Create an instant bill of materials. This is a likely area of heat loss at all four sides of the building: where the slab dropped down to form footings. It even has built in defaults for radiant heat slab VS radiant heat ceiling (as well as almost any kind of HWH you might want). The R-value of concrete is roughly .08/inch (US DOE). Considering the tradeoffs, perhaps it is time we pay more attention to quality control procedures to ensure that performance is not compromised as concrete is poured over radiant tubing circuits. referred to that work, but because the original testing was in warmer conditions (outside temperature had not been below 35F. Finally, the supposition that "if they have floor problems they can remove anything they need to" sounds highly suspect to me - it's not thought out. In fact the tubing was stapled directly to the surface of the styrofoam insulation. There is no doubt that in virtually every radiant-heat-floor-slab design we need continuous insulation under the slab and at slab perimeter, though the appropriate insulation amount might vary depending on the local climate. Store preferences for future jobs. Hooked everything up and after a few issues like broken line needing fixed the heat was turned on. Customizable parameters for each panel and loop. Estimate costs through "Quick Quote" within Right-Radiant without drawing a floor plan. | Site Designed by Axis Web Design, For more information call 1 800-451-7593 | FAX 802-626-8045, Site Map | Terms & Conditions | Privacy Policy. I blame builder that his installed tubing is holding moisture and being "sucked upwards" through the bluestone. Some spots are cold even though other spots are toasty warm. In fact, they never have to leave the actual program with all the calculations linked to the drawing, data never has to be extracted to alter. ThermoSoft, Corporate Headquarters The analysis performed was also based on steady state conditions. I read your fascinating article on installing radiant heat systems when pouring slab foundations; however, I'm in the process of purchasing a house with an existing slab foundation, built in 1974, and no history of whether insulation or vapor barriers were installed at the time. List of materials needed for a project like this (Click Link below to Purchase Product and see more Information), Quantity 1 - Hydronic Heating Mixing Valves (Optional), QuantityX -Cast Iron Pump (For Heating Side andDepends on System), QuantityX - Pump Flanges (For Heating Side and Most Likely 3/4 Inch), Quantity 1 - Hydronic Heating Thermostats and Floor Sensors, QuantityX - Sharkbite Quick Connect Fittings, Quantity X - HousePEX PEX-C Pex Tubing for Radiant Heating in Slabs, QuantityX - PEX Radiant Heating Manifolds, X = Various Amounts of Product needed- dependant on actual system, 2000 - 2022 Houseneeds, Inc. 131 S Main Street Suite HN, Barre Vermont 05641 (802) 583-2726, Condensing Boiler 3" Concentric Termination Kit, Hydronic Heating Mixing Valves (Optional), Cast Iron Pump (For Heating Side andDepends on System), Pump Flanges (For Heating Side and Most Likely 3/4 Inch), Hydronic Heating Thermostats and Floor Sensors, HousePEX PEX-C Pex Tubing for Radiant Heating in Slabs. particularly homes which have used radiant heat in the floor slab. Shown here is ThermoSoft's electric radiant heating mat, sold in 15 square-foot sections and that is used under ceamic or stone tile finish flooring. It's not just the quantity of insulation - R20 might be fine - under the slab. We also measured floor temperatures in different areas of the building, mapping clearly where the radiant heat tubing dropped to the bottom of the footing-portion of the monolithic-slab footings! The system is one zone and serves the entire house (~1400 square feet) and the insulated 4-car garage. - settings on the boiler's aquastat itself: HI LO DIFF whose construction details, methods, materials were unusually well documented as a project. All Rights Reserved. Repairs to this cracked ceramic tile floor are illustrated. If there is a leak in radiant heat floor tubing the boiler may automatically take on make-up water through a water feeder valve so you may not recognize the leak, particularly if the leaking heating tubing leaks down into soils rather than up into the occupied space. Heat always flows, and continues to flow from a warmer material into a cooler material. She may want to investigate under the slab to see what sort of insulation is there and if necessary she may want to add insulation before adding the radiant heat system. Our electric bill for the building runs on average $400 during the winter. Think of it as "heat flow resistance" through various materials. Tel: 847-279-3800 Fax: 847-279-8845 I told hubby he needs to figure out a more cost effective way of heating the building. Our CAD layout service includes the location of radiant boards, tubing, and manifold locations. Our photo (left) shows where we found the radiant heat floor tubing when we later broke open a section of the floor slab. Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia. I ask why and was told if the have any floor problems they can remove any thing need to. The workers in the photograph at page top, where our concrete slab was being poured, were not guilty of a thing. There was so much heat loss that we could not get the room temperature up even in cold but not bitter cold weather, and even though the same contractor had done a great job insulating the upper portions of the structure's roof and walls. "These results indicate that tube depth does have a nontrivial effect on the thermal performance of a heated floor slab. [Click to enlarge any image]. see SLAB INSULATION, RADIANT / PASSIVE SOLAR for a discussion of proper insulation below a heated floor slab. Copyright 2022 Wrightsoft Corporation. This option is available at no additional cost! Floor was nice and warm except at the outside walls. Easy to use module integrates with other Right-Suite Universal modules. Calculates flow rates, loop lengths, loop layouts, and head pressures, even where supplemental heat is required. Normally you would not bother to run radiant heat under cabinets and IMO even more important, not under a refrigerator, but if it does run there it's not a catastrophe. It'd be appropriate IF the thermostat was turning OFF the heat - thus thinking that you're warm enough. He is so busy working a full time job as well as the part time job in shed so I am trying to be proactive before fall arrives again with no answers to our problem. The 1948 heat loss research was important in part because it recognized that the rate of heat transfer from the heated building to the outside (earth and surrounding air) would be greater in proportion to the temperature difference between the heated space and the surrounding soils. It would be a shame to give up on an installed radiant heat system as "unrepairable" only to discover years later that a tiny switch on a circuit board was not set to the proper temperature range. That sounds perfectly reasonable to me. to the owner and to the contractor: I am doubtful that we can successfully and economically heat the cabin with radiant in floor heating as the current system is He was dead wrong - a SNAFU that led to complete abandonment of the heating system he installed. Start by asking for guidance from an **experienced** radiant heat floor installer in your area. The nonsensical view that one can heat up the soil below an building slab on grade and that the soil would magically stay warm forever was put to the test experts when the author was five years old and the contractor was not even a gleam in his daddy's eye. Any thoughts? The builder located sections of the radiant tubing so that there was about 6" or less of concrete (in the 12" footing section") between the tubing and the cold soil, giving us a heat transmission path (tubing to soil) of R 0.24 or less. His theory was nonsense, as both expert advice and actual field experience proved. to make the (many) mistakes this one did. Our plan service will call you to discuss manifold locations, zoning, and orientation of hardwood floors. We can use .dwg CAD files or a pdf format file. All Rights Reserved. To start the layout process, you must complete our Project Questionnaire so we can understand the project more completely. Generally a longer "ON" cycle is more-efficient; it takes about 5 minutes for a boiler to get up to full operating temperature. The folks who seem to disagree have been people like the bully contractor who himself admitted he had never read instructions, attended a class, nor asked for expert advice. It is indeed a sophisticated system. (1) regarding the "134 F" in the bottom right of the above table: Monterey Energy Group. So while it may not be intuitively obvious, and while it's true that the thermal conductivity of concrete and even sand (which is not as good as concrete) is greater than insulation, if we have enough sand or concrete above the tubing, and little-enough insulation below the tubing, heat flow down through the insulation can still be significant. How old are the concrete slab and the bluestone installation? In 2020, observing water leaking up through the slab in this location from below, the floor was opened to permit further investigation. Another theory I have read is that the heat as it goes down, which it will, some is that it radiates horizontally, which makes insulating the edge quite well. On their web page MONTANA SLAB EDGE INSULATION ANALYSIS FOR 2006 IECC ADOPTION [PDF] There seem to be so many theories on this. Either figure out why the in floor heating is not efficient or perhaps not hooked up properly or that the building needs to be insulated etc. I've suggested tubing too deep in slab and also tubing that runs through a too-cold section without proper insulation; you need to check the output and return temps at the boiler. - presence or absence of a domestic hot water tankless