WorldWide Drilling Resource

58 JUNE 2016 WorldWide Drilling Resource ® Geothermal Residential Radiant Floor Heat by Peter Tavino Litchfield Geothermal Publisher’s Note: Although this article is not about geother- mal drilling, we found it interesting and thought you may feel the same. When I trained IGSHPA (International Ground Source Heat Pump Association) installers in Indianapolis, Indiana, a few years ago, I was impressed by the Indiana Warm Floors company which provided customers with radiant floor heat as their main business. Generally, cold floors are not a solution for residential cooling air conditioning, so the vast majority of geothermal heating and cooling systems use ducted forced hot or cold air. Radiant floors here in the northeast are redundant sys- tems which are in addition to the water-to-air ducted heat pump operations. Comfort comes at a cost to install both ducts which alone do the job, and radiant tubing for warm floors, as well. While 1% have no problem with this, we geothermers strive to improve the in- door environment for all at a reasonable cost. One new house with geothermal I in- stalled, had staple up radiant at the prefab factory. It did not use tubing within the plywood, which is of course more efficient. Once up and running, the owner tried turning the air handlers off and heating in frigid weather with the radiant floors alone, and was disappointed it could not keep up. The prefab designers had not spaced the tubing for 100% heat, so the owner now keeps the blower fan on for heating and has warm but not hot floors for his comfort. This is better for oak floor shrinkage is- sues too. With a recent job on Long Island, New York, the owner similarly wanted to add new radiant plywood floors and retrofit his ductwork to geothermal on a budget. He wished to remove his heating oil tank and did not want propane radiant heat. Another water-to-water heat pump would have been required, in addition to two new water-to-air split systems, for his two existing air handlers. One large water-to-water with less efficiency did not appeal to him compared to refrigerant-based heating and cool- ing by line set. The need to switch from heat to air conditioning quickly without waiting for tank reset by a day or so, was important to him. Combination water-to-air and water-to-water heat pumps are very costly too. He had a separate new hot water heater, and did not require a desuperheater and new domestic hot water buffer tank. So we considered using the inex- pensive desuperheaters for two new water-to-air heat pumps, to power his new first floor radiant. From the Performance Chart as shown, the Hot Water Capacity (HWC) in the last column shows hot water capacity at about (2.5M) 2000 Btu/hr average part and full load, for the 3-ton first and basement unit, and 1500 Btu/hr for the 2-ton upstairs unit. This totals 3500 Btu/hr at the lowest 30ºF (-1ºC) Entering Ground Loop Water Temperature (below my 34ºF (1ºC) design with hot water extra), so figure about 4000 Btu/hr cold weather operating output. 4000 ÷ 23,575 Btu/hr design load = 17% of heat to rooms through the floor during the coldest days, and more on average winter days. This will keep the floors in the high 80s that will not heat 100% by itself, but will give warm floor comfort, which is all he really asked floor. The statements and comments in this article are based on information and references believed to be true and factual. If you have any questions or comments, please forward them to me in care of WWDR . Pete Peter Tavino may be contacted via e-mail to michele@worldwidedrillingresource.com !+34# 0/4#/# 2 #,'23(+'-& ((+%' 0& '/&'230/ 2#/ '/&'230/ $+4%0+/%20& *04.#+- %0. 777 $+4%0+/% 53 '7 3'& +43 0-' 1'/'23 2#) +43 "+/)3 #..'23 #..'2 +43 +6'24'23 ' 4+11+/) 4#$+-+8'23 -#7 +43 +1' "+1'3 0-4 0/ ''4* 5$3