low temp in boiler

rayhamari

have 4 yr old weil mclein gold series boiler that will run at 120deg F when heating basemnt slab. will eventually satisfy t-stat at 63 set point. have 1 pump on 1" boiler loop and 1 pump circulating thru 1250 ft of 1/2 inch pex in floor. aquastat set at 185deg F. 15psi pressure, mixing valve set at 100deg F. basement walls are R25 ICF, ceiling is R19 glass, 2" foam under slab. if i close 4 of 5 loops in floor, boiler will slowly temp up to set point. 30-40 minutes. any ideas? slab is 32 X 40

STEVEusaPA

Are you protecting the boiler from those low return water temperatures?
5 loops, what are the lengths?
Slabs, radiant and deep setbacks aren't going to work.
Which type of circulator? Probably not big enough/enough head.

rayhamari

not sure how to protect from low return water. loops are 250ft each. boiler loop circulator came on furnace, grunfos ups15-58fc circulator to slab, if that helps. thinking circulator pumping more than boiler loop pump

rayhamari

boiler is 105,000 BTU NON-CONDENSING

EBEBRATT-Ed

@rayhamari

As @STEVEusaPA mentioned you can't run the radiant loops through the boiler without a mixing valve or something to protect the boiler. If you do you will be replacing the boiler within a year or two. Post some pictures or a drawing of how it's piped