coil on the boiler Thoughts?? You will notice that the PEX Starts and comes back to the same location. (Oct 16, 2015) Sue said: System is 50 years old but boiler is brand new .. with foam insulation under the slab. The study data includes comparison with fully-insulated slabs too, but most important for our discussion, it does not address radiant-in-floor-slab heating designs that, without full insulation, can find an easier heat flow into the ground than into the building - not what we want to see nor pay for in heating bills. This system is *smart*! with the experienced heating people we use, have had no problems. As an aside the ceramic tile on the finished floor slab was set in mastic - leaving some air spaces and mastic that is a poor conductor compared with tile set in concrete (optimal) - but we doubt that's nearly as important in the system failure in this case. We have better insulation but much deeper placement. The system cannot keep up heating when it is cold outside. per month. I am just worried that the the plumber that I am bringing in won't be able to figure anything out for us, in which we will be left with a very expensive system that just won't work. The expert sources I found on this want tubing in the concrete and very close to the slab top surface, an inch or two at most down is best. Ask your heating service tech to take a look and let me know what you are told. I currently have it set up to provide 80 degree water to the floor piping and run it 24 hours per day, 7 days a week starting in mid-October through April. - Wendell Schubloom. I'll contact an experienced radiant heat floor installer and pursue having the slab checked for insulation. Virtually all projects select our panel layout service with some choosing a full turnkey system mechanical design and specification. Design snow and ice-melt radiant designs. 2) Pump is unable to circulate the hot water quick enough through the system, and is actually the reason why the system isn't able to stay ahead. Thank you again for your help and patience. small apartment units) and radiant heating applications." Tubing is at a depth greater than 2" from the top of the slab, typically at the slab bottom at 6-7 inches down from the floor surface, and at some locations is considerably deeper than that, in some areas more than 18" deep in concrete. the entire radiant heat system was not usable at all. At the time of installation it was heated by an oil furnace. Certainly you can test the plumber's idea by simply insulating the thermostat from the fish and from any warm air drafts but I doubt that's needed. - how to add a radiant heating system on top of an existing concrete slab floor. Thermostat set at 68 degrees and the timer set to kick on every hour for 15 minutes. - setting of temperature for the floor loops Complete Radiant Heat Mechanical Design Service. All rights reserved. The boiler cycles, burning for about 2 minutes and is off for about 12 minutes - so the total burn time per day for the boiler is 4-5 hours. Also Automatically design and layout radiant loops with a single mouse click. Stunning heating bills arrived, exceeding Additional information. Scroll below and click on loop and board drawings to see them in a bigger view. Meanwhile we shut down this unfortunate radiant slab heat system, installed a few portable electric heaters, and given the tight, well-insulated construction, we found we can keep the little cabin comfortable for a fraction of the cost of heating the earth underneath our floor with the contractor's heating installation. Thank you for any help you can offer. Even if money had been no object, the system simply could not heat the building to an acceptable temperature. The heat pump is a Nordic system. We have resorted to turning the whole system off in the warmer months and turning down quite low in the winter. When I use a temp gun to check the pad its running at about 23- 25 degrees C (73 -77f) Insulation is incomplete within the slab where tubing installed at a lower level is stepped down from the upper slab level and heat transfer is permitted into the gravel fill below the main slab area. Right-Draw and either Right-J, Right-F280, Right-CommLoad, or Right-N. (perhaps hot water in tubing in a radiant floor slab) into the occupied space (perhaps a room in a building over such a floor) can be calculated The thermostat will activate the pump and will send hot water into the floor. Indeed I like radiant heat floors provided the workmanship gives a successful job. I'm sorry but I'm utterly ignorant in this area so for clarification I have to ask - is it acceptable to have the boiler cycle on/off every 12 minutes or so as it currently does or is it not the best way to operate the system? You may use this feature if you imported a CAD file first. The old unit was leading edge in 1952, the new unit is leading edge now. One exception to the general order of priorities of where to insulate in buildings concerns homes