We are considering radiant heating for a new house in New England. The “pros” we’ve heard; it’s the “cons” we’re trying to understand. One concern is that because of the slow response time to desired changes in temperature, it may not be practical in cold weather to have the house be a comfortable temperature in the evening, cool down 10 degrees overnight to a more comfortable sleeping level, and then return to daytime temperature in the morning. Is anyone with radiant heating using it this way successfully, or does the house really have to stay a more constant temperature?
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We have nine year old home. Radiant heat thru out. Tile, wood & wall to wall carpet coverings. We use our thermostat to lower heat in PM, raise in AM - works beautifully. It does take a few hours to lower heat if you
Frank -
Thanks very much for your message. Sounds like you're a very satisfied customer, and one who uses the system as we would like to.
I think we got only a partial on the second sentence in your message, which reads "It does take a few hours to lower heat if you" - would appreciate it if you could repost.
Thanks again for the input.
Charlie
I understand that fuel prices differ by location. I've had 3 houses over 15 yrs with RIH.
It's so efficient that I don't play with the thermostat. No need to. You do need different zones to accomplish what you want. Living area at one temp, bedrooms at another. Try to get the baths on a zone different from bedrooms. Cozy baths are a treat.
Caveat. I always have slabs. Perhaps people doing it over wood find it easier to fiddle with the temps.
ShelleyinNM
Its not uncommon on larger projects to use radiant to base load the building, ie: bring the entire house or those targeted zones up to a lower temperature then using a fast responding secondary system to trim up the heat when required. The fast responding systems could be decorative panel radiators, reheat coils in the ventilation ducting, towel warmers etc.Often we think of ‘dropping’ temperature for night time comfort or energy efficiency rather than 'raising' temperatures for when we need it.Just a thought.
RBean
web: http://www.healthyheating.com
blog: http://wonderfulwombs.typepad.com
My very close friend is a HVAC contractor and just bought a house and completely renovated. He didn't use it. It is a very good heating system, efficient and even heating but it is very expensive to install compared to other systems. The materials are expensive, the mixing valves, tubing (that number of feet add up quickly), etc. Also the recovery time is somewhat of a problem. If your system does go down in the winter and the tech fixes the problem and starts it back up, you'll be waiting quite a while before the house warms up. The efficiency, i.e. low water temps, means it will recover slowly. Also if your system does go down, you will not know about it for a while.
Also radiant is a poor choice if your going with AC because the expenses are doubled. You will be running ducts for the AC, so why not run a heating coil with the AC air handler and use hydro air? Radiant is great for slabs in the basement or the garage, otherwise its a waste.
“It is a very good heating system, efficient and even heating but it is very expensive to install compared to other systemsâ€â€¦Which means non radiant systems are less efficient, have uneven heating and are cheap to install. Perfect - just the direction us aging folks want...pay higher fuel bills to be less comfortable.If the air system goes down and it takes forever to get a tech out - the plumbing systems will freeze creating a major renovation - at least with radiant – “if your system does go down, you will not know about it for a whileâ€â€¦that’s a good thing…even if you don’t notice until it gets to 65 or 60 deg F it still has stored energy to see you through until the tech gets there…if its an air system and sits at 60 deg F its only a matter of hours before you’re in trouble.
