Radiant Heat estimate

[Jagman]

I am close to finalizing a contract to build a 23 x 32 garage. The radiant heat portion of the contractor's estimate is as follows:

"$5800 to install Pex tubing in the concrete slab attached to mesh wire. Tubing to be centered on the floor by setting the mesh on wire chairs. Install new gas fired boiler in the (attached basement) including venting, gas lines and electric."

[The gas boiler proposed is a Quietside DPW-120 which is a dual purpose unit and will also replace an old existing hot water heater and provide hot water for the house.]

Does this $5800 cost estimate seem reasonable? I am located in upstate New York.

John D.

 

[keweenawbee]

I have more than that in materials and I am doing it myself, albeit my Triangle Tube Solo boiler was $3000 of it. With my circ pumps, zone valves, pex, manifolds, fittings & misc it was another $3000. Does he want it all up front and providing a taillight warranty? (as long as you can see the back of his truck leaving)

 

[Jagman]

The Quietside boiler [DPW 120] cost is estimated at $2936 plus tax. This is the unit that has a heat exchanger to provide a closed system for the floor and a second system to provide water for th house.

John D.

 

[HoosierBuddy]

Don't know about the estimate, but have you included polystyrene under your floor? I'd recommend 2" of it in the high density flavor.

Phil

 

[Jagman]

The plans do call for 2" of insulation underneath the slab and also on the sides. I will also have r30 in the ceiling and r23 in the 2x6 walls.

John D.

 

[trythis]

Make sure they select oxygen barrier pex.

 

[tdkkart]

I would Google "Quietside DPW 120" and then use the money you saved on the boiler to double the insulation under and around your slab. Yes, 2" is good, 4" would be better, especially around the outside.

 

[theoldwizard1]

"Tubing to be centered on the floor by setting the mesh on wire chairs. "

This seems vague to me. How many loops ? How close together ? What type of PEX ?

Who is responsible to the integrity of the tubing before, during and after the pour ?

GET IT IN WRITING !

 

[Catalyze]

I heat a 25 x 40 foot shop behind my house with 4 loops of oxygen barrier PEX. I use a 50 gallong water heater and with a line voltage thermostat controlling the Taco pump, I keep it set at 50 degrees. The entire cost of me doing all the work was about $1400. I live in New Mexico so it's not an Upper Peninsula type of system. It works as well as my climate requires. Lows of 20 at night in winter (we did have 3 days of -10F this year) and highs with sunny days around 40.
Craig

 

[keweenawbee]

That sure seems like a good price. I assume its all on a single zone which minimizes the need for expensive extra pumps & controls, and I see that the boiler has a built in circulator pump. I must say I have read negative comments about that boiler line, do some research. If you are going to spend $3k, get a Solo 110 from Triangle Tube, as it is all stainless and self cleaning, low flow resistance thru the heat exchanger, and does have a circ pump for domestic hot water.

 

[Jagman]

It will include 3 loops (approx. 250' each) of oxygen barrier Pex. The contractor will be reponsible for the intsallation and integrity during the pour. What is of most concern is the intial cost of putting in radiant floor heat. At $5800, that seems a lot. At the same time, if I don't put it in now--at least the Pex tubing- I will never have it installed. I am persuaded to do it because the winters in upstate New York can be very cold any snowy (170" so far this year) and I want to be warm in the garage during the cold months.

 

[keweenawbee]

I guess I am confused. $5800 just to install the pex? I did contract my 31 X 37 slab, with a "pause" in my agreement to allow us to install the pex above the insulation. My slab with everything but the pex and install was $6000 (3 identical bids) (I had to provide a graded level site). I spent about $800 for my pex and (2) in-slab manifolds, and it took my wife and I an afternoon to staple the pex to the insulation and connect to the manifolds. You can rent the special stapler for a day and the pipe to manifold connections supplied with my kit from Radiantec were simple compression fittings requiring a couple of crescent wrenches. This is a place you can save some money and finish after further researching what you want to connect to it.

 

[Jagman]

The $5800 price includes: (1) the cost of the Pex and installing it (3 loops); (2) the cost of the Quietside boiler and (3) the miscellaneous hookup including manifolds, wiring, vent, gas pipe, etc. Grading and pouring the slab are separate costs.

