I work in the commercial HVAC industry. We perform mechanical HVAC service and installations, but for large commercial buildings (hospitals/large office buildings, etc). We don't get involved in the small stuff. Well, now I'm looking for a new boiler for a house I recently bought and have no history on. The system in this house resembles a commercial system and I have removed an 80% cast iron boiler (95K IBR) due to a broken cast iron section. I could fix it but now seems like a perfect time to repl. There is radiant in-floor heat throughout the house which I assume is the first stage of heat, then a 5 ton fan coil unit with hot water reheat (and A/C), then 40G indirect domestic HW tank. An Erie Boiler Boss simple DDC boiler controller controlled the boiler previously and an Erie Zonetrak controller managed the individual zones and pumps. One large room has a glass curtain wall (low-e commercial glass) some 30 feet across and 18 feet tall! Great view, but will be the main energy hog in this house. The rest may not be too bad as it contains spray foam insulation. There is a main circulator pump in a primary/secondary arangement, and a pump for the slab radiant, another for the DHW and one for the AHU reheat coil. It's a pretty neat little system. I have narrowed my search down to the Triangle Tube (110 or 175) or the Burnham Alpine (105 or 150) pending heat load calcs this weekend. These are both high efficiency condensing hot water boilers. They use different types of heat exchanger technologies. I can buy both locally from suppliers I typically work with (at a decent price). I will install myself. I am going to perform heat load calcs this weekend, but between the two boilers I've listed, what are your thoughts? I spoke to one outfit that installs a lot of residential and they had great things to say about the TT. They did not have any experience with the Burnham Alpine to say one way or another. My supplier that sells the Burnhams says they've had great luck with the Alpine. The Alpine has a 5:1 turndown and many of the main parts are off-the-shelf components easily obtainable, for both I guess. The TT has a 3:1 and getting parts for this will be easy as well as we deal with that supplier a lot. I like that the Alpine can be had with a concentric venting option but it comes out the back, but the water connections are on the side that would make installation easier. However, the inputs on the Burnham are only 1" (my current main piping at boiler is 1 1/4) and it looks like I might possibly have to up-size my pump, perhaps to gain greater velocity through the boiler? Conversely the TT vents out the top and since the mech room is below grade that's a hugely nice feature (Mech Rm is only 4ft deep crawl space) ...and it has 1 1/4 connections and holds more water in the heat exchanger than the Burnham. Ok, beyond all that, does anyone have any thoughts between the two boilers and possibly point out factors that I may not have thought about which might make one a better fit than the other? This is my first post here, BTW. Thanks in advance. Truely appreciate your help. Gruni14

The System Piping diagram is [URL="http://s3.pexsupply.com/manuals/1253196590775/17467_PROD_FILE.pdf"]here[/URL] I have three questions concerning the System Piping diagram for my new boiler: 1) The System Piping diagram for this boiler shows an connection with an isolation valve between the return and supply, and is shown with an arrow pointed toward the supply side. What is the purpose of having this valve? My current boiler piping has no such valve. 2) How important is the flow control valve on the return side? Is that only to keep heated water from rising after the boiler shuts off? My current boiler does not have a flow control valve. 3) My system uses three zone valves. How important is the pressure-reducing valve shown between the supply and return? My zone valves complete the call for heat only when fully open, so it does not seem that I would need the pressure-reducing valve, unless that is needed for the case when only one zone is open and the pump is supplying too much pressure (new pump is a B&G Red Fox NRF-22, pump on existing boiler is a B&G Series #100). My current boiler does not have a pressure-reducing valve. Thanks, Eric Peterson