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[Updated 3/18] A new set of radiant heating questions!

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Comments

  • hot_rod
    hot_rod Member Posts: 22,022
    You still do not have a very good automatic air elimination. Until you get that Spiro or equal installed you have a very manually operated air removal system
    With a lot of loops and places for air to hide it could take days of manual power purge to get it right

    Keep in mind every time you add water power purging you add a % of air again also
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Gannon
  • SuperJ
    SuperJ Member Posts: 609
    edited February 2020
    Gannon said:


    Any opinions what setting to enable on the Grundfos Alpha 15-55f? Literature suggests auto adapt, but that's not specific to this system, of course.

    Did some homework on condensation. Looks like this boiler is a conventional boiler, intended to operate as a non-condensing boiler. I understand that all boilers can be condensing boilers, so curious on inlet temperature now. Is that influenced by the circ setting? That is, can the right circ setting keep water moving, therefore keep the system closer to an average temperature?

    Since your boiler has a fixed capacity (single stage), and your don't really have modulating valves on your primary (just a bypass option). I would suggest running your Grundfos pump at one of the 3 fixed speeds. Autoadapt is intending for systems with modulating valves the will see a benefit from the pump changing speeds. Constant pressure control could also work. You could vary the pump settings until your get to about a 20f temperature delta in and out of the boiler as a starting point..

    To protect your boiler you need a way to decouple the loads from the boiler if the return water temperature gets too low.
    -the crudest method is to put a bypass with a throttling valve in to allow some hot supply water to bypass your loads and mix back into the return.
    -More elegant, are temperature reactive valves that will essentially cause the water to circulate until the return water temperature is safely warmed up, they then gradually open. In your case adding a thermostatic 3 way valve to your primary loop would be the simplest and most effective.
    -Your mixing setup may have a boiler protection feature, but that only partially helps since you have the fin-tube zone as well.

    Here is some excellent reading:
    https://www.caleffi.com/sites/default/files/file/idronics_7_na-r1.pdf

    A sample valve (there are others):
    https://www.caleffi.com/sites/default/files/file/na10292_04.pdf
    Don't use a DHW style valve as it will likely have too much pressure drop at your flow rates.


    Gannon
  • Gannon
    Gannon Member Posts: 20
    edited February 2020
    Hi all,

    Have taken all of the latest comments into careful consideration. Getting this hydronic system we have working as well as possible is my new favorite pastime; my home's previous owners clearly never put any time or maintenance into the system, so lots to consider.

    Just wanted to acknowledge the comments and say thanks for each and every one. Looking to be back here in a few days--maybe a week--with a new set of topics for discussion.

    Greatly appreciate all this help. Never thought I'd be watching full episodes from this Coffee with Caleffi series, but here we are.

    Thanks and look forward to posting again soon!

    Edit: Dealing with an ice dam, so this has been delayed a bit. Stay tuned!
    SuperTech
  • Gannon
    Gannon Member Posts: 20
    edited March 2020
    Hello again after a long hiatus. I've taken some time to gather my thoughts, fix some other issues around the home, and battle what I believe is the Corona virus.

    Back now with a set of questions to pose to the group here. Feedback is greatly appreciated!

    Before getting to the questions, here's a 2 1/2 minute video walking through the system. Hoping it can help explain the setup of the system better than text.
    • https://youtu.be/nQQmzufBEZc
    • Not noted in the video is that the house is 2,200 square feet; built in 1952, windows original to that time period but insulation added to the attic a decade ago.
    To keep this organized, I've numbered each topic and question within.

    Thank you for reading!

    Part 1 of 2

    1. Low temperature return water considerations; avoiding flue gas condensation

    SuperJ said:


    I'm not familiar with your boiler, but can tell it's not a modcon. You may want to think about some sort of protection against low return temps and flue gas condensation. Especially with your cascading loads which pulls extra heat out of the return water. ... More elegant, are temperature reactive valves that will essentially cause the water to circulate until the return water temperature is safely warmed up, they then gradually open. In your case adding a thermostatic 3 way valve to your primary loop would be the simplest and most effective. ... Your mixing setup may have a boiler protection feature, but that only partially helps since you have the fin-tube zone as well.


    Proper boiler protection can only be achieved by a mixing assembly that monitors boiler inlet temperature and compares it to a set minimum value. Whenever the boiler inlet temperature is at or below this minimum value, the mixing assembly must reduce the rate of hot water flow from the boiler to the distribution system. This action “lifts” the combustion side of the boiler’s heat exchanger above the dewpoint of the exhaust gases. Controlling supply water-temperature to a distribution system, and protecting a boiler from sustained flue gas condensation also requires two mixing points within the piping system. One mixing point regulates supply water temperature; the other boosts boiler inlet temperature.

