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My runt zone not heating strongly.

Dave Kliman
Dave Kliman Member Posts: 11

I just installed a new weil-mcclain ultra 155. I have two zones in this old Victorian house.

when i first filled the system and started it up, the upstairs zone with radiators heated acceptably, bringing the temp from 45 to 70 in 6-8 hours (not 20 minutes like I'd hoped) but the downstairs zone with all baseboard didn't heat at all. i closed the whole system down and flushed the heck out of the downstairs zone until the black water was running clear. i guess that helped because the baseboards got warm. they didn't get HOT, they just got somewhat warm.

the baseboard loop downstairs consists of daisy chained 3/4 units adding to a total of about 44 linear feet. that zone is not heating the downstairs. today its 26 out and only 65 downstairs. upstairs it is 70. all thermostats are set to 70.

the outlet temp according to the boiler is 190. the inlet temp is 186. the boiler is barely turning on, but the pumps sure are going and going. it seems like i'm not delivering a lot of BTUs along zone 1. could it be more air? what is going on? would any little pocket of air anywhere in the system cause a major decrease in heating? the highest point in the loop is in the kitchen where there's an air vent. when i open that, water comes out.



  • Weezbo
    Weezbo Member Posts: 6,232
    hello , i t sounds like maybe it could be ..........

    something other than "air".....however just to be sure,why not purge each zone again until the water comes back with out air bubbles rising in the bucket with the hose end being kept under water as you pump it around the zones.one at a time.if you have a grundfoss recirc, dont forget to open the screw and let that air out also when you start the system back up. and by locking the zones off one at atime it helps when you start the system back up...any growling howling or gurgeling noise might be an indication theres some leak in the sysstem you hadnt caught...
  • Dave Kliman
    Dave Kliman Member Posts: 11
    no more air, but only 63 degrees

    ok. over the weekend i reexamined my design and wherever air might have accumulated i stuck an air vent. for example i had manifolds that i installed vertically (sigh) and now they have air vents on top.

    the bottom line is the system is running much more quietly now, so i would have to say that the air has been eliminated from the system.

    the upstairs as of this writing is 70 degrees and the zone is not calling. the downstairs with the baseboards has very warm baseboards but its 63 there. those baseboards are not so hot you can't leave your hand/foot on them for a while, though. both parts of the house are open to each other and i have no open doors/windows that i know of.

    so why am i not getting enough heating power downstairs?

  • Dave_22
    Dave_22 Member Posts: 232

    Well, if your baseboards are hot,seems to me that you don't have enough radiation to cover your heatloss. Unless your flow is way wrong.
  • Dave Kliman
    Dave Kliman Member Posts: 11
    flow seems okay but warm?

    the flow seems okay on the downstairs zone. the temp of the return is within a few degrees of the supply temp on that loop though.

    again: 3/4 pipe. about 40-45 linear feet of baseboard.

    before i switched boilers, the old boiler would get these things so hot you couldn't touch them. now everything is just ... very warm, but not sooo hot you can't touch them.

    meanwhile the upstairs zone with its huge cast iron radiators is resting and smiling with only very occasional calls for heat.

    must i upgrade the baseboards? should i put in cast iron baseboards? i was planning on putting in radiant heat next summer, but i don't want to get involved in that kind of job right now. what should i do?
  • Dave_22
    Dave_22 Member Posts: 232

    What is the supply and return temp of that loop??? If your old boiler did the trick- the new one should also... Must be something else....
  • Dave Kliman
    Dave Kliman Member Posts: 11
    supply and return temps of loop:

    one nice thing about the weil-mclain is the temp sensors. I'm tempted though, to stick thermometers all over the place to see what's happening... but for now, here are the numbers...

    I watched for about 8-10 minutes and the supply was staying right at 190 and the return at 184. both zones were calling. and now the tako 0010 on the system loop is squeeking a little :-/ no air, though.

    i turned on an electric heater in the living room 30 minutes ago. the electric heater along with the baseboards have gotten the temp from 63 to 66. its 24 outside...

    i still don't know what to do :-/
  • Floyd_7
    Floyd_7 Member Posts: 136
    I'm wondering....

    if the heat loss off of the old boiler didn't help you out quite a bit with the heat on the frist floor.
    44 ft on a old vic. doesn't seem like much baseboard.
    You could start to add the radiant to the frist floor before you ripped out the baseboard to help things out, doesn't seem like the baseboard needs all that much help....
    I hope you mean 0011 for the circ. pump, an 010 doesn't give very much head pres...

  • Dave_22
    Dave_22 Member Posts: 232

    How was the old system piped? Was there one pump and zone valves? Is there now a prim/sec setup? Does this baseboard setup have it's own pump just for that zone now? Can you put your hands on the supply and return of this zone? Are they as hot as your other zone?
  • Dave Kliman
    Dave Kliman Member Posts: 11
    i think maybe i figured it out

    and its not good heh.

    hi dave,

    The system was probably piped anywhere from 30 to 100 years ago. i THINK that the "new" section of the house which has the copper pipe is from 30-50 years ago. what I've noticed is there is a strange combination of iron and copper pipe with no particular rhyme or reason. i took out a 10 foot section of the iron pipe that goes into the downstairs zone and replaced it with a new length. looking through the pipe, its so full of crud that it is probably more like a 3/8" pipe rather than a 3/4". If that pipe is indicative of the rest of that loop, i have my work cut out for me. either dig out the crawl space (which has maybe 3" of air between the floor and dirt) or tear up the whole living room floor... or if I'm lucky maybe just some planks.

    just to answer your other questions, i have changed to a primary/secondary setup, as per the weil-mcclain instructions. the baseboard setup is sharing the taco 0010 (or was that an 0011... no an 0010) that the upstairs zone is using happily and normally with zone valves.

    i was starting to think of crud in the pipes when i flushed out the zones and it took considerably longer for the water to start running cold out the downstairs zone than it did for the upstairs zone.

    ok so i guess i have one question before i start ripping up my living room floor... can this black crud be removed in some way besides totally replacing the pipes? i guess i could figure out what its made of (calcium vs just rust or something) from the pipe i took out.

