Hello all. In my system I'll be using a 3-speed pump on my heat load loop and I just have a single load loop (water to air exchanger). I've done all the pressure drop calculations and know what pump to use based on my loop length (160') and pipe size (1 1/4"), but I'm also considering installing a flow meter so that I can pick the best pump speed based on real data rather than pump curves. Would it be just as good to set the pump speed based on the temperature drop across the exchanger? If I do decide to go with a flow meter, does anyone have information about sources for inexpensive rotameters? One related question I have is about the best way to plumb my planned side-arm exchanger. My water heater is located next to the furnace that will have the water-air exchanger. Should I plumb the side-arm in parallel with the water-air exchanger or in series after the water-air exchanger? I'm wondering if the temperature of the circulating fluid will still be high enough after passing through the water-air exchanger to provide enough BTUs to the sidearm exchanger. If it is in series the sidearm would receive flow whenever the house calls for heat, which is not optimal but very simple. If I run it in parallel I could also either use part of the flow whenever the house calls for heat, or I could get much more complicated and install a couple of zone valves and control system and have the circulating pump turn on if either the house or DHW needs heat. Opinions? Thanks for your help.