Dual Primary vs Primary/Secondary Loop

[duc852]

My house is a long 1-story with 2 furnaces on either end of the house. I'll be running Pex into the house through a single access point, and then on to each furnace separately.

Any advice on whether I should use a Primary loop into the house, and then 2 secondary loops to each furnace, or run 2 separate primary loops from the OWB to each furnace? I am more concerned with heating efficiency rather than the cost of the underground pipe.

thx for thoughts.

 

[Jacon Construction]

I’d use a boiler/primary into the house, then a separate supply and return to each furnace off the primary with closely spaced Ts.

You could also feed into a 2” manifold, feed both furnaces from the manifold and have future take offs for DHW, spa, slab heating etc etc.

 

[Jacon Construction]

I think which ever way you go will be good.

 

[duc852]

Thanks a lot for the reply. I've gotten the same input from a few sources now so I think this is the way I'll go. Of course, we only want to dig that trench once, so it was worth a little extra consideration imo.

 

[sloeffle]

If cost isn't an issue I'd bury 1 1/4" or maybe even 1 1/2" pipe, especially if you are far away. Or maybe even two runs of 1" pipe. With two furnaces, I doubt 1" at 8GPM max will be able to satisfy the full load of both furnaces on the coldest day(s).