Read the recent thread on radiant heating using the link below. There are probably many others, some under the HVAC forum. Use the Search feature.

I believe we spent about $60K for a 7,100 square foot home plus doing the garage (about 1,500 sq ft) in 2001. But if you read my post in the thread below, I've since added a $13K water heater/boiler. And you really should have a forced air system, too for reasons I described there (not a huge extra expense since you'll likely be installing central air anyway and you can put in the least efficient unit available since you'll seldom use it).

We're in No. California with lowest temps in the high 20's.

Bob

Here is a link that might be useful: Recent Garden Web Radiant Heating Thread

Not many contractors down here even know about a hydronic floor heating system, they only know the electric mats.

Our material quote from Radiantec was about $7500 for 5,500 sq ft; 6 zones. That price wasn't too bad, but using Warmboard for the subfloor or a gypcrete over subfloor in the rest of the house was cost prohibitive. And doing it just for the basement seemed like a bigger expense than was warranted.

Radiantec will also do a layout for you and build the valve assembly. Then you get a plumber to follow the layout and do the final hookups after the slab and water heater are installed. I think you'd spend around $3,000 on materials from Radiantec and another $1,500 for a plumber.

It was a non-negotiable item by my wife. I'm actually flying down to the Charlotte area (Denver, the house is up in Catawba) to meet with the guy doing our radiant heat and ground source heat pump system.

One neighbor uses a similar tankless system to what you are proposing throughout his house.

Another neighbor did just the basement floor DIY with materials and assistance from this company
http://www.radiantcompany.com/

I should have mentioned that it's virtually impossible to justify installation of radiant heating on a financial basis. There are, in fact, some efficiencies with radiant, especially in homes with high ceilings. But the up-front expense, coupled with the need to have a F/A back-up, make recovery through utility savings about as likely as recovering your investment on the extra cost of a hybrid vehicle...it ain't gonna happen, even if energy prices triple.

Bob

About the F/A backup, Radientec told us we would not need it at all after we answered questions about windows and insulation. Any more info as to why we would?

As for cost, our plumber is able to get all the supplies needed at a far lower cost than we first estimated. And my dh is going to assist with all of it (he worked for our friend's company in the past, so he has some experience) We are providing most of the labor by DIY the PEX. So we don't see the up-front financial difficulties mentioned above. I realize this is probably unique to us, so doesn't apply to everyone. But we have found that it's going to be no more expensive than going with traditional F/A.

We are starting in about 2 weeks (installing the pex), so I'll be glad to come back and give a complete breakdown of cost.

armomto3boys, if you don't ever turn your radiant heat thermostat down during the winter, then you won't need a F/A backup. We're retired and travel a fair amount during the off-season. When we do, we typically set our thermostats (all 14 of them, since we have one in virtually every room) down to 50 degrees. Upon returning home, it would take up to 12 hours to warm the house back up to 70 degrees using the radiant heating system. That's a long time to stay bundled up by the fire.

If you don't vacate your home much during the winter or only do so for short periods, you could simply leave the thermostats set at 70 degrees during your absence. You'd lose an opportunity to save some on your utility bill but it might be less expensive than paying for the installation of a F/A unit. But look at the cost of a F/A unit. You may find that it would be a nominal additional cost, since your A/C system will require ducting and a fan anyway.

Bob

armomto3boys, one more thing if you're doing the installation yourself. Be aware that the PEX that you chose will dictate the equipment that you use. PEX comes in two basic "flavors": with or without an oxygen barrier. If you use the cheaper of the two (i.e., without a barrier), then your pump, heat exchanger, etc. must be made entirely of brass (more expensive) to ensure against corrosion. With an air barrier, your equipment can be a less expensive variety containing ferrous metals.

Bob

We just purchased a second home in PA.

It already had a boiler and hot water baseboard heat. The basement was unfinished so we ran radiant in the joists (staple up), and we are removing the old baseboard units (We will re-use some of them in the basement).

