Workshop with in-slab hydronic - temp control

What's your tubing size, spacing and length? 110* SWT seems high for a shop.

My shop is 48’x32’ with a 5” slab. There are three loops of 3/4” tubing spaced 12” and roughly centered in the slab. So, each loop is about 500’ long including the runs back to the manifold. The contractor told me the loops were 400’ each, but when I looked at the few pictures I got before the slab was poured, it appears to me that this number is low and the square footage and tube spacing suggests that also. I wish 4 loops had been used, but the length is still within, barely, the maximum length recommended for 3/4” pex. The boiler has never even approached 110 SWT so I could easily set the upper limit back. In operation, I have never seen SWT higher than 82. I had hoped for a deltaT of around 10 degrees, but given the loop lengths the contractor installed, the actual deltaT runs closer to 20 degrees even though I have a Taco 0011 driving the three loops to handle the high head of loops of this length. The RWT is typically 62 or slightly higher. I wish TT had a display that showed the firing rate, but I assume the little cc50s is running flat out most times it fires given the 20 deltaT and the fact that the boiler temp never approaches the limit. I think the highest boiler temp reading I have seen is 92 which seems odd to me as the temp at the exit from the boiler has never exceeded 84 and this is within 2 degrees of the inlet temperature of the pex manifold. I think any difference there is just thermometer error as there is only about 4’ of 1” copper pipe between the boiler supply and the manifold inlet. I am not sure where internally the cc50s is taking its temperature measurement, but it consistently reads 6-8 degrees more than the temperature gauge I placed at the outlet of the boiler.