Hot Water Heating in Ceiling and Floor

Joe Elliott

Our home was built in 1950 by my great-grandfather. It has hot water radiant heat pumped through pipes and manifolds in the ceiling of the house as well as the concrete slab it sits on. My question out of curiosity is why would they put the heat in the ceiling, when the majority of the systems are in the floor only. Also, how could the heat get from the attic down through the ceiling to heat the home when heat naturally rises. Your response would be appreciated.

Joe Elliott

GMcD

Heat from the ceiling

Is far more "efficient" in terms of human comfort - the head and the extremities are the natural human body temperature sensors, so overhead heating most mimics the sun as the natural radiant heat source. Floors became the common approach after North America lost the plastering trades. It became a lot more expensive and problematical to install radiant heat in sheetrock/drywall walls and ceilings, leaving the floor as a practical location. The floor heating acted on the feet, and as one of your human body extremities, was a reasonable temperature (comfort) sensor. Personally I am a proponent of ceiling systems as the "best" approach for radiant systems, both heating and cooling.

Bill_29

> Is far more "efficient" in terms of human comfort

> - the head and the extremities are the natural

> human body temperature sensors, so overhead

> heating most mimics the sun as the natural

> radiant heat source. Floors became the common

> approach after North America lost the plastering

> trades. It became a lot more expensive and

> problematical to install radiant heat in

> sheetrock/drywall walls and ceilings, leaving the

> floor as a practical location. The floor heating

> acted on the feet, and as one of your human body

> extremities, was a reasonable temperature

> (comfort) sensor. Personally I am a proponent of

> ceiling systems as the "best" approach for

> radiant systems, both heating and cooling.

Bill_29

Radiant Heating

You will hear from plenty of people that heat dosen't rise, warm air rises. Joe's example of the sun is perfect. Radiant heat travels much differently than warm air blowing around. Radiant heat heats objects, which in turn heat a space. In some cases ceilings have advantages because you can run higher tempratures through the tubing to get more output. Too high of tempratures in a floor can be uncomfortable on the feet. Ceilings are also better than walls because you don't have to worry about where the tubes are when you want to hang a picture.

Gordy

ceiling

Joe, I think you are under the impression that the tubing for your ceiling radiant is in the attic. When it is actually embbeded in the plaster of the ceiling. I have ceiling radiant as well from the 50's. Don't go drilling holes in the ceiling.
Gordy

Gordy

Geoff

I myself was wondering on how the efficiency of modern practices would fair against the old way of doing ceiling radiant. I did not think myself the modern way of installing ceiling radiant could possibly compare in heat transfer to the old embbeded plaster tubes. Its to bad what people are missing with a good ceiling radiant system.
Gordy

hr

I'd bet

that PAP in transfer plates below the sheetrock could compare closely with the copper/ plaster ceilings.

With modern reset controls the comfort level may surpass the older bang/bang 180° radiant ceilings.

I remember being uncomfortable in some of the older electric radiant ceilings 60 vintage. Probably, again, due to the higher operating temperatures and bang/bang control logic. And my height

I'm starting to see more and more good applications for radiant ceilings.

But I so love warm floors. Maybe a mix of floors for the extended cold periods, rapid responder ceiling for the shoulder season and radiant cooling? Good way to sell more tube anyways!

hot rod

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GMcD

It's all about reducing heat losses

So the radiant system DOESN'T have to operate at extreme temperatures, creating the hot noggin effect. The problem with many "heating systems" is that they are applied to whatever nasty old building envelope/heat loss you are handed. The solution is generally to ramp up the operating temperatures to overcome excessive heat losses. Wrong approach. The first thing that needs to be done before sizing the heating system is to look at the building and spend $$ on eliminating heat losses, THEN deal with an appropriate heating system. The end result is that $$ spent on the building envelope reduces $$ spent on a heating system, and provides further on-going energy savings.

