New Radiant Floor Heat

[Leef]

Hello All,

After a long summer, we moved into our brand new house in October. The house is a ranch style home with an unfinished 2500 sq ft. full basement (with North walk out exposure). We used a general contractor and tried to plan for completion of the basement "some day". The bathrooms and a kitchenette are roughed in and we put the radiant floor tubing in the concrete floor to be "hooked up" in the future.

We were just notified that our application for the energy company rebates were rejected because the gas water heater doesn't meet the criteria (must have EF >= 62 but ours is 58). The plumbing contractor reminded me that the original quote called for an electric water heater (which he assumes met the requirement) which I changed to gas (added on $500 for exhaust flew).

This small tecnicality jeopardizes $2500 in rebates (ie all or nothing). I have expressed my displeasure to the plumbing contractor, he apologized for the selection of water heater, and now we're at the next step.

My thought has been to go ahead and hook up the radiant floor heat and hope to be treated fairly using the sub-standard water heater for the few months it gets used and install a qualifying gas water heater in its place for the rest of the house. Maybe even make that new heater larger than the 50 gallon we started with since we have four children.

The ball is in his court right now. I intended to do some research for alternative heat sources for the radiant floor and shop around for competitive bids someday, but since it has to be changed I might as well use it and hope they're fair with the net cost [img]/forums/images/icons/confused.gif[/img] .

Does anyone have a guess as to the cost of hooking up the radiant floor heat this way? I'd like to be prepared somewhat.

LeeF

BTW here is our web log which chronicaled our construction: http://heirloomacresadventures.blogspot.com/

[Pat]

Congrats on moving in!!!!!!!!! Sorry to hear of your glitch. I use a geothermal heat pump (Waterfurnace) for the hydronic heat, forced hot air, heating a 50 gal domestic hot water tank, and Air conditioning. Unless you have super cheap electricity (under 4 cents per KWh) I wouldn't use an electric hot water heater for hydronics.

A heat pump like mine costs more to buy and install but a good one will run at about 400% efficiency compared to 100% for an electric hot water heater. This means your electric cost will be about 1/4 of what it would be to use an electric hot water. IF yoiur electricity isn't super cheap then the heat pump will save enough electricity to pay for itself and give a return on yoiur investment during its expected life time.

My geo unit is water to water but a good air to air uniit can have about 20 SEER or so and that is darned good. Of course if you have significant winter time with temps below 40F then you need gas backup as the electric back up is again big bucks for electricity.

Are you doing "floor warming" only or are you intending to heat the house with hydronics? Some folks partially heat the home with the hydronics, just have comfortable floors, and supply the rest of the heat by other means.

Am I missing something or wouldn't you be $ ahead considering the rebates to just buy a qualifying unit and get reinspected?

I'm still waiting for later! I was going to do some of the finish work, especiallly in the basement later but not much has happened and nothing in the basement. I have installed a desorative propane gas log parlor stove in the sun porch and am close to installing the one in the sitting room and basement. I did tile 3 of the unfinished window sills a few days ago. Next for installing 800 sqft or so of pergo in wife's tea room. and shelves and built in cabs and ...

Pat [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]

[Leef]

Pat,

Yes, we would only use the hydronics for floor warming in the basement; the primary heat is forced air and we have a wood burning stove for additional heat as needed. That's why I've not been in any hurry to get it functional.

You are right, I'll be $ ahead just to replace the water heater with a more efficient model and collect the rebate. I don't know our electrical cost per kwh but it could be interesting to compare different regions - I'll look it up when I get home.

My dilemma is what to do with the current water heater? Maybe just have the contractor take it back and I'll pay the difference. Or have them use it to get the hydronics functional and pay for the cost of additional hardware like a pump and thermastat ... I'm afraid that additional cost will use up my projected rebate [img]/forums/images/icons/frown.gif[/img] or cost even more than the rebate [img]/forums/images/icons/frown.gif[/img] [img]/forums/images/icons/frown.gif[/img] .

Do you have any advice for me to discuss with the contractor when he calls with the estimate?

LeeF

[Pat]

Do you have any advice for me when he calls with the estimate?

YES! Be sitting down!

If you are comfortable doing some elementary plumbing you can hook up the water heater to the floor loops via a pump and thermostat. There is an excellent web site populated by true experts in radiant heat. It is sponsored by the RPA (Radiant Panel Associatioin) and you can get lots of good but free advice there. You can get help sizing and selecting a circulating pump and selecting a thermostat. I would be pleased to help also. I have a contact in OKC who is a real pump guru and they ship anywhere so if there is pump locating/specifying issue I got you covered. It would be useful if you knew the type, size, and length of the floor loop(s), i.e. 1/2 inch, 5/8 PEX or what. I had the best professional designers available in this end of the world on my project and it would be easy for me to relate any installation details to you so you could piggy back on their work for free.

Our 1000+ sq ft great room has 7 separate loops of PEX and is fed from a manifold system with individual flow controls for balancing the system. May sound complicated but I promise you if you have three fingers on one hand that work and know enough to pick up something when told that you can be guided through an installation that will be as good as a plumber would do and maybe better.

