AboutMorgan M. Audetat Expertise Radiant floor heating. Snow Melting. Boilers. Indirect water heaters. Tankless water heaters. Current owner BadgerBoilerService.com Minneapolis based mechanical contractor specializing in Mod/Con based, integrated heating systems. System design, consulting and technical training world-wide.
Currently designing hot water based heating and snowmelting systems for spaces ranging from 50 to 50m square feet. Consulting fees start at $500.00US
Experience 30 years. Organizations: Charter Board Member - Radiant Panel Association, former manufacturer of the first American-made, wall-hung, sealed combustion condensing boilers, son and apprentice of mechanical & plumbing contractor.
Continuing Education: Uponor/Wirsbo advanced design school 2007, Power Limited License (low voltage controls) 40 CE credits 2005, B&G Little Red School House 1993, Tekmar Controls residential and commercial 1993, Division Manager and Advanced Hydronic Seminar Host for the first Hydronic Radiant Floor Distributor in the USA 1990, Hydronic Heating Association Workshop participant with Richard c. Bourne, PE spring 1988, Master Plumbing/Hydronic/Solar Course Red Rocks Community College 1987.
Education: B.S. University WI 1981, 26 yrs. continuing education.
Licensed CO, MN & WI. Home Inspection license WI exp.
Awards and Honors: Radiant Panel Association System Showcase Award 2008
My momma's favorite son.
Past/Present Clients: References upon request.
Expert: Morgan M. Audetat Date: 5/28/2008 Subject: Bathroom Warm Floor Radiant
Question QUESTION: Hi Morgan,
I'm a DIY-er remodelling a house and would like to add warm water radiant floors to my bathrooms. My plan is to put a temperature zone in each bathroom and set the thermostat a degree or so above the rest of the house setting, and let the floor temps fall where they may. High heat output is not necessary as they will stay on the forced air system as well. The baths are currently down to the plywood, but the hardwood in the hallways will not be removed, so I'd like to minimize the height transition, and I'm not price sensitive in materials. I'm considering gypcrete, thermalboard, and warmboard over the existing plywood. What will give me the lowest installed height plywood to tile on this retrofit, 1.125" gypcrete plus whatever prep for tile, or 5/8" thermal board plus the (assumedly greater) tile prep? Is there another solution worth considering (other than electric, I don't want the operating expense and I want them on all of the time).
ANSWER: Do you have hot water heat now? If yes; let me know more about the current system.
MA
---------- FOLLOW-UP ----------
QUESTION: The house will retain an upgraded existing forced air duct system. The existing late 1980s furnaces and water heater will be eliminated and replaced by 4 furnaces with 4 zones per furnace. The hot water will be present because I am retrofitting a 2300 sq ft basement under the house with an insulated slab. I'm including 1 foot per sq ft of pex in the slab, and will zone it from two Polaris hot water heaters, one 199,000 BTU 100 gallon which will also serve a shower system that runs up to 22 gpm, and will serve the east zones of the basement slab and two of the bathrooms. The second polaris water heater will serve the west side of the house with one bathroom and the west zones of the basement slab.
ANSWER: As I have often posted in this venue. DIY installation is fine if you can acquire the skills to safely install HVAC components. However, DIY engineering can be a great waste of time and material, as I suspect is the case in this instance.
Dual use of domestic "drinking" water as a heat transfer fluid for radiant floor heating (not to be confused with copper lines going to a hydronic fan coil) is simply not done by informed professionals who consider it a serious health risk.
My only advice to you is to seek and heed professional HVAC advice.
You might like to read my previous posts for more conventional and safe ideas.
MA
---------- FOLLOW-UP ----------
QUESTION: This system does not use the potable water as the heat transfer fluid, but the water heater is used as the heat source through a heat exchanger, as designed by radiantec. Are their systems considered unsafe? I have already installed a complete system supplied by them in another house. The potable system operates at a higher pressure than the pressure release valve of heating fluid, so a failure in the heat exchanger would leak potable into the heating fluid, and create identifiable leakage from the release valve. Should I be concerned?
Answer Sorry, I jumped to a conclusion. I am glad you sought help though I can't fully understand the system you have described. A plate heat exchanger is perfectly safe.
I often have a problem with all wholesale/distributor types as they are limited in their designs by the products they have in stock.
To answer one of your questions. Gypcrete thought not a durable service is compatible - with a crack barrier - with tile. Sandwich systems must be covered with cement board before tile application.
You seem to have a great deal of equipment for your application, but I wish you luck.
