Radiant Cooling/Heating

Harvey Ramer

I would like to have a conversation about radiant cooling/heating combination systems. The entire project is going to be a chilled/heated water based system, powered by multiple low-ambient heat pumps. The system will be comprised of multiple hydronic air handling devices and a large section of heated and chilled above floor radiant. The radiant will be built on top of the wood deck. Radiant application ideas are welcome.

I don't know how many have done systems like these, but if you have, please share your experiences.

Harvey Ramer

No takers?

Alright, here's something more specific. The radiant cooling will carry a large portion of the sensible load. The rest of the sensible and all of the latent load will be done with a chilled water h20 coil/air handler. I want to control the fan speed based on the latent and sensible requirements. The fan speed slows down to accomplish more dehumidification and speeds up when the sensible load increases.

Anyone know of a specific air handler that I can control fan speed with an external input? Also be nice to know the sensible heat ratios of the h20 coil at various cfm's and water temps.

CMadatMe

Have 2 radiant heating and cooling jobs in residential applications. Used Spack Pak Air Cells. Jobs are both Geo with Viessmann back up condensing boiler. 1st floor over pours, 2nd floors Uponor Quik Trak.

First job, we used Taco IWorx but it got over complicated and second simple Tekmar Control system. Biggest complaint, too cold.. lol.. All Grundy Alphas, which the biggest hurdle was had to order the insulation kits from web site in UK since they aren't offered in the US.

Guy you want to talk to is James Day, Day Heating and Cooling, he floats around on here from time to time. His house is the 2nd job and worked with him on both jobs. Using Tekmar was a fraction of the cost of the IWorx, much easier and less headaches.

Harvey Ramer

I'm thinking of using the env control for this job. I'm pretty sure Tekmar won't do everything I want to do. I have to "nail it" if you know what I mean.

The biggest trick will be to maintain both the humidity setpoint and the temperature setpoint simultaneously. I will be able to do it with the proper controls and equipment though. After digging and digging, I found an air handler that will allow me to control the blower speed with a 0-10v input. Coupled with an h20 coil, that will allow me to precisely control the humidity without over cooling the space. http://us.stelpro.com/pro/att-details.asp?attid=V6µ3©e`÷±c

CMadatMe

Biggest issue you'll come up against is how the homeowner takes the comfort adjustment. Btu's being stripped from the body vs cooling the actual space. 73 doesn't feel 73 if you know what I mean. Feels like 68. Its the walk down the freezer isle effect.

We used the Tekmar 406

http://tekmarcontrols.com/images/_literature/406_d_02.pdf

Mark Eatherton

Some things to take into consideration.

In order to maintain full spectrum comfort, in some cases it may not only require dehumidifcation, but also humidification during the heating season.

As with any system design, it starts with a load calculation. I've been told that it is not wise to expect the radiant panel to be able to carry 100% of the sensible load, and the consequences of doing so with radiant floors are the chilled foot effect.

It does take some education of the consumer, just like we have to do on the heating side. Air temperature is a secondary effect, and should not be the primary focus. MRT is the same influencing factor in cooling that it is in heating, just on the other end of the comfort scale. I'd recommend the same approach as we use in radiant heating for a new users, except in the opposite direction. Start high (room temp setting) and go down slow until you hit YOUR comfort zone, then go back up one degree or two and let it soak for a while.

Humidity control is very important (duh...), and can be hard to control in some situations where the occupants have control over their operable windows. ENV is a great choice, and if it were my project, I think I'd consider putting proximity sensors into operable doors and windows, and unless all openings are closed in a cooling mode, no radiant cooling is provided until operable openings are closed. FCU's can run, but radiant surfaces are off. You can only put so many humidity sensors into a given application before costs get out of control.

As for dehumidification, I have talked to contractors who incorporate a FCU into the supply circuit to the radiant panels.

If humidity is high, then blower operates and dry the air out, then the tempered water heads to the panel for the sensible load. Although simple in design, by having it in series with the rest of the distribution system, it requires a pump with substantial head capacity to overcome the pressure drop. Also, paying attention to the Reynolds numbers is extremely important due to the low delta between working fluid and absorbing radiant surfaces. Keep the velocities high and the fluid deltas low.

Personally, I think it makes more sense to have a completely separate system, (think stand alone dehumidification/ventilation system with significantly downsized blowers, ducts etc) for tighter latent and sensible control if the panel is on or near the edge of its capacity.

Aligning yourself with a manufacturer who has spent the time and money to incorporate radiant cooling into their offering will help keep you from having to re-invent the wheel. They've been there, done that and know what to do and what not to do to make it work.

