I'm getting a real good real world lesson on Low mass boilers and Low mass potable water heaters in Buildings and lately in a 500 room hotel. They are cracked up to be the cat's meow and a lot of Engineers have no idea of how to design a system that is of proper size and application. I don't think I have ever met an undersized low mass boiler in a commercial setting. There are some nice Mod Con boilers that never reach their potential. There are potable water tube in shells that heat large loops and the temps are all over the place and can't keep up with loads and over heat under no load. Hydronics a field apart.
I don't think I ever see under sized either but a job I'm working on now is close. 2 p-k modu fire boilers 1 million BTU each. At 20F one boiler is running flat out to maintain temp. Tomorrow is supposed to be a high of zero with wind and I have to shut one down to fix a leak and clean it. The building will probably fall behind a bit. I love Hydronics, nothing like getting a messed up system and helping redesign it and make it work like it's supposed to. I see a lot of design build smaller commercial stuff and get to see some real screw ups.
As a guy who sells a lot of desgin build work, and loves mod cons, I can tell you engineers in general dont get it. This is why I lay out my jobs, and give everything to one of the engineers I use for review and stamp. I get exactly what I want that way and the jobs go better. I like when they trey ot use a cast iron condensing boiler, you know the one that they make the casting at the rear twice as thick as the rest in order to deal with the condensate? yeah right. those fuggers fail A LOT. for me, its a barrage of triangle tube or lochinvars designed to handle condensate. Like a recent project at a school where the engineer wanted a nine section weil rated at 1.5, and we used threee 399's which are still a little overkill, but give them redundancy in the event one doesnt fire for some reason.
