Still trying to figure out my OWB. I already got some of my questions answered, but here goes.
Bought a house in the spring with an OWB. Hot water runs from the boiler in 3 loops: one loop heats a 4 car garage (radiant floor heat), one "loop" is a heat exchanger for the hot water tank in the house, a 3rd loop runs to the indoor gas boiler. The 3rd loop is what I want to ask about. The house has baseboard hot water heat which is hooked up to a natural gas boiler. When we bought the house, we were told that the OWB supplements the gas boiler, but we were also told by the former home owner that they kept the OWB set at 130 degrees. A buddy of mine told me that baseboard heat is usually set around 180 degrees. If that's the case, then unless I keep the OWB hotter than the lowest temperature the water in the indoor boiler naturally hits between cycles, won't the OWB actually pull heat from the gas boiler and cost me higher gas bills? The way I see it, without the OWB in the loop, the indoor boiler will kick on to heat the house, then between cycles the temperature in the tank might fall "x" degrees (let's say down to 170, for arguments sake). When the thermostat in the house kicks the indoor boiler back on, it only has to heat the water back up to 185 from 170 and maintain it there during the cycle until the house heats back up. But with the OWB in the loop, that 185 degree water is flowing back outside into a furnace that's set for a lower temperature, and so the OWB actually becomes a heat sink, doesn't it?
For example, I loaded the furnace up last night, got the temp up and set the OWB thermostat for the damper at 160. Now, I put only softwoods and a few pallet pieces in there and the outside temp was in the 30's, so you'd think that the OWB would've worked all night, but when I got up this morning, there were still some pieces of unburned wood and pallets barely smoldering. I left the pump to the house on all day, and the damper on the OWB never opened even once, yet the water temp stayed at 160. Seems to me it must have been robbing heat from the indoor boiler to maintain temperature. Yeah, it was a nice day (upper 50's), but that water still shouldn't have stayed at 160 without a fire of any kind in the boiler, unless it was getting heat from another source.
So...if my logic is correct, then how hot do you keep your OWB, and how low can I turn down the setting for the baseboard heat on the gas boiler? If the former owners ran the OWB at 130, I don't know if I want to go all the way up to 185 and burn through that much more wood. At the same time, I didn't bust my tail laying up 16 cords of wood this summer just to have a little hotter shower water and to make sure the toilet in the garage doesn't freeze. My goal is to keep as much of my money in my pocket, and out of the gas company's, as possible. I'm thinking of meeting in the middle, maybe run the OWB and the indoor boiler at the same temp, say 170, for the baseboard heat? What do you think?
Bought a house in the spring with an OWB. Hot water runs from the boiler in 3 loops: one loop heats a 4 car garage (radiant floor heat), one "loop" is a heat exchanger for the hot water tank in the house, a 3rd loop runs to the indoor gas boiler. The 3rd loop is what I want to ask about. The house has baseboard hot water heat which is hooked up to a natural gas boiler. When we bought the house, we were told that the OWB supplements the gas boiler, but we were also told by the former home owner that they kept the OWB set at 130 degrees. A buddy of mine told me that baseboard heat is usually set around 180 degrees. If that's the case, then unless I keep the OWB hotter than the lowest temperature the water in the indoor boiler naturally hits between cycles, won't the OWB actually pull heat from the gas boiler and cost me higher gas bills? The way I see it, without the OWB in the loop, the indoor boiler will kick on to heat the house, then between cycles the temperature in the tank might fall "x" degrees (let's say down to 170, for arguments sake). When the thermostat in the house kicks the indoor boiler back on, it only has to heat the water back up to 185 from 170 and maintain it there during the cycle until the house heats back up. But with the OWB in the loop, that 185 degree water is flowing back outside into a furnace that's set for a lower temperature, and so the OWB actually becomes a heat sink, doesn't it?
For example, I loaded the furnace up last night, got the temp up and set the OWB thermostat for the damper at 160. Now, I put only softwoods and a few pallet pieces in there and the outside temp was in the 30's, so you'd think that the OWB would've worked all night, but when I got up this morning, there were still some pieces of unburned wood and pallets barely smoldering. I left the pump to the house on all day, and the damper on the OWB never opened even once, yet the water temp stayed at 160. Seems to me it must have been robbing heat from the indoor boiler to maintain temperature. Yeah, it was a nice day (upper 50's), but that water still shouldn't have stayed at 160 without a fire of any kind in the boiler, unless it was getting heat from another source.
So...if my logic is correct, then how hot do you keep your OWB, and how low can I turn down the setting for the baseboard heat on the gas boiler? If the former owners ran the OWB at 130, I don't know if I want to go all the way up to 185 and burn through that much more wood. At the same time, I didn't bust my tail laying up 16 cords of wood this summer just to have a little hotter shower water and to make sure the toilet in the garage doesn't freeze. My goal is to keep as much of my money in my pocket, and out of the gas company's, as possible. I'm thinking of meeting in the middle, maybe run the OWB and the indoor boiler at the same temp, say 170, for the baseboard heat? What do you think?