It is currently possible, without spending premium $$, to get a new house in a moderate winter climate that requires light bulbs and refrigerator condenser heat to keep it comfortable. Any "heating system" needed above that only needs to operate at no more than 78F to maintain comfort. We have the design information NOW, we just gotta use it better.

Gordy

Hot Rod

hot rod,My vintage system only runs at 110* to 115*. The 180 bang bang is only at the boiler:>).

Gordy

Bob Gagnon plumbing and heating

radiant ceilings

I have about a third of my ceilings radint heated now, and it is more comfortable than just the floor, I ran the leads in the walls with alum. plates for more surface area. I can't wait till the summer to try the cooling with all that extra sq. footage. Bob

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Linda_S

Does this mean.................

I could heat a downstairs living room with 11' ceilings using PEX tubing between the ceiling joists? Or, what kind of piping for the hot water would work?

We are in the process of renovating Circa. 1907 house. Putting R-19 on exterior walls and replacing all windows with vinyl insulated-panes. Boiler is about 7 years-old, used to pipe hot water through CI radiators. We pulled most of them out to do the renovations and I would love to have under-floor radiant heat. My Husband says it would be a nightmare to drill all the holes in the bottom floor joists, (crawl-space about 2 1/2') but the second floor would be easy.

Would ceiling-radiant heat work with 11' ceilings and could we expect that to heat upstairs as well? I loved the radiators and how cozy they heat, but don't like the bulky look and space they require. I had already decided that we needed kick-plate heaters for the new kitchen, no space for a radiator. We will be putting in ceiling fans, would this help to move the heat down to be more comfortable?

We have to completely re-do all pipe from boiler anyway, the Galv. CI is crumbling! Our boiler typically ran to 220°, is this too hot for PEX? If we go with PEX for the radiant heating of ceilings and/or floors, what would be the best (easiest/most cost efficient)pipe to run the main (big) feed lines?

GMcD

Linda

Theoretically, yes you can do that and it could be a very efficient system. BUT: you have to make sure that the heat losses from the upstairs area versus the downstairs area are more or less equal other wise you will be overheating one space at the expense of the other, or underheating one space at the expense of the other. The way to make sure the heat losses are equalized is to first do a complete heat loss for both spaces, and whichever one is greater, spend the $$ to reduce the heat losses to equalize them. This means better windows (vinyl double glazing to me is "low performance") as the most cost-effective way to reduce heat losses. Radiant ceiling at 11 feet is not a big deal.

The idea is to upgrade the house envelope to reduce the heat losses to a minimum, so you DON'T need to run hot water temperatures through the PEX tubing. The fact that you would intend to hang PEX in a joist space is problematical to begin with- ideally the PEX tubing wants to have direct, full contact to the surface you want to warm up. You may have to double up the PEX tube runs to run along the underside of the floor over, and back on the inside of the ceiling surface below. Like I said, it's theoretically possible, but will take a "Whole House" approach and some engineering to get it to work efficiently.

jerry scharf_2

Late to this

Linda,

I've been installing ceiling radiant the last couple days! And walls and floors. One ceiling was 17' up, so I got good at the process quickly.

With all of these, it's how you move heat from the tubing into the room surface, and how you keep the heat from wandering into all the places you want.

Getting the heat from the rubing to the surface is best done by conduction, which means direct contact and good heat transfer. My project has some warmboard floors, some thermofin floors, one thermofin wall and a fwe thermofin ceilings. In the wall and ceiling case, the thermofin is first stapled onto cross members, then the cross members are mounted so the fin is flush with the wall. when the sheetrock goes on, there is direct conduction, and you mostly see the R value of the sheetrock.

But that's not enough. Since heat flows to cold, it will go in all directions as a function of the R value. The higher the R value, the slower the heat flows that way. So you always want insultion on the other side of the radiating room surface to make sure as much of the heat as possible goes to where you want it.

With all this, you could heat both the upstairs and downstairs from the first floor ceiling joist bays. You would want to have two set of loops with transfer plate, one in contact with the ceiling and one attached to the floor above. You would also want to put insulation in between the two to keep the heat going where you want.

jerry