Coffee with Caleffi: Part 2 – Proper Component Selection for Boilers and Application Fundamentals

Training and education manager leads technical webinar for contractors, designers and wholesalers
Coffee with Caleffi: Part 2 – Proper Component Selection for Boilers and Application Fundamentals
Bob "Hot Rod" Rohr

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Bob “Hot Rod” Rohr, training and education manager for Caleffi Hydronic Solutions, leads a free webinar “Part 2: Proper Component Selection for Boilers and Application Fundamentals” from noon to 1 p.m. CT Thursday, Dec. 17. There is no cost to participate in the webinar, although registration is required.

Topics for the webinar include:

  • How do renewable energy (RE) fuel source systems differ from traditional fuel source systems?
  • What are the more common RE systems? What RE system components are manufactured differently than traditional? Why?
  • What are popular combinations of RE and non-RE systems?
  • What unique component selection mistakes can occur in RE systems? Operation mistakes?
  • I hear "storage is the key" when designing with RE, can you explain?

You’ve chosen your system boiler. Now, how do you ensure the boiler’s long life and optimize the system’s overall performance? How do you design your system to keep it in tip-top shape? In last month’s Coffee with Caleffi presentation, Rohr discussed key components used in hydronic boiler systems, how they work and their application considerations.

The following is a question-and-answer session from the webinar, “Part 1 – Proper Component Selection for Boilers and Application Fundamentals.”

Q: I am installing the Caleffi SEP4. The boiler is a Viessmann Vitodens 200, 26kW (88,716 Btu). I will be having four zone valves for different heating zones in the property. At the end of the webinar, one of the questions was about the pump, whether it’s best on the flow or return. In answering the question the expansion vessel was mentioned and it was said the best position for the expansion vessel is at a point of no pressure change. I found this comment very interesting. I would like to know where you suggest the expansion vessel is best placed on my project with the SEP4. The boiler has an internal expansion vessel with a volume of 12L (2.64 gallon). I will leave this to take care of the expansion within the boiler side of the hydraulic separator. I would like to know the best position for the expansion vessel on the heating side of the hydraulic separator. I’ve attached a sketch showing my proposed system layout. It would be great if you could suggest the best position and why this is the best position for the expansion vessel. Every day is a school day!

A: I would suggest just one expansion tank. Is the one in the boiler large enough to handle the entire system expansion? Maybe delete that one and add the properly sized one to the SEP4. Having two expansion tanks sort of confuses the hydraulics, as it tries to reference two points of no pressure change PONPC.

On the SEP4 we show the following options. The third option with “X” would work, but dirt can fall down out of the SEP4 and get onto the diaphragm in the tank and cause wear.

Q: What impact does near boiler piping design have on efficiency?

A: The efficiency is primarily a function of burner setup, return water temperature and cycling. If the design impacts cycling (improper hydraulic separation, for example) or if the design impacts the return water temperature (over pumping the boiler loop, for example), then there will be a reduction in boiler efficiency.

Q: In other presentations, I have seen that they recommend the pumps supply into the heat source/boiler and not draw out of the heat source. What are the advantages/disadvantages of each?

A: The boiler Bob showed was a high mass boiler, and not a condensing boiler. For a condensing many manufacturers will recommend pumping into the boiler to raise the temperature water can boil ... so it a way to minimize flashing.

Q: Is it possible to add the magnetic band to existing DIRTCAL Separators? Is the magnetic sold separately? Caleffi online supplier '"" says no. Thanks.

A: We are considering adding an accessory where the bottom of the dirt separator can be field converted to magnetic in the brass 1/2- to 2-inch size in 2016. Not 100 percent decided, but very likely.

Q: On the high flow manifolds (snow melt), are the threads 3/4-inch BST or NPT?

A: Supply and return are 1 1/4-inch NPT. Loop connections are our standard 3/4-inch M for compatibility with our standard PEX fittings.

Last month’s webinar, “Part 1 – Proper Component Selection for Boilers and Application Fundamentals,” can be viewed below:


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