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Help me with the basics

THETRUCK454
THETRUCK454 Member Posts: 10
The basics:

House is not very big, 1100sqft ranch.  Current boiler is 23yr old oil fired Baisi Vega 4 section boiler that's listed at 110 MBH gross and 94 MBH net that's set up for direct vent.  Off it are three heating zones (master bed bath, second bathroom, and the rest of the house which is a second bedroom and open concept for the rest) and a 4th for an indirect hot water heater.  The heat load of the zones are very unbalanced.

I haven't done a heat load/loss calculation yet so specific sizing will come later, but I do know the current boiler is way oversized and short cycles constantly.  Also with two layers of R30 in the attic and a standard 2x6 wall I can't imagine the heat loss is high enough for that big of a boiler in this small of a house. 

I have natural gas on the street so I'm switching to that.  Trying to decide on a mod con vs traditional gas fired.  I was thinking mod con due to the ability to modulate for the small and unbalanced zones, but would they not have enough heat load to bring water temp down enough for the high efficiency boiler? 

Or should I go traditional gas fired with a buffer tank to combat the short cycling issue? 

I'm don't necessarily need l a "right answer", but I'd appreciate some input/advice on what to consider. 

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,335
    Mod Con Versus Cast Irin is a debate tha continues................there is no right or wrong answer. With 1100 Sq feet you probably need a boiler with 50,000 output.
  • hot_rod
    hot_rod Member Posts: 21,868
    What type of heat emitters?
    If you ballpark 25 btu/ sq ft it would be a 27,000 btu/ hr boiler.
    A 50k mod con turns down to 8K. Calculate the heat load, then a heat emitter output calc.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    GGrossEdTheHeaterMan
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,798
    The smallest mod cons turn down to 8kbtu and max out around 80. That’s the best you can do. You can electronically limit them to make the top end lower. 
  • pedmec
    pedmec Member Posts: 936
    i would recommend a boiler like a lochinvar knight. With the knight you can wire in the 3 zones directly to the boiler and you can adjust each zone to different heat outputs, meaning different loop temperatures. Having an unbalanced system could be caused by not having enough baseboard or too much. With each zone connected to the lochinvar smart control they can have different loop supply temperatures which can help the required BTU output.
    EdTheHeaterMan
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    hot_rod said:
    What type of heat emitters? If you ballpark 25 btu/ sq ft it would be a 27,000 btu/ hr boiler. A 50k mod con turns down to 8K. Calculate the heat load, then a heat emitter output calc.
    All of the rooms are the thin fin style baseboard.  The bathroom that's by itself is Ultra Fin radiant running at full boiler temp.

    pedmec said:
    i would recommend a boiler like a lochinvar knight. With the knight you can wire in the 3 zones directly to the boiler and you can adjust each zone to different heat outputs, meaning different loop temperatures. Having an unbalanced system could be caused by not having enough baseboard or too much. With each zone connected to the lochinvar smart control they can have different loop supply temperatures which can help the required BTU output.
    Are there any other similar mod cons that are good quality you would recommend?

