Radiant Heat Up

Nick_16

Hi. I am installing a hydronic radiant floor in a home. The total R-value is 2.6 including subfloor, Pergo, etc. What could I expect for a heat up/ cool down time with 140 F water? Would I be able to gain 5 deg./hour? My joists are 14" apart. What to run 1/2" Pex. Any help would be greatly welcomed. Thanks again! Also, want to install 5 radiant zones, 5 3/4" baseboard zones + Indirect water heater with 23KW electric boiler. I would like to use one pump and zone valves. But, the radiant has up to 18 ft. head and the baseboard only has 6 ft. head. According to the pump curves, Taco 008 would give radiant proper flow but the baseboard would be flowing like mad. Way over 4GPM. How do you solve this? Can 2 pumps be used, one for radiant and the other for baseboard? Please let me know. Thanks a lot! Everyone on this site has been a great help so far. I really like hydronic heating and know more about baseboard/radiator heat. Radiant is still new to me. Thanks again!

Jeffrey Campbell

Where to start?

Well start with a heat loss for both the radiant zones and the basebaord zones. This will tell pump sizes and also what type of radiant ehating application is best for you. Sounds like you are thinking of staple up. I personalloy do not like the system. You are limited to very low output, slow response, hot cold spots, and not very efficient(higher supply temps-140+). Look at using heat tranfer plates, all tubing manuafures have them.. Better yet, look at a raidant board system which is installed on top of the existing subfloor. These products provide even heat, are more comfortable and are more efficient(lower supply temps). Also they provide much quicker respose times. You are in a forced air dream to think you can achieve anymore than a 1 degree temp rise per hour from a staple up system. Aluminum radiant panel product trans fer heat faster and more even. Staple up produces hot and cold spots.
Next you definately need to look into not only a two pump system but also a two temperature system. I suggest using tekmar controls. They control the boiler, both temperature zones, and domesic hot water. Tekmar controls use reset logic to change the supply temperatures depending on the outdoor temperature. Hotter supply when its cold and cooler supply when its warm. This will create the ultimate in comfort and efficiency. Remeber radaint heating is a comfort system if installed correctly. Have faith in the control system thousands of them have been install with great results. The Tekmar system does it all for you. Good Luck Jeffrey Campbell

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If you do

use 5 zone valves or more, on one pump, add a PAB/ PAV pressure activateD bypass or valve (same animal). This will help keep your flow rates in line better as ZVs open and close. Honeywell, Danfoss, Oventhrop among others offer these valves.

Until the delta P pumps arrive on the market

hot rod

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Jeffrey Campbell

RPA

Nick if you are a installer looking to do the right job look into the Radiant Panel Association. They are about educating everyone on radiant heating. Lots of classes, research, information, products, and fun. Yes, doing things right is very fun! Hot Rod is right, do use a diffrential by-pass valve if you are using more than 5 zones on a circuit.
Jeffrey Campbell

Nick_16

PAB/ PAV pressure activate bypass or valve

How is this plumbed into the system?