boiler short cycles & venting/gas supply question
Posted by Herb Tate on April 11, 2004 at 23:54:35:
I bought a 2900 sq ft home at 7100 ft elevation in the Lake Tahoe basin. It was built and inspected in 1996 then again in December 1999 when I bought it. The boiler for 3 zone hydronic heating is a Teledyne-Laars JVH160NCSI, derated for elevation of 5000 to 8000 ft with #47 orifice. The main burner turns on & off two cycles per minute !!! After running awhile, the temperature in is 115F with temp out at 140F at 20psi per factory supplied gauges. That is less than the 30 degree differential maximum. The temp differential when starting from cold is a bit over 30F. Thermostat anticipator is set at 1.0. Circulation pump is a Grundfos 15-42F (only 85 watts) with copper pipe slightly over 1 inch O.D. reduced via manifolds to 3/4 inch plastic tubing to the floors. Installation and Operating Instructions (document 1080C) suggest increasing hi limit switch to at least 20 degrees but does not indicate how! Can you help, please? __________

Instructions say gas pipe should be 1". Only 3/4" is installed. Venting requirement is 40 sq in at ceiling and 40 sq in at floor. There is only a 6 inch dia. vent at ceiling and a 6 inch dia. vent at floor!! The boiler is in a closed closet with a 75,000 BTU hot water heater. Are these conditions acceptable at 7100 ft elevation?________

This home was inspected Dec 1999 by a very expensive inspector that should have caught these things, I think. What do you suggest I modify if these conditions are as inadequate as they seem?________

Thank you,
Herb


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