The ell of our house with kitchen, pantry and dining room has radiant floor heat. It has its own thermostat and several loops feeding off one manifold. We don't change the heat there over the short term. We might turn it down if we will be gone for a week, but we don't change it over the short term. In our baseboard heat in the rest of the house , the radiators change the heat fairly quickly since the water directly heats the air, but the radiant floor heat first has to raise the temperature of the floor and then the floor raises the temperature of the air above it, so it's a much slower process. I don't find that the rooms heat more than a degree above or below the set temperature. With 3 windows and high ceilings, you have a large air mass with heat loss through the windows, so your time to heat the bathroom from a lower temperature will always be long. To my mind, it makes the most sense to keep the bathroom temperature at whatever heat you like and leave it there. It's the nature of radiant floor heat to be easier to maintain temperature than to quickly change temperature.

Yes, appears to be communication issue with contractor. Contract says in open beams above garage which is basically half of the floor. At the time, I was not familiar with this type of system, so I had no clue what it even looked like, the contractor knew we wanted all of the walking areas heated since my first request was to use electric pads in the walking area and he talked me out of that and said just create a separate zone off of your furnace for the kitchen floor. Not a big deal to finish it, half of the remaining floor is open beams in laundry room, and the rest is in ceiling above a bathrrom which I'm fine with them taking out the ceiling and replacing with drywall.

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.

Retrofitting a house that has cast iron radiators with an air-to-water heat pump represents the best situation for a project like yours because cast iron radiators (emitters) generally use the lowest Entering Water Temperature (EWT) produced from a heat source – except for properly designed low temperature in-floor radiant. Aluminum fin radiators require a water temperature from 160˚F to 180˚F. Cast iron requires a water temperature of 140˚F. The lower the water temperature required, the easier it is to accomplish with a heat pump, the less energy required and the more money saved. There are high-temperature heat pumps that do generate hot water up to 160˚F but generally these are geothermal and non-reversible (no air-conditioning). Using an air-to-water heat pump in the case of your building would mean that all your existing (cast iron) radiators would be plumbed to a Heating Only circuit (zone) of the output of the HP. This is because the existing supply pipes and radiators would ‘sweat’ in cooling mode, creating conditions we don’t want. Since you want air-conditioning and that the supply water temperature with a HP in heating mode would now only be about 120˚F, supplemental hydronic fan coils (for heating & cooling) are required. These are on separate zones, designed for heating and air-conditioning, fed with hot or chilled water, piped with Armaflex insulated piping where neither the pipes nor the fan coils sweat and will additionally make up for the lost Btu due to the lower water temperature. In cooling mode, the condensate from the fan coils is collected and properly drained as in any other air-conditioning system. The cast iron non-insulated piping and radiators are switched ‘OFF’ during cooling mode by switching ‘OFF’ either the circulators (pumps) or zone valves controlling the water flow to these ‘heating only’ zones to avoid any problems created by condensing water vapour. Some but not all of the advantages of this type of system include one heat pump able to provide efficient heating and cooling, domestic hot water (DHW) heating, possibly including on demand domestic hot water heating as a priority, simultaneous heating and air-conditioning if so configured, easily zoned - including zones requiring different water temperatures. The use of a buffer tank(s) for hot and/or chilled water means that you can have very small zones, such as a small bathroom in-floor hydronic heating or a bathroom hydronic towel rack as a separate zone without short-cycling of the heat pump, as the heated water is drawn from the buffer tank without the need to run the HP till the tank temperature drops below a pre-determined minimum that would then require a longer, more efficient run time. Unlike mini splits, these systems are designed and built more like commercial equipment that when installed with a proper design should last a very long time and add considerable value and comfort to your property. The same system with a geothermal source, while being more expensive would also be more efficient. Air-source will work fine. Either system is a premium system with a premium price tag. Factor in the price differential of the different systems available including installation, operating, maintenance and life cycle cost. Something to keep in mind & a reason to ‘Think Water’: "A given volume of water can absorb almost 3500 times a much heat as the same volume of air, when both undergo the same temperature change." 3/4"tube = 20"x12" duct 3/4"tube = 18" ø duct I find NO fault with mike­_home’s suggestions; different approach, different philosophy, different cost. Although your costs seem to be high no matter what you do. BTW: As you are in Brooklyn, I’ll mention that as a geothermal professional, I was invited to tour a massive institutional retrofit geothermal project in Manhattan where they converted hydronically heated heritage buildings that are well over 100-years old to a system that is basically as described above except with geothermal. They probably by now have saved millions of dollars on energy and maintenance and never dreamt they could have zoned air-conditioning as well. To give you an idea of the scale of this project the boreholes and there are many, have diameters measured in feet with each one drilled down to a depth of 18-hundred feet (1800ft) through solid Manhattan rock! Sadly, after 9/11 it has become more difficult to visit this type of critical infrastructure. IMPO SR