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Proposal for Boiler and Reverse Indirect

D107
D107 Member Posts: 1,777
So having decided to go cast iron rather than deal with the various mod-con issues, I have received the following proposal from a very competent installer. I have to choose between the Peerless MI85-03, Buderus GC144-3 and Burnham ES23. I am leaning towards the Peerless not only because of its extra-thick cast iron construction, reputation, parts availability and because the 60Kbtu firing rate, 51K btu DOE and 44Kbtu net IBR is closest in line with my 38Kbtu heat loss, which is likely actually a bit lower than that. Trying to keep the system simple.

I’m glad to receive your opinions on this. (See attached rough diagram.)


Existing System info:
Lower Hudson Valley, NY, 1924 Colonial, 3-zone gravity converted system into series ¾” copper.
Main and 2nd Floor, cast iron rads more than sufficient EDR; basement baseboard less than sufficient EDR.
6” spray foam insulation under roof rafters; 4 inch spray foam gable walls; 4 inch dense pack cellulose in house walls.
House Loss @Design Temp: 38,640. Total Existing House Gain @Design Temp: 34,480btu
.
Lowest loss Zone 2 @50ºF 1349BTUs.
68º indoor set temp; design temp 10degrees. Supply-return ∆T 20º;
Current boiler is 1981 WM 210Kbtu, de-rated to fire at 170Kbtu. Most cycles less than five minutes. HWH by direct 30kbtu 50 gallon HWH.
System water is hard and fairly high in chlorides.

Proposal
(Work done by others is not included in the estimate: Installation of a chimney liner.)

• Cut out and remove the existing hot water boiler, hot water heater and all the existing near boiler piping.
• Pour a new 4" depth x 24" wide x 24" length concrete pad for the Burnham ES23.
Install either a Burnham ES23, Peerless MI85-03 SPARK-WPC-N or the Buderus GC144-3 cast iron
hot water boiler with near boiler piping and controls containing:
• Isolation drain and purge valves.

• Air and dirt magnet separators.

• High efficient ECM Delta T VT2218 circulating pump with isolation pump flanges.
• High efficient ECM circulating pump with isolation pump flanges.
 _________
• 3- Low Energy draw zone valves.

• 3- Quicksetter flow control valves.

• Hydronic expansion tank with support bracket.

• Back flow preventer and auto regulator combo unit.

• Inline sediment and De-mineralized filters.

• Zone Control Box.

• Outdoor Reset Control.
Pipe the Flue pipe into the chimney.
Install a Turbomax 23 Reverse Indirect Tank.
• Cold and Hot water potable water side:
• Isolation valves.
• Thermostatic mixing valve
• Thermal expansion tank with support bracket.
• Set up with DHW priority with 30min max before returning to heat call.
(It will be piped primary/secondary via the Turbomax working as a buffer tank. The water temps will be set at a minimum of 160 on the supply side. DHW yield ––given mixdown to 120––will be 88 gallons for the 1st hour and 75 gallons continuous flow.

• Run an 18-gauge wire from the boiler to the north side of the house to install the outdoor sensor.
• Pipe the 3/4" cold and hot water lines from the existing location of the old water heater to the new location of the new Turbomax Reverse Indirect Tank.
• Install a Field Control CAS- 4 Fan In A Can Combustion In Take Unit.

• Pipe 4"x 10' 18 gauge galvanized pipe from the fan in a can to the ouside of the house with a termination hood.

• Wire the Fan In A Can with boiler.
• Fill the heating system with water and system cleaner.

• Power flush the system with Fernox F5 and remove any debris that is in the radiators and baseboard.

• Re-fill the heating system with de-mineralized water and Fernox F1 conditioner/inhibitor and power purge the air out of the entire heating system (radiator, baseboard).
• Perform a combustion analysis and make any adjustment if needed to insure the boiler is within the manufacturers combustion numbers.
Questions, Issues:
• I regret that we can’t get supply temp down to 150, but contractor wants to ensure return temps don’t get below 130. Were this a modcon and with our fairly well insulated house we’d be looking at 140º supply temps on a design day of 10ºF. Contractor says to get the lower temps it would have to piped like an injection setup but still the boiler water would have to be at a minimum of 160. Obviously ODR is kind of limited here. We could add an ODR mixing device to get heating supply temp down.

• Concern about Taco ECM VT-2218 overpumping. By estimated head loss method, I measure 12ft head @4gpm for the longest Zone 2; by actual calculated method based on the 1gpm required, head loss for Zone 2 is .711ft of head. Perhaps all this falls within a general range and should not be a concern. Current circs with oversized boiler are Grundfos 3-speed Brute for Basement Zone and Zone 2—both on slowest setting––and Taco 007 for Zone 1.

