To add PEX or not?

metar28

Hello. I'm getting ready to build a new house. Really wanted to do in-slab / in-floor heat throughout the whole house but the quotes were just way over our budget. Someone told me that even though we don't plan on using radiant now, we should still install the PEX tubing in the foundation just in case down the road we can afford it. Sounds logical. How many agree or disagree? If you disagree, why? 

STEVEusaPA

depends.

Depends on what you're doing for heat.  If you're putting in scorched hot air, why waste the money on the tubing.  If you're putting in a hydronic system, and putting in tubes now, wouldnt cost more to finish the job.  Plus your boiler would make your domestic hot water, with an indirect tank, saving you more money.  And you won't have such dry heat in the winter.

I would get a few more qualified quotes for the radiant.  If this is your last house, the extra money you spend now, for the superior comfort you'll enjoy forever, is well worth it, and will pay for itself over the years.

Plus operating costs will be much lower with the hydronic radiant then with scorched hot air.

What I did was.....radiant for heat, and was able to run an air-handler and duct work in the attic for AC.   All your vents are in the ceiling, more headroom in the basement.  And for a few hundred bucks more, I made sure it was a heat pump, so I can use it for back-up if the boiler went down.

If you personally know someone with radiant heat, ask them.

Good Luck

Mark Eatherton

Fer sure...

It is called "Radiant Ready" by Uponor.



No time better than the present to at least get the tubing AND insulation below the tubing into place.



While you are at it, have them rough in the necessary thermostat wires that will make the system conducive to future zoning, and make certain that their tubing layout patterns match your future intentions.



ME

metar28

Doing hydronic baseboard

We are planning hydronic baseboard. We will have separate air conditioning, but definitely not doing forced hot air. Just not efficient in New York. Currently contemplating a mod/con gas boiler, paired with indirect hot water, weather response control and high output HE2 baseboards. We are doing extra insulation to minimize heat loss. We might forgo the mod/con and HE2 baseboards and go with a Burnham Revolution and standard metal fabricated baseboards to save on costs up front. I know the upgraded system will save us money, but according to my calculations it will take 18 years to pay for itself. As for doing all radiant, I got 2 quotes, within a couple thousand dollars of each other. It was almost the price of doing a geothermal system.

CMadatMe

You Must Be Marcy's

Hubby...Put the tubing in the concrete.  The tubing is the most inexpensive material in a radiant job. You only get one shot. I've followed her post on the gas thread and recevied more info from her via e-mail.

My suggestion. Get another quote from someone that specializes in low temp hydronics before you make any decisions on which way to go. The design phase of the application is the most important phase in my opinion. Without the right map in your hand your looking for lost treasure.

metar28

No, it's me

No, not Marcy's hubby...it's me. Hubby doesn't have a clue to what I'm doing. He just gets to pay the mortgage. : - )  I'm going it alone on the house project. Hubby is only a bystander in the process. He trusts me...

STEVEusaPA

Hmmmm!

Help me out because I'm confused...Are you telling me you think it's cheaper to run all the tubing, hook up/install manifolds (how else will u pressure test for leaks during contruction), run extra thermostat wire................then, install a new boiler, with all its piping, and run/install all the hydronic baseboard?  Then what's the plan? In the future, take all the hydronic baseboard out, fix all your wood trim, probably carpet, have to paint.........then go to the boiler room, re-pipe your boiler, install new thermostats.  If your puttin in a whole new hyronic system, and running the tubing, you're 90% there, install wise, & cost wise.

Could you also give us (me) a little insight on the 18 year payback?  Considering the reduced operating costs especially with the mod-con, I think it would be way less then 18.

metar28

I don't know, that's why I asked

I don't know what is cheaper. I was just told that I should put in the PEX during the slab pour so it's there IF I ever wanted to use radiant in the future. Since once the concrete is in, there's no going back to put PEX in. It's now or never. I would love to have radiant, but all the quotes I've been given are too costly for us right now. I am under the impression that putting the PEX tubes in the foundation is not very costly. I guess it depends on what is considered "not very costly."



As for payback on the other system I am looking at (mod/con boiler, indirect water heater, weather response control and HE2 baseboards). I took the predicted amount of propane usage annually (based on my level of insulation should be 1,000-1,200 gallons) to get an annual cost. Figured 30% savings using the upgraded heating equipment. Then I looked at the amount of extra mortgage that will be required to cover the upgrade costs. Took that amount and subtracted the 30% savings to give me the true annual savings per year. Then I divided the cost for the upgrades by the true savings and got 18 years to payoff. Maybe I did it wrong?

metar28

Good point

Good point that you make about removing the baseboards in the future if we were to go with the radiant. Couldn't you just leave them in place and simply close off the valves, essentially deactivate the baseboards?

STEVEusaPA

I guess what I was trying to figure out ...

What I was referring to were these 3 options:

A.  Cost of Hydronic baseboard heat--labor, materials

B.  Cost of Hydronic baseboard heat--labor, materials.  Plus, cost of material and more importantly LABOR, to install pex, manifolds, additional wiring.  Then when/if you switch over, cost for addtional materials to finish radiant, re-pipe the boiler, change thermostats, plus additional labor to remove all the baseboard, plus costs to fix/patch repair room finishes.  Also, is the boiler oversized now?