built with slab-on-grade construction, That was not the case for the home shown here. The result: the owners ultimately had to abandon the entire radiant heated floor system. So the insulation, air tightness, materials, heating details were known. Our contractor (Nightmare-works Construction), didn't want to insulate below the radiant-heat floor slab at all, insisting that "Once you get that dirt heated up below your floor your the earth will stay warm and your home will cost almost nothing to heat.". replaced with one using proper insulation and tubing placement. In the structure described here, not only was some tubing 12 to 18" or even more below the slab top, the insulation below the slab was incomplete, inviting ready heat flow into surrounding soils. You may find that on the coldest days of the year your heater is running almost continuously but on other days it should be running at a much smaller percentage of the time just as you described. Thanks for those added details. I will be heating with a boiler system with a separate hot water tank for household use. That's when we began digging into the installation details of this project. Radiant PEX In Floor Heat Tubing Layout Tube In Cement Slab with 1 Manifold - Typical Layout with 3 Port Manifold. As our reference document(s) below show by calculation and model, ultimately, the heat flow into the ground for tubing really too deep in the slab can be significant, even if there is insulation below all or part of the slab. He is the author of Modern Hydronic Heating and Radiant Precision (available from the Radiant Panel Association (www.radiantpanelassociation.org, 800-660-7187). After the one-year period ends, you must purchase Wrightsoft Software and Support (WSS) each year for continued software updates and technical support. - boiler fuel: oil/gas Save common properties within your preference library for future jobs. That's why we had to abandon the whole radiant floor installation. 701 Corporate Woods Pkwy An annual license allowing you to use software, download updates, and receive technical support for one single year. plan). Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly. They added some optional sensors, but the capability for the sensors is built into the base unit. Free Shipping Policy excludes LTL Truck Deliveries and just a few oversized products. Right-Radiant, like most other Right-Suite Universal products, has the ability to save common properties within the preferences library to use for future projects. Literally. Copyright 2002 - 2017, Robert J. Starr. Contact Mr. Cranor at 804-873-8534 or by Email: Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals, Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the. Our complete system design service includes CAD radiant board, tubing, and manifold locations plus room by room heat loss calculations, heat source selection, pump selections, control selection and wiring diagram, product specification, and complete system schematic. there could be water coming up through the slab from water below-it. They were more. Placing concrete atop radiant floor PEX tubing stapled to the foam-board insulation might work IF. I've read quite a lot of supporting research on slab and slab perimeter insulation for radiant heat flooring, and I have some direct experience with installing radiant heat and more with inspecting radiant heat flooring problems. OPTIMIZE PERFORMANCE AND EFFICIENCY, RADIANT FLOOR HEATING IN THEORY AND PRACTICE, INSTALLING PEX TUBING FOR CONCRETE SLAB UNDERFLOOR HEATING, RADIANT FLOOR HEATING MAT INSTALLATION MANUAL, Basic Hydronic underfloor - thermal storage 8 to 14 hours of control, Solar Water Heating System Maintenance and Repair, Solar Water Heating System Freeze Protection, Scaling and Corrosion in Solar Water Heating Systems, i-Link SERIES ZONE CONTROLS (CIRCULATOR PUMP SWITCHING RELAYS ) FOR HYDRONIC / RADIANT FLOOR HEATING SYSTEMS, i-Link SERIES ZONE VALVE CONTROLS FOR HYDRONIC / RADIANT FLOOR HEATING SYSTEMS, UNIVERSAL DIGITAL TEMPERATURE GAUGE: DS-60P, DIGITAL NON-PROGRAMMABLE THERMOSTAT FOR HYDRONIC RADIANT FLOOR HEATING, DIGITAL PROGRAMMABLE THERMOSTAT FOR HEATING/COOLING & HYDRONIC RADIANT FLOOR HEATING, HOME INSPECTION EDUCATION COURSES (Canada), HOME INSPECTION EDUCATION: HOME STUDY COURSES, Insulate below the entire floor slab. Purchased a Mini Broiler and in floor thermostat. With 6" of sand and say nominally 6" of concrete, your tubing is 12" down - way too deep, and furthermore, the first 6" of material (sand) between the tubing and the occupied space, does not quite the same level of thermal conductivity as tubing in contact with solid concrete. Our photos above and below wer made possible by breaking into the floor slab with a jackhammer, removing concrete to expose the exact details of how and where the radiant heat tubing was installed in this floor - shown below. Our photo (left) illustrates a successful radiant heat system installation in Minneapolis, MN - a