Need info on black pipe installation for a new twin boiler install

Comments

• Alan (California Radiant) Forbes Member Posts: 2,625

  August 2020

  Sounds great! I like old school.

  • Do you have a lead-lag control in mind to control the boilers?
    

  • What model boilers will you be using? They must be very small, i.e. 80,000 BTU each?
    

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• DCastle Member Posts: 15

  August 2020

  Thanks, Alan: one boiler is Weil-McLain @61K BTU, the other is a New Yorker rated @59K BTU, Where can I read about "lead-lag control" and please describe?? Once I have my plans finalized, I'm going to post them here, Thanks again, Dale

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• DCastle Member Posts: 15

  August 2020

  Also, and again: this is to everyone: Maybe there is a good book on plumbing with black pipe and fittings? Or maybe some source online? Thanks, Dale

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• EBEBRATT-Ed Member Posts: 8,066

  August 2020

  I wouldn't use forged fittings they would be very expensive.
  
  Personally for water I would use sweat copper but black fittings are fine. Your old system probably has cast iron fittings and malleable iron fittings are also acceptable. Any reputable P & H supply house in your area should have the right fittings. Personally I would stay away from the big box stores and Chinease fittings and look for Ward or Anvil brand fittings
  
  So if you know how to thread and use wrenches what information are you looking for? Seems to me you need a piping diagram

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• Alan (California Radiant) Forbes Member Posts: 2,625

  August 2020 edited August 2020

  There was a time when splitting the load between two boilers made sense, but with the advent of modulating gas valves, I don't see it done, at least, not on a small residential scale.
  
  Having never installed two boilers on one system before, I can only tell you the small amount of information I've gleaned over the years and perhaps others with more experience will chime in where I've fallen short.
  
  Ideally, you turn on one boiler on a call for heat and if that boiler can't reach setpoint, the other boiler is fired. A 2-stage thermostat can do this by sensing the time it takes the air temperature to respond to a call for heat. Alternatively, a lead-lag boiler control can do this by monitoring the return water temperature. The benefit of a lead-lag control is that it will alternate boilers to reduce wear.

  Often wrong, never in doubt.
  
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• STEVEusaPA Member Posts: 4,733

  August 2020

  Read thru these. You'll have all the info you could possibly need:
  https://www.caleffi.com/usa/en-us/technical-magazine

  steve

  

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• DCastle Member Posts: 15

  September 2020

  Thanks so much again, Alan: I decided on two high-mass boilers as opposed to a condensing boiler for a few reasons: As I've said before, I'm a home handyman, and I lack experience with modern mod-con condensing boilers, also they are relatively new (especially compared to high mass boilers, that have been around for app 150 yrs). They are extremely expensive, I've heard that they have component failure problems sometimes semi-annually on the order of $200-400 and they are somewhat noisy. Also, I mentioned before, my system is 111 year old converted gravity system with 137 gallons of very diry, rusty water and I don't feel (even with my Spiro-Trap) that circulating this water through narrow "heat-exchanger" passages is a wise idea. I bought these two boilers from private sellers, some three years ago, and, at least at that time (on a Heating Help post somewhere) my opinions on high mass vs. low mass boilers agreed with about 50 % of the readership.
  
  
  
  

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• EdTheHeaterMan Member Posts: 1,590

  September 2020 edited September 2020

  @DCastle
  Go with what you know!
  Lead-Lag is a good idea, but you can set up analog aquastats to keep it simple. If you add a quick connect (extension cord male and female) to the burner control... you can just switch plugs each year to make boiler B the lead boiler in odd years and boiler A in even years.
  
  You got This!
  

  Edward Young
  Retired HVAC Contractor from So. Jersey Shore.
  Cleaned & services first oil heating system at age 16
  Specialized in Oil Heat and Hydronics where the competition did Gas Warm Air
  
  If you make an expensive repair and the same problem happens, What will you check next?

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• DCastle Member Posts: 15

  September 2020

  Thanks for the encouragement, Ed! I crave simplicity, I like your idea, but I don't grasp it; could you make a sketch- schematic or diagram to help me understand better?
  
  Thanks, Dale

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• EBEBRATT-Ed Member Posts: 8,066

  September 2020

  @DCastle
  You can make your own lead lag system with 2 aquastats, two spdt switches and 2 relays. I will make a diagram and post it

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• EBEBRATT-Ed Member Posts: 8,066

  September 2020

  @DCastle
  
  I posted the lead lag drawing in another thread "cheap lead lag system" if your interested

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• DCastle Member Posts: 15

  September 2020

  Thanks, Ed,
  Dale

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