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Forced water baseboard system can't heat rooms to temp

nybigapplenybigapple Posts: 38Member
edited January 11 in THE MAIN WALL
I have a two story house (3 apartments - 9 baseboard heaters) that uses baseboard heating (boiler in basement). Ever since the water boiler was installed a few years ago the heating has never been great. All three apartments have put their thermostats on the maximum 90 degrees. But the rooms will not heat past the low 70s on a 50 degree day, and low 60s on a blistering cold day. Every baseboard heater is getting heat, just not very much.

The water boiler is a Weil Mclain CGa 4 SPDN. The water boiler temperature never gets very hot. 140 degrees and 25 psi or so under load. I can see the low is set at 140 and high at 200.

I've bled all the air from the three zones, but there wasn't much in there. Though after the first zone a bit of black gunk started coming out. That made me think the rubber bladder in the extrol might have failed, but it is indeed half hollow, half filled based on tapping, and half warm, half cool, based on touching.

I was thinking that they might have undersized the boiler, but the low water temperature makes me question if something else is wrong. In order to test how possibly warm it could get, I left all three zone valves to open. Shouldn't the boiler fire endlessly when this is done? Instead, I find the boiler turn itself off after 15 minutes or so(cold star, after bleeding) though the taco is still circulating the water.

I already called in a "professional" who was well reviewed on yelp. He said the flue damper wasn't always opening and switched it out to a new one. He just ended up scamming work. There was absolutely no difference in heating temperatures from before and after, and he charged $ to tune the system, clean the boiler, and install a new part. The person who was "watching" him was an oblivious woman who said he never did anything with water, and was out in less than 1 1/2 hours. He didn't even bother bleeding the system, in all his tuneup work. But he did say the system was working fine, and since all the baseboards are getting some heat it's something else. I don't trust that assessment at all.

Any ideas what the possible problem could be?


  • nicholas bonham-carternicholas bonham-carter Posts: 7,825Member
    The first problem is Yelp!
    Can you post some pictures of your boiler, and it’s piping. Was that also installed by a Yelp recommended specialist?—NBC
  • BrewbeerBrewbeer Posts: 576Member
    You said the boiler doesn't get very hot. How hot is the water going out now? Can you program the boiler to send hotter water to the radiators?
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread:
    System Photo:
  • IronmanIronman Posts: 5,009Member
    Part #5 in the diagram is the limit switch which controls the water temp. In the back part of the switch is a dial that rotates and has numbers on it. There's a metal pointer beside the dial. The dial should be set to 180* for baseboards.

    Bob Boan

    You can choose to do what you want, but you cannot choose the consequences.
  • sallaberrysallaberry Posts: 7Member
    Baseboard is about 500 Btus per foot but it doesn’t seem like an under sizing problem just temperature.
  • JellisJellis Posts: 115Member
    when your thermostat calls for heat and your boiler is at 140' F then the burner should light and run until the boiler reaches 200' (you stated your aquastat was 140-200)
    If your boiler never goes above 140' F and the burner stops running during a call for heat then there is certainly a problem.
    Pictures are very helpful to get an idea how your system is set up.
    Did you contact the original installer about the issue?
  • EBEBRATT-EdEBEBRATT-Ed Posts: 5,727Member
    This is who you need
  • JohnNYJohnNY Posts: 2,247Member

    This is who you need

    Thank you very much for your confidence, my friend .
    For installations, troubleshooting, and private consulting services, find John "JohnNY" Cataneo here at :
    "72°F Mechanical, LLC"
    Or email John at [email protected]
    John is a professional Master Plumber, licensed by The Department of Buildings of The City of New York, and works extensively in NYC while consulting for clients in and out of state.
  • mikeg2015mikeg2015 Posts: 785Member
    Does boiler run continuously or cycle on and off? Is it a 3 speed or single speed pump? What speed is it on? What is the aqua stat set to? What are the supply and return temperatures? If not gauge, just take a digital meat therm and place it against the pipe and wrap it with a dry towel. Will be close.
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