Hello,
I have hot water radiator heat. I am planning on remodeling my bathroom and would like to take out the radiator and put in floor radiant heat. I was thinking of using a product like “warmboard”. Can I tie this in somehow to my boiler? The warmboard guy said I would have to use a mixer to cool the water. Any help, suggestions would be great. I plan on tiling the floor in the end.
thanks
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Replies
He's right.
Boilers run pretty hot, and for RFH you really want the water to be in the 110-120 range. give or take, depends on a few variables.
So yes, you could branch off the boiler and add a mixing valve to temper the hot water. Sometimes you can pull it off with a heat exchanger off the boiler.
Or you could add a new small water heater just for this loop.
Or you could go with electric resistance cable clipped to the subfloor, or to a cabled mat laid down on the subfloor. The thinsetted tile goes over the cable. There are some BTU output restrictions with this as well.
Several options, but a good radiant guy can lead you down the path.
You're right the options are numerous. I am really trying to find the most cost effective option. I know I don't want to add another water heater. (Seems like it would be such a waste seeing I have two already!) I could definatley put in the electric grid myself but I have heard that they are more for warm floors and don't heat the room very well. Which leaves me thinking with the in floor radiant heat. I am wondering if this would run only when the rest of the radiators heat or if I would have to put a thermostat in for just the bathroom? Has anyone out there had this done or see this before?
Different resistance mats (electric heat( have different outputs. And you;re correct, most are designed to just warm the floor, they don;t have the output to actually heat the room. That said, the ability to "heat the room" also depends on the room's ability to hold the generated heat...meaning quality of construction, etc.
There are a slew of resistance products out there. There is definitely one to fit your situation if electric is the way you want to go.
As far as hydronic being tieds to the rest of the house, thermostat and heat demand wise, no...you can set the bathroom's hydronic loop on it's own t-stat and circulating pump.
Believe it or not, a small water heater would only need a circulating pump and a t-stat. That actually might be easier to set up, as well as less expensive to install, then trying to pull a separate loop off an existing boiler. Pulling an extra loop might require breakign onti the existing and adding new black pipe, possibly a 4-way mixing valve with a controller, adding a cold water T, etc, etc.
Tough to diagnose, but for hydronics, honestly, the third (gulp) water heater is probably the least expensive and easiest install to do.
Electric mat installs aren't terribly difficult, but the long-term problem occurs if the product is ever damaged. Often times you can't "patch" a damaged wire. It's a whole-floor tile tearout and replacement. Electric radiant is gaining in popularity and better/more durable products are being brought to market every few year.
Sam,
I can only add input as a homeowner ... I just remodeled 2 bathrooms in my house and replaced the old baseboard heat (FHW) with radiant. I can tell you, it is wonderful and there is plenty of heat generated to maintain the setting of the thermostats. Since it was a remodel, and I absolutely HAD TO HAVE radiant heat :) we had the radiant tubes stapled up under the floor. While I was at it, I decided to replace the baseboard heat in my kitchen/dining/family room (open floorplan and was always cold). The downstairs bathroom shares the same zone with the rest of the first floor. The upstairs bathroom has the tubes running through the subfloor (I think the same material you mentioned) and has it's own thermostat. Both bathrooms have tile floors. I can feel the heat on the tiles much more in upstairs bathroom (tubes closer to the tile). Sorry I don't have more to add about the mechanics of the installation, but I wanted to share how pleased I am with radiant heat in general. I can't imagine ever having baseboard heat in a bathroom again.
The difficulty with most any boiler is that this floor is going to require too little heat for it to run on its own zone (microzoning). The boiler would quickly bump agaist its high setpoint, and kick out.
Many ways to go about providing warm water to a small area.
See this great article for more insight: (note, their website was down this afternoon- be patient)
http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,62497,00.html
thanks for everyone's insight. I am another who "has to have" this heat in my bathroom, so I will figure it out one way or another. The article is extremely informative, thank you. It will be a few months down the road but I will let you know how it works.
My MIL told me they had RFH in Levittown 50 years ago. Any idea why it is suddenly so popular? Did everyone just go "Doh!" when they realized that heat rises? Did electric heat mats in bathrooms make people like warm floors?
