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Boiler Room Layout Mock-up – reasonable, flawed or both?

HydronicRookieHydronicRookie Member Posts: 52
Hello all again, I’ve been inching my way forward on this diy system-overhaul project and have finally come up with a layout mock-up that pleases me enough to share.

I’m hoping to “shed my rookie status” with this one, but could never do so without your expert advice, and for that I thank you all.

This layout is tricky mainly because I’m trying to fit everything in a 4’ x 5’ corner (hoping to leave room for a stacked washer/dryer to the side). I’ve produced several variations, but this one has the merit of minimizing DHW pipe-length and leaving a space by the floor for a future in-floor radiant manifold.

The scale of the boiler is correct, and all the other components were loosely based off it, and so, not terribly accurate just yet. Next steps include: refining the size of all the components ensuring everything can actually fit as laid out; filling in all the details like near-boiler piping, isolation valves, missing components; establishing relative depth of all the piping to allow for overlaps; and most importantly, choosing a pipe-diameter for all this.

Does anything look totally impossible, or strikingly wrong?


  • HydronicRookieHydronicRookie Member Posts: 52
    I thought I should...

    say a little about my proposed system.

    Those manifolds are piping Pex-Al-Pex to cast-iron rads, one manifold per zoned floor pumped by a ECM circulator. The mod-con will run off an outdoor reset.

    The plan was initially to have TRV's on each rad, but it proved too cumbersome given that the rads/bushings are all left-threaded and TRV tail-pieces are not.

    I've read here that OR and zoning doesn't play nice together, hopefully there is a remedy to that.

    A room by room heatloss was performed, the rad heat-emission calculated as well as the necessary flow rates.
  • SWEISWEI Member Posts: 7,356
    Outdoor Reset and Zoning

    are not in themselves incompatible per se.  The problem comes from the pairing of on/off zone valves (or conventional pumps) with tight ODR parameters.  As the ODR is tuned to maximum efficiency, the temperature differential between the heating fluid and the surrounding air is reduced.  This increases the lag time between a call for heat and its satisfaction.  The result is long sinusoidal cycles in room temp with wider swings than the thermostat deadband.  The solution is proportional control, such as that provided by TRVs.  Remote bulb TRVs can easily control a floor or group of rooms and (with proper placement) can provide near-perfect comfort.
  • HydronicRookieHydronicRookie Member Posts: 52
    edited July 2014
    Proportional thermostatic control at the zone level via remote sensor

    Thanks for explaning that - I was trying to figure out in my head why both zoning and OR aren't necessarily an ideal combination, but I couldn't figure out why. Makes a lot of sense now.

    If I understand you correctly, you're saying I could have proportional flow control of an entire zone? like a TRV for a manifold?

    That sounds awesome.

    Would these be the components?

    I'm guessing the straight-valve would go where you're typical on/off zone-valve would normally go, at the manifold supply pipe.
  • SWEISWEI Member Posts: 7,356
    You got it

    TRVs provide nonelectric proportional control of flow based on room temperature.  Whether that flow is to a single radiator or a dozen rooms is just a matter of piping.
  • ZmanZman Member Posts: 3,517
    Getting there...

    You approach looks good. Take at look at the attachment for some minimum clearances.

    Be sure to check valves at the boiler and DHW circs. You will want isolation valves on almost everything.

    You might look into a combination hydrolic separator/ air eliminator. They are nice units and will save some space.

    Do you have a plan to purge this? You will need a combination of boiler drains and valves that will allow you to "power purge" using the fill valve. You will also need to have the ability to pump in glycol or other additives if needed.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ChrisChris Member Posts: 3,056
    Exp Tank & Feed

    Are in the wrong place and you don't need the spriovent. Take out the vent at the top of the LLH. Once removed the tap is 1/2" Stick a 1/2 x 3" nipple, 1/2 x1/8 Reducing coupling and a nice auto air vent.

    You want the exp tank and feed on the boiler return side before the boiler pump thus you are still pumping away.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • hot rodhot rod Member Posts: 7,085
    Better air and separation

    agree with Chris, look into a multi purpose device to provide hydro separation, air, dirt, and magnetic separation.

    Also the expansion tank connection needs to be were all pumps "see" the PONC.

    More reading in this just released tech journal.

    Also if you don't want to give up on the TRV at the rads, Anvil sells double threaded left hand nipples. Cut the threads off, weld in a 1-1/4 X 1/2" bushing. It's easy to build those LH conversion fittings.

    An example, before welding.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • HydronicRookieHydronicRookie Member Posts: 52
    edited July 2014
    The allowances diagram is great

    thanks for that, its just what I was needing to do next steps. I hope to have a refined iteration on this layout in the next few days.

    By power purge, do you mean having a fast-fill parralel branch where I use a manual valve to unleash fully pressurized water into the system? Thanks for the reminder on that, I almost forgot. The additive insertion point is another good consideration - its hard to remember everything on your first go.
  • HydronicRookieHydronicRookie Member Posts: 52
    edited July 2014
    Nice catch

    thanks for catching that Zman and HR, i was looking at simplified system diagram for reference, if I had turned a couple of pages in Siegenthaler's book to page 602 I would have seen the exact arrangement you mention. It seems he suggests it can also be placed on the other side of the low-loss header if need be, which I might have to use for spacing purposes.

