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Hydronic baseboard not heating

Looking for some ideas on how to get my hydronic baseboards working again. We bought an old farm house last year and have been doing some remodeling including moving/ adding baseboard heaters. When I went to fire up the boiler this year, everything seemed to be working fine, but the baseboards aren't heating up. I have gone through and replaced all the autovents upstairs and went around purging every baseboard until only water comes out, but still not heat.



Comments

  • Jamie Hall
    Jamie Hall Member Posts: 22,877
    Well... let's consider the possible villains.

    First, how does the system pressure vary from cold to hot? I notice that there is what might be a compression tank hung above the boiler. Is that a bladder type expansion tank, or is that a true compression tank? If it's the latter, is it waterlogged? You mention autovents which, if you have a compression tank, worries me.

    On this subject, if you don't have a reliable pressure gauge, get one.

    Now. I also notice that all your pumps appear to pump towards the boiler, not away from the compression tank. Is that correct? If so, you need higher pressure in the tank than you would otherwise.

    Next item. When you turn up a thermostat, what happens? Anything? Since this appears to be a zoned system with pumps at the very least the pump related to that zone should turn on. Does it?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • In your first picture, have you turned off the black handled valve and purged the loop from the hose bibb above it?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    edited November 2021
    Well, the piping is a nightmare. What's with the circulators on the supply and the return, AND 2 circulators in series.
    At least they didn't pipe the return in a way that would block swinging out the door for a proper cleaning...oh wait, nevermind.

    If you purged everything, and keep the pressure up the entire time, and get no heat, then it's flow related.
    Or adding/removing baseboard and probably an original gravity system, something is out of balance.

    If I came over to help you, I'd probably have to start with a piping diagram, and trying to figure out if the right size pipe is able to deliver the right amount of btu's to each zone, and which size circulators you need.
    From there you can come up with a plan to redo the near boiler piping and fix your problems once and for all.

    steve
    HVACNUT
  • Outofhiselement
    Outofhiselement Member Posts: 5

    Well... let's consider the possible villains.

    First, how does the system pressure vary from cold to hot? I notice that there is what might be a compression tank hung above the boiler. Is that a bladder type expansion tank, or is that a true compression tank? If it's the latter, is it waterlogged? You mention autovents which, if you have a compression tank, worries me.

    On this subject, if you don't have a reliable pressure gauge, get one.

    Now. I also notice that all your pumps appear to pump towards the boiler, not away from the compression tank. Is that correct? If so, you need higher pressure in the tank than you would otherwise.

    Next item. When you turn up a thermostat, what happens? Anything? Since this appears to be a zoned system with pumps at the very least the pump related to that zone should turn on. Does it?

    Hey Jamie,
    Thanks for the response. I believe it is a bladder style tank with an air fitting on the end. Pressing on it does release air so I assume the bladder is intact. There is only one pressure gauge on the system and it reads about 20 psi.
    What pressure should be on the tank if I need to increase it?
    When he thermostat is calling for heat the boiler kicks on and the circulator pump for that zone kicks on as well. It just doesn't seem to be circulating water as the only pipe that gets hot is directly above the boiler. All others stay cold.
  • Outofhiselement
    Outofhiselement Member Posts: 5

    In your first picture, have you turned off the black handled valve and purged the loop from the hose bibb above it?

    That zone feeds the sun porch and isn't currently in use, but I have bled that line as well.
  • Outofhiselement
    Outofhiselement Member Posts: 5

    Well, the piping is a nightmare. What's with the circulators on the supply and the return, AND 2 circulators in series.
    At least they didn't pipe the return in a way that would block swinging out the door for a proper cleaning...oh wait, nevermind.

    If you purged everything, and keep the pressure up the entire time, and get no heat, then it's flow related.
    Or adding/removing baseboard and probably an original gravity system, something is out of balance.

    If I came over to help you, I'd probably have to start with a piping diagram, and trying to figure out if the right size pipe is able to deliver the right amount of btu's to each zone, and which size circulators you need.
    From there you can come up with a plan to redo the near boiler piping and fix your problems once and for all.

    Hey Steve,
    The circulators are only on the water returning to the boiler. Also only one of the pumps that are in series is wired. This is the way it was plumbed when we bought it. The system worked fine last year and in all of the renovations we removed significantly more baseboard than we added. Estimating around 30-40ft of baseboard was removed and only one 5ft section and 2 toekick heaters were installed. All of these used the existing pipe only shorter in length and were on what I will call the second zone (middle pump). The main side of the house that we currently use is the first pump to the left.
  • Jamie Hall
    Jamie Hall Member Posts: 22,877
    As @STEVEusaPA said, you have a flow problem. Do any of the zones get any heat? Your tank pressure is OK. A bit high, perhaps, but all things considered, OK -- assuming that the system pressure gauge is more or less reliable.

    Problem is, pumps push water, and they have to have water to push. With the pumps on the return, if there is any air left in the system, they won't be able to move the water. They'll just make the air bubble bigger.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Outofhiselement
    Outofhiselement Member Posts: 5
    @Jamie Hall right now, no zones are getting any heat. I agree there is a flow problem. Just haven't figured out where there is an air in the system and how to get it out.