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Posted by Joe Brix on October 13, 2004 at 10:40:29:
In Reply to: Condensation in the boiler posted by PB on October 12, 2004 at 19:45:14:
The problem with such a low water temp is that your return water is probably below 120°, which may induce condensation in the boiler shortening it's life and increase soot build-up. Also an oversized boiler will short cycle even more since it can heat the water so quickly to a lower water temp. A trick used in radiant heating systems is installing an indirect water heater as a buffer tank wth primary/secondary piping. You allow the boiler to heat the tank to 160-180° degrees then a secondary loop feeds off the tank to the rads. The heating loop will not be as warm as the tank. The boiler gets to fire at a higher temp and cycle less frequently as the heating loop will take a while to suck the BTU's out of the large water mass in the insulated tank. You may want to save space replacing your current water heater by getting an external tankless water heater. This tank has a copper coil for the domestic hot water flow inside a tank full of boiler water (20 gal. +). This tank will now produce your hot water and become a 20 gal buffer (primamry loop) to the heating loop (secondary loop). Checkout www.ergomax.com, www.thermo2000.com, and www.dunkirk.com (artesin WH) and www.tfi-everhot.com
Here's the perfect design link:
http://www.pmmag.com/pm/cda/articleinformation/features/bnp__features__item/0,,78589,00+en-uss_01dbc.html