    The lochinvar knight 55k & 85k are 43-3/8" tall and my basement is only 50" to the bottom of the floor joist.  Lochinvar recommends 24" of space above for servicing reasons so not sure how much I would get myself in trouble for putting it in my basement. 
  • hot_rod
    hot_rod Member Posts: 21,868
    The Lochinvar Nobel is a bit more compact. 6" clearance from the top. Service will be a neck breaker. It doesn't has as many control features, probably an imported fire tube HX from Korea.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • pedmec
    pedmec Member Posts: 936
    @hot_rod lochinvar noble fire tube heat exchangers are made by a AIC.
  • Teemok
    Teemok Member, Email Confirmation Posts: 483
    You might check out the IBC HC. The Noble is a arguably a better performer but it is also a stainless steel fire tube. As good as they are, they have no great heat exchanger cleaning option, so long term longevity is questionable. Especially if your application happens to tends to clog fire tubes. The heat exchanger of the HC is proven and is easily cleanable. It doesn't sound like you'll be doing much condensing. The aluminum block hx provides some buffering effect but the burner will only go down to 13.5k input. Installed well, I've found these Intergas HX's in good shape 15 years old. 10hx/5parts warranty isn't bad. The Ibc SL 10-85 is a good boiler.
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    hot_rod said:
    The Lochinvar Nobel is a bit more compact. 6" clearance from the top. Service will be a neck breaker. It doesn't has as many control features, probably an imported fire tube HX from Korea.
    When it comes to service, why would you need that much room above?  I was watching YouTube videos of technicians working on Lochinvar Knights and at least in those videos did do anything that looked like they needed much clearance.  If it's just for install I can deal with the misery myself, just don't want to screw the technician that does the final setup or servicing.  I already curse the design engineers when I do any automotive/power sports work haha
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    edited February 18
    Based on the advice her and spending way too much time reading other threads here I've settled on a Lochinvar Noble 80k BTU and using a 40gal Bradford and White SS indirect.

    To help give you where I'm coming from skill wise is I'm just your avid homeowner DIY'er that so far between tearing an engine down to the short block to rebuild it or gutting and redesigning my kitchen/bathroom/master bedroom. So far I've managed to pull anything off with successful results although there has defiantly been some hard learned lessons and moments of panic along the way.

    The current boiler is set up with the heating zones below:

    Zone 1 is 36.3' of fin tube heating with 3/4" copper
    Zone 2 is 12.2' of fin tube heating with 3/4" copper
    Zone 3 uses ultrafin radiant with 1/2" pex with four runs of 9' with a total of 20 ultra fin pairs.
    Zone 4 is the indirect hot water heater.

    There is a single circulator that is on the return side with 4 zone valves.

    I haven't added up all the bends and restrictions to calculate flow, but I just looking at it tells me I should probably take out the zone valves and go with individual circulators due the huge variance in flow restriction. As it is now when only zone 3 calls for heat you can hear what I assume is too high water velocity cause by the single circulator going through that small loop.

    From reading the Noble installation manual it looks like they recommend a primary/secondary setup. What I'm having a hard time with is what circulators to use for the schematic below from Lochinvar. Bradford White recommends 14gpm through their tank, Lochinvar recommends a minimum 1gpm low fire, 3gpm at high fire, and max 17gpm. For the fin tube I believe the recommendation is 4gpm and I can't find anything for ultrafin. Do I use ECM CP circulators, or ECM delta T circulators or is it a combo of both?

    My initial thought was for the domestic hot water circulator and the boiler circulator I was leaning towards a Alpha1 15-55 and play with the CP settings and then use delta T circulators like the Taco VT2218 for each loop circulator? Is that a bad idea to mix and match circulator brands/types or is it more of a bad idea like using a small block Chevy in a Ford Mustang? Thanks for all the help as I learn more and more.

  • hot_rod
    hot_rod Member Posts: 21,868
    my suggestion.
    Boiler pipes to separator.
    DHW is parallel piped, as the Lochinvar drawing shows
    Zone with zone valves and single delta P circ, Grundfos 15-58E or Alpha 15-58.
    These replace the Alpha 15-55 models

    Boiler can run on outdoor reset.

    The zone pump will modulate as the loads call on and off. So never over pumped.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    hot_rod said:
    my suggestion. Boiler pipes to separator. DHW is parallel piped, as the Lochinvar drawing shows Zone with zone valves and single delta P circ, Grundfos 15-58E or Alpha 15-58. These replace the Alpha 15-55 models Boiler can run on outdoor reset. The zone pump will modulate as the loads call on and off. So never over pumped.
    Thank you for the quick response and drawings!

    If I were to use Taco Sentry Zone Valves, am I correct I don't need a zone controller as I'd wire each thermostat to each sentry ZV and then tie them back into the Noble
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,590
    edited February 18


    Thank you for the quick response and drawings!

