, please let me know if that gives you a better view. Thank you.
  • ipman ipman @ 5:44 PM
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    I verified that the pump arrow is pointing up and going towards the zone valves. The water supply line goes to the expansion tank which then goes to a T that splits towards zone valves. I was wrong about the 1/2" being capped off. More pics attached.
  • Zman Zman @ 11:08 PM
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    I know those guys

    Looking at your photos, I had a feeling I had seen this artist before. Check out this video  . Curly starts the good stuff about 5 minutes in.

    As I was leading up to, and slimpickins stated, you have to correctly pipe your boiler in order to fix your air problem. In a nutshell. The expansion tank needs to be directly upstream of you circulator. It makes sense to put the air eliminator and fill valve there as well. In your case it will take some work to get it straightened out. It might be worth hiring someone. If you decide too take it on. I would highly recommend buying "Pumping Away" from this web site. Dan does a better job explaining boiler piping than I ever could.

    As for the gas line.If you post the BTU rating of the boiler as well as the size and length of the pipe. Someone can tell you if it is correct. An undersized line will give you low pressure at the burners and poor efficiency.

  • ipman ipman @ 12:52 AM
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    The other thing I find odd about my heating system is that most of it is half inch pipe and rather long runs. At any rate the system appears to be functioning correctly right now so I might just leave it alone for this Winter but I will definitely see about improving it later. Thanks for the book recommendation, I will check it out.

    Couple of questions:
    1) I've noticed my PSI go up to 20ish at certain times depending on what zone valves are open/closed. I've seen it drop to 10-12ish. Temps between 150-180 degrees. Temperature in my area is 50s in the day and 30's at night. I've read that 12-15 psi usually the PSI you want when the boiler is cold for a 2 story house. What is the PSI you want when the boiler is hot? My aquastat is set to 180 degrees F. Would air bubbles cause this kind of variation or is it normal? Heat seems to be going to every room now. I do not hear any gurgling on the second floor anymore.

    2) Is there anything you recommend I do immediately to help the situation before I do a complete overhaul? I'd like to avoid an overhaul until next year.

    3) Most of my system is 1/2" pipe and probably over the recommended max length for a loop. Is it worth doing anything about that? It would be a supremely expensive (or time consuming for me) to upgrade the piping to 3/4" or reduce the lengths of the runs. House seems to get heated pretty well the way it is. Would installing pipe insulation on all the accessible pipe help reduce the impact of the long runs?

    Thanks for all of your help.
  • Zman Zman @ 7:53 AM
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    The pressure in your system should be pretty even. The expansion tank if sized and working properly should make up thermal expansion. Air trapped in you system should actually stabilize your pressure. To definitively evaluate your expansion tank, you need to remove it and check the pressure. If you tap the side of an installed tank and the entire tank sounds waterlogged, it is probably bad. If the pressure goes way up or boiler relieve valve discharges you have a problem with the tank. The location of the circulator and expansion tank in your particular system will also make the pressure do strange things.If the pressure changes immediately upon the valve opening, it is because of the pump location. If it increases as the temperature increases it is an expansion issue.

    I would not recommend cutting into your system until you are ready to do it right.

    The size of the zone piping is probably fine. There are many factors that go into the selection of pipe size. What it comes down to is, are you getting enough GPM to the heaters? It sounds like your heaters are getting hot. That is a good thing.
  • ipman ipman @ 9:21 AM
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    Thanks. Do you think its a good idea to insulate the pipes anyway?

    Also when I installed the bleeders on the new vents I believe I made a mistake. I put the 1/8" hole facing towards the right, not facing up so the coin vent is on the right side of the elbow not the top of the elbow. Do you think this is a big deal? I made it this way to make it easier to bleed the water out into a bowl with the baseboard cover on but later on I realized it should have faced up.
  • ipman ipman @ 11:34 PM
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    Gas Line Specs


    The yellow gas line says "Gastite 3/4" on it. It is roughly 40" long, maybe 42" if you include the nuts. The heater says 140,000 Btu/hr (41,0 kW) on the label. I've attached several pictures of the gas line. Is this properly sized?

    Also while I was taking pictures I happened to look at my water heater and noticed a drop of water next to the hot water line. Looks like it is leaking but after I cleaned the drop nothing came out of it for days. Looking at the attached picture it is clear that the water heater threaded line is corroding. Do I have to cut the copper pipe and redo it or is there a way I can seal it up?
  • Zman Zman @ 9:01 AM
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    I would remove it

    That size line is probably not causing a pressure problem in your system. It is really unprofessional. Are there any straps on the vertical pipe? What would prevent someone from leaning on it and severing the weak csst above? Did they ground your gas line to prevent electrical damage? The installer saved some time by not using hard pipe and left a liability. I would repipe it.
  • ipman ipman @ 1:42 PM
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    I don't think there is a strap. I'll have to check for grounding.

    Is it supposed to be hard piped all the way to the boiler or is it supposed to be a lot closer and have a short flex line?

    I was planning on using a 3 foot flex line (as shown in the dryer instructions) on a gas dryer. Is there something wrong with them for all applications or is it just a boiler thing?
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