If you hook up the excess gas water heater to the basement hydronics I think you will find that when it is in operation due to various factors that the other heat sources will most likely not be required much if at all. The coldest my basement gets is about 70. It gets "waste" heat from the equipment space and the forced air isn't required. In summer enough cool air comes down the stairway to keep if cool down there so unless conditioins are extreme heat or cold I don't have to purposely heat or cool the basement. My walkout is on the south side but I have about 11 feet of overhang above the basement's patio. I don't get much if any solar gain there in summer and just a tad in winter. Of course the R-11 outside the walls and under the floor helped. the basement ceiling is a horizontal analog of ICF with several inches of styrofoam under the slab and a layer of sheetrock for the basement ceiling finish layer.

Probably when the basement's kitchen is finished and used to support backyard get togethers the traffic through the heavy double pained sliding doors will allow enough outside air to enter to make the forced air system useful to have available.

Here is where the pros hang out

===> http://www.radiantpanelassociation.org/

Pat [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]

[Leef]

Pat,

Well you were right. I got the estimate back and I'm disappointed. They'll replace the water heater with a RUUD gas 50 gal. unit for "a discounted" cost of $675. Then they'll use the spare original to hook up the radiant floor for $2100 icluding all necessary parts. There goes my rebate.

I looked at the website, but don't see a forum to browse and I don't know where to begin. At this point in time I've only authorized the water heater work to get the rebate approved.

I do feel capable of installing the hyrdronic system with advice, but I hesitate because of lack of spare time. Since I'm in no hurry for that, I would like to explore that more. Where do I begin?

Leef

[Pat]

Leef, Maybe I had a senior moment or maybe something changed but when I went to the RPA site I didn't see a forum either. I will look into this and see if I can recall or re-find the FORUM that I used to visit a few years back and got so much good advice.

There are vendors that ship to DIY folk. There are lots of vendors that will only ship to lisc professionals. At least the vendors who ship to DIY folk and help with design and component specification are readily available on the net.

Wht did you put in the floor? Is it PEX or what? What size? what lengths? I hope you used multiple loops and placed the runs closer together where the expected heat requirements were higher (under windows, along outer walls, and such). You can't ballance the heat output if it is all one run. If any of the runs are too long the water will shed its heat before getting to the end of the run and that part of the floor will be a cold area. IF the last part of a loop is layed with closer spacing that helps compensate for the water being cooler toward the end of the loop.

You might want to browse some of the DIY suppliers who offer advice and design assistance while I try to find THE or A forum to get you more help.

If you are not in a hurry and would rather invest more time and less $ then I'm sure we can get the rest of your system specked out and that you will be able to assemble/install it yourself.

I have two types of hydronic controllingwall mount thermostats. The majority are air sensing and are for heating only. One stat uses a sensor burried in the thinset of a tile shower to control the temperature of the shower walls.

I am assuming that you want to control the temperature of the basement air by varying heat to the floor and are not trying to control the slab temp. Forget setback as the time constant of the floor slab is large compared to the 24 hr daily cycle of occupancy. If you turn the basement heat off at bedtime you will not get much temp reduction for several hours. Similarly you have to turn the heat on so far in advance that that the advance turn on overlaps the evening setback period and they clash. They are mutually exclusive (MUTEX.)

You will just need to set the stat and let it ride pretty much all winter and shut down the system when the spring temps permit.
There is a tendency durning the "shoulder seasons" where you will alternately under heat and overheat if you try to get all heat from the hydronics becaust the outside temps will vary much faster than the hydronic system can respond.

During these periods a more even heating can be achieved by setting the stat to a lower temp on the hydronic system and using some air based supplemental heat when needed. The floor is still comfortably warm but the room is less liekly to overheat. I have a decorative gas log parlor stoves and a gas log fireplace for that purpose.

I don't have radiant in my basement because I was expecting to carpet much of it and that limits carpeting choices (R-value considerations.) Radiant floors are compatible with carpeting but my hot water source is a geo heat pump and it doesn't produce the higher temps needed to push the heat through a carpet. Your water heater would be happy to produce way hotter water than my heat pump.

Here is a sampling of sites, some with more inifo that others but all have something of interest.
http://www.radiantcompany.com/

http://www.pexsupply.com/
Look at the bottom of the page for links to lots of how to info.

http://www.radiantec.com/installation-manual/index.php
Click the Installation manual tab and look at the domestic water heater installation (PDF.)

http://www.mvsupply.biz/hydronic_heat.htm

http://www.warmlyyours.com/homeowner...rd=heatradiant

http://www.radiantdirect.com/index.php?google

All these sites have info of interest. There are lots of other Hydronic heating sites. These are just a sampling.

Ain't GOOGLE grand? Later,

Pat [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]

[Chillimau]

Is it under the "Networking" button?

[Pat]

Hey thanks chillimau, Apparently your sharp eyes and active brain won the day. I was going too fast I guess and didn't see or explore that button.

That site was a great source for me. I met some really great people who know their stuff in radiant panels and practical application of same. In particular one Viet Nam era chopper pilot who does the lecture circuit on radiant panels. We bought some aluminum heat sinks (heat spreaders) that grip the PEX and spread the heat to help eliminate hot spots and get more heat trasfer ouit of the PEX. That was for in-wall and in-ceiling applications, not floors.

Anyway, thanks for the assist. You prevented my looking completely off base with the suggestion of the RPA site.

Pat [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]