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Hot water heating system problem

Jack_2Jack_2 Member Posts: 27
I recently replaced finned aluminum to cast iron but when I turned on the heat to test, it was not getting hot. I have a mixed finned and cast iron hot water system where the other units were getting hot but not the ones I replaced. I have one supply and one return system on boiler but don't know rest of piping as it's in the walls. House was built appx. 1950. Any ideas? Thanks.
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Comments

  • ZmanZman Member Posts: 5,334
    We are going to need a lot more info. It sounds like you may have modified an old monoflow system.
    Do you have pictures or a drawing?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Solid_Fuel_ManSolid_Fuel_Man Member Posts: 1,758
    I bet it's a monoflo and you will need to bleed bleed bleed!
    Serving Northern Maine HVAC, and Controls
  • Jack_2Jack_2 Member Posts: 27




    The first pic is the piping in the boiler. The second and third is the original aluminum fins and the last is the cast iron convectors I had installed as a replacement. Thanks
  • Intplm.Intplm. Member Posts: 981
    You most likely have air in your system. You will need to replace that air with water.
    Purge the system and bleed the air out of the radiators. You should get heat when you do that.
  • Jack_2Jack_2 Member Posts: 27
    It was already bled. Is it possible that the guys who did this missed turning a valve back on that supplies those radiators??
  • Intplm.Intplm. Member Posts: 981
    Its possible. You have two circulators. That should mean you have two zones. Do you actually have two heating zones or is one circ. used for a indirect water heater?
  • Intplm.Intplm. Member Posts: 981
    Also. Those types of rads can be a bear to purge. Patients and determination is key to getting all of the air out.
  • ZmanZman Member Posts: 5,334
    Do you have pictures of the tees underneath? A picture of the boiler from farther back?
    I am thinking you have a monoflow and you are pumping into the expansion tank. Kind of a frustration setup to get purged.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • HVACNUTHVACNUT Member Posts: 2,629
    The pic of the CI rads is not wide enough. Do the rads themselves have air vents?
    If it is a monoflo system, they need them, just like the old ones had.
    And if it is a monoflo system, was any piping changed at the branch Tee's?
  • Jack_2Jack_2 Member Posts: 27
    It was a 2 zone at one time but I made it into one zone with both pumps controlled by one thermostat. I will post a wider pic of boiler but clearance in very limited in very small boiler room. I'm not familiar with tees and branching since all that stuff is the walls and between floors. The CI has air vents on supply and return sides. Will post pis of that as well. Thanks.
  • Alan WelchAlan Welch Member Posts: 184
    Make sure both blue handles in the first picture are open.
  • STEVEusaPASTEVEusaPA Member Posts: 3,481
    edited August 5
    Did it get warm as you were bleeding it?
    steve
  • Jack_2Jack_2 Member Posts: 27



    The first pic probably is not so clear as to which pipe goes where but you can see the purge tank on top left. The second pic is the air valves on both sides of the new CI rads. I was wondering since the piping on the new rads is not exactly straight like the previous aluminum slants, could this cause weak flow and necessitate a more powerful pump?
  • Jack_2Jack_2 Member Posts: 27
    So anything with a blue valve should be open, correct?
  • Jack_2Jack_2 Member Posts: 27
    Should the purge tank valve be open as well?
  • Jack_2Jack_2 Member Posts: 27
    I'm assuming blue means cold water and red is hot water?
  • Alan WelchAlan Welch Member Posts: 184
    I mean the two blue handles (round wheels) above the black circulator on the horizontal pipe, and above the red circulator on the vertical pipe. the expansion tank appears to be in the upper RIGHT , and the silver handle to the left of the union should be open as well. ( or just call the installer and have them take care of it because you aren't heating)
  • Jack_2Jack_2 Member Posts: 27
    Alan, I moved into this house about 4 years ago and this boiler with its piping is the way I got it. I know I'm going out on a limb here, but do you see anything that is strange or could be improved? Thanks.
  • Alan WelchAlan Welch Member Posts: 184
    My point is that if someone else did the job it should be there responsibility to make sure it heats. Did you tell them how to do it? They may have left a valve shut , they may have piped it wrong. I can't tell how they looped the 2 units together, maybe they kinked a pipe, maybe you didn't give it enough time to heat. Cast iron and baseboard don't work well together on the same zone.
  • Jack_2Jack_2 Member Posts: 27
    They didn't test it after they finished the job. I think because of the issues I'm having now. One large CI rad they replaced is working perfectly since a smaller CI rad was there already. I'm assuming the piping for that one was done correctly before I moved in 4 years ago. So, I already had mixed CI with aluminum slants BB and they worked well with a stronger pump I installed about 3 years ago. Th reason I replaced some BBs is because they tended to cool down much faster than the CIs I already had when the boiler cycled off. But I will test this weekend by air purging all the units i have (about 25) and will let you know how it goes. The installers suggested I should also consider a stronger pump because the piping for the new rads are not as straight as the old BBs they replaced.
  • Alan WelchAlan Welch Member Posts: 184
    Can you remove the lower panels on the 2 radiators and post a picture of the piping?
  • Jack_2Jack_2 Member Posts: 27
    Yeah. I figured you might want that. Will post tonight when I get home. Thanks.
  • Jamie HallJamie Hall Member Posts: 11,442
    "Th reason I replaced some BBs is because they tended to cool down much faster than the CIs I already had when the boiler cycled off."

