Two story house - radiant in-floor on main floor only - who's done it???

[stee6043]

So someone started a "plans for next season" thread this week that got me thinking about my biggger plan of eventually going to in-floor radiant heat. I've done a little reading on pipe, manifolds, the "flashing" bending, etc. For the money I think you can't beat this type of heat. Especially doing it yourself in a simple between-the-joists type application.

My problem is that I have a two story home. Radiant in-floor is absolutely not an option on the second floor. Has anyone out there in hearth.com land ever installed in-floor on the main floor and used a forced-air HX to heat the second floor? My simple mind thinks a fair amount of heat will radiate up from the first floor and that heating the upstairs would require very little effort. Is this a bad assumption? My mainfloor is very open with two rooms that are open to both floors. So I typically get a fair amount of air movement between the floors.

How have other folks managed this? Install a thermostat for the forced air heat on the second floor and close all of the registers on the main floor? Something more ellaborate?

Thanks in advance for any thoughts. I'm just brain storming for a "maybe" 2009 project, but more likely 2010....being able to use water temps down in the low 100's is what really has me intriugued by this technology...

 

[smokinj]

should work fine and iam thinking of doing the same in fact i have already started just dont know how much hot water i can produce yet

 

[WoodNotOil]

I have radiant in my downstairs and baseboard in the upstairs. I have a separate thermostat up there for it. Works great. Here is a link to some good resources on it here.

 

[Piker]

I am using forced air and radiant in different locations. Radiant upstairs, forced air downstairs, until I finish remodeling. Everything will go radiant as I finish the remodel, but for now the system works pretty good.

I actually plan on keeping the forced air in the great room. The great room has 17' ceilings and a loft. The loft was finished before I decided to go with radiant floor, and it's not possible to get tubing in there. The heat load of the room will not be satisfied by the radiant floor in the first floor alone... I expect it will actually be cooler in the loft than the downstairs, so I will leave a couple small registers hooked up to the air handler that will run off of a thermostat in the loft. Should work pretty well, but it's kind of a hybrid system and can't be absolutely certain how it will work. I know I will be warm, but I don't know how even I will be able to keep the heat throughout the room.

I kind of like to have the forced air to huddle over in the mornings when I wake up, and to heat the house up fast if you feel like it.

I wouldn't expect radiant floor heat downstairs to migrate upstairs like your hot air will. The beauty of radiant heat is that the the heat doesn't really rise. The warmest air is at the floor, the coolest at the ceiling... just the opposite of forced air. This is why radiant heat is much more efficient as you don't waste much heat at the ceiling where it doesn't neet do be. This works especially well with high ceilings in homes and especially in garages and pole buildings.

cheers

 

[Nofossil]

I hope that it works well, because that's also on my project list. I expect that with radiant on the main floor, my upstairs will need MORE heat than it does now. My thinking is that radiant gives you warmer temps at floor level and cooler temps at the ceiling level. That should translate to less heat migrating upstairs. It seems possible that using radiant on the main floor will mean that my upstairs zones will have to work harder.

Time will tell.

 

[Piker]

I hope that it works well, because that's also on my project list. I expect that with radiant on the main floor, my upstairs will need MORE heat than it does now. My thinking is that radiant gives you warmer temps at floor level and cooler temps at the ceiling level. That should translate to less heat migrating upstairs. It seems possible that using radiant on the main floor will mean that my upstairs zones will have to work harder.

Time will tell.

I believe that your expectations concerning this are correct. This is why you can heat a 5000 sq ft service center that has 16' ceilings easily with less than 150,000 Btu of output as long as you are heating through the concrete slab with radiant. Radiant heat reverses the stratification of the air by just keeping the area you occupy warm... the first 6' of the room from the floor up.

cheers

 

[easternbob]

I've been told and have read in a few places that radiant heat only heats the objects that are within 8 or 9 feet of the floor. So I would assume you need some sort of heat for upstairs. I'm in the process of building and I did staple up radiant on the first floor and radiators (new euro. style) on the second. There are separate zones for each rad. upstairs.
Good luck,
Bob

 

[topofthehil]

I just put on an addition with all infloor heat.
however, The old house has two stories with forced air.
The first branch (1” Pex) off the main manifold supplies straight boiler water to the plenum HE in the basement of the old house.
in a nut shell, Each story has its own thermostat that controls the furnace fan for that particular damper.
Thus, if the down stairs is calling for heat, but the second floor is warm enough, the second floor damper closes so no heat is delivered and vice-versa.
works good.

 

[slowzuki]

My office mate has in floor radiant in his basement. Open stair to basement. House is well insulated. His heat pump for the main and second floor never start until it is well below freezing outside. He is concerned because the boiler for his floor is electric so he isn't taking advantage of the 2.5 COP of the heat pump. By the time the heat pump comes on its almost all electric strips since the air temp is too cold to get any heat out of it.