climate similar to that where we had trouble with the Two Harbors system above. said the owners would face winter heating bills of about $30./month based on his prior experience. We are hoping that the problem isn't the lack of insulation. [4]. John Siegenthaler, is a professional engineer specializing in radiant heat designs and heat transfer theory in buildings. Have considered not running the system at all in the winter as the area it heats is not used that much. Holdrite, Tel: 1 (877) 700-4242 Web: https://www.holdrite.com/ - We could not find a physical address on the company's website. Radiant heating system design or installation mistakes that must be avoided. Hydronic Heat Pumps with Ecowarm RadiantBoard, Hydronic Systems Compared to Traditional Forced Air, Radiant Flooring & Finished Floor Coverings, Ecowarm Compared to Climate Panel Or Quik Trak, Ecowarm Compared To Above Sub-Floor Plate Systems, Ecowarm Compared To Grooved Boards Without Aluminum, Ecowarm Compared To Under Sub Floor Plates, Staple Up, Or Hanging Systems. Thank you very much for the swift reply! FREE FedEx Ground shipping on all orders over $99.00. Would they conclude that some builders of the time were just too lazy to bother lifting the tubing? But a thermal scan of the floor can often find where leaks are occurring by noticing the spread of heat pattern. The Quick Quote mode was designed for a first pass assessment, a design-free way to estimate a project, complete with a bill of materials. thank you for your rapid response. The contractor and others tried to improve the system's performance by changing the boiler settings from those set by the manufacturer on its integrated circuit control board, upping the circulator size and capacity, checking flow rate through the system, checking the thermostat controls. Worse than too-deep radiant floor heating tubing, in this case, because the contractor put NO insulation at the area of soil where he stepped the slab down to the depth of the monolithic integrated footings, we have heat transfer from some of the tubing through concrete right into the cold soil, not just through concrete up into the room through the ceramic tile floor. Simply add panels and connect manifolds, all other calculations are based on preset preferences and the load calculation from your floorplan. The existing loops really do seem to be fine -- a sample of water was drawn for a repeat test of concentration for the X100 anti-corrosion agent, and the water was clean and clear. All loops share a small boiler circulator that moves water through the boiler loop, but each other setup has it's own in-line pumps. Pumping faster, with some subtle technical exceptions, puts more BTUs per minute into the floor; Siegenthaler explains in various articles that the rate at which a hydronic heating system can actually move "sensible heat" from the heating source We agreed that the description of the failure of this installation needed some clarification, and added the following information that should be considered: Keep in mind that this was a small new structure (624 sq.ft.) Our photo above shows accumulating groundwater just below the slab insulation. We have switched out the thermostat already. Do you think placing insulated foam on outside wall would help? As the contractor and his crew learned about it, they taught us, since we had to play a bit with the supply target range to find the sweet spot that didn't overheat floors. In conjunction with Right-Draw, Right-Radiant is a comprehensive CAD-Quality radiant design and calculation tool. I have had 2-3 different servicemen come and check the settings as well as calling the company and have them talk me through the settings but still not working properly. In fact, the utility cost to heat this tiny cabin resulted in bills that more than doubled the corresponding costs of the nearby 1960's vintage two story large old, comparatively poorly-insulated house on the same property, exposed to the same conditions. Counter-arguing: under a refrigerator a warm floor might cause the fridge to have to work harder to get rid of its heat, thus increasing ints operating costs. Previously, the US National Bureau of Standards had already indicated that the heat loss of a concrete slab (floor) on grade (on the ground) is proportional to the perimeter of the building. Building floor slab insulation design advice. Estimate costs through "Quick Quote" without drawing a floor plan. My point is that drilling one inspection hole in a radiant heated floor to examine the insulation scheme and tubing depth, even if you could avoid cutting tubing, wouldn't assure you that there wasn't a problem elsewhre under the floor. See details at SLAB LOG CABIN SIDING - cabin photos and other comments. The design will be completed by Monterey Energy Group who has designed over 400 radiant systems per year for the past 22 years. Details about this radiant floor slab heat failure and and research on its cause are provided