    This bit from idronics seems consistent with SuperJ's comment, but SuperJ's is a lot easier for me to understand.
    • 1.1) Boiler return temperature appears to be monitored by wire to Tekmar 356 mixing control. Boiler minimum on the 356 mixing control is set to 130 F. Manual talks about it acting on that BOIL MIN setting by limiting output of the variable speed injection pump. If I have set my pump to fixed speed (per previous discussions), will this override that, or have I lost that protection?

    2. Mixing control calibration

    Connected to the boiler is a Tekmar 356 mixing control. Calibration of the "Characterized Heating Curve" for the mixing control has me select a terminal unit. Curious whether this is correctly configured for my system.
    Currently the 356 is set for High Mass Radiant floor. That appears to be incorrect for my setup, but not sure if I should then select Low Mass Radiant or Fin-tube Convector. Worried that selecting the higher of the two might make it difficult for the floors to operate, as they run at a much lower temperature (or maybe they'll just pull from the main loop less frequently, as hotter water will hit the temp. quicker).
    Here are the "terminal units" referenced.
    • 2.1) With this setup, what's the correct terminal unit setting here? If my system isn't set up to handle this properly and we can kill two birds with one stone by helping reduce flue gas condensation, that seems best route. Would the temperature reactive valve mentioned by SuperJ also help here?
    • 2.2) Here are the settings I have in case there's more that might be amiss. I live in Wisconsin for purposes of assessing the outdoor design temperature and the WWSD. If helpful or relevant, boiler is set to 200/175 F, 25 F differential.

    3. Adjusting flow to fin-tube convectors via manifold

    • 3.1) Just to confirm, am I OK to adjust flow to various zones using the blue caps on the manifold? I see the manifold manual describes these as balancing valves (so I damn well better be able to use them for this purpose!), but I really just want to be sure I am not causing havoc somehow. I suspect I can completely close off a zone (a la an actuator), but can I significantly limit the flow to a zone without, for example, significantly increasing the pressure in that zone or elsewhere? (Or is that pressure just diverted elsewhere and accommodated by the expansion tank in any case?)
    • 3.2) On the same topic, I see that when the cap is removed, I can place an actuator there (future pursuit maybe), but I also recognize I can turn using a radiator key. I'm not brave enough to turn the key, but what would that affect? The manual shows this is used to balance the manifold and is related to pressure loss, but I guess I don't understand what means in this context. Seems that is what turning the blue caps is doing, no? Can somebody straighten me out here please? Perhaps it's modifying flow rate, but I can see that measured in the GPM gauge on supply side, so not sure how those are intertwined; seems redundant from what I understand.

    4. Pipe sizing

    I have noticed a few things regarding pipe sizing. Curious if these are intentional (and if so, what their purpose is) or perhaps even problematic.
    • 4.1) On the "typically open valve" that supplies the radiant floors, why 1" to 1/2" pipe and valve? Case of "that's what was on the truck," or a valid reason? Any harm being caused? If it fails, best to replace with the same, or better to go to 1"?

    • 4.2) Boiler manual calls for 1 1/4" supply. Whole system is piped with 1". In addition, my boiler (Crown AWI095) has input of 95,000 BTU, DOE heating capacity of 78k, and IBR net rating of 66k. I believe the run length of the copper affects how many BTUs it can carry, but I have seen that 1" can perhaps carry only 75k BTUs. Any reason to suspect an issue here?

    5. Measuring system pressure

    • 5.1) Since my circulator is up against my boiler (pumping into it), the boiler's likely the highest point of pressure in the system. Is there meaning in the value that I can measure from my expansion tank? Is that the system pressure sans effect from the circulator pumping? Getting 12 psi at the exp. tank so hopeful that in fact reflects the system pressure.

    6. Noisy boiler

    All winter, the boiler's been screeching when it shuts off. It's gotten louder over time. Sorry if this one sounds silly, but I didn't have a point of comparison and grew accustomed to it. I'm now convinced this can't be normal behavior. Given lack of maintenance apparent in system, I suspect something could be blocked. Noise is almost like a whistling, consistent with a constriction of something in there.
    If you haven’t watched the video and heard the audio, here’s a link to that timestamp in it (careful if wearing headphones). If timestamp link doesn't work, please skip to 2:24.
    https://youtu.be/nQQmzufBEZc?t=144
    • 6.1) Is this something I can service myself? Local HVAC company here serviced the boiler but didn't do anything that didn't require removing the front cover to access the pilot and burners.

