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TacoHavoc
Dec 31, 2007
It's taco-y and havoc-y...at the same time!

If you go here:

http://www.uponorpro.com/Technical-Support/Manuals.aspx

And hit the "Complete Design Assistance Manual (CDAM) 7th Edition - Full Copy" link, read chapter 8 and use the associated appendices. It explains how to manually calculate what their expensive program will do for you. You will have to do a heat loss calc (manually or with a program, up to you), but other than that it should be pretty simple.

I work in the HVAC industry (on the software/hardware side), if you have any specific questions on this stuff I can probably get answers from a guy at work for you.

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TacoHavoc
Dec 31, 2007
It's taco-y and havoc-y...at the same time!

tetrapyloctomy posted:

An HVAC guy told me the tile in our kitchen is cracking in part due to too high of temperatures through the PEX because of lack of a mixing valve on the hot end. (It also causes the PEX to get stiff over time.) So there's that. You said wood floor -- I swear I could remember reading that you should use quarter-sawn wood with radiant heat, but I could be confabulating here.

You have to mix down for radiant, absolutely. Typically a primary/secondary layout off the boiler is used, with a mixer of some sort to the secondary and zone manifolds off that. Uponor/wirsbo recommend no more than 145f for wood floors. Based on your redone construction and insulation I can't see you needing water this hot to maintain setpoint, but I haven't done the math. You are correct about quarter-sawn wood being considered generally better over radiant tubing. This is a rule of thumb thing though, I don't know the science behind it.

Kastein, I agree with the far right layout, both for cost of parts, ease of routing, and correct heat dispersion in the room.

TacoHavoc
Dec 31, 2007
It's taco-y and havoc-y...at the same time!

kastein posted:

Interesting. I never would have considered such a thing, I'll have to look into it.

You can run the numbers, but in NE and other regions where it gets cold and stays cold a heat pump setup is typically going to have a higher operating cost. You have to remember to derate the heating efficiency numbers to take into account the cold outside temps. A heat pumps efficiency and output drops dramatically as the outside temps get lower. You will use the electric backup heat a bunch.

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