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hikerjohnson · 07-31-13, 11:28 AM

The vacuum pump and the micron gauge are definitely the two biggest $$ purchases, and I am holding out for a little overtime and good ebay timing. There is no trusting bourdon tubes at the extremes of their scales.

I have not seen that manual in person, but i did find THIS!

The engineer said he generally used 3/4" for slinky loops, but at the 800 foot length, it can be a toss-up between 3/4" and 1". The deciding factor is head vs. flow (which must be fast enough to be turbulent) for the system pump. Basically, is it cheaper to purchase a higher-head, lower flow pump, or a lower-head, higher flow pump? Also, the heat exchanger plays into the decision, as it must not have too much head loss at the increased flow you would need for 1" lines. He uses packaged heat pumps, of course, so his exchanger choices are more limited than a DIY-er.

I'm on my way to the library this evening to get my shiny new library card and put in a request for the two IGSHPA manuals. Thank you for mentioning this possibility, in the internet age, I forget that the library exists as a resource most of the time.

I didn't realize it would be so difficult to get to 140, and I have been provisionally sizing equipment based on those numbers. I have just found a Mollier diagram for propane, and I am going to look at it over the next day or so to get an idea of mass flow and compressor requirements to design a theoretical 140F system. Who knows, it may be theoretically feasible but too technically difficult. Isn't digging into the unknown FUN?!

Good luck on your flooring project, I am watching it closely. I just refloored my upstairs, and the downstairs must follow in a couple of years, and I'd love to do radiant, but like you, I have found all the commercially available heatboards to be beyond absurd in price. Sam with insulation, the house is OK for now, but when it comes time to do siding, I plan to out-sulate with foam board beneath the new siding, and really button the house up tight. All in good time, no?

07-31-13, 11:28 AM	#1537
hikerjohnson Submarine Renovator Join Date: Jul 2013 Location: Southern Maine Posts: 35 Thanks: 4 Thanked 5 Times in 5 Posts	The vacuum pump and the micron gauge are definitely the two biggest $$ purchases, and I am holding out for a little overtime and good ebay timing. There is no trusting bourdon tubes at the extremes of their scales. I have not seen that manual in person, but i did find THIS! The engineer said he generally used 3/4" for slinky loops, but at the 800 foot length, it can be a toss-up between 3/4" and 1". The deciding factor is head vs. flow (which must be fast enough to be turbulent) for the system pump. Basically, is it cheaper to purchase a higher-head, lower flow pump, or a lower-head, higher flow pump? Also, the heat exchanger plays into the decision, as it must not have too much head loss at the increased flow you would need for 1" lines. He uses packaged heat pumps, of course, so his exchanger choices are more limited than a DIY-er. I'm on my way to the library this evening to get my shiny new library card and put in a request for the two IGSHPA manuals. Thank you for mentioning this possibility, in the internet age, I forget that the library exists as a resource most of the time. I didn't realize it would be so difficult to get to 140, and I have been provisionally sizing equipment based on those numbers. I have just found a Mollier diagram for propane, and I am going to look at it over the next day or so to get an idea of mass flow and compressor requirements to design a theoretical 140F system. Who knows, it may be theoretically feasible but too technically difficult. Isn't digging into the unknown FUN?! Good luck on your flooring project, I am watching it closely. I just refloored my upstairs, and the downstairs must follow in a couple of years, and I'd love to do radiant, but like you, I have found all the commercially available heatboards to be beyond absurd in price. Sam with insulation, the house is OK for now, but when it comes time to do siding, I plan to out-sulate with foam board beneath the new siding, and really button the house up tight. All in good time, no?