    Also, thanks for the automatic air-vent tip. I realize now that its a bit redundant - just thought the spirovent could be useful in removing air during filling period being positioned right by the domestic water source.
  • HydronicRookieHydronicRookie Member Posts: 52
    She's a beaut

    Hey Hot Rod, that Caleffi looks beautiful, though I think I'll should stick with the LLH that matches my boiler, its got a temp sensor well that senses return water temp and shares that info with the boiler. Maybe I can find a way to wrap magnets around the bottom portion too.

    Thats a sweet fix for the left-threaded TRV situation - its very clean. I think it'll definitely be worth the effort at least for a couple of rads in rooms that deserve that level of comfort.
  • hot rodhot rod Member Posts: 7,085
    sensor well

    is that brass plug at the top of the Sep 4 pictured.,

    Best air & dirt removal is with a media inside the LLH. Also magnets can only be applied on the outside of brass or plastic components. You would not want to strap a magnet on a steel LLH.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • ChrisChris Member Posts: 3,056
    Reason Why

    The reason Viessmann wants the exp tank/feed valve on the boiler side is that there is a potential for air to come out of solution exiting the LLH. In essence you're protecting the HX from seeing possible air. Don't reinvent the wheel, install the exp tank feed as it is in the Viessmann manual.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • HydronicRookieHydronicRookie Member Posts: 52
    Updated Mock-up

    Here's my updated mock-up having added in some isolation valves, near-boiler fittings, and placing the expansion tank on the boiler side as per Viessmann manual.

    I think the circulators come with check valves, but I'm sure I'll need a few elsewhere.

    Still don't know what to do about the recommended allowances, i.e. 10x pipe-length before circulator and 4x pipe-length after. I don't have those distances with this setup, so does that mean back to the drawing board?
  • HydronicRookieHydronicRookie Member Posts: 52
    Purging and Chemicals

    I plan on rigging up a circulator to the rads. one-by-one, and have Fernox F3 circulate in them for a couple of hours each before commissioning, with a good rinse after that.

    As for purging, will getting a feed-water valve with a fast-fill mode be enough? Or should I have the feed-water valve on a branch with a isolation valve in a straight line with the backflow preventer?

    I haven't quite figured out what is the best component to pump chemicals into. Is it like one of those twin valve components from webstone?
  • HydronicRookieHydronicRookie Member Posts: 52
    More straight pipe before and after to the circulators

    I realized, I hadn't really done anything to mitigate the dangers of cavitation w/n the circulators by giving the circulators some more straight pipe length upstream and down. SOmething you brought to my attention ZMan

    Here's a modification of my earlier sketch. I even threw in a little flourish of reverse-return for the various zones.

    Anything stick out? I still have to figure out the expansion tank situation/placement.

  • hot rodhot rod Member Posts: 7,085
    either or

    will work just fine, the LLH or hydroseparator chamber allows the entire device to see, or become the PONPC.

    If Viessmann prefers boiler side, go with that.

    The separator you show, and shown a few posts up, if it is a Sep4 has a built in microbubble air removal , much more than a LLH and it commonly gets installed with Viessmann equipment.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • bobbob Member Posts: 813
    3 D

    Remember that when you build this it will be in 3D . Mount your piping in two planes. Mount all verticle pipes in one plane and all horizontal pipes in the other . When ever you change directions change planes . You will never run into yourself this way .
  • HydronicRookieHydronicRookie Member Posts: 52
    Vote of confidence

    Thanks Hot Rod. Indeed I'm looking at the SEP4 - it appears to be fully compatible with a Viessmann setup, and the sensor well is in the more-or-less the same place. My only task now is to see if the Viessmann sensor can fit inside the Caleffi sensor well.

    What I've gathered so far is that the Viessmann sensor might be too long for the well.

    Here Caleffi states that the "probe holder" is 35mm long. I don't know how long the Viessmann sensor is, but I do know their LLH well is much longer than that, so I infer their sensor is too.

    I guess I'm wondering if I can use any other sensor that fits the Caleffi even though Viesmann states I 'must' use theirs. Perhaps they mean, I must use theirs with their LLH.
  • HydronicRookieHydronicRookie Member Posts: 52
    That extra dimension

    Thanks Bob, Its a good thing to keep in mind even while drawing these mock-ups, I definitely don't want any pipe collisions.
  • HydronicRookieHydronicRookie Member Posts: 52
    A little more refined mock-up

    So the boiler is hung and the venting is proceeding nice and neatly with CPVC piping. I've roughed in the DHW circulator supply line and I'm hitting all the allowances of straight pipe I was after so I'm quite happy.

    The SEP4 and the zone valves are coming in next week so I hope to have it all wrapped up soon. I wish it was as easy to locate old rads to fill in the missing spaces as it is to track down all the fancy hydronic stuff.

    Thanks to all for the help and suggestions along the way. I'm still open to critique if anything is spotted as I haven't fully piped anything.

    One question I haven't resolved is how to introduce chemicals into the system should they be needed.

    Pictures forthcoming when I get a little further along.
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