Comments

  • HVACNUT
    HVACNUT Member Posts: 4,209
    Is that your oil Buderus in the pic? Why get rid of it? It doesnt seem cost effective to convert to an atmospheric gas boiler if that's yours.
    D107
  • hot_rod
    hot_rod Member Posts: 15,064
    I'm not a huge fan of constrained delta T operation, not ideal for high mass emitters or odr control, here is some reading detailing how heat transfer works. A delta P is a good choice for zoned systems either with valves, or TRVs if that is an option.

    https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_23.pdf

    Pages 22-24 talk about constrained operation
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    D107
  • D107
    D107 Member Posts: 1,777
    @HVACNUT No, that user photo Buderus is from another house--that's 12 years old and going strong. My current boiler is a 1981 WM CGM Seriers 7. @hot rod Thanks will have to check that out. This seems to be an ongoing debate within the industry.
  • D107
    D107 Member Posts: 1,777
    edited September 2018
    @hot rod Also, I guess you are considering my proposed system to be on the 'high mass' side. Peerless contains about 12 gallons I think, plus the turbomax 23 (26 gallons) as buffer, along with cast iron rads in two of the three zones(?)
  • hot_rod
    hot_rod Member Posts: 15,064
    Yes, the cast iron rads both weight and water content would be considered on the high mass side. Like a concrete slab, they cannot respond to temperature change quickly.

    The load calc represents a point in time, as conditions like wind, direction, wind speed, temperature, sun, appliance use, occupancy use all constantly change, so does the load. heat emitters sense the changing condition, respond as does the delta.

    So an ideal heating system would also be dynamic, not constrained. Regulating output by flow is not linear, like temperature modulation, as seen in an ODR graph, temperature modulation is straight pretty much a straight line. Flow modulation gets you that bell shaped curve.

    So constrained delta T operation prevents the system form doing exactly what it needs to accurately meet the flow and at the bottom end of the curve, it becomes a heat output limiting device.

    Looks like you are doing plenty research, you should end up with a nice system.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    D107
  • Zman
    Zman Member Posts: 7,005
    I like where you are going with this.
    I agree with hotrod that the high mass radiators could use some tempering. They may also drag down the system temp when they come on line.
    Are you thinking about a domestic water priority mode?

    It is unfortunate that Turbomax does not have a chart or online calculator that shows output at different water temps

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    D107
  • Danny Scully
    Danny Scully Member Posts: 1,329
    @Zman, Turbomax does have that chart right within their brouchure, unless I’m misunderstanding you. It shows output at 110, 140, and 180.
    D107
  • D107
    D107 Member Posts: 1,777
    edited September 2018
    @Zman @Danny Scully See attached Turbomax ratings. Somewhere I thought I saw the Turbomax 23 was discontinued; not sure how the Turbomax 24 differs. When they say based on boiler net output, that's net IBR, yes? though couldn't we assume DOE output since piping and startup losses would not really apply as much with DHW as with heating? Peerless DOE output is 51mbh.

    Also @Zman yes, DHW priority up to 30 minutes.

    Any thoughts on the boiler choices?

    finally uploaded turbomax chart large enough to read.


  • hot_rod
    hot_rod Member Posts: 15,064
    David107 said:

    @Zman @Danny Scully See attached Turbomax ratings. Somewhere I thought I saw the Turbomax 23 was discontinued; not sure how the Turbomax 24 differs. When they say based on boiler net output, that's net IBR, yes? though couldn't we assume DOE output since piping and startup losses would not really apply as much with DHW as with heating? Peerless DOE output is 51mbh.

    Also @Zman yes, DHW priority up to 30 minutes.

    Any thoughts on the boiler choices?

    finally uploaded turbomax chart large enough to read.

    A bit more coil surface in the 24, 26.2 feet compared to 19.6 in the TurboMax 23.

    I think the model numbers have to do with number of coils and the size of the coil.




    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    D107
  • hot_rod
    hot_rod Member Posts: 15,064
    Remember once you pull the tank temperature down, you kinda of have a tankless WH, so the 50K boiler might make about 1 gpm continuously.

    You push the envelop when you run the tanks at a lower temperature and have a small output boiler :) If you have any large dump loads, there may be some wait time for recovery.

    A DHW production, a rule of thumb is 50K will generate about 1 gpm as an instantanous load, so generally the smallest tankless are around 110- 120,000 able to supplying about 2 gpm at 70° rise.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    D107
  • Tim Potter
    Tim Potter Member Posts: 272
    edited September 2018
    I have a cast iron boiler at our rental house at the Winter Park ski area. I use a danfos thermic valve, similar to the https://www.caleffi.com/sites/default/files/file/na10292_r1.pdf
    to protect the boiler, & I upsized the Turbomax to the 44 series to make sure you could not outrun the boiler and cold shock it. The setup is stupid simple & never run out of hot water.
    Winter Park, CO & Lenexa, KS
    D107
  • D107
    D107 Member Posts: 1,777
    Thanks for the answers folks. I think aside from trying to find a smaller circ, and deciding on a ∆T or P ECM circ, I would only ask additionally if others think that a thermic valve or an upsized Turbomax is warranted to prevent cold shocking the boiler and provide greater HW supply? I've had no comments on boiler choices so I'll assume any of the three would be OK.