    If I were to use Taco Sentry Zone Valves, am I correct I don't need a zone controller as I'd wire each thermostat to each sentry ZV and then tie them back into the Noble

    With any zone valve you do not need to have a zone control panel. I just find that they make troubleshooting easy ten years from now when there is a problem. Several advantages: The call for heat is indicated by an LED, The open valve and a closed end switch is indicated by an LED.
    With those two lights on, the reason you have no heat in that zone is not electrical, Maybe look for air in the pipes.

    I remember an electrician apprentice that had no heat as a result of a frozen pipe. He actually destroyed a zone controller trying to “fix” the zone with “no heat” by swapping out wires and removable ice cube relays from the control so many times that one of the relay sockets from the board dislodged.

    WhenI I finally got there, I wired the circulator on the defective zone to run constantly, and then tried to purge air ... When I got no flow from the purge valve, I knew it was a frozen pipe. Found the frozen pipe (before it burst) and he has heat as soon as I hit it with the heat gun. I guess if you are a hammer everything looks like a nail/ If you are an electrician….

    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    GGross
  • You don't need a zone valve control, but it will make wiring and future troubleshooting easy. Use either a Taco or Caleffi.

    IBC has a "SL" series that has side tappings which will make piping much easier in tight spaces. It's more expensive, but I like the fire tube HX as it's self-cleaning.

    But why a mod-con boiler with a copper fin tube system? It will never condense and will have a short life (20 years) compared to an atmospheric boiler (40-60 years).

    Burnham has a model 202E that has an input of 38,000 BTU, but it looks as though 60" is the min. height to fit.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    EdTheHeaterMan
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    You don't need a zone valve control, but it will make wiring and future troubleshooting easy. Use either a Taco or Caleffi. IBC has a "SL" series that has side tappings which will make piping much easier in tight spaces. It's more expensive, but I like the fire tube HX as it's self-cleaning. But why a mod-con boiler with a copper fin tube system? It will never condense and will have a short life (20 years) compared to an atmospheric boiler (40-60 years). Burnham has a model 202E that has an input of 38,000 BTU, but it looks as though 60" is the min. height to fit.
    My thoughts for a modcon is the ability turn down as my zones are so small.  The current oil fired one just short cycles itself during the heating season.  Also the turndown ratio let's me some what have better hot water recovery.  I'm limited in size for an indirect and my wife loves to burn her skin off every shower... 
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,590
    edited February 18

    You don't need a zone valve control, but it will make wiring and future troubleshooting easy. Use either a Taco or Caleffi.

    IBC has a "SL" series that has side tappings which will make piping much easier in tight spaces. It's more expensive, but I like the fire tube HX as it's self-cleaning.

    But why a mod-con boiler with a copper fin tube system? It will never condense and will have a short life (20 years) compared to an atmospheric boiler (40-60 years).

    Burnham has a model 202E that has an input of 38,000 BTU, but it looks as though 60" is the min. height to fit.

    Selecting the boiler based on the lowest turn down ratio makes sense. It will be more expensive than the smallest cast iron boiler but it will greatly reduce the short cycling.

    As far as the IBC SL. not a good fit. you are looking for the smallest input boiler, not a "light commercial" with 260,000 max input. Is there a smaller SL?
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • @EdTheHeaterMan They have an SL10-85 G3 model that will modulate down to 10K BTU’s. 

    I had a 50,000 BTU Munchkin in my 1,200 [] house with a 50 gal. indirect for 15 years until the HX started leaking with plenty of DHW for me and the wife. 
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    EdTheHeaterMan
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,590
    edited February 19
    Do they still make the SL10-85? I only found the SL26-260 and larger in a google search. The 10-85 you mentioned would be great for the application.

    Still think the Lochinvar Knight is better for them, since you can connect their "Micro Zones" directly to the boiler's control, and the control's programming will better suit the situation
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    Alan (California Radiant) Forbes
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    hot_rod said:
    my suggestion. Boiler pipes to separator. DHW is parallel piped, as the Lochinvar drawing shows Zone with zone valves and single delta P circ, Grundfos 15-58E or Alpha 15-58. These replace the Alpha 15-55 models Boiler can run on outdoor reset. The zone pump will modulate as the loads call on and off. So never over pumped.


