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Posted by GWR on December 17, 2005 at 00:14:13:
My home, built in 1925, is approximately 3000 square feet, located near Philadelphia. The heating system is gas with cast iron radiators and a total EDR of 1055. A 40 year old Bryant 300,000 BTUH water boiler was replaced with a 305,000 BTUH Weil-Mclain PFG-6 model (80% AFUE) about six years ago. Since then about half of the house walls have been insulated to R11 and the attic upgraded to R30. In the spring the steel casement single pane windows will be replaced with Marvin double pane argon Low-E types. The chimney has been lined and an efficient damping system installed. Even the garage door is now insulated to R9. Based on a calculation using HVACalc 4.0 software (0 outside 74 inside) the resultant new heat loss will be about 100,000 BTUH. This would translate on a mid-efficiency unit with input rated at 140 to 150,000BTUH.
The existing boiler will be tremendously oversized!
Is it worth replacing a six year old system, over 100% oversized, to achieve efficiency or is it money wasted? Will the addition of outdoor reset controls and a damper be enough or are the greatest savings realized with both these items and a new boiler?
Note that since 12/01/04, gas prices in my area have been raised by 42%!!! Before the increases my Winter gas bills were in the $600/month range. I am looking for cost effective savings wherever possible.