It has been great so far. We got a programmable thermostat that turns the heat up for the weekends. I think we spent about $1k on the tubing, valves etc. Labor was free because hubby is a master plumber.

Barb

there is no comparison with comfort -- radiant is the way to go.

Here in Fairbanks Alaska where we routinely get temperatures of -40 for days at a time, radiant flooring with glycol filled tubes is the way to go, with many having no backup at all. I will have a backup masonry heater (80% efficient burn firepot with massive stone heat sink) which are being studied here at our Cold Climate Housing Research Center in my log house, but most folks tell me it's totally overkill. We don't air condition here at all, but for fuel efficiency we use HRVs (heat recovery ventilation) systems which can also move air in the summer if it gets too warm.

For the first time, I put in radiant basement heat--Pex and White CombiBoiler--in a custom home at the owner's request. It cost about $8,500 plus a complete FA system for a two storey 3,100 sf. home with a 9' high basement and 9.5' first and second floors. The contractor agreed that the only installations they do are not based on economics but comfort.

Of course, if you get free labour and discounted supplies and AC is not needed there may be some economic sense to it. In a FA system, supply ducts are positioned in front of windows for comfort. I can't imagine that heat radiating from a distant basement floor is as comfortable.

If I were you , I'd look into whether you can run radiant heat off of a tankless water heater. From what I've been told they cant keep up with regular household usage much less heating all that water you need to heat your house

nacnac, you're being sold a load of hooey (or you are specifically spreading it yourself). As I said in my earlier post, not only can you run a radiant floor system off a tankless, I have spent many days as a house guest in such a house (it belongs to the neighbor two lots over from where I am building).

They also use the tankless for the regular domestic hot water.

I'm going to be using the WaterFurnace heat pumps to with a ground-source heat pump to provide both the radiant floor hot water and the airconditioning.

I've read a lot about tankless heaters over the past year(I've been thinking about upgrading).

Here is what I've learned:

Tankless Gas heaters still need to be ventilated like traditional hot water heaters. Tankless electric heaters can be (and are often) stored in closets or attics and are about the size of a small desktop computer tower.

The gallons per minute that they can typically heat is slightly lower than the gallons per minute that a tanked water heater can push out (if I recall correctly, tankless are around 5 gpm and tanked heaters can push out between 6 and 7). While this is a lower gps flow, the average shower flows at about 2 gpm.

So a single tankless water heater can be used to do laundry, run the dishwasher and still give you a hot shower all at the same time without much effort.

I'm not sure what the flow requirements are for radiant heat, but the tankless heaters are relatively small and inexpensive. Considering the size and price, you could have a dedicated tankless electric heater for each level of the house without a lot of overhead or expense.

The only real downside I've read about is in particularly large homes. If the tankless heater is on one side of the house and a shower (for instance) is on the complete opposite side of the house, the time it takes for the water to heat up is noticably longer than a tanked system. This is because a tanked system heats up water in the pipes through convection; whereas the tankless system is completely on demand. The solution to this problem is simple. Put the tankless heater in the center of the house, or have multiple tankless heaters.

Tdegen, Im curious through your readings if they addressed on tankless water heater installs, where the incoming water is extremely cold even in the warmer months, how that effects performance. I know it was a problem in the early tankless days, wondering if it still is. Thanks!

After reading the initial replies my inclination was to forego Radiant floor heat.
However. I'm typing this email from a vacation rental in the Blue Ridge Mountains that uses passive solar gain and radiant floor heat no forced air. I must say that the comfort level is incredible. There is a wood furnace but we only used it once for asthetics not really heat. After initially convincing my wife that we could do without radiant I'm reconsidering that.
What's the best way to implement it? Use it on the first floor and basement only? The other issue is that the forced air heat causes nosebleeds in my kid I would like radiant heat on the second floor for that but obviously cost is probably going to be prohibitive.

