I've been trying to figure out proper boiler/pump/line sizing and just how to do this for years. Figured i'd come on here and look but I need a pro status to even look in that section... I know how to design the system... I just don't get how I figure out what size my lines need to be or what size my pumps need to be....every time I search for pump sizing i'm attacked by pages and pages of pump curve graphs and really garbage explanations (i have a feeling i'm missing something really basic/easy, but I just don't know)... I even signed up for a pump sizing course a few years ago but not enough people signed up... you'd think they'd teach this stuff in school but they really don't... they just teach you the basics in schools so you don't seem like a complete moron when your done. I still have all my books/modules and alot of extra reading material... (i'm really not stupid, I've just had to learn everything on my own since I left school, never had a 'good' manager or a relative in the business and my teacher was a [figure it out yourself, no ones gonna help you in the field] kinda guy) So anyway when I start searching on how to size my lines etc I end up getting to pump head/pressure n' then i'm overwhelmed/lost... The company I used to work for would install cast iron boilers and the manufacturer would just send them "a few random pumps" and because it was all cast iron it wouldn't crack if the return temperature wasn't set right, Boiler system line/pump sizing has been one of the worst things to try and learn on my own... manufacturers just seem to want to push there product out the door or want to see my boiler system design. I've just been telling people that I don't install boilers over the years but i'm running into so many houses in my area that NEED boilers... there's no way to install ductwork in alot of these places and i'm losing customers because of it. ANY help would be appreciated, my email is Email Address Removed if you wanted to message me directly.