  • jerry scharf_2
    jerry scharf_2 Member Posts: 414
    Primary/Secondary explains a bunch


    I was confused by that low delta T at first, thinking it was for the loop. With P/S low flow in the loop would produce high delta T for the loop and low delta T for the boiler. It also seems like the water is way too hot, probably as a way to try to make a system with flow problems work. You're wasting at least a chunk of the efficiency that the Ultra has by running the water that hot.

    If you want to prove this, you should get one of the two channel sensors that Hot Rod recommends. They just strap onto a pipe, then you cover them with pipe insulation to get a reasonable reading. If you see a very low return temperature, that confirms your suspicion. Another way to measure temperature is to get an IR sensor and walk around and read the pipe temps.

    A possible bandaid might be to put a high head circulator for just the basement loop. You may get some noise, but it might get you through the winter before doing the real fix. If there is one circulator now and zone valves, you chould change to two circs with flow checks so the high head doesn't cause the upstairs problems.

    The only way I know to save the existing pipes is really expensive. You contract out to these folks who come in with a big setup. First they sandblast the inside of the pipes to clear the crud. Then they blow hot air and epoxy in the pipes to seal them. Ends up with a pipe with higher CV than bare pipe. Since the price is probably around 20K$ as a wild guess, this would really only be useful for historic preservation IMO. There's one group out of LA that has the best system I've seen for handling small diameter tubing.

    Possibly, instead of replacing the existing pipes, you could abandon the old pipes and run PAP to the baseboard instead. With those high heats, I'd rather see something with less expansion. Often times if you don't have to follow the same path, a creative solution with less damage can be found. As painful as it sounds, check out the pipes on the upper floor as well. If they need it too, you may be able to fix at least part of the piping at the same time, then save the rest for a later date.

  • Weezbo
    Weezbo Member Posts: 6,232
    that sure is a bad deal.....

    you over pump it and the new boiler will look like the pipe:(if you seperate the outside loops through a buffer tank that might fill the buffer tank up with the crud first...like a giant drip leg....puting an over sized strainer on the return to the boiler from the buffer tank might get it....the best thing would be to lose the old pipe and the copper..then too the recircs are bound to not like it much even at that.....replacement is the ticket. taking the baseboard for a drive along some lonely road near the metal recycling plant might be in the cards also.............
  • Dave Kliman
    Dave Kliman Member Posts: 11
    replacing the pipe

    i have put that plastic stuff on all the windows, and closed off the colder parts of the house and now the system can just manage to keep the living room at temp, so i'm good temporarilly.

    how's about this: i want to get a 1" manifold with 6 1/2" pex connectors and then run individual 1/2" loops to each baseboard separately. each would have a balancing valve on it at the manifold. would that be reasonable until such time as i install radiant heat? when i take the first one out, i'll find out if this major crud is filling the baseboards as well as the black pipe that lurks under the floorboards.

    i guess a lot of you have taken up tongue & groove 8" pine floorboards before? what do i do? cut one of the tongues with a saw? (sigh) I see the necessity to remove at least 3 of them to get under there.

  • Chuck_12
    Chuck_12 Member Posts: 29
    mixing baseboard with existing rads

    one basic problem mixing older column rads with baseboard (cast iron or fin) is the temp loss difference will easily prevent proper flow through the pipes. If you read a few basic articles on this site it is key to rememebr how to balance a system particularly the upper and lower floors due to water flowing to upstairs rads first. Combine that the old rads are prolly on a gravity sys and now you have smaller 3/4 opngs to the baseboard and the added complexity of 44 ft of baseboard run with fast heat loss. Sounds complicated...it can be. It can be calculated on the amount of flow you have to the radiators based on pipe size and temp of water and the heat loss. You want to get each rad run to about hte same so that each loop will heat about the same rate based on temp ad time of heating. This is not easily accomplished and modificaitons have to be made to compensate. Where are all the good old heating guys? Yeah thqts right retired or 6 ft under. Anyway there are valves, flow monitors and secondary circ pumps that can be installed ot remedy this problems.
  • Chuck_12
    Chuck_12 Member Posts: 29
    col rad replaced with baseboard - gone sour

    Simply put... I replaced a 16 fin three col cast iron rad 23" high with a new 12' section of cast iron Baseray. The supply pipes remained the same which were 1" galv off a 1-1/2" main. My problem... the baseboard rad does not heat well. Flow seems restricted due to other rad lines heating up more rapidly than this run. From the main I have approx. 20' of 1"supply to 12' baseboard and then return with approx 12' of return. (8' differential) Also keep in mind the static flow of the new rad compared to old column type. Several things may be happening here... other lines from the "Main" heat up fully at boiler temp and therefore the return (when hot) then restricts the cooler flow return from the baseboard line. Hence...slower (or restricted) flow and cooler baseboard rad.
    The pitch of my piping is fair but due to the new longer run of 8' supply, the pitch is less. Does that matter? Any suggestoins to help me along to get flow back to this radiator? I prefer NOT to use seperate circ pump for just one rad run. Any suggestions? I am guessing that I need to somehow get the baseboard rad run to heat closely to the temp and time frame of the other rad runs to prevent the cold/hot water bucking each other on the return line. Would a mono flow valve solve this, better pitch of lines? Shorten the length of the supply from main to the Baseray so hot water enters sooner? Help!
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