Do I need Primary / secondary piping?

Discussion in 'Boiler Forum' started by Crooz1n, Nov 3, 2013.

  1. Tom Sawyer

    Tom Sawyer In the Trades

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    3,225
    Location:
    Maine
    That condensate line is about as illegal as illegal gets. If its dumping into the sanitary waste system it needs to be indirect wasted into a vented trap
  2. Reach4

    Reach4 Active Member

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    2,385
    Location:
    IL
    Nice looking install. What is that gray thing inline with the upper black gas pipe?
  3. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    Condensing boilers and old cast iron radiators are a perfect match. We have been installing them in Minneapolis/St. Paul since 1990, without the "benefit" of primary/secondary piping. We don't even "pump away" from the boiler since this is missing the point and really less than optimum for any low-mass boiler.

    The installation is amateurish but adequate, but for the illegal condensate hook-up to the sewer system.

    The pump is oriented upright (there is an installation drawing in the box), no drip-leg or union on the gas service (see pages 29 of the installation manual, pictures no reading necessary), Delta T is fine (happy accident), outdoor reset sensor likely still in the box or placed safely inside the cabinet (no wiring needed). I would like to know how the outdoor reset is configured but looking at the pump I think it is safe to assume in would be a waste of time. Old-fashioned air scoop and vent are for hot systems (this never really was) and should have been removed preventing future sources of air and leaks.

    We install Peerless Surefire here in Minneapolis but re-pipe, install outdoor sensors (they come in every boiler box) program and follow the installation check list which includes combustion analysis and tuning as necessary.

    If your condensing boiler installer can produce a heat load and show up with an electronic combustion analyzer he is light-years ahead of his "peers".

    Other than that, it should be A.O.K. :)
  4. Dana

    Dana In the trades

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    No, I think you should set up the outdoor reset curve, and keep tweaking the curve downward until it just barely keeps up.

    Reach4: The "...gray thing..."is a gas pressure regulator. (Not my install- picture clipped from the web as a clear example.)
  5. Crooz1n

    Crooz1n New Member

    Messages:
    26
    Location:
    Roanoke VA
    Badger- Thanks for replying. The air scoop is still n place but the relief valve was removed and plugged. new vent valve installed There is a new pressure relief on the boiler.
    Outdoor reset is installed on north wall and hooked up. I have it set to 160 @16 and wwsd at 70. I currently have it limited to 120 boiler max to see how low I could go and still heat the house. Maybe that is a mistake on my part.
    Should I set boiler max back to 160 and reduce the curve top end from 160 down to 120 or lower?
    I am doing the parameter tweaking as the contractor simply turned it on and left everything at default. "Oh we don't mess with the computer!" - I was told.
    The pump orientation has been changed after I bitched about it. RTFI!!
    The drip leg and union are above the unit but I will ask the inspector about the location that it's in.
    Inspector said nothing about pump but I'll ask about that as well.

    Here are the parameters as set
    Boiler settings
    1 Pump mode -19 (CH)
    2 Location -USA
    3 Vent material PVC
    4 Freeze protection 40
    5 Blower Post purge-30 sec.
    6 additional Safety - LWCO not installed

    CH settings
    1 CH mode 1 thermostat and ODR
    2 CH pump purge- 20 Min
    3 Gen circ purge-0
    4 Pump delay step modulation-OFF
    5 system Type- User Defined
    6 wwsd-70
    7 reset curve design- Boiler 160, outdoor 16 Changed to140@16
    8 Reste curve mild weather- 120,70 Changed to 80 @65
    9 Reset curve boiler min-80 max 150
    10 Boost function-Temp 18,Time 20
    11 Anti cycling-10
    12 CH response time was 60 now 40
    13 CH rate100%

    FYI-- 580 Sq ft of cast Iron radiators in the house.
    Last edited: Nov 15, 2013
  6. Dana

    Dana In the trades

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    Carefully read the section titled " 3. Outdoor Reset Operation:" on p42 (p45 in PDF pagination), and how to set up the curve in figure 8.6, using a user-defined reset curve. (preset 7 in table 8.7)

    It looks like you set up the curve to deliver 160F water at an outdoor temp of +16F (which is about your 99% design temp), and deliver 120F water when it's 70F out (which is a bit much!) I suspect you'll never need more than 140F water @ +16F, and may not even need 130F water. With the curve as-is it'll be delivering ~140F output when it's 43F outside, a temp that would probably have you covered even at +16F.

    Start by dropping the mild-weather output to 80F @ 65F outdoors and see if it short-cycles (probably won't, in a high mass system), and set the design temp output to 140F @ 16F outdoor. Hopefully it'll still keep up, but without overshooting on the warmer days.

    If it turns out that it won't keep the house up to temp during cooler weather, raise the design temp up by 10F to 150F @ 16F and see how it makes out. If it fails to keep up, bump it another 10F on the design end. When you find the point were it keeps up, back off 5F, see if it continues to keep up, then ride it out for awhile. If it always keeps up, never overshoots or short-cycles during milder weather, you're golden.
  7. Crooz1n

    Crooz1n New Member

    Messages:
    26
    Location:
    Roanoke VA
    Tom the inspector agreed about the condensate drain once I pointed it out (Thank You!) and the contractor has been told he has to install it into a trap. he said sort of like one you'd dump a washing machine in. Both will be back tomorrow to hopefully get the final inspection done.
  8. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    With all due respect. There are currently no residential ModCon boilers in the US with built-in flow meters, mechanical or electronic. As you suggest, Delta 'T' is the benchmark. Most manufacturers of ModCon boilers prefer a 20°F Delta 'T' but many will suffer 45° depending on the orientation of the pump.

