I did find a flow control valve that was not set properly and therefore let the hot water from the boiler circulate through the piping even if the circulator was not running. This explains the difficulty of the heating temperature control, which did not always happen, but especially during cold days (I guess the temperature differential between the hot boiler water and the water after running through all the radiators was high enough to start a circulation based on the different densities of water. So now it is not firing that often, but it still is firing too often for my liking. Question is if my system is really designed the the way it works - how would I be able to find out if it is designed to maintain the temperature?

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?

The best thing, in my opinion, is to first do a proper heat loss calculation on the house with the new addition. Taco's free FloPro Designer software, along with many other software programs, and even the old Manual-J method will get you your heat loss calculation, and then you can go from there. The old "rule of thumb" methods for calculating boiler size are no longer the way to go. After tightening up the building envelope, installed new windows, caulking gaps, etc. your old boiler might even be oversized... Your boiler is very efficient, and if it shows no signs of failure, and you have it properly maintained, I wouldn't worry about it. I have a Weil-McLain Gold Oil Steam boiler (from 1995) which was converted to hot water when I converted my 3-family from one steam system to three hot water systems. While it is WAY oversized for my 1st floor apartment, I just couldn't part with it. PexSupply.com is a great place to research boilers and find prices and specs. If you decide to have a plumber install the system, insist that they perform a heat loss calculation before selecting a boiler for you. They will usually have a "favorite" brand that they like to install, which might not be the one your looking at. Good Luck, Nick

Everyone, Once again thank you for all your very helpful comments that you gave me this past May. As "heating" season is going to start soon here in the Northeast, I will be again relying on my gas boiler again. Since the last posting here, I had a professional come out here to clean & inspect the boiler, double check the chimney (he stuck a mirror into it and we both saw daylight) and he proclaimed the unit in perfect working condition. The Pro did advise me on two things that I wish to run by you all for further opinion, lf you don't mind. 1) The Pro advised (he has over 30 years of experience) that I should get a "better quality" spill switch than the one that I currently am using. The one I have (and already changed 2 times) is the one that is made specifically for this unit (rated at 210F): http://www.supplyhouse.com/Weil-McLain-510-300-013-Spill-Switch-w-Reset-210-F He said I should get a better quality one made by Field Controls, something like: http://www.supplyhouse.com/Field-Controls-GSK-4-200-Gas-Spillage-Sensing-Switch-w-Manual-Reset or even http://www.supplyhouse.com/Field-Controls-FTS-6-180-Safety-Switch-w-Manual-Reset-120-240V Now, my question is this: Since my Weil-McLain EG-45 SPDN unit is rated at 210F, and I will put a spill switch that is 200F or even 180F rated, is that okay? The Pro did confirm that my existing spill-switch location is in the right spot and that I do not need two of them for my type of a unit. 2) As far as the Vent-Damper (to remind, I installed a brand new one last winter, made by Field Controls). The Pro said that he would just leave it in MANUAL mode. When I asked him about the danger of having "bad gasses" leakage into the house, he stated that the boiler will shut itself off as there are other protection sensors there and that this AUTO function is now included into the Vent-Dampers more for better efficiency of the unit than for safety. Is he right? I should also add: a) I do have a 4" clean-air going into the boiler room directly from the street (boiler room being a closed-off section with 2 doors, with two return 20 inches x 8 inches ventilation grille's that have the air escape into the rest of the basement). The actual room measures 6 feet long x 7 feet wide x 8 feet high and only contains the gas hot water heater and the gas boiler. b) On the advice of the Pro, I tried turning on the heat (via my Thermostat) a number of times during the summer's hot & humid days (it was like 80F in the room, so I had to set the Thermostat manually to 82F). The unit started-up every time without problems and I let it work for 5 mins or so before turning it off. The Pro said that during the very humid days that the heavy air that gets trapped in the chimney could force the Vent-Damp to trigger the spill switch. It never did. I await your comments. Thank you again in advance for your time and knowledge.