Umm, the invention of Pex tubing...most l of Levittown's (both of them) RH systems are long gone now as you probably know. Concrete and copper are not a good mix.
This was an example of waiting for the right technology to fill a need I guess.
I echo what the last guy said, PEX tubing is the greatest influence on the renewed popularity of embedded types of radiant heating, but not the only influence by any means. I can't tell you how many 50 year old plus abondoned systems I have discovered over the years. 1/4" & 3/8" copper tubing embedded in the plaster of ceilings and walls were very popular. Another influence is that good sheet metal work in house is rare making "good" forced air systems also rare. Hacks abound, as do flex and vinyl. Large open floor plans and tighter construction aggrevate the trend in poor FA systems, making it easier to create greater comfort with RFH. (BTW, a properly sized, designed and installed forced air system is cheaper, every bit as efficient if not more so, and has more advantages than ANY hydronic system, infloor or out).
"(BTW, a properly sized, designed and installed forced air system is cheaper, every bit as efficient if not more so, and has more advantages than ANY hydronic system, infloor or out).""In other words, it is hard to beat the comfort and efficiency of a properly done RFH system. Go for it." So, which one is better?????????? LOL
Depends, do you have an enigineer or a competent designer to do the system right and to oversee the contractor to make sure that it is installed right? Do you want air conditioning, dehumidification in the summer, the ability to filter the air and humidification in the winter? If you had the right people involved, which in todays market is very unlikely, and the knowledge to know what to pay for and what not to, the forced air system would be the choice.
Or do you want a system that the average hack will have a hard time screwingup? Warmfloors are great, but they are only a small part of the HVAC picture. As many have discovered, you have to add some means to cool/dehumidity and some means to ventilate spaces that only have the senisible heat addressed. All of the "healthy" hydronic and "scorched air" BS aside, relative comfort of an RFH system in a primarily heating environment as compared to a poor forced air system is superior. Either/or is not the right choice to make. Do you want seat belts or good brakes?
My comment was regarding the idiotic concern of "these types of systems freezing up", not what is the best, most cost effective way to condition living spaces.
That debate is for another time and another place. My opinion is that IF no corners are cut, the forced air system is a better option.
Edited 4/9/2005 12:45 pm ET by Timbo
It’s not possible to discuss comfort and mechanical systems without talking building efficiency.
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The average healthy body loses the majority of its heat via radiation so our thermal comfort is directly influenced by any surface cooler than our skin temperature. The more inefficient a building the lower the interior mean radiant temperature (MRT) and thus the greater radiant heat loss from the body. The only way to counter this is to raise the MRT which can be done by improving the building efficiency and or conditioning one or more surfaces by heating them up – i.e.: radiant heating. The other option is let the occupant adapt to the environment by a number of solution like adjusting clothing, activity level etc…the only challenge here is the occupant unfortunately has to experience discomfort in order to adapt.
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So the most perfect forced air system in ‘standard’ (relative term) construction can not address the radiant losses, floor temperatures and temperature stratification which contribute to discomfort…nor can the most perfect radiant system deal with latent cooling loads, IAQ including (de)humidification .
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Comfort is definable, specifiable, measurable, and desirable. It can be obtained a number of ways with or without radiant…but it can’t be discussed without addressing the building efficiency.<!---->
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I have placed a free presentation on thermal comfort on our website in the solutions/design tools page called “CIPHEX West 2004 Thermal Comfort Slides”RBean
http://www.healthyheating.com
http://www.healthyheating.com/blog
Mr. Bean,
"The more inefficient a building the lower the interior mean radiant temperature (MRT) and thus the greater radiant heat loss from the body".
This statement is untrue. An inefficient a buiding envelope will require more energy to accomodate the energy lost or gained to the surroundings than a more effiecient building envelope. However inefficient, the MRT can be maintained at whatever level you choose. Which, is not really that important.
Your first assumption: "The average healthy body loses the majority of its heat via radiation ..." too, is untrue, or at best incomplete. Significant body heat loss is affected through conduction, convection, evaporation, respiration as well as radiation. The radiant losses are by far not the most significant portion when considering a clothed body under reasonable indoor controlled conditions.