From a radiant panel selection point of view, it is no secret that I am a big fan of radiant ceilings. Using the ceiling for heating and cooling makes perfect sense, for all the right reasons. If they want warm floors in their bathrooms and dressing rooms, have them use electric radiant floors. Quick response means it doesn't have to be maintain in a hot ready steady state. You turn it on an hour before you plan to use it, and the floors are toasty warm when needed. Otherwise, they drift along with the rest of the space. Radiant ceilings also negates the chances of cold uncomfortable feet. There is a limitation on the cooling with radiant floors that is the counterpart to the maximum recommended 85 degree F floor temperature, except on the other end of the floor. the exact number escapes me, but all practiced manufacturers are very aware of this number and it must be adhered to to avoid overly cool surface complaints. Using a radiant ceiling will increase the panels sensible capacity for the same reasons you can get more heat out of a radiant ceiling than you can a radiant floor. Humans are not in contact with the surface, and the surface can be drawn lower to extract more heat and influence the MRT.

All distribution piping MUST be well insulated and vapor sealed to avoid any possibility of condensation production.

Current industry practice dictates that the "master" control point to avoid the production of condensate on the chilled water side, is the outlet of the cooling source. This way, you have made a good faith effort to control the production of condensation.

Field observations have proven that even if you have a near brush with the dew point, due to thermal conductivity, air movement, etc., that the production of condensation of the cooling surface is negligible. Outdoor reset is also a strongly recommended practice on the cooling side for obvious reasons.

If you decide you want to go hydronics for the sensible and latent, it will probably require a 2 temperature cooling system to keep mechanical systems reasonably sized. The lower temperature for the FCU for dehumidification and balance of the sensible load that can't be handled by the panel, and a higher temperature for the radiant panels. It will add some complication to the system, but with the ENV logic, you have access to a lot of I&O, so it shouldn't be a problem.

The other advantage of a radiant ceiling is that if you have a ceiling fan, you could extract additional but's by turning the fans on. A second stage cooling system if you will.

Done right, these system can produce a much higher degree of comfort, with a much lower cost of operation. Done wrong, no one will be happy. Do the math, follow the instructions and don't take any short cuts.

The Mason-Dixon line is no longer the hop off point for radiant surfaces anymore.... The AHR class that the RPA put on in Orlando that Harvey attended was the highest attended and rated class of the seven classes the RPA produced this year. Over 90 people in attendance.

Get ready for the next radiant revolution. Radiant cooling is here, has been proven commercially over the last 22 years in some extremely harsh environments.

Thanks for starting this conversation Harv. Let's keep it going. There is a lot to learn.

PS: The US Government (DOE) is recognizing the potential behind this method and is soliciting participation in demonstration projects.

ME

njtommy

What type of building is this? I have nothing to offer. Lol

Harvey Ramer

I never get the easy jobs, and this one is no exception. The building is a church that will be turned into a physical therapy unit. At each end of the building are rooms that will well insulated. These rooms will be heated and cooled with spacepac aircell FCU's.

The center/main part of the building is a sanctuary. Roughly 2,000 sf, 12' Masonary walls, lot's of windows and a cathedral ceiling. The ceiling is very ornate with exposed timber framing and beautiful trusses. It is not to be touched or interfered with. No ducts, pipes or wires. It has no insulation. Only 2 layers of 3/4" boards with a slate roof.
This is the area that will be heated and cooled with radiant.

I plan to place a FCU in each gable of the space for air quality control.

With the system requirements, I will have 2 water temp requirements at all times. So for radiant cooling, no extra hardware will be needed, only software logic.

The latent loads in this space will be a goliath. There isn't the slimmest chance they could be satisfied with a DX AC system that didn't meet sensible load at the same time. At that point the radiant cooling would either be nonexistent or it would feel like an ice box. The only way to get around that is to add a reheat coil to the FCU.

An h20 coil, on the other hand, will never freeze up. Therefore I can slow the cfm down to a crawl. A coil's sensible heat ratio changes proportionally to the increase or decrease of air flow. Most coils, at nominal cfm will produce 75% to 80% sensible cooling with the rest being latent. Even that is not really enough for humid areas or buildings with high infiltration. I found an air handler with an ecm blower that can be controlled with a 0-10v signal. By slowing the air to a crawl, I should be able to get the sensible heat ratio of the coil closer to a 1-1 or better. That will allow the floor to carry the correct portion of sensible cooling even while dehumidification is achieved.

The only part that concerns me slightly with this setup is that I get enough air mixing and don't create cold drafts. I would like to avoid using reheat coils if at all possible but I'll have to see how all loads and conditions pan out.

It will be a very interesting project.

Mark Eatherton

They asked you to bid for a reason. You obviously know your stuff. Let us know how this project proceeds.

What numbers are you using for the transient latent loads? I can see how that would be a killer load (people breathing and evapotranspirative cooling). The number I've seen bantied about is 500 btuH per person, with 350 being sensible, and the balance being latent.

Best to incorporate the reheat coils into the design/bid, and let ENV make the decisions as to whether on not they are needed. You can write your own algorithyms in ENV, so it is limited only by your imagination, so long as they don't conflict with other programs.

ME

Mark Eatherton

While on this subject, our next guest for HydroniX Talk has a LOT of experience in radiant cooling.

Join Us Thursday, February 18 at 7 PM Eastern Time for Lively Topical Conversation, Camaraderie and Education
Guest: Al Wallace, owner of Environmental Energy Corp.
Show Description: Our next Hydronic Talk will be a conversation with Al Wallace, owner of Environmental Energy Corp. from Colorado. Albert Wallace founded Energy Environmental Corporation (EEC) as a veteran-owned small business in 2006. Al's expertise lies in the integration of high performance systems for low energy buildings.

