Well, I called the service company again this morning. The smell of raw fuel oil was spreading through the house yet again. The nice young man who came out seemed very knowledgeable and very business-like. He removed the side panel and I asked him what was behind there -- it is the flue collector for the boiler. It was completely clogged with dry black gunk in less than 2 days. If I hadn't seen, with my own eyes, how clean they were this past Friday, I wouldn't have believed it. He cleaned that area out. He said it was getting waaay too little air and he could tell that by the sound alone. He set the air intake up by several multiples from where they were originally set by his predecessors (and my friend, who opened it up a bit more but was afraid to open it up too much, figuring it was set that low for a reason). It was originally set at about 3.5, my friend set it to 4, and this guy turned it up to 11. Then he opened up the chamber door to check the flame and made some adjustments there. He suggested that the chamber be replaced. He checked the draw to the chimney and said it was excellent -- no problems there. The black smoke we were seeing on occasion was from an incomplete burn and the clogging in the flue. Then he read the previous service orders and said "Three visits and no one changed your filters?" If they did change the filters it wasn't on the service orders. He went outside and checked the smoke from the chimney. It was back to being white. This service guy opened up the part where the nozzles were located, took them out, looked them over, and said they looked good. In fact, they looked new, so they may have been replaced but not written up on the previous service slips. According to this guy, I should call the office and get a price on a new chamber and have someone come back in a day or two to change the filters and check everything again. Oh yeah, and leave the basement windows open to let it air out for the day. :-) Baymee and Paulbm, you guys rock. Thank you. I've learned a lot. Let's hope these corrections "take". I will be calling the service company in the morning for a follow-up. I'm still wondering, since this unit is about 12 years old, if it would be better to get a new boiler altogether. Are they more efficient now than they were back in the late 1990s? I know that 12 years is not that old for boilers, but if newer ones are vastly improved, it might be the way to go.

The boiler is 55 years old (original to the house) so I don't think that a tempering valve was required when it was installed. When the village went to wells in place of spring water the coil was cleaned annually. A spare was purchased to avoid down time. A water softener largely fixed that so I don't think that the cleaning was kept up as it should have been. Long-term investment in efficiency will not pay off in this case. Pulling out the oil burner and substituting a gas burner in the existing boiler was a consideration, but dad decided that the Crane was too old to risk it. Cost considerations means that $1500 for a separate water heater is not being considered. Venting anything out the side of the house for two appliances might be problematic due to the layout of the house. (The new boiler might have to go up the existing chimney with plastic pulled through it and I assume that a separate water heater would require a second exhaust. ) Dad does not have large hot water needs. My position right now is that if someone in the future needs more hot water, they can install an indirect tank run off what ever he puts in now. I hear what you are saying about the heat loss. We had an evaluation of the house last fall under a New York state program (NYSERDA) so we have some numbers. Main contenders for the boiler included more than one brand of modulating boiler and Weill-Mcclain GV+ (non modulating with a cast iron primary and SS secondary exchanger.) We were leaning toward the latter due to lower expense of one bid. Recently we hit the reset button because I found that dad is most probably eligible for a 50% rebate on the cost in the NYSERDA program. There is only one contractor that is eligible under the program (BPI certified) within an hour drive. I don't have any problem with that contractor, but they were high. I am talking with them again, but I have to hold their feet to the fire (I'll use the Crane) on proper sizing. I'd like to use them because they are less than a mile away. That is a big deal if the boiler breaks in a blizzard. They quoted a Rinnai, but the DHW/heating output for that line appears low compared to other brands so I am not sure it is the best fit. I may go back to them and ask what other brands they are comfortable with. I'd like to think that a condensing or modulating-condensing boiler will work well enough to make the investment in the house. It has seen a lot of improvements in insulation and windows since it was originally built so it is very likely over-radiatored for 180 F water. There are three radiator runs, ground level [16 kBTU], conditioned basement [11 kBTU] and sun room [12kBTU]. The last does not get used in the coldest weather and has radiation that is probably closely matched the demand since it is a late addition. I guess what we'd need is a measure of the radiator output at condensing temp compared to those figures to know for sure. Lastly, I don't know what temperature was used for the heat loss calculations. I have been told that -10 or -20 is most appropriate for the area. Yes, it does get that cold and sometimes even colder there. The rebate program pays out up to $5000 so we are very willing to make a $10k investment but I want to put the money were it will do the most good in a relatively short time. At the same time, we can try to avoid ham-stringing future owners of the property in case we get a savvy buyer that is not simply blinded by the bright lights on the read-out from a fancy-pants modulating boiler that might not work well due to poor system interaction. This post was edited by ionized on Fri, Nov 28, 14 at 14:25

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.

Oversizing boilers and furnaces has been very common and maybe still is. On the other hand, maybe improvements to your structure has knocked off a few thousand btu (but have there been additions?). I am surprised that no one has yet measured your emitter capacity. That measure is mandatory for a boiler replacement IMHO, just as or more important than total heat loss for the home. If emitter capacity does not equal or exceed the boiler capacity, you will short-cycle, no question. That goes more for a low mass boiler than a high mass. If your replacement does not have the buffer capacity that the old boiler does, it could short cycle even if the existing boiler does not. If I had a house of the right size with a high-mass boiler system, I'd seriously consider dropping in a Westinghouse WGR060NG076. It is designed similarly to the HTP Versa-s, and a twin to their Pioneer water heaters. It needs only a 2" pipe for venting flue gas. It has a 3:1 turndown ratio (rather than 5:1 for the Versa-s and no heat exchanger to make them combi boilers). They are high mass. Most of that mass is in water and the boilers/water heaters use the natural temperature polarization of the heated water as what appears to be a very effective heat exchanger. Pretty ingenuous IMHO. You'd need two of them, but if you did install them, you'd have mid to high efficiency for less than $5000 in boiler costs, you could install them yourself, and you might be able to wrangle a 6:1 turndown ratio, on a manual basis if not automatic. I don't know, however, if one at a time, they could provide the GPM that you need. You know, in engineering circles, there has been serious consideration of installation of small, high-efficiency, modulating boilers sistered to existing high output, lower efficiency boilers. The idea is that the old behemoths will take over during a few hours a year near the design temperature while the modulating boilers run at very high efficiency meeting most of the heating needs. Maintaining, and possibly, replacing, two boilers adds a lot of complexity and cost. Balancing that, you have some redundancy.