Are 400 Watts enough to keep water in a closed loop of copper pipes at about 120 degrees Fahrenheit?

Question

I am building my own type of heating system: A meander of copper pipes under the floorboards of my house is filled with water. The water is in a closed cycle and gets warmed up by an instant water heater, which gets its power from a wind turbine capable of delivering 400W. While this may not sound like much, consider that the water heater will be fed with pre-warmed water all the time, as "what goes around comes around" I am hoping to create some serious heat with this (well, at least enough to keep an old Victorian house cozy at temperatures around freezing point). Would you say that could work? I am very unsure of myself, because I know nothing about plumbing and heating.
I'd be very grateful for input.
Thanks.

Answer 1

400 watts might keep the water hot if the pipes are very well insulated. No way can you heat your house with 400 watts. In a well insulated house, you need 2 or 3 KW to heat an average room when it's freezing outside. In an old Victorian, unless windows, doors, and insulation have been updated, you probably need more.

Answer 2

My first instinct is to answer no - 400 watts is not going to heat even a small, modest home. And if the tubes are efficient in transferring the water heat to the surrounding air, "what goes around will be a lot hotter than what comes around." Your water heater will be working 24/7 during the colder weeks, and even then it will not heat a sufficient amount of water to maintain 120 degrees throughout the piping.

However, there's really not enough information to give a very exacting answer. For instance, how well insulated is the house? How large is the house? How many feet total of copper tubing? Copper tubing size? Total water volume? How well you insulate under the tubes and provide for reflective radiant heat from the bottom of the tubes are also major factors. And 120 degrees F may not be hot enough to generate the heat you are anticipating - forced hot water baseboard heating is generally 180-200 degrees - and steam heat, obviously, is greater than 212 degrees.

Bottom line - if you can heat your Victorian home on 400 watts (a typical hair dryer is 1000 watts), you will have to hire body guards to protect you from Exxon/Mobile agents !

Answer 3

I wouldn't suggest heating your house in this manner. A heat transfer analysis needs to be done with your proposal. Start with 400 W a large fraction is transfer to a liquid. No transfer is 100% efficient. This liquid travels hundreds of feet loosing thermal energy along the way. Energy is also needed to power pumping mechanism. The fraction of the energy emitted by the pipe radiates towards the floor. A fraction of the energy makes its way pass the floor boards and coverings. What needs to be calculated is; Is 400 W at the beginning enough to provide the thermal energy to make your house comfortable? My gut feeling is that too much heat will be lost along the way and not enough heat will be available to warm the inside of a home. There are many radiate heating coilings on the market, but they serve as supplements to a central heating system. And, they are installed directly under the floor covering (wood or tile) within the home's interior. Alternatives are passive systems such as increased insulation, earthen exterior wall covering, coal buring boilers, and electrical supplementation (windmills, solar cells, thermal storage). If you have 400 W of power available, it may be wiser to bleed your electricity into your power grid to lower your utility bills. Purchase a better more efficient central heating system.