windyhill4.2 wrote:Well,i am no expert on heating systems,i did design & install our current system with no professional help.We have an OWB heating 3 buildings & DHW for 2 houses all using 1 " Pex, including 1 pex pair that is over 500' till water gets back to the stove,that 500' run heats 1 hard to heat house & DHW & then goes on to #2 house to do the DHW b4 returning to the stove,with a Taco 007 circulator,we've been doing this since Sept. 06,also 1" pex to #2 house 160' round trip for heating,also 1"pex 160' round trip to our repair shop for lots,& lots of heat,no problems with heating ability or low water temps in 1" pex,apparently i should have used 4" pex (BIGGER IS BETTER). Where's the backhoe?,gotta tear it all up & go bigger ,sorry i don't follow that logic,but unfortunately we are heating with wood so maybe coal needs bigger pex???????????????????
The "logic" is that you size the pipe and pump according to the load. Bigger is NOT better, more like "as big as necessary, as small as possible".
Just because something works for one house doesn't mean it will work for another. Whatever house you are heating has a heat load within the capabilities of your system...great. I bet if you were heating a spray-foam insulated doghouse with that OWB you wouldn't have used the same size pipe or pump.
True story - Last winter I had to help out a friend that was sitting in a cold house getting the death glare from his wife...imagine spending 10k to put a coal boiler in a detached garage only to find out that the 1" pex and Taco circulator he used was not adequate to move the heat to the house. The boiler was sitting in the garage at 200 degrees, ready to do its job but the system couldn't move the heat to the house. The flow rate was too low, and the radiation in the house could not get above 160 degrees on a subzero day. I had him swap the circulator to a Taco 011, and the system in the house promptly came up to 180 degrees and the house reached the thermostat setting. It still struggles on the -20 days, but at least he isn't getting the death glare any more. To use your statement, if he wants to get more heat into the house he needs to go get a backhoe and go bigger. If he had used 1.25" in the beginning, he could be using less electric to run the circulator and get the same or more heat to the house.
That reminds me, when looking at the cost of a system, make sure you pencil out the cost of running the circulators for 10 years or so.