I think that both of you guys are asking questions that are impossible to answer without knowing a lot more about the particulars of your situation.

I reccommend this program: RadiantWorks.

It is free, thorough, and will give you knowledge of radiant heating better than asking dozens of experts questions for months... thus saving you (and them) a heap of suffering.

-AC

I will definitely give the software a try, thanks for the link!

If you don't mind one more question, I'm wondering what kind of difference I could expect from a 'expertly designed' installation vs. one that a relative ignorant person like myself designed would be? I do plan on doing my homework, but I've learned that just doing something is usually much better than doing nothing, so I'm curious just how much of a differnce I should expect? My thought would be that any heat I can add to the basement will improve the comfort level, even if it's not the optimum solution (especially if that heat is obtained for mostly free after the system is constructed!). And like you said, keeping said heat in the basement is a big part of the equation, so ensuring appropriate insulation is also in the works.

Sorry this turned out to be another unanswerable question w/o alot more information....just trying to gauge where I should put the effort.

Again, thanks for all the feedback!
mike

I wouldn't put tons of faith in professional installers. A well read DIYer can put in just as good of a system if s/he knows what they are doing and thinks things through. It does require a lot of time researching things up front though.

Mikek

Yes these are some loaded questions. I'm with Daox as far as professionals are concerned. I find it still hard to believe that some companies are still promoting the staple up type of floor heat. Thats old school with very limited results. The best results are from the hydronic tube on top of the sub-floor. Products like Uponor or as AC Hacker suggested Roth panel.

I do like your comment: "I've learned that just doing something is usually much better than doing nothing." If you educate yourself. Spend money for better materials with the money you save DIY. Maybe even buy tools to make your job easier or better. Remember any job doing is worth doing well. There is a treasure trove of information on this site for what your trying to do.

The job your about to tackle will not be cheap but remember you get what you pay for. The results can be spectacular. We enjoy the heated floors alot. The operational costs are very economical.

Being that your project is the basement and not your primary living area you can do it in stages. Remove everthing from your area. Bust out floor. Dig a little deeper. Put down ridgid foam insulation. Put in reinforcemt mesh. Tie in your hydronic tube. Pour cement. Weekend projects.

Randen

closed cell foam re open cell
 

Randen,

Excellent suggestions. The only correction I would make is to make sure the sub-slab insulation is CLOSED CELL. Open cell just gets wet. You don't need a lot as each inch is at least R 4. I would suggest putting down two inches.

The delta T from deep earth in this area might be 30 F (45 F to 75F) so much more than two inches may not have a substantial ROI.

The labor is the expense here as closed cell foam boards are not expensive.

I did a basement of this type (1991), put in foam (as above) and then put four inches of dry sand on top of the foam. This entire volume was kept dry with even deeper french drains so the dry sand enhanced the insulation effect and also added to the thermal mass. Then four inches of concrete - the total is a huge thermal "bathtub".

Today, I would certainly put in a radient system, but the latest tubing in 1991 was polybutylene and it would not have worked well (and was incredibly expensive).

I do agree with AC - do a heat load analysis first and plan, plan, plan.

Steve

Why not put in base board radiators instead?
Cork is about R3 per inch, almost as good of an insulation as foam, so I'd put a cork floor down over foam and hot water baseboard radiators, that way more of the heat stays in the house and the floor will feel warm even if it's not heated.

I think these folks are interested in solar...

In most locales, the feed temperature (sent to a baseboard heater), required to generate the heat output rate sufficient to balance heat loss form a normal house would be considerably higher than what is reasonable to expect from solar heated water.

However, in the case of someone living in a warmer climate, and/or someone with extraordinary insulation and infiltration elimination, it could be possible.

If someone were living in a challenging latitude like Michigan, for instance, and/or had only a code house, or lower, the results could be very disappointing.

-AC

OK, everyone else has weighed in so i guess it is my turn (haha).

First, insulation under the floor....min 2", more is better. EPS is OK IFit is high density, none of this white stuff that you can break with your hands. The EPS has a lot lower energy content anyway (although most of what i put in is XPS).

On the basement walls, closed cell foam ONLY against the concrete, even 2" will do wonders but it is even better if all the insulation goes on the exterior of the foundation. You can always use thermal mass but it is almost useless if there is insulation between it and the conditioned space.

Floor heating.........I have been using PEX (Wirsbo and Rehau) since 1989 and Rehau has the best O2 barrier around (and yes it is important) and a closer spacing and shorter loops means a lower water temp needed which means more use out of a solar thermal system.

Floor finishes....look into Marmoleum by Forbo. It is a real linoleum floor that can be bought with thin cork backing (thin enough not to have any major effect on the water temp) and can be done in click flooring. Very healthy product.

There is a lot more but you have time....

How thick is the cement floor? I've seen some smaller houses where the cement is only 2-3" thick and altho it's annoying to remove, cutting it out and digging down a few inches can be well worth it in the long run! then you could insulate and re-pour new cement with radiant tubes in it.

Ryland

Well you are right busting out concrete is heavy work and of coarse the thicker the harder it is. Growing up my father was a contractor and we had done alot of concrete removal and replace. I remember it well. A room 20 x 20 with a big hammer and breaker bar depending on the concrete would be 2 good days by hand. But at this stage of the game I would rent a big compressor with a jack-hammer and have it all broken by lunch time.

I know its a lot of work but you can't get nothing for nothing. It all costs. Labour materials and the sweat of your browe as well as the sore muscles.

I have two brothers they are old school. They like to off-set their heating bills with wood heat. One brother had stopped by the shop a few times while I was building the Geothermal heat pump. His remark was "man, thats a lot of work building that." Yes it is but I won't be going out to the bush and cutting fire wood for 3 weeks each year. After I'm done, I'll just turn on this heat pump each heating season.

My point being work really hard only once.

One other thought and maybe Mikesolar will stop-in. If you are planning seriously about the solar heating I would suggest 2 dedicated loops in the concrete floor one for the LPG hot water heat and the other for the solar hot water. The extra cost of the plastic tubing is off-set by not needing a heat exchanger. Installing the dedicated solar hot water loop in the floor would eliminate any losses in the heat-exchanger to the floor loop. Pump the heated glycol straight to the floor loop. I know what you may be thinking" the heat is free so what if we loose a little" Well the heat your not getting into the floor your paying for its replacement. Gather all the free stuff you can.

Randen