C.  Install complete Hydronic radiant system.

My thinking was.....B costs way more then A or C.  Also, with 'C', you'll use a smaller boiler, need less BTU's, and will use less energy to heat your home (some say up to 30/%).

So if it were me, I would consider the cost difference between options A and C only.  Take that difference, minus fuel/energy savings, and use that cost amortized into your mortgage to get, what I feel, is a more accurate number.

Don't forget the added comfort of radiant. 

I'm sure you have blueprints for your new home.  Have your contractor do a complete heat loss calc for both hydronic & radiant.  You'll see the difference. Ask him/her to include total estimated operating costs for both designs.  That should help on your calculations.

One place I would definately consider putting in tubing would be if you would want to add a snowmelt system for driveway/sidewalks in the future. If you add a pool, you could put both snow melt/pool heating on a separate boiler, or plan for a multiple boiler operation.

It may also help, depending on where you are in your process, to check out 'find a contractor' from this website, for someone in your area.

That was wayyyyyy more then 2 cents.

NH03865

Consider all Costs

BEFORE making the decision.  As HVHEHCCA pointed the cost on PEX tubing is relatively inexpensive, it is easy to put into the slab before you pour and most importantly, you only get ONE shot at it.

But ME really hit the nail on the head.  You need to also install insulation UNDER the slab to have a radiant system that works properly.  The conundum is that the insulation IS NOT inexpensive and you also only get ONE shot at it.    That means that you really need to commit to a radiant floor before you pour the slab, otherwise, while you may be able to heat the slab later, it will be very expensive to do so because you will be heating the earth under the slab as well.

metar28

Planning on rigid foam polysterene

Regardless of the heating system we choose, we are planning to install 2" of rigid foam polysterene under the slab and 1" on the sides of the foundation. Chris at HVHEHCCA is local to me so I've asked for his help. I feel I am in good hands. 

NRT_Rob

If the area is to be heated

the slab should be insulated, whether it's radiant or not.



if it's EVER going to be heated, the slab should be insulated. In general, slabs should be insulated.

metar28

Should I be doing more?

NRT Rob - should I be doing more insulation around the slab? Planning 2" below and 1" around the sides. Thanks!

NRT_Rob

depends

Personally, I would do 3" or 4" under slabs. more advanced heat modelling like the passivehouse calculator shows that there are many circumstances where that would make more of a difference and short of figuring out for each project what the soil circumstance is and what the effect is, 3" or 4" is a safe bet. but 2" is the standard recommendation in our industry and I don't pretend to have solid science to prove it's wrong. I just think it is based on things I see (basements that are still very cool in the summer, etc). I could be wrong.



Edges should always be 2" minimum.

pipe4zen

NYS Energy Code

Requires insulation in the slab, and foundation walls any way. 2" min is more than enough. It can be debated if 4" will do more good or not in the context of " being green"



Go ahead, put tubing in slab the least expensive way now, otherwise if you decided to finish the basement later than you will have to build up the floor on top of slab if you really want radiant at that point.



Good Luck

CMadatMe

Marcy's Lower Level

Heat loss of the lower level is only 22K. Zone 1 Garage, Zone 2 Gym/Sewing Rm, Zone 3 Family/Bed/Bath. Water temp needed at design is 85 degree water. So should she put it in the slab? PS, that was using an R-Value of 5 for the under slab and perimeter.



Total heat loss of the entire house is 50K in round numbers. Now that includes radiant in the Kitchen/Dining/Living. If I change these rooms to base or panel rads we are talking around 60K.





Here is her problem. Can't do it for the budget she is looking for. The only way to fit her budget is to do atmosheric with a little ODR and fin tube. The radiant in the lower level and fin-tube (Hi-Cap sized for 160 design water temp) for the main floor option could be done for over what she wants to pay. Could do electric matt for the small bathroom and master bath to keep the floors warm.



No place for anything except a kick in the kitchen which is open to the dining room. Only one wall in the dining room which I would assume there will be some type of furniture piece against. That wall is out. Thus why I did radiant for these 3 threes. The family room is off the dining room which is separated by a what looks like 2-way gas fireplace.





She needs a 25K-30K total budget for DHW, radiant in the rooms described and panel rads sized to utilize the joist trak water temp of 120. Could do it with a little Vitodens 100. Boiler reset would take care of the 120 water temp and utilize a Taco I-Valve for the lower level radiant. Zones would be controlled by Taco Zone Sentrys with system pumps being Alphas. The radiant/panel rad option gets her condensing 100 percent of the year. The radiant/BB option which would be controlled the same way about 85% of the year based on our avg daily and night time temps. This option is somewhat in her budget provided she worked with her contractor in provding the labor to lay the tubing. 

As for payback. I don't think any of us nor can a propane company give you an honest anwser. To many varibles in boiler and system operation. There is no flat btu or water temp, they both change daily. What value do you give for total comfort and un-obstructed wall space in the main living spaces?