I am just finishing my 150ft sunroom remodel in Minneapolis and will soon start my radiant install. I will be using 1/2" al pex in conjunction with heat transfer plates from Blueridge. I chose them because their double run plates are .024" thick and will be using their plywood rip system. My question concerns expansion noise. I remember reading in Build it Yourself Solar that he used a bead of silicone in the plate grove to increase heat transfer and to abate expansion noise. Is that standard practice? Thanks, Tom

We wouldn't know as we never recommend or install HR plate systems because they are very expensive and not very efficient (i.e., poor ROI and we always advise folks to consider this). However, the companies that sell the plates or install these systems will tell you otherwise. Plate systems are also infamous for being noisy because of the metal plate contraction/expansion as you indicated. So you would be wise to take appropriate steps during installation to minimize this. Build it Solar is a great DIY website.

My investment in materials for this room is about $450. Doesn't include manifold or boiler and other essentials but you need those for whatever kind of radiant your doing and since I'm providing my own labor seems cost effective to me. Tom

Yes, doing you own labor on a plate system will definitely save you some big $$$. Your operation costs will still be higher because you will need a higher supply temp than would be required for a slab, thin-slab, or above floor system to generate the same BTUs. However, if those options are not feasible for your HR application, there is no reason to lose sleep over it. We have free DIY HR design software on our website should you want to run the numbers. We are also listed on Build it Solar too. Good luck with your project!

Their plywood rip system is above floor. In 2600 sq ft I have one spot that makes a little noise when I walk on it, I think that wouldn't have happened if I had glued the plates down as well a screwing them. I did use glue on all of the rips, and used a screw length that would fasten down both the plates and the rips. I didn't caulk the pipes into the plates yet I get no expansion noise, however YMMV. The only noise I got was from the supply trunks, however I don't even hear those since I got the insulation and drywall up in the basement. I did leave a couple of inch gaps between the plates so that alignment didn't need to be perfect. The tubing fits very tight into the plates, I'm not sure it would have been possible to install without the gaps. I will note that this system is very labor intensive to install, so if you are paying to have it done there are less expensive ways, however DIY I don't think you can get a top mount system for less. And as far as efficiency we have been exploring the depths to which this system can operate, I've been 14 degrees under design temperature (this has truly been a rotten year for weather, first floods, now cold), yet the system has been able to dump the entire output of the heat pump into the building, which works out to be about 12 btu/ft-hr @ 90 degrees.

Here it is from Builditsolar

http://www.builditsolar.com/Projects/SpaceHeating/SolarShed/House.htm#Press

Chris

Thank you for the clarification. Yes, that does look very labor intensive, but I suspect it is quite good with regard to efficiency. I imagine the lower cost of these plates and doing the labor yourself more than offsets the cost of using another above-floor product like Warmboard that is more expensive but less labor intensive.  What are your finish floor options given the unevenness created by these plates?  Any concerns about all the plywood spacers working loose over time and causing a creaky floor?

I will be doing the screw and glue thing and finishing with tile or slate. I have been using Beopt for my energy calcs. Hoping for floor temps of 100. I choose this system because 1. I can do it myself and 2. The plate thickness is within .001" of Warmboard and hoping to get close to it's performance. Tom

Do you really need floor temps of 100F?  A 100F floor is well above the maximum recommended floor temp of 85F.  Most well insulated/sealed buildings can get by with perhaps a 75F floor temp and perhaps use a hydronic fluid supply temp of 90F to achieve it.

I should have said 100 or lower. This is a 74 year old house. My summer projects will be window replacement and insulation upgrades. If I can get close to 85 I'll be happy. Tom

Dave111. I will be doing the rest of my house ( 2100sf) as well. Curious as to how many hours it took you. Were you working alone? Tom

I used two floor coverings over the plates, Ditra plus tile, and a floating engineered bamboo with a thin dense pad. The plates were not a problem for either covering, although I suspect it could be an issue for carpet. I did some pricing of Warmboard, and I really like the product, but the material cost difference was on the order of 3X. However, that said, I suspect that if you paid for labor you would more than burn the difference (and for those who split hairs I am including the subfloor price).

Sorry, didn't see your question til after I posted. Went back and looked at the wife's blog, took her about 3 weeks start to finish. I was on the roof putting the shingles on, so she did most of the radiant floor. The only part that I helped with was to rip the osb, and apply construction adhesive to the back of the rips, the large gun takes a bigger hand than her's.

Thanks for the reply Dave111. Most of the floors in my house have 3/4" oak floors that have seen much better days. My plan is to remove and replace with engineered wood with raidiant underneath. I would like to see your wifes blog to see if I can pickup some tips or hints to help with what lies ahead if you don't mind providing a link. Thanks, Tom. Apparently this site doesn't do paragraphs when using Chrome.

Posted By sailawayrb on 06 Feb 2014 05:56 PM
We wouldn't know

True enough.

Posted By sailawayrb on 06 Feb 2014 09:08 PM
Yes, doing you own labor on a plate system will definitely save you some big $$$. Your operation costs will still be higher because you will need a higher supply temp than would be required for a slab, thin-slab, or above floor system to generate the same BTUs. However, if those options are not feasible for your HR application, there is no reason to lose sleep over it. We have free DIY HR design software on our website should you want to run the numbers. We are also listed on Build it Solar too. Good luck with your project!

How much higher, exactly? Doesn't depend on the heat source?

Posted By sailawayrb on 07 Feb 2014 11:26 AM
Do you really need floor temps of 100F?  A 100F floor is well above the maximum recommended floor temp of 85F.  Most well insulated/sealed buildings can get by with perhaps a 75F floor temp and perhaps use a hydronic fluid supply temp of 90F to achieve it.

In Oregon perhaps. Get to a cold climate like Minneapolis, add the challenge of making 100 year old house perfectly comfortable without the luxury of putting down sandwich systems or over-pouring gypcrete and reality dictates extruded aluminum plates. If you have to use a thin plate follow Dan's advice and by all means apply outdoor reset in your control strategy. And while were are admonishing, be careful of heating "experts" living and working where the average daily January mean temperature is well above freezing and about 45°F along the coast.

If you need a 100F floor temp to heat your building, you would be far better off not using HR floors for your heating system unless you intend to wear shoes in your building while it is operating. In Oregon and Washington where contractors have to be licensed, heating systems must be designed to satisfy the required outdoor design temp and NOT the average mean temp. The required outdoor design temp is typically between 10F and 20F in southern OR and is much colder in northern WA. HR floor temps seldom need to exceed 75F in new construction to meet this requirement. I don't believe recommending 100F temp HR floors in poorly insulated and sealed buildings located in cold climates is a very green approach.

Sounds like you are still dealing with an anger issue Badger. You should really work on that...its not healthy. Your oft-repeated diatribe also doesn't benefit this educational, green construction forum...although I do confess that I find you very entertaining. God bless.

And while were are admonishing, be careful of heating "experts" living and working where the average daily January mean temperature is well above freezing and about 45°F along the coast.

That's a good general rule of thumb that cuts in all different directions.

We took our architect-designed home to the major heating contractor where his new designer is from....Michigan. A little small talk about hunting and fishing in Michigan and then down to business showing him the 60 page engineered plan on the home's heating requirements, modern design, green, passive solar, heat pump, radiant, etc., etc. Talk of lifestyles and utilities (propane, but no gas available) yadda yadda....

Fast forward to the plan he drew up; $25,000 worth of ducting and dual 90K BTU forced air gas furnaces.......

Precisely...and I bet your HR floor temps are not 100F and you are not using plates either.