I have a pretty new radiant system installed by the former owner. The system consists of (in no particular order) 1 zone, tubing suspended below the subfloor, outdoor reset, indirect water heater, Maine winters, am I missing any info? The heated space is only 750 sq. ft. and well insulated. Its just me and my dog, so I don't use a lot of hot water and the house really wouldn't fit enough people for huge water use. By my heat loss calculations, I need about 19,000 btu/hr. My boiler is now a one-year old oil-fired Weil-McLein that provides 75,000 btu/hr. Even assuming my calculation is off by a lot, the boiler is probably 3X too big. Right? I like the analogy in another thread of driving a Winnebego to commute to work. I have noticed it short-cycling. Am I also using 3X too much fuel for the same job?


Here is my proposed solution that I'd like some input on. Without going into too much detail, I may be able to sell my boiler (and potentially the water tank) and buy a new unit that would fit better. I'm also kind of anxious to go to gas. First I was sold on tankless, but there just isn't any consensus on this board. Munchkin boilers seem to have a good reputation. Would I be asking for new headaches by trying to change horses midstream? Can anyone suggest a better replacement for the heater and/or DHW? Other comments? Thanks.

You could consider a Munchkin T50M. It's a wall hung unit that starts off in low fire (approx 13k btu), and modulates up to 50K. Vents in 2" PVC and will give you 92% efficiency on a staple-up application. Add a 30 or 40 gallon indirect and you're off to the races!

your not using 3x the fuel as the short cycling limits the amount of fuel burned. Probably 20-35% more than what the munchkin would use.You could repipe existing setup to minimize the short cycling if you use the existng indirect as a buffer if piped in series w/ boiler. you can also derate an oil boiler easily and I doubt you could pay back conversion costs if you change to gas as oil in our area is the cheapest form of heat because of the 140000 btu per gallon and 85% boilers. proceed carefully.....Eric