travelover
Give me a museum and I'll fill it. (Picasso) Give me a forum ...
- Joined
- Mar 31, 2007
- Messages
- 14,328
Here is my situation. I have a 40 year old 200,000 Btu (input) gas furnace that works fine, except is only about 60% efficient. My house loses about 32,000 BTU / hour at 5 degrees F. I’m wondering if I can improve the furnace's efficiency or if I should just quit worrying about it until the furnace dies.
A couple of possibilities to improve the efficiency are a flue vent damper and de-rating the furnace. I’m looking for some quantification of the effectiveness or possibility of these strategies. According to the Department of Energy web site:
EERE Consumer's Guide: Gas-Fired Boilers and Furnaces
Anybody out there have any experience with either of these two options?
P.S. The payback on a high efficiency furnace is at least 10 years, more if you include the lost opportunity of investing the money, so I’m passing on that for now.
Thanks for any thoughts on this subject
A couple of possibilities to improve the efficiency are a flue vent damper and de-rating the furnace. I’m looking for some quantification of the effectiveness or possibility of these strategies. According to the Department of Energy web site:
EERE Consumer's Guide: Gas-Fired Boilers and Furnaces
Vent dampers
The most common retrofit is the addition of a vent (or flue) damper. A vent damper prevents chimney losses by closing off a boiler's vent when the boiler isn't firing. Steam boilers benefit from vent dampers more than hot-water boilers, and bigger boilers benefit more than smaller ones. Vent dampers, however, may not be cost effective with properly sized, newer furnace models.
In researching the internet, I haven’t been able to find any quantification of the efficiency savings for a flue damper (not even a good range) and I’ve found no one that has de-rated a furnace successfully, as alluded to in the DOE article.Derating gas burners
Many boilers and furnaces in today's homes are oversized, particularly if you've upgraded the energy efficiency of your home. It is sometimes possible to reduce the heating capacity of your gas boiler or furnace to make it operate more efficiently by reducing the size of the gas burner orifice, and possibly also the baffles. This is a difficult process that should only be performed by a qualified technician, and in some cases, it could violate local building codes and void manufacturer's warranties. If allowed, though, the modifications should cost less than $100 and can save up to 15% of your fuel costs.
Anybody out there have any experience with either of these two options?
P.S. The payback on a high efficiency furnace is at least 10 years, more if you include the lost opportunity of investing the money, so I’m passing on that for now.
Thanks for any thoughts on this subject