    Ooops. That's the nature of finned baseboards. Can't fixt that.
    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
  • Jack_2Jack_2 Member Posts: 27



    Alan, sorry I didn't get back to you earlier. Here are the pics you requested but don't know if you can make anything out of it. I'm assuming the supply is on the right while the return is on left of the second smaller CI. The piping in the middle is to attach the larger CI on right to the smaller one on the left. When I open the purge valve on either side, only water comes out. Thanks.
  • pecmsgpecmsg Member Posts: 963
    Assuming the supply is on the right you could have AIR trapped in the high point!
  • pecmsgpecmsg Member Posts: 963
    Even if its the return it could still be air bound
  • Jack_2Jack_2 Member Posts: 27
    pecmsg, "high point" meaning what, exactly? I have purge valves on both rads and only water comes out so don't know where the air might be trapped. From what you see, is the piping correct? Thanks.
  • Alan WelchAlan Welch Member Posts: 184
    I think what you are calling a purge valve is a bleeder, meant to get air out of the top of the radiator. what pecmsg is referring to is the piping on the lower right hand radiator. the piping coming out of the floor pitches down to the left, and air can get trapped there and stop the water from circulating.
    even if you get the air out i'm not sure it would heat well, a lot of restriction in the piping. it would have been better to make each radiator its own loop off the main.
  • ZmanZman Member Posts: 5,334
    If it is is a typical monoflow with just 1 venturi, there may be too much resistance in all that piping to allow flow to radiators.

    Do you have pictures of the tees under the floor? What size circulator and piping?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Jack_2Jack_2 Member Posts: 27
    Zman, all the connections and tees to the mains are inside walls and floors and I would have to break into them to see what's going on. But the guys who did the above also changed another CI rad into a larger size with the same connections but no pipe pitching like above and that works great. I will post pics of that rad maybe tonight and you'll see it's more or less the same. The original piping going into the aluminum slants looks to be 1/4" although not certain. About 3 years ago, I changed the circulator pump into a much more powerful one and that solved my heating problems then because some of the aluminum slants weren't getting hot. I don't why the installers slanted that pipe when they should've raised the rad accordingly.
  • Jack_2Jack_2 Member Posts: 27
    Does anyone here know if the Walabot can see thru pipes and detect air pockets? Or some similar device that can do this? Thanks.
  • CanuckerCanucker Member Posts: 565
    Infrared camera might show you where the heat is stopping. Never used walabot
    You can have it good, fast or cheap. Pick two
  • ratioratio Member Posts: 2,134
    I don't think a Walabot will see through a metal pipe. Perhaps plastic, IDK. Mine hasn't performed as well as I had hoped, but I've only played with it so far.

    I second the IR camera, though. I've got a Fluke VT-04 that has preformed admirably in chasing a leak in a radiant floor; & I recently purchased a FLIR One after seeing video made with one here. (I'm on a phone, else I'd add links & @mentions, sorry.)

  • ratioratio Member Posts: 2,134
    Come to think of it, @Canucker might want to tell us about his phone, maybe? :sunglasses::sunglasses::sunglasses:
  • CanuckerCanucker Member Posts: 565
    > @ratio said:
    > Come to think of it, @Canucker might want to tell us about his phone, maybe? :sunglasses: :sunglasses: :sunglasses:

    You know you want one. Write it off as a business expense? :p
    You can have it good, fast or cheap. Pick two
  • Eric_32Eric_32 Member Posts: 264
    edited August 19
    With that type of system, the vents are the high point and air will be sitting at the top of the piping. You have to PITCH or Angle the piping UP towards the vent. The piping should be angled up towards the radiator piping. You can clearly see that radiator on the right... the right side tapping is lower than the pipe coming up through the floor, so your installer angled the copper piping down to connect the radiator to it. That pipe coming up from the floor should have been lowered so the pipe can angle up to the radiator. With air trapped on the right side when you bleed the radiator you are most likely drawing water through the left side pipe only.

    The only way to make it work the way it is piped is to put a purge station in there which would be a ball valve and boiler drain right next to it and force bleed it using a hose and water pressure in the system, then you can push the air out even if the piping isn't angled up to the radiator.
  • Alan WelchAlan Welch Member Posts: 184
    Where are you located, Jack? Eric's idea is what I was thinking as well, they put a valve on one side, I think it needs a valve and purge setup on the other side if there's no access below.
  • Jack_2Jack_2 Member Posts: 27
    Alan, sorry I didn't sooner but just got back from vacation. I'm located in Brooklyn. I'm not sure what Eric is referring to. What if I ask the installers to raise the radiators so that the supply piping is pitched upwards slightly or leveled? The are 2 bleeders on right and left CI radiators as you can see in a previous pic. What's a valve and purge setup and where would that be placed? Thanks.
  • Jack_2Jack_2 Member Posts: 27
    Is it like a level measure where the air pocket stays on the right when the left part is pitched downwards? But if so, why doesn't the water pressure force that air out when I open the bleeder valve?
  • Alan WelchAlan Welch Member Posts: 184
    I would call back the installers and ask them to make it work, otherwise there a lot of good and knowledgeable folks in your area in the find a contractor section. You can't get the volume of water out thru the bleeder to push out the air pocket, and any time the system gets drained it will be back. Raising the radiator will probably work, just might not look so great.
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