nic89 said:
I would use 7/8 OD
Pex with oxygen barrier if you have a boiler that can be hurt from oxygen.... if your house system is separated from boiler then oxygen barrier is not needed....
http://www.radiantec.com/systems-sources/systems.php
http://www.radiantcompany.com/ can help you set up a system. They can tell you what size pipe and pumps....
I would look into a system with 1 more powerful pump and solenoid valves to zone rather than having 1 pump per zone. Something to look into.
In concrete I laid down a vapor barrier (plastic) then 2" foam then wire mesh that was basically 6" squares and I tied my pex on 6" centers. My pex is 1/2 and I think it would of been better to use 7/8 OD pipe
If your project is complex with lots of zones you may need help setting up the system
Some rules are: 300 foot runs are the longest - so one part of my house has 3 - 300 ft runs in the concrete all 1 zone
if you have 150' run and find out you need to add another run in that zone it also needs to be 150 other
wise the shorter run will have more water running through it than the longer run and that will effect heat output...
I was reading that you could have longer runs with more powerful pump. something to look into..
Whoa there padna'....Not trying to belittle your experience or recommendations but let me interject a few comments here before this poor guy gets himself in trouble.
First of all, the companies you mentioned are probably responsible for more failed attempts at radiant heating than ANY other companies in the USA. Just go over to the Wall at
www.heatinghelp.com and mention the name.....then duck and cover. I'm sick of companies like that giving radiant heat a bad name because they gave a poor or ill advised recommendation.
Second, do a heat loss for the structure to find out what you actually need for heat ouput. Nothing you can do will paint a clearer picture of what size tube, control method, pump size, loop length etc, etc. When you know the btu requirements you can make informed and intelligent decisions about the entire system. If I learned one thing early on in my heating career it was to do your own homework. Don't rely on some guy that just wants to sell you "stuff". If you are going to undertake the installation personally, you owe it to yourself to understand the ins and outs of what you're doing. Don't do it if you don't understand why. You'll be glad you did.
Third, all of the experienced heating professionals I know use O2 barrier tube for all heating applications regardless of whether it's an "open" system or not. In Europe, where radiant heating is much more "mature" than here in the U.S. barrier tube is mandatory. I have learned to pay attention to the Euro people when they talk about heating because they speak from knowledge and experience, especially the Germans. That being said my two favorite tubing brands are Viega and Rehau. Both are top drawer product. When you're putting it in cement and consider the cost of a tube failure there is no substitute for the best. I've met a lot of people that brag about how they bought 1/2" tube for $.?? a foot only to hear a few years later that their system is abandoned because of a failure of some kind. Tain't worth it man! Buy something with a good warranty and a long (15-20 year) reputation. Read the fine print. A lot of companies warrant the tube but not associated repair costs. Big deal
Now, as to tube size and length, there are a number of schools of thought on temp drop and heat transfer and each argument has it's own merit. I'll just say that the main thing you want to avoid is a system with high head. That means you adhere to these rough guidelines: 1/2" tube = 250-300 feet, 5/8" tube = 350 to 400 feet. 3/4 tube in a residential application is a waste of effort and needless expense along with being a PITA to work with.. The only time we use it is in 500' runs for a snow melt application or for a main.
Lastly, I want to apologize if I come off a tad strong on the radiant heat/ tube stuff. As a heating professional I have run into a lot of jobs that are screwed up and don't work because someone got some bad advice.....or worse yet, tried to do it cheap. I get to come in after the fact and try to straighten out a mess ar worse yet, tell the customer there's no fix for what they have done. They get a bad taste in their mouth about radiant heat and my business suffers because they go around telling all their friends they would "never do that again".
I don't begrudge anyone the opportunity to do it themselves, just do it right or else don't do it at all.
The soapbox is now open.
BTW: Don't neglect edge insulation in that basement
!!