    Hotrod, for the hydraulic separator, I assume if use one with an air separator and magnetic filter built in that ok? 

    Should I also put an eliminator/mag filter in the loop going to the indirect hot water heater??  

  • hot_rod
    hot_rod Member Posts: 21,868
    edited February 19
    Yes a 4 in 1 sep will handle all the air, dirt, and magnetic particle removal.
    Add a purge valve on the piping from the indirect. Once it is purged the sep will handle any small air that gets around to the boiler and sep.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    Sorry to ask more questions, but I was reading the Noble install manual, great bed time read btw, and I stumbled across this 

    "If the space heating call for heat is active,  and the tank thermostat or sensor starts a DHW call for heat, the boiler will switch to the DHW mode. If programmed for normal DHW operation (not as a zone), the DHW pump will turn on first, then the boiler pump will turn off (boiler and DHW pump operation briefly overlap to ensure flow is maintained through the unit). This will divert the boiler’s outlet water from the heating system and send it to the tank coil instead. The control will then modulate to maintain the outlet temperature to the DHW boiler set point.

    The boiler pump will run whenever the burner is firing, unless the DHW is programmed for Normal Mode and the boiler is heating the DHW tank. It will continue to run for a short time after the burner turns off.  The system pump will run whenever there is a space heating call for heat demand. It may be programmed to run during a DHW call for heat when the DHW is programmed for Zone Mode. It will continue to run for a short time after the end of the heat demand. The system pump can be programmed to run continuously if desired, except during outdoor shutdown and/or a DHW call for heat."

    In your diagram wouldn't that basically dead head the DHW pump as the boiler pump would shut off during a DHW call?   Would I just move the boiler pump to upstream of the tee, just downstream of the return from the hydraulic separator?   That way both the boiler pump and the DHW are pushing into each side of the tee feeding the boiler return? 
  • hot_rod
    hot_rod Member Posts: 21,868
    In this example the DHW pump is in parallel with the boiler pump. During DHW call it flows through the boiler and the tank coil. So either pump flows through the boiler heating or DHW. Only one pump runs at a time.

    Really no difference between the Lochinvar drawing and mine as fare as piping.

    Pipe the indirect with 1' copper to get the full output of the boiler to the tank. Check valves downstream of both pumps. Or pumps with the integral checks.

    There are a number of adjustments available for DHW as you noted. You can also define a boiler supply temperature for the DHW call. The manual should show factory pre-sets and explain customization options.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    edited February 19
    Gotcha. 

    Another one, with the 1" 4 in 1 hydraulic separators, they all list a recommended flow of 10gpm.  Would I not exceed that through either the DWH(indirect recommended 14gpm and boiler has a max of 17 gpm) or if all three zones open up (or 4 if my wife gets the addition she wants)  Should I upsize to a 1-1/4 just for the separator? 

  • hot_rod
    hot_rod Member Posts: 21,868
    The flow to the indirect doesn’t ho through the sep, so if you piped and pumped the indirect for 14 gpm, no issue. An 80k boiler probably wouldn’t need more than  8 gpm or so,

    The sep sizes to the largest floe, either boiler or heating side,  unless you have s 140k or larger boiler, the 1” is adequate 
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • THETRUCK454
    THETRUCK454 Member Posts: 10
    Ok, I tried to add in more detail to the schematic. How does it look?



  • hot_rod
    hot_rod Member Posts: 21,868
    That looks good. Minimize the up and down piping, the return from the indirect, when actually installed try to eliminate high points that could trap air
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    THETRUCK454
  • If you add one hose bibb between the ball valve and the return of your last loop, you can purge all the loops from one location without having to move the hose.

    And if you had a hose bibb between the union and ball valve on the return side of the boiler, you can purge the indirect and boiler, again from one location.

    And I would add a bypass around the fill valve for a more forceful purging.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    hot_rodTHETRUCK454