i'm in the same situation. one installer told me the alpine has issues, and national grid will stop selling them in june 09. let's face it, the utility is contracting with burnham to buy trailer loads of boilers for oil to gas swaps, and hi efficiency is really not their goal. you get what you pay for, imho. i'm considering the wm155 ultra, upon recommendation of an installer. however, others, like triangle tube, buderus, veissman may be even better. the whole technology is so new, many installers simply don't have the sweat equity or knowledge. any installer will basically install what you want, as long as they make a sale/money. we're doing our research online, which we have to, and hopefully we can teach ourselves to make a wise choice. i dont think we can make too much of a mistake with any of these new mod/con gas boilers. i'm more concerned with heat loss calculations, and proper sizing and piping of the installation. i'm in blue point, where r u located? have you decided or come close to deciding which installer you will use?

Navien is a well established manufacturer with a good reputation world wide. I see them extensively used in commercially designed residential applications where many multiple boilers are installed providing staged capacity and redundancy. Are you aware of any class action law suits against Navien that have been successful? How would you know whether the ‘terrible reputation’ is the result of ‘terrible installation' or not? We know the definition of ‘insanity’. Doing the same thing the same way repeatedly and expecting a different outcome. That is what I expect is going on. Modern hydronics consists of 2-discreet component systems that each have to be designed and tuned for maximum efficiency with the distribution system also designed and tuned for comfort and then mated to each other. This is likely what’s not happening with the failures you’re eluding to. Something else is happening there to cause these failure, like a poorly designed distribution systems that results in low efficiency, short cycling, corrosive chemistry in flue gases or heat exchangers, improper ∆T between supply & return fluids, improper selection or setup of circulators, buffer tanks or (no) hydraulic separators, lack of proper controls, programming and monitoring, as just a few examples. Replacement ‘conditioned’ pre-mixed system fluids can be stored in liquid reservoirs feeds with low-level monitor alerts to ensure replacement fluids are of the right, non-corrosive chemistry. The days of straight up tap water as a replacement fluid is long gone unless you like corrosion, scale and expensive service calls. Yes, if serious algebra is part of basic arithmetic, then that’s all that’s needed. If California is doing something else - that’s just fine! IMPO SR

Have to be careful mixing radiant loop with potable water, concerning germs and such. Personally the only way I have seen it done on TV is with an indirect water heater, where the boiler heats water, the water passes through a coil in the water heater tank and transfers the heat to the potable water, then the coil water returns to the boiler. Sounds like you could use a tankless in place for a boiler. The thermostat (and whatever zones you have set up) could activate the pump and the tankless would start heating once the flow starts.

We had a Bosch Greenstar condensing 151,000 BTU propane combi boiler/water heater (model #FS151) installed less than 2 years ago - a brand new system in our old 1850's farmhouse. This supports the forced air heating system for our main floor. In the past year and a half - last winter, and this winter - we've had non stop issues with the system. We use a Nest thermostat to control heat while we are away from the house, or when we have guests staying there. Right now, the Nest app is showing the heat set to 80 degrees but the room temp not rising above 60. What tends to happen is the system blows cool air for a long period of time (more than an hour usually) which in turn cools down the house instead of heating it up. The company that installed it also provides our propane. We have had them out no less than 6 times over the past year and a half to fix it - each time they fiddle with a few things and then it starts working again... for a period of time. But it never seems to actually solve the issue long-term. Most recently they replaced a valve on the back of the unit. The invoice was over $300. This appeared to correct the pressure issue as the gauge precisely would sit in the lower red area, but after this valve replacement, was now sitting in green. Im trying to understand if this is an installation issue, if this kind of issue is typical, and if any one else has experienced this low level of reliability with their Bosch Greenstar boiler. Im told by the company that installed it that we are now outside the warranty period, but im frustrated that the issues persist even after several service calls. Any advice? Do I call a different company to audit the unit and installation? How do I deal with this beyond constantly feeling like the system is unreliable? Its brand new - replacing it is not really an option, as we spent $16k installing it in the first place - less than 2 years ago!