Need some advice

tommyoil

I am considering repiping my Weil-McClain CGI 5 Boiler. I have never done primary/secondary before and am apprehensive about trying something new on someone besides myself. Currently running 4 heating zones and a Gold Plus 40. All zones using 007's. Piped in the standard pumping away fashion with a Spirovent, all circs on supply, Taco 506 exp switching relay. Zone one/ First floor is monoflo (1-1/4" main with 1-1/4" x 3/4" monoflo tees) with sun rads. Zone two is sun porch with Slant fin 30 (approx. 20'). Zone 3 is second floor S/F 30 as well. Zone 4 is basement(2 nickle plated rads) And zone 5 is the indirect. Would like to do primary/secondary with outdoor re set and all the bells and whistles. The only primary/secondary I have seen is in pics here on the wall. Some pics look better than others, but I like the idea of cutting my fuel bill even more than I have already. Where do I begin? Can someone offer some diagrams and some instruction? Doing the actual work will not be problem, but I need to know what to look out for with regard to do's and dont's. I lead a very sheltered life with regard to piping hot water boilers. I would like to break the ice and do my own home first before I try it elsewhere. I'll be my own crash test dummy so I can grasp the theory of primary secondary. I'm really anxious to get this project underway. Where do I begin? If I cant get any advice here, I probably will not make the attempt. Been reading "Primary secondary made easy" nightly but still am not comfortable until I either work a job first to see whats what, or hear from more experienced installers. I guess chicken would be a better word. Any and all input is greatly appreciated. Thank you gentlemen.
Tommy

Unknown

Start with the numbers

I start by arranging the zones in order of water temperature. The hottest first, I'd go indirect, then monoflow, then baseboard upstairs, then baseboard downstairs, and last the rads in the basement.

The next thing I'd do is figure exactly the Delta T of each zone, as it is piped and pumped. This is important in figuring primary loop size, later.

Not counting the indirect, if each zone were to drop the primary loop 10° F, the total delta T for the primary loop would be 40° F, so the pump and pipe size would be HALF the size as they would in a 20° delta T. With fewer zones running, you are in even better shape with this small pump and pipe arrangement.

Don't assume a large delta T. If it isn't there, the piping might become undersized as you plan it.

We have a 100,000 input boiler here at the factory, with an output of 80,000, that has four zones on it, each 20,000 BTUH.

Each zone is piped 3/4" for 4 GPM. The primary loop handles 80,000 BTUH at a 40° delta T. That turns out to be 3/4" (4 gpm) primary loop piping and a 007 is almost TOO BIG for the primary pump.

That's a 3/4" primary loop feeding 4 3/4" secondary loops, and the boiler just digs in and runs.

Do it on paper, first. See how it looks.

Noel