Hi folks, I am a new homeowner with an oil fired boiler (H.B Smith series 8) and am trying to squeeze the greatest efficiency from my heating system. I have browsed through the threads in the boilers section and have learned enough to know it is a complex issue, but have not managed to discover an answer to my several questions. One vein is the optimal hot water for my 3 zone baseboard heating system - I have read that the hotter the water the more efficiently the baseboard heaters radiate it (i.e. 190F), but also that the boiler is more efficient at low temps (i.e. 130F), which seems mutually exclusive. (Where does the "loss" go with 130F water? Back into the boiler and up the flue somehow?) I also understand that the boiler is more efficient in its operating termp range, rather than when cold. I am not sure how to make all this converge into the most energy efficient settings for the aquastat. Comfort is not really a big issue - we are hardy folk and keep the tt at 45F in 2 of the 3 zones and 60 in the bedrooms (unless we have company, of course). Temp swings also do not bother us much, especially downwards ones. One suggestions I read is to choke the system so that the circulator is running about 60% of the time with low water temps and the boiler is coming on and off at low duty cycle, providing slow btu's into the emitters and running in its operating temp range, but I am not sure that is the right move in my circumstance. I also understand that having an overpowered boiler can be less efficient and I am wondering if we can change our nozzle to a lower flow one to reduce fuel consumption and maintain slow heating. I think it was somewhat oversized when spec'd and given how we "heat" our house and additional insulation we have added, it is probably well oversized. One thought was to set the lo as low as possible with a large differential, which would let the burner run longer when it comes on. My concern is with the boiler getting too cold and condensing - or will the longer run burn off the condensations with a large diff? I assume that the DHW will not be adversely affected since it has its own zone and the hi will probably be at least 160. We have a toddler and keep our DHW at 110F. I also do not have a bypass for boiler protection or adjustment right now, which seems like both a good idea for the boiler and a useful way of choking the system to provide slow heat. I plan to put in a manual one soon and perhaps an automatic mixing valve in the long run. Any suggestions or feedback would be greatly appreciated. If this has been covered, a pointer would be great. I tried a dozen times to search, but the anti-spam captcha does not seem to work - I tried visual and audio repeatedly to no avail. :wall: Details: H.B. Smith series 8-4 boiler with Weil McLain indirect fired hot water tank on its own zone, honeywell R8184 aquastat. 15 psi@150F.

Is there any reason that a thermo coupler wouldn't last very long? The one at my Fathers house has gone out, or quit working four time in the past year. The water heater is just over two years old. What causes one to go bad in the first place?