 

[pybyr]

wall hung radiant panels could be an option, instead of forced air, for places where you can't fit radiant floor. I have nothing against air- it's the system that I have and know my way around best, but it is not ideal if you have other options, unless, maybe, you need the ductwork for central A/C anyway (no need for central A/C in my climate, nor on my budget)

 

[Jackpine Savage]

I'm working on the same. I have the main floor done, I used extruded aluminum plates between the joists. For the second floor I plan on adding radiant panels to the two bedrooms and a radiant towel warmer for the bathroom. I am gutting the rest of the second floor this spring and putting in radiant ceiling. I didn't want to mess with the floor in this space.

 

[tom in maine]

I have installed radiant floors in several of my homes over the years. Always used baseboard or convectors on the second floor.
I agree with Pybyr, I would consider radiant panels on the second floor. It will be simpler to install and probably cheaper than air.
The most recent heating system we did was a radiant panel system in a small house. They were in and running within an hour and a half.
Each panel is like a separate zone, if you use a thermostatic control on the panel.

The second floor usually has lower heat loads than the first floor and there will be some heat that makes its way upstairs, so if you are working off a
storage tank, it will not usually be a problem as the storage tank drops.

 

[in hot water]

The nice think about hydro-air is you have the ability to air condition, humidify or de-humidify. Also some air filtration IAQ indoor air quality adjustment..

i'm a big fan of all things hydronic, and really like the heat and zone-ability of panel radiators. But it is nice to be able to circulate some air. If the sleeping areas are upstairs cooling may be a nice thing to have.

Radiant surfaces will warm anything they can "see" The energy from the sun, 93 million miles away is a good example. Even on a bitter cold winter day the energy from the sun feels good on your body.

Same concept with the radiant tube heaters ceiling used in tall warehouses. Anything in the direct path of that radiation will be warmed, but not under shelves, boxes, etc.

Radiant energy can travel in any direction from warm surfaces to the cool surfaces. Ceiling radiant heat is common in many European commercial buildings. it allows for any changes in furnishings, floor covering, etc. It can be run at higher temperatures than floor radiant, as no one walks on it. As such you can get some good output. Chilled water will run through the same ceiling panels to cool the building.

Don't count on much radiant heat from downstairs rising up to the top level, unless you remove some floors

hr

 

[sweetheat]

stee, it's a good choice. always seems warmer, as I go up to the 2nd floor the temp cools down a bit but not so you need more clothing on. I've set my 1 zone, a slab-on-grade at 64 degrees. Zone water supply temp is 100 degrees. The 2nd floor eventually will have a zone for some baseboards when someone is living there. My friend installed staple up pex fastened to aluminum heat fins that attach to the bottom of the wood floor. Works good, to warm for me in there. sweetheat

 

[stee6043]

As expected the Boiler Room has not let me down! Lot's of good info here. My biggest challenge with the second floor would be getting the plumbing up there for any "new" heating elements. Not to mention I have 4 bedrooms up there which means the possibility of a crap load of zones. Hmmm....so much to consider....

 

[Piker]

If I am you stee... I would just use the existing forced air upstairs rather than tear everything apart to add hydronic. Like someone mentioned, your upstairs is going to heat relatively easy anyways, so I don't feel that you will lose a great deal of efficiency by using forced air over radiant. Do the math and see how much load there is upstairs, how much airflow you have with the existing ducts, and then size a heat exchanger so that you can use low temps to heat with. This sounds like it would be your most cost effective choice. But that's just my opinion from several hundred miles away.

cheers

 

[BrownianHeatingTech]

Not to mention I have 4 bedrooms up there which means the possibility of a crap load of zones.

Panel radiators offer the flexibility of having individual zoning by radiator.

We have an old farmhouse that we bought a few years ago. Slowly upgrading various things.

Initial installation of the wood boiler will connect to a coil in the existing ductwork.

Next step will be to install radiant under the kitchen floor, as the underfloor insulation needs to be replaced, and I'm not going to insulate, then tear it down to install radiant.

After that, the rest of the main floor will be attacked in sections, room-by-room. As each room is converted, the ductwork will be disconnected.

The majority of the first floor has tin ceilings, and the second floor does not have ceiling height to lose by doing an over-floor radiant installation. So, the second floor will mostly be heated with the ductwork, initially, then converted to panel radiators over time.

That should sort of show how the conversion can be done in stages, if desired.

Joe

 

[Mike T]

I have a log cabin with radiant floors on the first level. The upper floor has a combonation of baseboard in the bathroom and closet area and a PSU unit in the master bedroom.
This way the boiler heats all areas without the need for the duct work of FHA.
The PSU unit works so well we placed a small one in another section with an unheated upper loft to get more heat there.