It is true in standard construction with high mass systems that radiant has a longer thermal lag but in modern low mass floor systems like Quicktrack(tm) or Warmboard(tm) in energy efficient homes (R2000) this does not apply and to prevent further confusion thermal recovery is not the same as thermal lag. Radiant heat transfer is instantaneous – the BTus’ move as soon as there is a temperature difference – they don’t have to think about it. That’s why radiant works so well in aircraft hangars, warehouse or anywhere where there is sudden heating loads due to large volumetric changes in air volumes.As far as air conditioning goes…there are two cooling loads – latent and sensible. The only load radiant cooling can’t address is the latent ( that being environmental humidity and humidity generated form human activities such as cooking, showering and would include biological functions – breathing, perspiring and expelling of waste.). When you take care of the latent load with the ventilation system by condensing out the moisture the sensible load which is solar, heat from motors, people, lights, dryers, ovens, stoves etc…can easily be handled by radiant cooling (up to 14 Btu/hr/sf) which is used extensively in commercial projects but is now moving into residential applications. Why? Energy efficiency. A radiant based HVAC system with dedicated outdoor air for ventilation and latent cooling can reduce electrical motors loads and transmission losses by as much as 60%. How? The horsepower for a blower based on air volumes for sensible and latent cooling is exponentially higher than a motor for moving water – consider this - a 6 inch duct for air is equivalent to a ½†pipe with water. Air has no heat capacity therefore you need lots of it. Water has great heat capacity therefore you need less of it. That’s why in larger buildings its more efficient to move energy around for heating and cooling using water rather than air. The principals apply to small structures as well.If Mercedes, Kohler, Fine Homebuilding and Starbucks based their marketing plans on cheap we would only have cheap products to select from…reminds me of putting the purchasing agent in charge of buying the lowest cost toilet paper…does the job but no where near the same experience.RBean
web: http://www.healthyheating.com
blog: http://wonderfulwombs.typepad.comEdited 6/14/2005 2:22 pm ET by RBEdited 6/14/2005 2:27 pm ET by RB
Edited 6/14/2005 2:27 pm ET by RB
“It is a very good heating system, efficient and even heating but it is very expensive to install compared to other systemsâ€â€¦Which means non radiant systems are less efficient, have uneven heating and are cheap to install. Perfect - just the direction us aging folks want...pay higher fuel bills to be less comfortable.
You can read but I guess you struggle with comprehension of the text. In the excerpt above, where did I ever say that non radiant systems are less efficient or heat unevenly? I'll help you, I did not. I referred to radiant system qualities only.
Also, the "savings" from radiant will only offset the higher equipment and labor costs if you plan on staying in the house at least 15 years.
Edited 6/14/2005 8:01 pm ET by DDay
Ah yes DDAy and I wrote what I did to engage in a robust dialogue with you because you said “Radiant is great for slabs in the basement or the garage, otherwise its a waste.†I want to know what would make you say such a thing? What is being wasted?If its money then who’s money? If payback is the basis for ‘the waste’ - the most energy efficient mechanical system isn’t any other type, its not a variable speed motor on a furnace blower, its not condensing technology, its not solar, nor heat pumps, not even fuel cells or micro turbines …the most energy efficient system is the one which never runs. The greatest payback is always in building efficiency – never mechanical efficiency regardless of the heating sales pitch of the week. So buying a mechanical system because of its efficiency vs. investing in building efficiency always needs to come into the conversation before we start calling anything a waste. If you take an R2000 home in Canada and try to justify the payback on whatever system gets installed you may as well buy a T-Bill or term deposit. There is no load. Therefore there is no reasonable payback regardless of the system. Comfort is another matter all together and in standard construction there is no heating system on the market that can address radiant losses from the body (40 to 50%) like a radiant heating system and it doesn’t matter if it’s in the floor, walls or ceiling. You can blow hot air all you like all day long into a typical North American home and if the walls, floors, ceiling including any glazing is cooler than your body – your body will release its energy to the cooler surface creating discomfort regardless of air temperature and the only way to counter radiant losses is with radiant energy. But going back to the R2000 home, now here’s where a well designed air system can come close – not perfect - but close to the radiant comfort. Why? Because the energy efficient home by its very nature has warmer walls, floors and ceilings thus robs the body of its radiant energy in smaller amounts which translates to higher comfort. So in this case I would agree that other types of systems can provide high level of comfort only because the building load is so low.When it is said - radiant is a waste, I take issue with that because I have lived with air only, with radiant only and now have a dual system - both air (for indoor air quality) and radiant (for indoor comfort quality). I have also had air and radiant in my offices and shops – so I speak from over 25 years experience having lived and worked in both environments and in my books when it comes to radiant comfort there is nothing wasted - regardless of where it’s installed. I’m not discounting you friends experience or your own thoughts (they belong to you not me) but the statement ‘it’s a waste’ is a big wide brush that needed a haircut.Sorry, I do apologize for getting you going, it was done deliberately.Won’t happen again.
RBean
web: http://www.healthyheating.com
blog: http://wonderfulwombs.typepad.com