I had given thought to 'pausing' the contract to install the Pex myself (doesnt' look that difficult) but if I have the contractor do it, he will be responsible for getting it right. Also, even if I installed the Pex, I still need a licensed contractor to install the boiler by local code. Once I subtract the cost of the Quietside DPW-120 boiler ($2936) the actual installation cost, including the Pex and hookup is $2864.

It just seems the cost of installing radiant floor heat is going to be a lot more than if I just had a gas ceiling heater installed.

John D.

 

[gtivr4]

You might also want to run some long term calculations in terms of how far $5800 will go towards your gas ceiling heater and heating costs. How long would you have to run the setup to get your money back? I'm guessing a long time in this case, although radiant heat is nicer overall.

 

[yevangelis]

its a good price as long as EVERYTHING IS IN WRITING, and he is responsible for anything that is his fault, (the concrete guys might damage the tubes in which case they would have to pay for repair).

btw i would install it in this order, foam, tubing, then mesh

 

[Fastback]

Wow. Thats a bunch of money, I think I would learn what I needed to do and DIY the whole deal. I have under $1300 in my 720 sf slab, granted I just went with a cheap electric on demand unit but my total electric usage was around 1200 kw hours a month for a January bill in Indy, that includes a huge air compressor and welders lights etc..
The thing is I can buy a ton of kw hours for what you will be spending on that boiler alone?

 

[Fastback]

And I would add...DO NOT staple the pex to the foam, get the pex elevated as much as possible in the slab! If you are planning a two post lift design the pex around where it will go now and make sure the rest of the slab has the pex in the upper third of the slab. Studies have shown this increases efficiency and puts less of a demand on the under slab insulation.

 

[Jagman]

The plans call for the Pex to be attached to the mesh and then elevate the mesh with chairs to raise the pex to the mid-level of the 4" slab. This will allow for a 1" cut to be made to the slab and avoid cutting the Pex. I will install a four post lift as well. I'm not sure if it is required but the Pex will be routed around the areas where the posts will be located.

I agree that that a gas ceiling heater would probably be less expensive, but I keep hearing how great radiant floor heat is and if I am going to do it, now seems like the only time.
Thanks to the suggestion above, I will add language to hold the contractor responsible for the correct installation of the Pex, etc.

John D.

 

[PhreeBeer]

Have you considered electric radiant heat as an alternative? It's a whole lot less expensive than hydronic systems and there's no pumps or boilers to maintain or wear out or take up floor space. It's a lot easier to install (a DIYer can do it easily in a 1/2 day - with breaks )

If you use something like ThermaRay's Earth Thermal Storage System then there's no concern about damaging the heating system should you ever need to drill or screw into the floor. And if you have time-of-use rates available to you, you can take advantage of really cheap electrical rates.

Disclosure: The link is to my company. I hate spammers, too, but when I see how much people have to spend on hydronic systems (and their subsequent maintenance issues) I can't sit quietly by when what they really want is a cost-effective and cost-efficient solution to a heating need.

 

[koditten]

have you had a energy loss calculation done? Is the contractor having the floor system professionally specked out? If you have this information you don't have to lay out the big coin for a boiler at this time.

If it was my project I would have everything done exept the boiler. As long as the tube system has been tested to hold pressure you can choose you heat input device at your convienence. Of course my system uses a conventional boiler for my system, so I may be a bit biased.

It took me 2 years to get my system running, but I don't regret taking the extra time to research what would work best in my case. The tube system is the most important part. That has to be layed out right the first time.

I have around 550 bucks into the pex and insulation for my 26 x 32 shop. By the way I attached the pex directly to insulation to avoid anyone cutting tubing with the concrete saws.

 

[Steve in Mi]

I have around 550 bucks into the pex and insulation for my 26 x 32 shop. By the way I attached the pex directly to insulation to avoid anyone cutting tubing with the concrete saws.

How did you insulate? Where and how thick? Is this a slab? What kind of insulation did you use?

 

[koditten]

I hope you knew I was referring to the slab insulation. The 2" foam board under and around the perimeter of the concrete slab. The slab is 4" thick. 2 years old and still no cracks, which really suprises me to be honest.

 

[boyAND1]

Koditten,
Don't want to steal the post, but did you use rebar all the way through, or rebar around edges and mesh in middle? Did you raise the bar in middle during pour or anything special? Getting ready to do mine in about 1 month.
I'd appreciate any info you have. Last slab i poured cracked in about 9 months