I am about to redo concrete floors in a bathroom and want to put down pex tubing in preparation for future solar radiant heat. I don't know yet if it should be tied into a future whole-house solar water heating or if the floor heating should be a small separate system. At this point we are just talking about a large bathroom, but I'd like to expand to an adjacent couple of rooms when we get ready to change those floors. Any advice on such a piecemeal process? If I do a separate solar water heating system for domestic water in the future (solar preheating of water before storage in existing electric tanks), couldn't the floor heating system be a very simple setup with a closed loop with no heat exchanger? Just the tubing going from the collectors to the floor and back? The collector would be very basic, just some pipes in a black-painted box. My main question would then be, what elements would be required in such a loop? I haven't finished researching this, but I'm thinking: - air release valve and expansion tank at the highest point of the system. - centrifugal circulator pump - some kind of pump controller, thermostat or switch - return manifold - zone manifold to turn of a zone, for example if a towel warmer would be on a separate zone. - 5/8" pex tubing with 10% polypropolene glycol in the water - collector: Any advice on the materials or size? Please advise if you think I'm missing something. What to do about the system in summer? Can I just cover up the panel? I believe if the collector is mounted somewhat vertically, the summer heat gain would be neglectable, and the system could be left on year round. I've understood that the water shouldn't be hotter than 150ðF, if that happens, what should be done? Or is that what the expansion tank is for?

The most efficient way to heat your radiant in-floor and domestic hot water is with a water-to-water geothermal heat pump. If you would also like air-conditioning too, use a triple function geothermal heat pump; full capacity hot water for radiant in floor and domestic hot water as well as forced air for both heating & cooling. Divide your electrical rate by the COP of the GSHP to determine the cost per kW. ItÂs usually a factor of 3.5~5. Geothermal has the highest initial cost but the money goes directly into the value of your home. Geo also has the lowest operating & lifecycle cost and highest user satisfaction rate. Did I mention GREEN? After opening the link below, click 'Products' then click 'TR-Series', then download the R410a Models pdf. SR Here is a link that might be useful: Nordic Triple Function Series GSHP

Yes, electric heat is typically always cheaper to install (First cost)and yes electric heat will probably cost more to operate if your current boiler is natural gas. Your boiler (Assuming a remodel not expansion) is sized for the whole house heat loss and would operate more efficiently heating the kitchen. I would install a hot water toe kick heater and allow for an access panel in the bottom of the cabinet in which it is installed as you will have to bleed air from this unit. Installation may be slighly higher than electric heating system, but keeps your central heating system intact. This will give you a separate zone for the kitchen, have a remote thermostat for this system installed if you like. Keep Warm, Dan Martyn

Since you have chosen warmboard over gypcrete, what was your reasoning behind it besides responsiveness? I am sorry for the confusion. I didn't build a house with Warmboard, I had it in a house where original owner had installed it. It wasn't a house I built. I used it in the sense that I heated the house with it. I looked at the Gypcrete system and somehow feels uneasy about it. Doing a concrete pour over first and second floor does not sound structurally sound to me. Gypcrete has positives and negatives but shouldn't be overlooked because of structurally sound. I think a competent and knowledgeable designer is much more important than which type of system you use. So if you don't have a lot of experienced local people, you have to find experienced people who can help design at a distance. I would start with Radiant Engineering (talk to many companies though). A long somewhat unbiased discussion of radiant: First, it should be noted that radiant heat isn't an efficiency discussion. As people have pointed out many times hydronic radiant systems rarely have a positive payback. They are simply too expensive to install and they never payback if you are installing central air. However, every decision in your house isn't about payback. There are many decisions, such as paint color, cabinet color, cabinet design, many fixtures, etc., that are about your enjoyment of your home. No one has a pool installed because they want it to add value to their house. Radiant fits soundly into that category. Next: A discussion of trade-offs between the different systems. It is important to note that ALL radiant floor systems will provide a comfortable environment to a home that other heating methods struggle to achieve. There are basically five considerations in radiant heat (1) installation costs, (2) operating costs, (3) responsiveness (4) allowable customization and (5) noise (as hot water passes through cold aluminum plates it makes noise). If we look at the different systems we can typically see how they handle each of these things. Warmboard is (1) very expensive to install, (2) it has a low operating cost as it is a warm water system rather than a hot water system, (3) incredibly responsive for radiant heat (able to heat a structure in hours rather than days), (4) low customization and (5) low noise. Underfloor transfer plate systems are (1) moderately expensive to install, (2) low operating costs as they are also warm rather than hot water systems, (3) are somewhat responsive (4) highly customizable and (5) have more expansion noise. Gypcrete overpour is (1) moderately expensive (still cheaper than the two above), (2) have low costs as,they too are warm water systems, (3) not responsive at all, (4) are highly customizable and (5) eliminate almost all noise. Staple up systems are (1) pretty cheap (2) high operating costs as they are a hot water system, (3) not responsive at all, (4) limited customization (they are more limited by physics than design), and (5) are pretty noisy. So looking at Warmboard vs. similar systems - the only real concern from using any aluminum covered plywood system is the noise. Warmboard eliminates expansion noise because of the "special" glue they use to adhere the aluminum to the wood. I can't really tell you how special their glue is, I feel confident they will say super special and their competition will disagree. Warmboard type systems vs. underfloor transfer plate systems - Warmboard is quieter but the loops are not really customizable. Loops are 8" apart with Warmboard, so you can choose not to put warmboard in places but you can't get the loops closer together. With transfer plate systems you can customize the heat of a room by simply moving the loops closer together. This means that you can make the floor right outside the shower warmer than the floor beside the toilet (not many people spend a lot of time standing beside their toilet), but there is more expansion noise. Warmboard is a bit more responsive than transfer plates. Warmboard vs, gypcrete overpour - Gypcrete overpour gives you almost unlimited customization without the noise associated with aluminum transfer plate systems. However, it is not at all responsive. Staple up systems - They are more expensive to operate than any of the above systems but are cheaper to install and easier to maintain. You are not likely to nail through a staple up system with a nice thick transfer plate. Also easier to remodel with staple up systems. TL:DR In the end, if I was ranking a radiant system today - I would probably rank it - underfloor transfer plates > gypcrete > Warmboard. But it is a three way photo finish so it wouldn't take a lot to change the order. Also noisy houses don't bother me at all.