Edited 4/11/2005 10:51 am ET by Timbo
Timbo,<!----><!----><!---->
On the statement, ‘Which, is not really that important.”, are you suggesting the MRT is not that important? In what context? Comfort or energy consumption or both? If this is what you mean, then in your opinion would it follow the operative temperature is also not that important? <!----><!---->
If this is not the meaning of your communication you’ll have to explain it to me another way…my Canadian brain is frozen for most of the year and sometimes in the spring, it takes a little thawing to get ‘it.’<!----><!---->
Body heat loss/gain is well documented – we both know all forms of heat transfer play a role – some more than others depending on a number of variable from met rate, clo values, DBT, RH, angle factors, MRT etc…the word ‘majority’ was a poor choice since this is only true in some cases and not in others…for example, in some environments the nominal split for a nearly naked body could be 15% evaporation, 10% respiration, 10% convection, 3% conduction and 62% radiation, in other environments the evaporation could be 60% or higher and the radiant as low as 15%…so yes the percentages “float” in consideration of all the measurable metrics in human comfort and building science…so sincere thanks for questioning the lack of specifics and pointing out the generalizations. Having bowed to your observations, building and body heat losses/gains are predictable and measurable in their environments and can be modeled with reasonable accuracy.<!----><!---->
Since we are talking heating (clothed or naked) , I am interested to know if you have research data that suggest radiant as not being the largest single factor in body heat loss in general “heating” terms…something which contradicts Dr. Fangers work in consideration of the above dialogue. I’m also interested in your solutions to reduce radiant body losses other than raising the building MRT or preventing losses by adjusts clothing levels. Along the same lines, “the MRT can be maintained at whatever level you choose”…your solutions and reasoning are also of interest to me. Please explain how one chooses and if you have time provide the logic as to why one choice over another? You have my curiosity. <!----><!---->
You seem very passionate about your mission…I learnt along time ago in the presence of differences it’s wise to be willing to learn – if you want to teach. I’m listening.<!----><!---->
<!---->RBean<!---->
Edited 4/11/2005 5:42 pm ET by RB
Edited 4/11/2005 5:45 pm ET by RB
First, I think I got sidetracked and/or distracted during that post. The statement was part of a thought that I did not complete. I would argue, however, that the mean radiant tempereature has limited value in the day-to-day design of effective heating and cooling systems. I'm sure that your Canadian brain is fully operational, as you have a great deal of information on this subject. I will attempt to expain my perspective on this.
I have been designing mechanical heating and cooling systems and building HVAC systems for a few years (18). When I was designing heat sinks for electical components at my first engineering job, detailed heat transfer analysis was required and applicable. Later, as a mechaincal engineer designing HVAC systems, the science gave way to the "art" if you will. I do not have any research data other than my experience in the field. I do know how to design effective systems. I know how and why systems that do not work, fail to do so and how to modify them to accomplish the intended function. I can, and have on many occasions, designed and seen installed, effective and comfortable systems in what could only be described as "inefficient" buildings. I have yet to determine the MRT of a buiding surface.
It is reasonable and practical to expect and account for, seaonal differences in clothing. It is also foolish as a designer to expect to provide a comfort level for any building or dwelling that does not account for clothing. With a large amount of the body surface covered, then I expect the radiant transfer of heat from a body to be minimized.
The quaility of the air (temperature, moisture content & velocity), in my experience has the greatest effect on comfort. Obviously, a cold surface creates discomfort, and needs to be dealt with by proper locaction of terminal units, be they registers, diffusers, radiators or cenvectors. Does this raise the MRT of the surface and therefore affect the comfort level? I thionk so and this is what I meant by the statement “the MRT can be maintained at whatever level you choose..". Whether that is accurate or not you can judge. My point is, that the research is relatively useless other than quantifying individual pieces of the issue that has been effectively addressed for decades.