Doctj ~ do a search here (at the bottom of the opening forum page) to get lots of opinions on radiant heat.

I lived with it for several years in a rented OB house. Couldn't get much plainer: water was sun-warmed in a black tank, piped to pre-warm water in a standard water heater and in a tank which had the radiant pipes, (the floor's water was mixed with cold because WH water is too hot) and then circulated through pipes under a tiled floor. Learned two things: a) given a choice, I wouldn't waste money on any other type heat even though I am in "humid mixed" climate with widely variable daily temp swings; and b) folks do seem to like to make a simple system complicated! Maybe it's all the available electronics and maybe it's a manufactured demand for 'up-to-date' methodology, but given pre-thought, planning, pex, thermostatic valves, and a source of heat, radiant is basically one of the simplest forms of heat available. Add in solar-assist for heating the water and you've also got one of the least expensive-to-use forms of heat.

I would expect you to prefer heat on every level, and with area controls so as not to heat space that isn't used. One thing to keep in mind is that radiant is usually used in well-insulated construction, and -because heat rises albeit slowly if not actively pushed- upper levels may not need as much actual heat added in order to maintain a comfort zone.

Now that I think of it, I suspect you'll find realistic info from the forum linked.

Here is a link that might be useful: renewable energy forum

>>
Tdegen, Im curious through your readings if they addressed on tankless water heater installs, where the incoming water is extremely cold even in the warmer months, how that effects performance. I know it was a problem in the early tankless days, wondering if it still is. Thanks!
Everything that I read indicated that the gpm (gallons per minute) decreased proportionally with how much you wanted to raise the temperature of the water.

Assuming that most water coming into the house is around 50 degrees and you want a hot shower (about 105 degrees), you want to raise the temp about 55 degrees. This would give you a flow rate of 5.5 gpm.

On the other hand, if you have really cold intake water and you want *really* hot water - and want to raise the temperature by 80 degrees, your gpm would drop to 2.2.

Every tank is different, the more you pay for the tank, the less gpm is affected. All tankless heaters are rated in this fashion and you should be able to get the exact figures of the model you are looking at buying. The best thing that you can do for yourself is to try to figure out how many gallons per minute you would like to use on average and how important it is for you to be at a certain temperature with a certain water pressure.

That is, I like my showers hot, and I like the water pressure high. So all of my calculations will be based on my shower. If my washing machine takes a little longer to fill up, I don't really care. For things like radiant floor heating or maybe a jacuzzi... that's something out of my purview.

On a side note: unless you want to be cleaning the heater every month, you will probably want to buy slightly larger heater than what you need. No matter how clean your water is, you'll still get some calcium build-up on the heating elements. This will lower your gpm slightly. I'd suggest buying about 10% over what you expect to use.

Ok regarding heat and ac I've decided to go geothermal. I still want to place pex tubing in the basement slab for hookup to a solar water tank later (because I want warm floors when I finish the basement). I've contacted radiantec but their pex quote is a little high. If I buy my PEX independently (oxygen barrier type) where else can I get manifolds? Also does it matter if I buy the pex in 2x 1000 ft rolls and a 500 ft roll to cover about 2400 sq ft? Radiantec was quoting 300 ft rolls x 8 for some reason. Thanks for all the input guys

doctj - look at your local plumbing supply house for pex supplies. If not there, check out pexsupply.com I have not shopped there but have heard good things and they have the good stuff (wirsbo) with decent prices. I got on a buddies cash account at fergusons (local - but national chain) and they beat almost all internet prices. Easy returns too.

There are a couple of reasons why buying 1000 ft rather than 3 - 300ft rools is not a great idea. 1000' would be much harder to handle, 1/2" and smaller are fairly easy, but 1000' would still be a large roll. If you had a long continuous run over 300', I can see an advantage with a larger roll. With the 300' rolls you also have better opportunity to return unused rolls. Cut into a 1000' roll and it is yours even if you only use 300'. At fergusons, I pay the same price per foot regardless of the size of roll. I think pexsupply is the same.