    It is interesting that the some European manufacturers mention "over" pumping in contrast to the manic preoccupation we have with P/S and minimum flows to the point that many manufacturers including our own Weil McLain and the German built Buderus void warranties if P/S pumping is not employed regardless of system engineering. The fact is the more you pump, the more you spend. KISS.
  9. Dana

    Dana In the trades

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    I've never seen a mod-con with an internal flow meter either, but since several tankless water heaters out have some sort of kludgey flow metering I couldn't rule it out completely. Without intimate knowledge of this particular boiler, it didn't seem completely outside of the realm of possibility since the technology exists.

    Dumping the condensate into it's own trap isn't really the right solution, since that trap is all but guaranteed to run dry when the heating season ends. It really needs to be a shared trap with something that gets more regular use, and higher volumes.

    Having tweaked the curve how is it behaving? Any hint of short-cycling? Is it keeping the place up to temp overnight? Time the burns if the burns per day start climbing. If it's not quite keeping up, bump the output temp at +16F up by 10F- if it always keeps up there, back off by +5F. You'll eventually zero in on the number that works. On the +65F outdoor temp end of the curve there's no point in changing it unless it's short cycling or too unresponsive. Bumping it up would make it more responsive during mild weather, but you'd run into the room-temp overshoot issue again if you go too far.
  10. Crooz1n

    Crooz1n New Member

    Messages:
    26
    Location:
    Roanoke VA
    The burn times have averaged around 2.5 hrs. The total run time has been 97 hrs and 4500 Cubic feet in the last two weeks. I forget exactly how many ignition cycles there have been ( 57 maybe with 5 fails ) as I am not at home with my data but I have started writing this info down each Wednesday morning before I leave for work so I can obsess over it.:D
    This past week has not been too cool. Several days have been in the 50-60 range but its supposed to cool down over the weekend and next week. I'm still getting 2-4 degrees overshoot but it also seems to wait until the temp dips below the setpoint by nearly as much before calling for heat as well. I have adjusted the anticipator on the thermostat in the hopes that it will further bring the temp swings closer to 70. I haven't been able to catch it exactly when the boiler starts but I know the supply temp was 64 the other day and still not calling for heat. And the supply temp is measured at the boiler in the cold basement as well so that may not have much bearing on when the call for heat actually starts.

    But overall the house is keeping warm although the wife is cold in the morning (Not unusual though as she has several circulatory issues where she gets cold easily)

    As to the condensate pump there is a check valve in the pump to prevent backflow.
  11. Dana

    Dana In the trades

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    Sounds like the overshoot is more of a thermostat issue- if you can narrow up the hysteresis delta on it you'd get shorter burns but lower temperature swings. Since you're burns are measured in HOURS, I'm not too worried about short cycling the thing. If all else fails a PID-algorithm Tekmar thermostat would deliver extremely tight room temperature control.

    A check valve on the condensate pump is one thing, but the drain trap something else. There needs to be liquid in the trap for it to function properly, and when the boiler is idling or off all summer the trap will dry out unless it has a regular source of water from somewhere else.
  12. Crooz1n

    Crooz1n New Member

    Messages:
    26
    Location:
    Roanoke VA
    Yes the inspector even said we'd have to watch it during the summer and keep some liquid in it. He said if we started to notice a smell then its probably dried out. Seems like the other way was better. At least it was sealed. Now the top of the trap is open.

    Do you or The badger have a recommended Thermostat model that will hold the room temp closer than what I'm currently seeing?
    Last edited: Nov 21, 2013
  13. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    A thermostat may cure the overshoot but design water temperature is usually the culprit depending on radiation, insulation et al. As for the trap. We do find dry basement floor drains occasionally but most basements are damp and traps don't get much dry if filled once a year. A little glycol will slow the evap rate as well.
  14. Dana

    Dana In the trades

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    The PID T-stat recommendation was predicated on the " ...all else fails..." condition, eh? :) We're not there yet.

    With burn times in the 2+ hour range it may be pretty close to the right water temp, but maybe not. The hysteresis in the thermostat may be way too high, or the anticipation is WAY off, creating a phase problem severe enough to induce a very low frequency under/overshoot oscillation if it's designed/tuned for low-mass radiation & oversized boilers. Let's see how it makes out with taking the anticipator function and differential to the limits on the existing thermostat. If there is a programmable differential on the thermostat, take that to the minimum too. Some are set to a fixed at 1F or 1C (or some other value), others can be adjusted to a pretty tight 0.5F or even less.

    In the meantime keep knocking down the programmed output temp at +16F by 10F at a time until it doesn't keep up. You take it in 10F steps adjusted daily you should find the bottom pretty fast. Then start bump it up by 10F to where it kept up in the prior and start decrementing by 2F daily. If the over/undershoots go away, great! If not, keep pecking around at the thermostat adjustment minutiae.
  15. Crooz1n

    Crooz1n New Member

    Messages:
    26
    Location:
    Roanoke VA
    Thank you gentlemen.
    I will continue to work SLOWLY with the heating curve. As I am leaving to go hunting for a few days and we are expecting a cold snap, I don't think it advisable to lower the temperature while leaving the wife at home.
    Since she is cold natured anyway I will wait until I return next week so as not to face the wrath of a cold spouse.
  16. Dana

    Dana In the trades

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    Location:
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    You can't convince her to go hunting with you? ;-)

    Good luck- I'm sure this boiler will eventually work out great, once you've dialed it all in.
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