chad_m, The humidity comes from the snowy cars coming in and melting off day after day, night after night. It's one of the issues besides operating cost of a tight, heated garage. The humidity plus road salt equals bad news for your vehicles. I have the tubes in the floor and have not yet hooked up the heat source for mine and this is one of the concerns I have. There are some humidifiers that work at lower temps, but some just keep a window cracked. This'll make the green police shudder of course. So you have the cost to heat it, then dehumidify it. In my case gas is free so the heat angle doesn't bother me one bit, but I don't want to rust out my cars so I'll probably bite the bullet on humidification. My garage has a future apartment above it so keeping the garage at 50 degrees would help keep the apartment floor warm. I had a master bedroom and closet over an unheated garage at the last house and the floor temp difference was noticeable.

How are you heating the water with your present system? I'm going to assume that you're taking city water and heating it in a boiler and then circulating the water or using a heat exchanger to transfer the created heat to the water. When you turn on your tap water and release cold water, that water is usually not a tepid 55 degrees, it's colder, which means that your system has to input heat from, say 40 degrees, up to what is needed. Geothermal brings two advantages, 1.) the water is sent into the ground and picks up heat, bringing it up to 55 degrees, or whatever the temp is in your locale (the sun heats all the earth around you and you're extracting a little bit of this solar energy from a cubic footprint of ground) and 2.) the heat pump compressor creates additional heat more efficiently than heating direct by electricity and natural gas. In a nutshell, here are the two stark alternatives: 1.) Let's assume that this is your system. Take city water at 40 degrees, burn natural gas to heat it to 120 degrees, meaning you have to burn natural gas to create BTUs which are then transferred directly to the water. 2.) A geothermal system with a loop field, starts at, say 55 and then the Heat Pump uses electricity and refrigeration principles, to heat the water up to 120 degrees but does so 3-5x more efficiently than a direct electric heater would. You're getting free heat from the ground (55-40) and the 15 degree differential (or whatever it actually is) is exploited by the heat pump which uses the embodied heat within that water to boost its temperature even higher and then sends the cold water that the process produces back into the ground where it soaks up the solar energy that has been "planted" into the ground and the process starts all over again.

There's a lot of good information in the healthyheating post, but unfortunately, some misleading/inaccurate info as well. The good - building a really efficient house is definitely the way to go. The better insulated and air sealed, the more stable the temperatures, and the less it will matter what type of heating system you use. As the poster noted: "Its not just about the flooring its about the system the building (affects heating load what you pay the utilities) the flooring affects resistance) the tube spacing (affects fluid temperature affects efficiency) .theyre all joined at the hip" I'm not sure what the comments about VOCs have to do with heating systems. I might be missing the author's point, but the implication I get from reading the posting is that somehow radiant heating helps reduce the VOCs in your home. I know that's not the poster's point, but the way it's mixed in with talk about radiant, it's quite misleading. To clarify, VOC levels are a function of materials used in the house and the fresh air ventilation rates. As for radiant heating efficiency. There is a lot of controversy surrounding the efficiency of radiant systems. The industry claim is that you can set your thermostats lower because the heat radiates up from the floor, resulting in greater psychological and physiological warmth. In actual practice, the studies have had conflicting results. While it is true that in a low-temperature radiant installation, you can operate water heating equipment at more efficient temperatures, it's not true that it's a slam-dunk savings in all situations. This is particularly true in basement radiant slab installations where a fraction of your heat is going downward to heat the earth or out the edge of the slab. This can easily result in a 10-30% efficiency penalty, or more depending on the installation. The comments about the emissivity of the floor material is a red herring. While the follow-up comment about the R-value of the floor material is valid. What matters is the ability of the system to transfer heat into the living space. Tubes in concrete, exposed, is most capable. Tubes hanging in the joist bay, under the wood floor under a carpet is a worst case scenario. It is simply not true that the floor material does not make a difference! Consider this - if you have a concrete floor and a carpet, both at 70F, which one will "feel" colder when you stand on it in bare feet? The feeling of "cold" that your feet pick up is due to the heat being more effectively transferred from your feet to the concrete floor than to the carpet. The thermal conductivity of the concrete is much higher than the carpet. The floor material makes a profound difference to the actual functioning of a radiant floor heating system. Also be aware of the flywheel effect. Large, heavy masses take a while to speed up and slow down. The same with thermal masses, like concrete slabs. They have a capacity of holding lots of energy. Because of this, they take a lot of energy to bring up to temperature. With a forced air heating system or conventional baseboard heaters, you can set the temperature back at night or when you leave for the day, saving considerable energy. With a high mass radiant system, it takes a lot more heating energy to get the slab up to temperature, so it is slower to respond. This applies to the time it takes to cool down also. Quoting from the EERE website: "Thick concrete slab systems have high heat capacity and are ideal for storing heat from solar energy systems, which have a fluctuating heat output. The downside of the thick slabs is their slow thermal response time, which makes strategies such as night or daytime setbacks difficult if not impossible. Most experts recommend maintaining a constant temperature in homes with these heating systems." This is particularly problematic in the spring and fall, when it may be in the 40's at night but sunny and in the 60's during the day. Ask people with radiant systems about their comfort in these situations and you'll find a fair number who are dissatisfied with the comfort. This is a good reason to keep a forced air system for heating as well as the radiant. Use the forced air for primary heating during mild weather and radiant when it's colder. The healthyheating describes this on their website under "myths". Unfortunately, the way it's discussed is highly misleading. Radiant heating systems do NOT act like heat lamps. Heat lamps operate at very high temperatures and have essentially zero heatup time. Heat lamps do work by radiant heating. In floor systems do not. They operate at very low temperatures and can take considerable time to warm up and cool down. Depending on the design, this can be many hours. Quoting from the EERE website: "Despite their name, radiant floor heating systems also depend heavily on convection, the natural circulation of heat within a room, caused by heat rising from the floor. Radiant floor heating systems are significantly different than the radiant panels used in walls and ceilings." I don't want to seem negative on in-floor heating systems. I like them and use them in my own tiled bathroom floors. But you need to know that it is not "child's play", even for a competent installer, due to complicating factors.

An electric hot water heater typically will not make sound when it runs. I would think this system you have is a closed loop, meaning you fill the tank and loop the incoming water is shut off and the water is moved thru the loop in the floor via a in line water pump, controlled via temp sensor(s). I am only guessing here... Note: just because the circulation pump is off doesn't mean the resistance heating strips within the water heater are off. (The pump you should hear, the strips you will not) Your electricity rate is pretty average, but being on balanced billing it can be upwards of 11 months of usage on your end until you realize the increase. Unless your balanced billing works differently? I had a customer of mine in which it took 11 months of the balanced billing to drop after I installed a new more efficient air conditioner. So if you use a lot of energy in any one month on balanced billing the energy company may rack this up and charge you for it pronto < I can only assume it would be this way because the energy company wants to get paid and possibly alert you to a problem. With all of that said, was this water heater sized properly for the 'heating' load you are putting it under? The colder it is, the heavier the load. At some point, the load 'could' be so great in which the elements that heat the water do not shut off. The only true way to know the heating elements are off in an electric water heat is to hook amp probe around electric lead and see what the amp draw is. If it reads 0 they are off. Because you are in an all electric house, there could be issues with your other systems. While rare this does happen >>> an electric resistance heater the strip breaks and shorts to ground. This causes the strip to remain on indefinitely, only turning off due to heat limiting controls of the appliance in question. The other outcome, even more rare than above besides this is an electrical fire. We all know these occur as well.