 

[BrownianHeatingTech]

I have a log cabin with radiant floors on the first level. The upper floor has a combonation of baseboard in the bathroom and closet area and a PSU unit in the master bedroom.
This way the boiler heats all areas without the need for the duct work of FHA.
The PSU unit works so well we placed a small one in another section with an unheated upper loft to get more heat there.

Yup. The PSU and PSH fan convectors are very nice units (for those unfamiliar, the products are made by Smith's Environmental. Some of the quietest fan convectors I've ever used.

They also make special low-temp baseboard, which I've not tried, but it does look like a potential match for thermal storage systems.

Joe

 

[4acrefarm]

I have a cape 1800 sf half of the second floor has never had heat of any kind. I have staple up radient on first floor ( 1200 feet of 7/8). I have a wood stove on first floor that gets used occasionally. The house is fairly well insulated with good windows. It runs fairy stable around 60 on second floor. I run first floor at around 65. this is with temps in the teens at night and twentees durring the day. I would like tolike it warmer but wood supply and homemade boiler can only do so much.

 

[tuolumne]

In our entry/laundry area we have radiant heat on the first floor and a Buderus wall panel radiator on the second floor that share a zone. The radiator is sized to run 120 degree water. The combination works great.

 

[jklingel]

You may want to read on healthyheating.com and/or greenbuildingtalk.com

 

[Chris S]

Stee,

You mention in your original post keeping the airhanlder for the second floor. Keep in mind, that if you have a one zone forced air system ( zoned with duct dampers is a differerent thing) that you can't just shut off a whole bunch of registers, as the air flow will be all wrong. Generally stopping air flow at the registers themselves will cause velocity noise- whistling.

I am not a forced air expert, but I do work with them regularly, and they size their systems for proper airflow across their heatexchanger, each duct should be sized for what it will carry cfm- wise. One of our customers has a 900 s.f. master bedroom suite with hydroair, and radiant in the bathroom. They tried closing the air off in the bathroom so they could enjoy the warm floor, and what they got was a very unbalanced system. The AC man wound up slowing the blower down for winter-time operation, and then turning it back up every spring so the AC would work well. It means 2 visits a year for the AC tech, but the homeowner is happy, and willing to pay for it. Our other option is to add more radiant, which will probably happen, then the air handler won't work at all.

Hot rod mentions having air circulation as a way to control humidity, move stale air etc. This is very important. We have 2 new homes under construction right now. One is ICFs, the other is stick framed with polyurethane insulation. Both of these homes have heat recovery ventilators installed. Any new (tight) home needs this to keep the humidity level down. In an older drafty home, we do the opposite. For anyone remodeling, I doubt you could make your home airtight enough to create moisture problems. For anyone building a new, tight home, this is a definite consideration.

 

[stee6043]

Stee,

You mention in your original post keeping the airhanlder for the second floor. Keep in mind, that if you have a one zone forced air system ( zoned with duct dampers is a differerent thing) that you can't just shut off a whole bunch of registers, as the air flow will be all wrong. Generally stopping air flow at the registers themselves will cause velocity noise- whistling.

I am not a forced air expert, but I do work with them regularly, and they size their systems for proper airflow across their heatexchanger, each duct should be sized for what it will carry cfm- wise. One of our customers has a 900 s.f. master bedroom suite with hydroair, and radiant in the bathroom. They tried closing the air off in the bathroom so they could enjoy the warm floor, and what they got was a very unbalanced system. The AC man wound up slowing the blower down for winter-time operation, and then turning it back up every spring so the AC would work well. It means 2 visits a year for the AC tech, but the homeowner is happy, and willing to pay for it. Our other option is to add more radiant, which will probably happen, then the air handler won't work at all.

Hot rod mentions having air circulation as a way to control humidity, move stale air etc. This is very important. We have 2 new homes under construction right now. One is ICFs, the other is stick framed with polyurethane insulation. Both of these homes have heat recovery ventilators installed. Any new (tight) home needs this to keep the humidity level down. In an older drafty home, we do the opposite. For anyone remodeling, I doubt you could make your home airtight enough to create moisture problems. For anyone building a new, tight home, this is a definite consideration.

That is some excellent advice. You are correct that I have a single zone forced air system for the whole house. I suppose I figured the "close some registers" idea would be far to simple to actually work! Thanks, Chris.

 

[BrownianHeatingTech]

The AC man wound up slowing the blower down for winter-time operation, and then turning it back up every spring so the AC would work well. It means 2 visits a year for the AC tech, but the homeowner is happy, and willing to pay for it. Our other option is to add more radiant, which will probably happen, then the air handler won't work at all.

Get a two-speed control for the blower, so it runs the "medium" tap for heat, and the "high" tap for A/C. The manufacturer of the particular air handler may have a simple upgrade, or a relay could do it. Should cost a lot less, in the long run, than repeated service calls.

Joe