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Radiators at end of loops dont get hot

i have two circuits/loops/returns feeding off my supply line of the main floor of my home. the circulators are tied into one thermostat and come on at the same time. the radiators (one each) at the end of the loops don't get warm. recently had a new furnace installed and had the installer check out these two radiators. it was reported that both could pass water so there wasnt a problem with the radiators themselves. ive got thrush adjustable supply tees at each radiator (about 3 or 4 radiators on each circuit prior to the last one).

the end units just dont get good heat. ne interesting hting is that the end radiators thrish tees are installed horizontally (that is the pipes feeding from the tee to the radiator goes out for several feet then up to the radiator), all other radiators have their tees pointing up prior to any 90 degrees to get to the radiator). all piping is in basement.

circulators are on return side. i understand they only induce flow and dont have a lot to do with the pressure.

how should i start to isolate the cause of this problem.


  • Ironman
    Ironman Member Posts: 6,895
    Could you...

    Post some pics. of your near boiler piping and of the rads you're having trouble with?

    Also, what is the pressure on your system and how many stories is the house?

    Did the rads work OK before the new boiler was installed? Have you bled all the air out of the problem rads?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Chris Ecker
    Chris Ecker Member Posts: 10

    the radiators at the ends have never really worked well, new boiler had no impact.

    when you are asking for pressure i assume you want something more than the standing water pressure shown on the boiler of 30 psi.

    i'll post some pictures tomorrow.
  • Jean-David Beyer
    Jean-David Beyer Member Posts: 2,666
    How tall is your bulding.

    I am not a professional, but 30 psi for a hot water system is too high unless your building is very high. My house is two stories and I run at around 13 psi. At 30 psi, your pressure relief valve should be releasing pressure and dribbling water all over the floor. And if you had a 30 psi relief valve in there, you would need a boiler rated for that higher pressure.

    You may wish to check your boiler fill valve, the one that regulates the pressure. If the pressure is 30 psi all the time, that valve is probably bad. If it is that high only when the boiler is firing, the expansion tank is probably bad or has lost air pressure for some other reason.

    I do not know if high pressure is causing your original problem or not, but I think it is trying to tell you something.
    GREENMAN Member Posts: 25
    Radiators dont get hot

    if this radiators never work well before. was the piping to them sizes right? if you bleed this system and you still have the problem . we need more info. post a pic and tell us what kind of system you have one pipe ,two pipes ?
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,839
    edited November 2010
    Wet, Lazy and Stupid....

    That's my description of water and my ex-brother in law.

    Water, like my E-BIL, has to be shown how, when and where to flow. Given its own devices, it is naturally going to follow the path of least resistance, which is most probably NOT the way YOU wanted it to go...

    If you throw up controlled resistance, by partially closing valves, it will have no choice but to follow the path you've shown it, provided your pumps are capable of generating the pressure needed to force it to go where it NEEDS to go, and not where it WANTS to go.

    It's called "balancing", and it is difficult to do because you have to be in 10 places at once. If you install non electric thermostatic radiator valves on it, then it becomes automatically self balancing, flow and heat output wise.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
This discussion has been closed.