new 2nd system for addition or increase size of existing system

Mitch_4

done a load calc? tying into the existing system with out a new trunk line will screw up the air delivery of the existing system (if it was done properly)

Spend the $$s and have a proper heat load done, rip out he whole she-bang, and get the right system. you'll be more comfortable. save more money (especially if the original system is suspect on the efficiency #s as you implied).

Get a pro to come in and consult. use the link here

timden

new 2nd system for addition or inc size of existing one

We have a 115yo 2story victorian home in denver that is 1900 sq feet and a cellar where a 2year old air ease 80% 90,000btu furnace sits with a 3.5ton ac 10 seer unit. The system was installed by a handyman and its efficiency is likely suspect but due to the clearance levels in the cellar and the inability to add new ducts in the home make altering the current 5inch ducts fairly limited. I have gotten several quotes on what to do with a 2story with basement addition ( 380 sqfeet on each floor of the addition). Some have suggested to put in a 5ton ac and 115,000btu 90%efficient unit while others have suggested to make a second zone using a 2ton or 2.5 ton ac unit 13 or14seer with a 60-80,000btu 90% two stage variable speed unit. The addition will contain most of the living space we will spend our time in and we will try to supply heat and ac to two bedrooms in the old part of the house (250sq feet for both of them) and ducts to cover half of a dining room and kitchen in the old part of the house (350sqfeet total). All of this would then use a completely new duct system and we would just use the old system at 62 degrees in winter and 78 degrees in the summer as those areas would not be used much- which systemt is better in the long run? It seems like the two zone system is being quoted cheaper right now- will it cost more in the future in energy?

jerry scharf_3

just a guess

Tim,

It's hard to be certain without looking at plans, but I would almost certainly not increase the size of the current system. If you say the duct sizes are suspect, the worst thing you can do is add more load to it.

One thing to watch out for in the layout you describe. You can run into some interesting problems when you have one area being heated ot cooled by two different systems on separate controls. I would see if it is at all possible to move those rooms completely to the new system.

With the trends for electric prices, I would sink the money for a better efficiency system on the A/C side. I figure CA is leading the way, and that soon enough other areas will be facing some of the same pricing for peak summer demand. The PUC passed a ruling that allows some number of days for the peak charge to be increased to $.85/KWh.

jerry

Steamhead

Have you considered

hydronic heat and a mini-duct A/C system? The latter could go in the attic, and the former wouldn't add bulky ducts to the basement. And the comfort and efficiency would be superior.