    To be continued in a second comment.

  • Gannon
    Gannon Member Posts: 20
    edited March 2020

    Part 2 of 2

    Continued from previous comment.

    7. Manual venting solutions

    • 7.1) Is there any meaningful value to installing a venting device—like a Hy-vent—on the manifold? Seems an 1/8" threaded air vent might help here, as it'd be the highest point in the system--fin-tube convectors aside--where I could add a vent (until further work done in a few months to add a DISCAL).

    8. Maintenance questions

    • 8.1) I see that I can drain the system via the valve on the boiler. I see I can also drain using the valve shown here. Will where I drain have an effect on the system? I don’t have a ball valve or Webstone valve elsewhere else in the system to isolate components, in case that affects the answer.

    • 8.2) The boiler is vented through the chimney. Any maintenance I can perform on that? Don't see any corrosion on exhaust.

    9. Short-term next steps

    Given struggles with air elimination ongoing, these are the next procedures I have in mind:
    Reconfigure system piping as follows:
    • Boiler -> Microbubble elim.* w/ exp. tank -> Circulator -> Supply
    *Now that I know Caleffi is in Milwaukee, I'll go with a DiscalDirtMag instead of the Spiro. :)
    I would plan to leave the air scoop and air vent (no harm in leaving them?) but would relocate the expansion tank (no use in having two).
    • 9.1) Greatly appreciate feedback on this approach to the situation. Given previous topic on low temperature return water, I am hoping to expand this to include a solution there (if one is needed).

    10. Long term planning for boiler replacement

    Boiler was manufactured in late 2011 and should theoretically have plenty of life left, but I don't have any faith in it being set up, maintained, or even operated properly since that time.
    With that said, I would like to start looking at replacement boiler considerations now so that my hand isn't forced if the system does fail and need to replaced.
    • 10.1) Does it make sense to replace with an operationally similar, non-condensing boiler, with similar BTU output? Supposing keeping BTU output makes sense, so long as the boiler was properly sized for the house to begin with. Is there an advantage to switching to a modcon boiler if I have a chimney to vent to?

    11. Fin-tube convectors: current state and bleeding (in)ability

    Upstairs convectors are relatively new and have a Taco coin vent and can be bled easily. All good there. Downstairs convectors are ancient and most vents are calcified.

    • 11.1) Simple technology, I know, but curious on thoughts on replacing these old convectors--the vents definitely need to be swapped out at a minimum. Once the wood covers get painted and go back on, if the convectors work, who cares what they look like, but I'm not sure how functional these really are; in other words, are the new slant-fin designs much better at putting out heat?

    12. Thermostat location in house; remote indoor sensor

    Our Tekmar 518 thermostat is located near a large fin-tube convector and indirectly receives afternoon sun. The effect is that the area with the thermostat is the warmest in the house, and the rest of the (poorly insulated) house is typically below the set thermostat temperature.
    • 12.1) Is an indoor sensor like a Tekmar 076 a workable solution to measure temperature somewhere that better represents the ambient temperature? I have access from the basement to fish a line from first floor and install sensor in the wall, so I prefer a permanent solution over something wireless.
    ---

    Hoping this gets an award for longest set of questions in this forum's history. More over, hoping that those here can help me better understand this system (I'm stuck with it for decades, I think) and work through the questions and issues.

    Thank you!
  • Gannon
    Gannon Member Posts: 20
    Hi all,

    Didn't get any takers on the first go-round, so wanted to try floating this post back to the top.

    Happy to take any answers piecemeal, and in these trying times, I will also donate $10 to the WHO's COVID-19 response fund for each question that we knock off the list.

    Will of course post back proof of those donations to keep things fair.
    https://covid19responsefund.org/

    I counted 16 questions in all, so let's raise $160 and get this heating system working along the way!
  • Zman
    Zman Member Posts: 7,561
    edited April 2020
    I like your style. This would be easier to talk through over the phone. I'll send you a PM with contact info, let's get you dialed in and raise a little cash :)
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    GannonErin Holohan Haskell
  • Gannon
    Gannon Member Posts: 20
    edited April 2020
    Huge help from @Zman! One 45 minute call, 16 questions answered, and $160 raised to fight this stupid virus.



    I'll be back in time to post a summary of what we discussed and how I'm proceeding; hope it can be helpful for the next person.
    ZmanErin Holohan Haskellrick in Alaska
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 2,276
    This is really wonderful, guys. Thank you.
    President
    HeatingHelp.com
    Gannon