These patent-pending solutions integrate geothermal, solar thermal, radiant in-floor hydronic heating and cooling with highly reliable simple-to-operate controls for superior comfort, indoor air quality, and energy efficiency. EEC has developed off-site manufacturing methods for integrated systems which provide showcase quality installations with the highest reliability and lowest first cost. EEC's design/build projects have won numerous regional and national awards and have been featured in national publications.

EEC is one of two GeoPro Master Dealers in Colorado with WaterFurnace, the technology market leader for geothermal heat pumps and controls in the U.S.

Please join us on February 18 at 7 :00 PM Eastern time for some great controls information, and general comeraderie.

Where: Join us online at https://iapmo.webex.com/iapmo/onstage/g.php?MTID=e4d9027d1fc7b02628f530e7a6be958d6.

Password: htxrpa

About Our Guest

Al was on the technical committee which created the 2015 Uniform Solar Energy & Hydronics Code, is on the City of Centennial's Building Code Board of Review, and serves on Uponor Corporation's North American Radiant Advisory Council.
Al Wallace consults worldwide and provides training seminars throughout the U.S. He trained at the Master Builder Gewerbe Akademie, Rottweil, Germany, and completed software modeling training with Vela Solaris in Winthur Switzerland, based on integrated systems developed by the University of Applied Sciences Rapperswil (HSR), Switzerland. EEC's radiant floor cooling controls are currently hosted on modular hardware manufactured by Beckhoff Automation in Germany. Al serves on the Board of Directors of the Timber Framer's Guild and is a contributor to their newsletter writing on sustainable design and systems.

He served as the radiant floor cooling consultant for engineering the U.S. Army's Special Operations Forces Net Zero Energy Barracks at Fort Carson, Colorado in 2015.

Mr. Wallace holds a Bachelor of Science degree in Aeronautical Engineering from the U.S. Air Force Academy, a Master's degree in Business Administration from Golden Gate University in California, and dual Master's degrees in Architecture and Landscape Architecture with Certificates in Design/Build and Historic Preservation from the University of Colorado at Denver.

njtommy

It sounds like a really nice project. I hope to see radiant cooling system one day.

James Day_2

I have a radiant cooling and heating system in my house as well as 1 customer as chris listed above.

my house I have a 3ton water to water geothermal heat pump
50 gallon buffer tank
2-chilled water air handler loops for dehumidification
mixed radiant loops for heating and floor cooling ( using tekmar house control monitors dewpoint and calculates mixed tempeture.

Works very well. The air handlers come on for dehumidification as well as 2nd stage cooling.

NYplumber

Subbed for the good info.

Harvey Ramer keep me updated what you end up with on the project.

Chris, i recall you telling me about the job two years back. Great analogy about the cold supermarket eisle. I bet a great application would be schools and places of gathering due to the high mass.

Good info Mark. Thaks for sending me to this thread.

SWEI

http://www.magicaire.com/ makes a wide range of direct drive FCUs with EC motor options. Their modeling software is supposed to handle a much wider range of inputs than most others, which I am told helps a lot in this type of application. Ping me offline and I'll tell you a bit about a project where we're going to be controlling them.

Harvey Ramer

@James Day
Have you analyzed the results of your sensible versus latent cooling. What equipment is handling what percentages of the loads? Also, what is the climate, or geographical location and what kind of house build? Has a situation ever occurred where the floor had the sensible load satisfied and the FCU, in an attempt to dehumidify, cooled past setpoint? Or ended up with higher than desired humidity levels. Does the tekmar learn the capabilities of the equipment and based on the conditions, is able to satisfy humidity and temperature setpoints simultaneously?

I'm full of questions but only because I want to know.


@Mark Eatherton
500 sounds about right. I usually go a little lower than that in homes due to decreased metabolic activity.

One of my biggest hurdles is the uninsulated ceiling. When the sun is shining on the roof, the bottom side will turn into a giant radiant ceiling, dramatically increasing the sensible load in proportion to the latent load. On the flip side, during night time hours or cloudy days, the rampant infiltration through the roof will allow latent loads to increase substantially in proportion to sensible loads. I really have to have an animated system to keep up with the ever changing conditions.


@NYplumber
I'll let you know how it turns out.

James Day_2

Havnt fully analyzed the percentages of what is running. Originally tekmar wouldn't Allow you to use floor cooling below 76 degrees. So 1st year I played with different temperatures. They updated there control and thermostats to allow radiant cooling all the time now. They sent me there programming tool to update the code in my thermostats. Humidity levels always stayed comfortable and system didn't have to drop below setpoint. Located in NY state. Hudson valley.

SWEI

Mark Eatherton said:

What numbers are you using for the transient latent loads?

These often come in handy.

JOBO

I am going to be building my new house a year from now. I'm looking at geothermal with radiant heat and cooling in floor. James Day, what else can you say about the cooling?