Hyrdonic heating system question
Coffeymaker
| Posted in Energy, Heating & Insulation on
I’m planning a kitchen remodel and I’m considering using hydronic radiant floor heat in place of the copper fin tube radiators that are currently in place. Is it counter indicated to use a PEX tubing system in conjunction with a boiler feeding cast iron radiators in the rest of the house? Are there other steps/precautions I should take? Other considerations: 1. Oak will be the finished material for the floor, 2. I’ll be using the staple-up method (attaching the heat trasnfer panels and PEX to the subfloor from below 3. I recognize I’ll have to insulate well from below. 4. the room is about 160 Square feet.
My alternative would be to install a new bulky cast iron radiator.
Any advice would be appreciated.
Replies
Assume you know that your control temp for the hydronic will be a lot less than thr radiator.
I'd go to heatinghelp.com and look for "the wall"
Solid hardwood requires the surface temperature be maintained below 85 degrees to prevent warping issues.
Staple up tubing and nail down floor are usually incompatible.
You will need to provide a thermostatic mixing valve and a small circulating pump and some basic controls at a minimum. How do you propose to control the heat i the space? Many options to choose from.
A Raupanel (by Rehau) type of product (or Warmfloor or QwikTrak, etc) might be a good option. You have smaller (3/8" vs 1/2") tubing and you can see the tubes so that you don't put a floor nail through the PEX. The panel total height is 1/2" or so and for a small area, the pressure drop through the samller tubing will not be a significant concern.
I hadn't thought about warping issues. I suppose I could make this a separate zone with it's own thermostat, and use a mixing valve as you suggest to get the temp down. I wish I could do the nail down method with the track system, but I can't afford the aditional floor height. As for the pump, won't the recuirculating pump on the boiler suffice to push the water flow?
If you haven't laid the floor yet it would be best to use engineered oak flooring. The oak surface is thick enough for numerous refinishings if necessary and you won't find a nicer looking hardwood floor. Solid doesn't compare.
Coincidentally, I'm ordering up some of that joist-trak stuff uponor makes tomorrow. Definitely go with that because staple up, (as in stapling it up), makes noise when the pex expands and contracts and you won't like that at all.
Also, I'm no expert, but you might want to consult someone about low boiler return temperatures because you're definitely going to need lower temps for the floor than the fins and domestic hot water, as stated. There's a bit more to it than just getting the correct temperature to your floor via mixing valves. The type of boiler you have is important.
Tim is incorrect. Nailed wood floors are done with all kinds of radiant systems all the time, and if the FLOOR SURFACE TEMPERATURE... not water temperature... is kept to 85 or so and the wood is installed properly, there shouldn't be too many problems.However pumping 180 water into your joist bay is not a great idea. Some kind of tempering valve and pump is strongly recommended at least. but knowing what you need for water temps can do a lot for the system on both sides of that valve. Many homes are overradiated.-------------------------------------
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Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
I am installing hydronic heat in the home I am building for myself right now. I have had a very difficult time getting reasonable quotes and designs specific to my home from the plumbing shops around my area.I have used Wirsbo/Uponor brand components for tubing and manifolds and found the ADS design and heat loss calc software very helpful in determining the actual needs for my specific project.Once you have determined the method of installation of the tubing, the manufacturers all have design and heat loss software that integrates their products and generates a materials list.HeatingHelp.com and HealthyHeating.com are invaluable resources. The books by Seigenthaler and Dan Holohan? are great references also. Plumbing supply houses have access to manufacturers reps that may provide services if you buy their products.I have learned that the "Rules of Thumb" in hydronics often lead to oversized components and then most plumbers oversize above that to boot.Good Luck!
Mr Coffe,
Staple up under oak floors are done all the time, IE: my house. You need to do your math to figure heat loss, as to what temp. water you will need to circulate threw the pex to heat the room. Pex is used for this application all the time. You will need a mixing valve to temper the water down, you can't pump water @ 180 degrees threw the floor, to hot. You want a constant circlulation @ a constant temp, and you will need some sort of a floor sensor or thermostate to control.
The guys at heatinghelp.com are vey helpful.
Your might find a contractor that would let you run the pex and the staple up and the contractor could handle the near boiler piping.
I did something like this in a bathroom floor. I ran 3/4 copper piping about 2 to 3 inches below the floor in between each joist bay with reflective foil and fiberglass under it. The 180 deg. copper pipe heats the air in the joist bay under the floor and that heats the floor. Works great.
Since this is a bathroom I didn't heat the joist bay under the toilet. Didn't want to melt the wax ring.
I have no idea how you would calculate the heat gain from this. I added a small base board radiator with manual mixing valves incase I needed more heat.
Consider a sleek radiator. Adding a low temp radiant floor zone will significantly complicate your existing boiler system. At the least, you will need a mixing valve, pump and controls for another zone.
http://runtalnorthamerica.com/
That might be true to some extent, but in a kitchen where wall space is a premeuim, you could be hard to find wall space for a panel rad or baseboard. That's why toe kick heaters are popular in kitchens and bathrooms, but can give out uneven heat and can noisey!
But when you walk accross a heated floor in the winter time and stand waiting for the coffee to be ready, it will all be worth it!!!
I think that I'll be taking your advice--at least in part. I've had some experience with Runtals, and they just don't hold heat like cast iron. I'm sure I can find a slender cast iron raditor that will do the trick.
It wasn't the complication that put me off, it was the comment about the noise that could come from the staple up system that concerned me. Anyone else had experience with noise being transferred from the expansion/contraction of PEX tubing?
Noise from a staple up system is largely from a improperly installed system, not the type of system!
Use a good grade of plates, install plates properly, set pex in plates properly, allow a non restricted loop at the end of joist bay. Properly sized hole threw joist, and pex/aluminum/pex, with a constant circulation = a silent system.
go cheap & sloppy, you will go nuts!
Noise in a staple up install is a function of whether the job is done right. Correctly done there is no reason to have noise.
Runtals will also perform exceptionally. Again it is a function of installing practises.
Steel rads and cast iron are different types of emmitters that requires different water temps and control.
Do yourself a favour and try heatinghelp.com way more real expertise over there.