I own a 2-story colonial with a finished walkout basement, located about 10 miles SE of Philadelphia, PA. The 1st and 2nd floor is forced-hot-air heated by a condensing, gas furnace that was installed in September 2010 (replacing an old oil furnace), while the basement zone remains heated by a Thermo-Dynamics HT-110 oil boiler (114,000 BTU/h output), which also supplies the domestic hot water (a typical summer/winter hookup).
The finished basement and laundry room (approx 700 SF total) are heated with 45 feet of finned-tube baseboard, while the adjacent utility room (approx 375 SF) is warmed by the furnace and boiler located there.
I just used an online heat load application that calculated ~ 60,000 BTUH heat loss for the 700 SF finished basement and laundry room – but I don’t know how accurate that is. I’ve read that baseboard radiates ~ 580 BTU/h per linear foot, which would mean the 45 feet of baseboard puts out ~ 26,100 BTU/h… and the basement remains comfortable on the coldest days.
We’re now planning to replace the Thermo-Dynamics HT-110 in order to move from oil to gas as the means of heating the basement and DHW – and while there are only 2 of us living in the house (showering at separate times), we want enough hot water that 2 showers could be taken simultaneously with water to spare and a reasonable hot water recovery rate (for when guests stay over).
I’ve considered several options including: 1) converting the Thermo-Dynamics HT-110 from oil to gas + indirect hot water heater or heat pump hot water heater; 2) condensing boiler + indirect hot water heater; 3) condensing combination boiler (for both heat and DHW); 4) smaller condensing or atmospheric boiler + heat pump hot water heater; and 5) atmospheric boiler + indirect hot water heater.
I’ve talked with two reputable heating companies in my area and have received estimates ranging from X to 4X depending on equipment.
For instance, one company will charge X to convert the Thermo-Dynamics HT-110 to gas and install a 50 gallon indirect hot water heater – and while the other company has suggested more options, its most expensive is about 4X for a condensing boiler (like a Triangle Tube Prestige Excellence or Prestige Solo) + a 50 gallon indirect hot water heater.
However, I recently read that finned-tube baseboard operates best with 180 degree water and condensing boilers are far more efficient with 130 degree water (i.e., finned-tube baseboard radiates only about 250 BTU/h using 130 water and condensing furnaces operate at ~ 85% efficiency with 180 degree water).
Consequently, I think I’ve ruled out a condensing boiler owing to their high initial cost and apparent incompatibility with finned-tube baseboard.
Instead, I’m now thinking about configurations like (but not limited to) the equipment listed below:
1) Burnham P202 gas atmospheric boiler, 27,000 BTU, Electronic Ignition, 81% AFUE + 60 gallon A.O Smith Voltex heat pump hot water heater, 2.4 EF (yipes!!!). Obviously, with this type setup the boiler only heats the basement zone. (Equipment cost about the same as X above.)
2) Buderus CG124 gas atmospheric boiler, 110,000 BTU/h (DOE), Electronic Ignition, 84% AFUE + 40 gallon Triangle Tube Smart indirect water heater, 112,000 BTU/h input. Obviously, with this type setup the boiler heats both the DHW and the basement zone. (Equipment cost about the same as .8 X above.)
I’m looking for the most practical and cost effective approaches to achieving the goals of switching from oil to gas, heating (with finned-tube baseboard) a 700 SF finished basement and laundry room, and having an adequate supply of DHW.
Your ideas and suggestions are welcome and appreciated.