below. The tubes coming out of the floor are noticeably cooler. We couldn't see those details without destructive chopping up of the concrete or finding photos taken during construction. Thin film radiant heat systems, other electric radiant heat floor systems as well as hydronic or hot water radiant heat flooring systems are described on this page and at the RECOMMENDED READING links at the end of this article. Earth would be warming the home from "ground heat" (which is below 40 F in winter there). On 2020-05-22 - by (mod) - Builder claims its my fault because I used bad concrete. (It should have been roughly mid-slab). SNOW AND ICE MELTING (SIM) SYSTEMS TO The tubing materials themselves, either copper or PEX or something similar, do not absorb, hold, nor give off moisture. Check the temperatures entering the floor loop and then returning out of it; you might see that there is a bigger drop than anticipated, hinting at heat loss into the ground at a rate not anticipated. DJ The following un-edited discussions, a continuation of RADIANT HEAT MISTAKES, illustrates efforts to track down the reason that a radiant-heat slab system is not heating adequately. $400./month or more than ten times the estimated amount. Despite varying opinion by some radiant floor installers, consumers, and installers as well should be wary of ignoring the advice of the radiant heating design experts and heat transfer engineers about tubing depth in radiant floor slabs shown just below. - be sure there is a thermal break at slab edges between indoors and outdoors We have a block building with poured walls that we placed in floor heating. The installing contractor decided on his own to skip the frost footings specified for this slab, instead building a "floating slab" that was simply set atop the ground. Would it be better to have it run continuously for longer periods of time? 12 years later and we installed a ground heat pump system that would eliminate oil from our property and save us $$. Also seeRADIANT HEAT DESIGN FAQs - questions & answers about installing & troubleshooting radiant heating systems. Think concrete is about 3 to 4 inches thick, based on pictures taken and have on computer. I found your article very interesting and educational especially since I am considering in-floor heating and trying to find out all pertinent information to do a good installation. - the amount of water in soil below the slab, - the slab construction details: reinforcement, drainage, insulation, thickness, soil conditions below the slab, If I turn the heating in the floor off could the frost get into the concrete and heave it up. The mixing valve was removed completely (Weil-Mclain says this is a condensing boiler and it does all the modulation, the mixing valve is not needed and was actually inhibiting flow); the pipes have been straightened out and several 1" lines are now 1.5"; and there's a proper overtemp cutoff in place on the floor loops. Is water going to fast that transfer is not effective?or is it ok the way it is ? - temperatures seen on the boiler gauge (and pressure) The large patio is under a covered porch. - outdoor temperature When future archeologists dig up the ruins of our buildings several centuries from now, will they ponder why we put the heating tubing at the bottom of the slab? Insulation will help wherever you put it; outside, be sure you don't provide a path for carpenter ants or termites up into wood framing. info@thermosoft.com Tel: 855.819.3015 Email: John Cranor [Website: /www.house-whisperer.com ] is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. Can the pipes plug up? Yes individual circuits or loops can clog, particularly if they were run as separate loops off of a main. We also offer optionally complete mechanical design services. For an overall view of this process visit HOW TO BUY. See details at HEAT LOSS PREVENTION PRIORITIES. I'd like to know the boiler brand and model so as to read its specs. Running the radiant heat pushed heat faster into the ground than it did up into the building, even Thank you for your time, Dan. Use Right-Radiant in conjunction with Right-Proposal to create a parts takeoff. This formula is not as intimidating as it may seem. If water temperature in is 15 degrees lower then water temp out And it cycles in the high limit switch of the boiler until the thermostat settings are met .. is this ok ? They place the foam down and put the PEX directly to this and then place 4 to 6" of sand on top before pouring the floor. Interactive in its design, once you drag a radiant panel into a room, select a layout, and connect it to a manifold, Right-Radiant will layout the pex in a variety of patterns (1,2 and 3-way serpentine, perimeter, outside wall tightly spaced with serpentine, counter-flow spiral, et cetera). If the floor slab had been very well insulated, the installation still would not have performed well because of the excessive tubing depth in the slab ( over 12" down in some sections ).