View Full Version : Correct installation of hydronic radiant heat
04-22-2008, 11:40 PM
I have radiant heat being installed in my house and I don't know if they are blowing smoke up my butt or what.
They said I don't need a reflective insullation. I can't find anywhere that doesn't recommend it on the web.
Not running tubing under objects like kitchen counters or the bathroom vanity,shower areas? They just left the tubing hang down where counters were located above. What a mess trying to insulate that.
I thought they were going to run it up and down the joist bays flush to the ceiling. It looks like a mess to me.
04-23-2008, 12:40 AM
Go to: www.healthyheating.com - or www.heatinghelp.com, lots of info & advice there from "wetheads". Sounds like a lotta smoke to me. :(
04-23-2008, 07:19 AM
you do need reflective type of insulation. even on floor between conditioned space.where will the heat go? some will go up but some will move down because of radiation easier through air than wood floor. but when i install i let the insulation contractor insatll insulation. its ok to run the tubing under cabinets but i've insulated the tubing so as to haet the space you don't need heat into. if they are installing it in the joist is fine, if the ends are going under the joiist to the next bay is ok if they insulate the u it makes between bays. aslong as it is in a crawl space or unfinished basement. is better to me to drill a hole for the tubing to thread through but is more time consuming but looks better. are they using the aluminum radiant panels while installing the tubing or are they just putting the tubibg to the floor? www.rehau.com also has some information the is helpful. hopefull you won't tell us that this is the low bid guys installation. good luck
04-23-2008, 07:19 AM
Staple ups don't belong too close to the floor. Thats how they gets nails stuck in them.
04-23-2008, 12:54 PM
They are using aluminum plates. It is not stapled. This was not the lowest bid. They are doing my ac and heat. It looks like an insulation nightmare. Insulating the tubing under the cabinets makes sense but wouldn't it help heat the area above if you were heating the cabinets?
04-23-2008, 04:17 PM
It could end up drying out the cabinets, and damaging them. Your not suppose to try and help heat the house through the cabinets
One bay under the cabinets would generally be ok on cabinets open to each other. But not on a small single cabinet.
04-24-2008, 12:15 AM
Sound like poor installation if tubing criss crosses below joists, as far as the reflective insulation not needed, just make sure the r-value is greater on the unconditioned side of the tubing then the condition side,remember most everything has an r-value.You must take under consideration sub-floor,carpet,and padding or anything else that may be put on the floor.
04-24-2008, 12:24 AM
Clarification on reflective type insulation,reflective works with radiant energy i.e sunlight,or radiant heat. The misconception is the tube is not suppling radiant heat.
It is supplying conductive heat to a thermal mass that projects the heat via radiation.
04-24-2008, 07:19 AM
if you can't staple to the floor , how do you attatch so that its not hanging out in space? yes, you may have nail hits, but you should also be aware of where walls are located above you and try to stay minimum 6" for 1/2 " tubing from the wall. even that doesn't guarantee anything though but it will lessen the chance. we had a nail hit that didn't show up for 3 months after the system had been in operation. i had 9 zones with air guages with 100 psi and only 2 zones took hits. one, twice but the wall that made the hit wasn't on the plan,just added.:confused: the salesman we purchased the tubing from gave my supervisor the instructions for the tubing insulation and it should be 4" below the tubing and reflective barrier toward the tubing. the insulatioin contractor didn't install the reflective barrier type insulation as requested but it still works. but the idea is to try to make as much radiating heat go up instead of down. you are trying to get 100% of the heat where you want it not where you don't need it. putting heat under the cabinets will just be problems. that floor area is not considered into the useable heated floor area.
04-24-2008, 07:25 AM
You don't staple pex to the floor itself. You either use the plates fastened to the floor. Or staple the pex to the joist.
04-25-2008, 09:27 PM
this is taken from www.rehau.com from an installation download.
In an RFH system that is installed above a heated space, it is
recommended to insulate the joist cavity below. This prevents
unwanted heat transfer to the room below, and decreases the
response time (time to change the temperature) of the heated
space above. It is required to insulate the joist cavity below an
overpour RFH system that is installed above an unheated space.
■ The insulation should be installed 1-2" (25-50 mm) below the
bottom of the subfloor.
■ Ideally, a reflective surface of foil should be installed on the top
of the insulation layer to reflect radiant heat to the bottom of
■ In joist space installations over a heated space, the R-value of
insulation below the subfloor should be 4-5 times greater than
the total R-value of the floor structure and coverings above.
Recommended minimum R-value over a heated space is
■ In joist space installations over an unheated space, use insulation
with a minimum of R-30 below this air gap.
■ Insulation in the joist cavity may be a combination of a reflective
“bubble foil” insulation closest to the pipe, with fiberglass
or PS (polystyrene) board insulation below to achieve the
■ Be sure to insulate all ends of joist cavities or other places
where heat could escape the joist cavity.
rfh is radiant floor heating. maybe some of my numbers are incorrect but i'm pretty close. without a doubt though this is the best type of heating you can buy. to me anyhow. we also use this for our sno-melt for our car washes. although the company dislikes the cost of the bubble wrap under the tubing. probably the most work/ greatest satisfaction in installation of home heating.;) hope this helps.
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