Radiant Heat Control Design - Warmboard + basement slab
Last Post 19 Dec 2014 01:46 PM by Rache@AECDaily. 11 Replies.
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HQ TinwhistleUser is Offline
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03 Nov 2014 10:41 PM
Hi there!  First time poster here.

I'm in the middle of nailing down a radiant heat system for my new build.  Basement will have a 4" slab and the upper floors will have Warmboard S.  My HVAC sub has recommended thermostatic mixing valves for the zone control, but I've read that these are not good for slab control.  Can anyone offer perspective on this, or suggest a good way to control the different zones? i.e. valves / thermostats?

Info:

1300 sq ft over two stories
670 sq ft 4" slab
Envelope entirely ICF: 8" basement, 6" upper floors (R22.5)
Location: Saskatoon, SK

I ran some heat-loss calcs with NRC's Hot 2000 and got around 35,000 BTU loss on a -37 degree design day (probably conservative).  So far have spec'd NTI Trinity Tx 51 boiler (9,000 - 50,000 BTU) for heating with indirect hw heater. Smallest I could find.

I'm willing to hire out some design, but hard to find that sort of thing here in Saskatoon.

Cheers!

Patrick
jonrUser is Offline
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04 Nov 2014 09:59 AM
Keep your boiler water temp as low as possible - avoid mixing.
sailawayrbUser is Offline
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04 Nov 2014 03:40 PM
I would agree with Jonr...try to avoid the complexity/cost of mixing valves and the associated lower operational performance if possible. First you need a good room-by-room heat loss analysis. By good, I mean accomplished by someone good such that it is close to reality and doesn't just look good on paper. Then you need a good HR floor heating system design that will result in the required BTUs being generated in each room/zone and tells you what the circuit/zone supply temps and flow rates need to be. Then you can finalize the HR design and procure the right heat source.
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
HQ TinwhistleUser is Offline
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04 Nov 2014 07:06 PM
Thanks for the help.  Is there some sort of directory or index of knowledgeable designers that I can use?  As I say, I don't know where to look.  It seems to me the local well-known radiant floor designers tend to design "by feel" which I inherently distrust. 
sailawayrbUser is Offline
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04 Nov 2014 07:29 PM
As well you should… There are HVAC affiliations who have membership lists, but affiliation memberships are easily purchased and no credentials are required to join, so I wouldn’t recommend that path. Your best option is likely to do some research and find someone local that you can check credentials and get references. It can certainly be a challenge to find a good contractor in some areas and when this is the case it may make sense to tackle the project as a DIY project. We do have free DIY design software and info on our website just for this option that you might want to consider. We only accomplish HVAC design/installation in OR and WA where we are legally licensed to operate.
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
Rache@AECDailyUser is Offline
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17 Dec 2014 01:56 PM
Interested in learning appropriate applications of radiant heat systems and technology, check out the following link: http://aecdai.ly/mp
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18 Dec 2014 10:32 AM
We design/build systems with our friends at WarmBoard and are installing one right now in Minneapolis for a new house.

We are also working on a similar project in BC and speak a little Kanook if need be.

Send us a DWG or .pdf.

jonr has good advice. We avoid the overrated mixing valve strategies.
MA<br>www.badgerboilerservice.com
FBBPUser is Offline
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18 Dec 2014 07:17 PM
Tinwistle - try Frontier plumbing. They will build you a complete panel here and Calgary and ship it to their Saskatoon plant. Probably not the very best but certainly acceptable. I've known the guy who builds then in Calgary and he has a long history in the business. He likes NTI better then I do.
sailawayrbUser is Offline
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19 Dec 2014 08:07 AM
This post is a couple months old and Tinwistle has likely left the building... Not sure what that Rache site is about as I figured it was some virus site and I didn't want to risk going there to find out.
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
Rache@AECDailyUser is Offline
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19 Dec 2014 09:22 AM
Hi there! We are not a virus site. AEC Daily (www.aecdaily.com) is an online education provider for construction professionals. We promote being Green and the majority of our courses is made up of sustainable design information.
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19 Dec 2014 12:45 PM
Okay Rache, but why post this site link to an old post? Perhaps start a new thread and introduce yourself too. Welcome!
Borst Engineering & Construction LLC - Competence, Integrity and Professionalism are integral to all that we do!
Rache@AECDailyUser is Offline
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19 Dec 2014 01:46 PM
Great idea! Thanks!
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