I will agree that the heat gains and losses of any building can be very accurately modeled, IF all the variables are known and controlled. Reality seldom lends itself to detailed analysis. The compromises that are inevitable in materials and construction cannot be accurately modeled, and to attempt to do so is a waste of the designer's time and their customers money.
My experience in the HVAC industry is primarily with every type of building except single family residential (though in some limited applications, I have designed systems for these, as well). In every commercial, institutional and industrial application, control of the air pressure, relative pressure from space to space, air movement, temperature and humidity are paramount concerns, as well as providing adequate air turnover to meet ventilation code requirements. When a system is capable of controlling these parameters within a reasonable range of conditions, exposure and occupancy, concepts like "met rate, clo values, DBT, RH, angle factors, MRT etc…" are of no practical use.
If I can properly control the quality of the air, comfort is a foregone conclusion.
Edited 4/12/2005 2:08 pm ET by Timbo
The five reference documents we use for design direction are:<!----><!---->
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a)ANSI/ASHRAE Standard 62.1-2004, Ventilation for Acceptable Indoor Air Quality. <!---->
b)ANSI/ASHRAE Standard 62.2-2003, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings. <!---->
c)ANSI ASHRAE Standard 55, Thermal Environmental Conditions for Human Occupancy. <!---->
d)CSA Standard Z317.2-01 Special Requirements for Heating, Ventilation, and Air Conditioning (HVAC) Systems in Health Care Facilities. <!---->
e)CAN/CSA-F326-M91 Residential Mechanical Ventilation Systems.<!---->
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<!----> <!---->
An excerpt from Standard 62.1 (Ventilation / For buildings other than low rise residential) <!---->
“For the purposes of this procedure, acceptable perceived indoor air quality excludes dissatisfaction related to thermal comfort, noise and vibration, lighting, and psychological stressors.”<!---->
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An excerpt from Standard 62.2 (Ventilation /Low Rise Residential)
“Thermal comfort requirements are not included in this standard (see ANSI/ASHRAE Standard 55-1992, Thermal Environmental Conditions for Human Occupancy3).”<!---->
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An excerpt from Standard 55 (Human Occupancy)
“This standard does not address such non thermal environmental factors as air quality, acoustics, and illumination or other physical, chemical, or biological space contaminants that may affect comfort or health.”<!---->
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An excerpt from CSA Standard Z317.2-01, (Ventilation / Health Care)
“HVAC systems shall be designed to contribute to a healthy environment by suitable control of the<!---->
following factors:<!---->
(a) temperature;<!---->
(b) relative humidity;<!---->
(c) ventilation rate;<!---->
(d) ventilation effectiveness;<!---->
(e) air movement;<!---->
(f) mean radiant temperature;
Note: The mean radiant temperature is a parameter that affects occupant comfort. Other factors affecting occupant comfort include clothing and activity level.*
(g) noise level;<!---->
(h) relative space pressurization; and<!---->
(i) air cleanliness.”
* Clo Value and Metabolic Rates
It appears we'll have to agree to disagree based on our own experiences as designers and use of standards.
Respectfully,<!---->
RBean
http://www.healthyheating.com
http://www.healthyheating.com/blog
Edited 4/12/2005 6:50 pm ET by RB
Edited 4/12/2005 6:51 pm ET by RB
For the most part I agree. We need to look at the complete building as a "system" and educate our clients.
I like RB's analogy of contractors and designers as sports teams.
Up here, we have to have ventilation by code, so to me it is a no brainer. RFH with HRV and coils in a air handler, combined with tekmar's new controls can't be beat.Air conditioning with warmfloors, that's comfort. Just wish I could afford it.
Heck, the Romans used RFH.
The Levittown systems were comfortable and visionary for their time, but had some problems. The first was that the copper tubing set in concrete corroded through over time. Copper embedded in slab was done around here right into the 60s, though most of those systems are abandoned by now.
Another problem was the lack of insulation. It has been said that you could have flowers in the winter if planted near to the slab.
PEX is the first slab-embedded material with a proven record for reliability and longevity. Modern boilers and control systems can deliver water of just the right temperature to match the structure's heat loss, something Levittown could not deliver.
Edited 4/8/2005 2:37 pm ET by csnow