Raspy

Have you considered putting a hydronic radiant heating system in a thin slab over the existing floor? Then finish out with epoxy paint, tile, linoleum or cork squares.

After you apply the moisture barrier coat on the walls, fur them out with flat 2X4s of pressure treated lumber that are shot on with a powder activated nailer. Usually on 16" or 24" centers. Then lay in blue board styro insualtion between the furing strips. Do any wiring as needed by routing out grooves and laying in romex (or drill the furing strips and pull it before insulation) and you're ready for finish.

Radiant makes the coldest place in the house into the most comfortable and makes it an exellent place for a workshop or playroom and the heat there will contribute to heating the rest of the house. It also drives out moisture. This completely transforms basements that were once cold and damp into very inviting places.

If, some day, excessive moisture is behind the walls, on the outside of the concrete, it will come in through the cold joint at the base of the wall and over the floor. If you see no evedence of this it probably will never happen unless there is a big flood or you leave the hose running near the wall or something. The fix for it is to grind out a wide groove at the base of the wall and fill it with an externally applied water proofing material. It seems like a poor fix but it works.

HOHN

I've thought about doing radiant heat, either hydronic or electric. I really like the idea of the electric but it's awfully pricey. The nice thing about electric is:
1) only heat the areas you need
2) no need for more concrete, just run it under the subfloor
3) no need for basement HVAC drops

By comparison, a PEX tubing system seems a lot more affordable. Do these systems circulate a glycol solution or just water?

Back in the day, hydronic systems were notorious for leakage and failure. But now with PEX tubing and such, I believe they are much more reliable.

wyododge

You can do either tap or glycol. There are positives and negatives for both. With tap, you just run a loop off of your existing or new furnace no fancy stuff, but glycol holds a bit more 'heat' releases it more evenly throughout the loop and is a bit 'softer' on your piping. As far as leaks, as long as your loops have no fittings, you should be okay. You just use a bit more pex, unless you can figure out your loop length in advance and order your pex in the appropriate lengths.

You are absolutely right about electrical heat, it is the most expensive to operate. Enough that it will effect the value of your house, downward. (I am a real estate appraiser also).

IMO if you currently have a forced air system, you should stick with it, but take the time to have a GOOD HVAC guy come out and make sure your furnace will handle the extra load. Unless you already have. If it wont, you will have a few different options to consider since you will be looking at new forced air, or small radiant for your basement. But two systems means two supplies and two exhausts, !!

As far as pex goes, It is all I use nowadays. Way fewer fittings, way faster, way more freeze resistant. Very cool stuff. One thing I do is plumb to the fixture in pex, then build an air shock and wall stub out of copper. That way your stub coming out of the wall has a little rigidity to it.

This project sounds really cool, your definitely gonna have post some pics!!!

Raspy

Any hydronic radiant heat system should be closed loop. Whether you use glycol or not simply depends on if you think the system will ever freeze or not. Glycol holds no more energy than water, transfers no more energy than water, and is more expensive to use. Down in a basement floor the chances of freezing are minimal. Up in a joist bay on the upper floor, maybe, in very cold climates. Your call.

Radiant systems are not just loops off of domestic water systems they are closed loop for a number of reasons. Pressure, materials, chlorine, oxygen, etc.

Zoning can be done just as well with hydronic as with electric. Some of my projects have 10 or more thermostats. Each loop of tubing can be controlled individually if needed.

It's not a good idea to dig up the old stereotype that hydronic systems are prone to leaking. Not now. Old systems had electrolysis between dissimilar metals and concrete cracking that broke the metal tubes. PEX is inert to concrete chemistry and will stretch if needed at cracks. It is guaranteed by the manufacturer for 25 years in radiant applications. It has nothing to do with the fittings! We try to not make any joints in the slab, just to make it perfect, but there are very good couplings available and sometimes they have to be used when someone drills into the slab and hits a tube.

Electric systems are generally much more expensive to operate, slower to respond and are more likely to have a failure. Stick to hydronic if you can. Sometimes electric makes sense in a very small area like an entry or small bath on a raised floor, but that's about it.

I'll be glad to expand on any of these points if you'd like.

HOHN

That's a great post, Raspy.. Thanks for taking the time to write that.

Can I use hydronic in a sub-floor rather than thinslab it?

I'm planning on floating the basement floor since I have the head space to do that and a drop ceiling and still have 8ft ceilings.

My house is plumbed with PEX and I think it's the best stuff since sliced bread. I'd love to use it to heat the basement and would have full confidence in it.

Justin

Raspy

HOHN,

Yes you can use radiant in subfloor applications. This is done by either pouring a Gypsum 1 1/2" slab over the wood subfloor or putting the PEX runs up in the joist bays from below. I prefer the thin topping slab but either works fine.

To install in the bays, run the PEX down and back in each bay with a long loop. Then jump under the joist in a notch and pull the next loop down the length of the next bay, etc. Then return the end run back through the same notches to the starting point. If you don't want to make notches make a small soffit to cover the jumps. You'll end up with two passes per bay with standard 16" OC framing. Pulling through drilled holes is far more difficult.

Fasten the tubing to the sides of the joists up high in the bays. This avoids being hit with nails during flooring installation. Use plastic, two hole, 1/2" copper piping straps held on with 3/4" screws with 1/4" hex drive to attach the straps every 2 feet or so.

Don't use the metal fin system on the tubes. Not needed or desirable.

Don't Kink the tube!!

Try to keep the runs more or less equal length and no longer than 300 Feet for the 1/2" PEX which measures 5/8" OD.

Keep the loops arranged so the different rooms can be separated with different thermostats and/or flows can be balanced to adjust the relative heat.

Insulate from below with foil/bubble or foil backed fiberglass.

Try to keep cold water lines out of the heated bays to keep them from becoming hot lines. It would be nice to also keep Romex out too, but not necessary. Short blocking not as high as the joists can be used, such as 2X8 blocking with 2X10 joists. Fit these with space left above for the tubing.

Joist bay systems have a little different character than in-slab systems and also would like a different temperature. If you arrange the two into one system I'll help you with the temps and flows, etc.

I have no idea what you are planning for a heat source. Big, whole house systems need a dedicated boiler (not a tankless water heater) or large heat exchanger setup on a conventional water heater, indirect water heater, or high efficiency water heater. Smaller ones like for a kitchen, can use a heat exchanger or even a dedicated water heater. For bathrooms I use a small 2 gallon electric water heater. I dedicate 25 BTU/sq. ft as a good starting point. For continuous systems like bathrooms, 10 BTU/sq.ft. minimum. For single thermostat, whole house systems, 50 to 75 BTU/sq ft is nice.

All loops will attach to a manifold with the ability to balance the flows and, if needed, create thermostat zones. An excellent choice is ZURN manifolds.

By all means, go with radiant heating. Silent, invisible and unmatched comfort

I can expand on any of these points as needed.

Colo_River_Ram

Justin,

More ideas to ponder, they manufacture an electric heating grid that goes under tile and or wood laminate flooring here is a link to one of the companies:

http://www.thermosoft.com/

wyododge

Hey Justin,

How goes the basement??