I was going to go with underfloor radiant but the cost, complexity of the controls and manifolds, and time consumption for my labor or $$$ to have someone else install it just made it too much for me.

We heat with a wood stove as our primary heat. We switched from doing underfloor to doing a flat panel radiator system. We are using a simple 1 zone control system with thermostatic radiant valves on each radiator. We are spending around $3000 on our radiant panels and control system(minus the heat source). The individual room zoning with the trv's will supplement our wood stove very nicely.

I agree about Fergusons. I've used them here in Charlotte. A 4 week lead time specail order faucet handle at Lowe's was in stock and picked up the next day with Fergusons.

I don't know of another radiant heat company that designs the layout and builds the manifolds. Radiantec's value isn't in the material price, but in the on site labor savings. I believe you only have to make four water connections to their setup.

My whole house (3 floors) is heated w/ Radiantec supplies. Regarding 300 vs. 1000 foot rolls, make sure you compare apples to apples. The stuff I have from them is 7/8" ID tubing; longest roll is 400'. Most other PEX used is smaller diameter (which moves less "heat"). Effective heating is driven by the heat difference between objects. The more heat your tubing is able to retain up to its last foot of length, the more even your heating is going to be. Your system will actully be more efficient with shorter rolls than longer rolls (the shorter rolls are not connected together to make longer ones).

You never said what stage your build is in. If you do not have a concrete floor poured in your basement yet, then dont 'even hesitate about putting in radiant in the floor. Do it. As a DIY you can install the tubing and manifold in about 3-4 hours of time. Done. If you are planning an overpour, then it will take a couple hours longer. Ductwork however will take you longer than that for FA.

Also Radiantec's pre-made manifolds are to die for if you are acting as the plumber - well worth the money for the simplicity they provide.

Lastly I want to debunk one all too common myth. HEAT DOES NOT RISE. It has no affinity for one direction over another. However, hot air does rise. This difference is critically important when discussing the differences between FA and radiant systems.

This is for ronnatalie .... I noticed you said you live in Catawba. That is such a small town and I actually have relatives who live near the Catawba post office. Are you near there?

I'm not in the town proper but a few miles away right on Lake Norman (down at the end of Monbo road if your relatives are familiar). The Catawba Post Office is however our post office.

There's pictures of the house over in the March thread.

For whatecer it's worth, we did the radiant heat in our basement (FA everywhere else) and the basement is by far the most coxy and comfortable climate in the house. Cant speak to the economics involved (new house and have not received a utility bill yet)but if you plan to spend any time in your basement, you will like the radiant down there very much.

Thank you for the follow-up post.

I am just now trying to figure out what we want/need in a new construction, and I really like the idea of radiant heat and the idea of the geothermal heat pump. I think that is what it is called. Not really sure how it all fits in together, but I am researching it.

I have heard it is expensive. But I am use to our big old drafty house, and we would use a full tank of propane (500 gallons) per month in the winter time.

And the central air wasnt really big enough for the house, so we had cold/hot spots in the summer time also.

I am looking so forward to being warm in the winter time. As a kid, we had wood heat, and use to have to run around in shorts with the windows open.

I am wanting to do the basement, a main level, and an upstairs. And thinking of stained concrete flooring. I like carpet, but heard it doesnt work as well, although I did find some place stating the contrary. But we also have a few allergies in the house at times, so being without the carpet might not be so bad. I think we mostly liked the idea of carpet because we didnt want cold floors underfoot, so that wont be an issue with radiant floor heat :-)

Gop: The radiant floor heat needs mildly hot water. However that gets heated is up to you. Some use a traditional boiler, some can use a tankless (or even tanked) water heater, you can use a heat pump (geothermal or otherwise as my system is).

My floors are a mixture of tile, wood, rubber, and concrete (not all at the same time, but in different places). All the floors are nicely warm by the radiant heat.