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Lochinvar/Caleffi Mechanical Schematic: Whats wrong with it? Pics attached

Hi guys, thanks for all the great knowledge found on the forum. After a lot of back and forth with the pro's in my area, I've decided to go with a lochinvar boiler/indirect HW setup. My pex lines are all installed on 3 floors and terminate in the basement. I've been reading the caleffi idronics series, and talked to a tech rep last week, and I think I have a system figured out........ My questions. 1. I've put a caleffi hydrolic separator in the indirectWH/ main loop.... is that a bad idea? as I have hydrolic separators in the caleffi mixing stations and there's a pump on the loop? 2. What pump should I use for the indirect/main loop? thanks for any ideas! Pics attached



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Comments
The PEX looks like a mess, to out it nicely
The way you have this drawn, the indirect will not work. The water will just shortcut through the separator and very little will go to the indirect. Water is lazy and will take the path of least resistance.
What are the design temps of your radiant loops? Why the mixing? If the radiant temps are close to each other you can do domestic priority and outdoor reset control for heating. The system will be more efficient and house more comfortable.
Albert Einstein
Albert Einstein
Those Caleffi pump stations do have a LLH built in, so you need to eliminate that also if you use a hydraulic separator.
Stick with the Sep 4, it solves a lot of issues.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
If they can run at the same temp, you could lose the mixing valves and really simplify things.
Albert Einstein
The boiler will kick up for DHW on it's own, wire the indirect to DHW contacts in the boiler. No need to run it at high temperature and mix down.
Depending on the Lochinvar minimun flow rate, you may be able to direct pipe. If you are individually zoning at the manifold, you may not meed boiler minimum flow requirement, so a hydrosep would still be a good option.
I like the sep option so you get all 4 functions in a neat clean piping. I also like the indirect before the sep for quick DHW, no need to heat the sep and piping for indirect call.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Control the DHW with priority and use the boiler's outdoor reset to control the heating water temp. No mixing valves required.
Albert Einstein
1: the boiler will be most efficient under two conditions, the lowest return temperature and lowest firing rate. Keeping below 130 will increase the efficiency a bit.
2: Running at low fire also as you expose a lot of boiler HX surface to a small flame.
Idronics 25 goes into good detail on both low operating temperatures as it relates to mod con efficiency, and also the details about outdoor reset.
Possibly you can run. the 105 and 90° zones at one temperature? Maybe 100°. need to get to design condition to know that.
One rule of thumb id if zone temperature requirements are within 10° of one another, no need to do additional mixing. You are a bit beyond that, but you load calc and design may have enough fudge that both would be fine with 100° SWT.
AND, if that is true, that boiler will be very efficient running 100° and lower for heating loads
You want to install the "System Sensor" from the boiler about 12" or more downstream from the hydro sep supply to the system. It will see an accurate "blend" temperature there.
Dial in the ODR and that system may run 80- 100° SWT it's entire life, that would be great!
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me