Replies

1. 
   Arsten | Aug 26, 1999 08:04pm | #1

   *
   approx. 22M. There are no frequencies with enough
   energy to cause internal heating at this distance.
   That would change if the material of the person's
   clothing was changed to any substance which
   absorbed strongly in the infrared, such as PET
   (Polyethylene Terepthalate), known as microfiber,
   dacron, polyester, etc. In that instance
   targeting would be facilitated by IR heating of
   the clothing, and as long as the signature
   frequency was 22M and with sufficient energy to
   trip the threshold setting, the device is
   launched.

   --

1. 
   Steve_Weeks | Aug 27, 1999 01:08am | #2

   *Arsten,If this is your answer to a question on the "wet operations" board, mistakenly placed on this one, I wonder how the heat pump answer will be received by your fellow coverts.

1. 
   Barry_Miller | Aug 27, 1999 01:10am | #3

   *Arsten,This is Fine Homebuilding, not Fine Homebombing.

1. 
   David_Thomas | Sep 03, 1999 11:47pm | #4

   *Wow, that targeting post was out of left field! Back on thread:A ton of refrigeration equals the melting of one ton of ice in 24 hours (one suspects this is a old unit, but it's still in use when sizing A/C units and their component parts). One ton = 12,000 BTU/hour.SEER = Seasonal Energy Efficiency Ratio = sum of cooling output divided by the sum of all electrical inputs. Through the magic of the heat cycle, these efficiencies are typically much greater than 1 (like in the range of 8 to 12) when in cooling mode. Usually these ratings are for cooling equipment. Make very sure the ratings you are going to use apply to heating mode.1 kilowatt-hour = 3413 BTU/hour - a handy conversion factor.-David

1. 
   tedd | Sep 30, 1999 02:03am | #5

   *Tell me boys, do them heat pumps need a pressure tank to hold al them BTU's ?Where in North America is a domestic heat pump going to pay back its capital and installation costs ? When the BTU's get up in the millions, we might as well build nuclear reactors in our back yards. If you have a free source of heat like a hot springs (something considerably hotter than the ambient temp of the earth), then maybe its cost effective to tap into it with a heat exchanger. Tilt ... am I missing a boat or two ?

2. 
   Ron_Schroeder | Sep 30, 1999 05:23pm | #6

   *Tedd,In some areas (like Florida) a heat pump is so far ahead of any thing else that I am suprised that furnaces are even sold. In other areas an more detailed comparison of install costs, fuel costs, maint. and life needs to be done. I have seen cases even in Canada where a heat pump was the most economical choice. I have also seen places where the install cost was so high that even with free electricity it would take 20 years to break even. They seem to be most cost effective where the house is well insulated and A/C is wanted and lest cost effective in poorly insulated houses in climates that need little A/C.And this is the SHORT answer.Ron

3. 
   tedd | Sep 30, 1999 06:29pm | #7

   *Ron ...Are the systems used in the south (cooling climate)combinig some kind of air cooling function other than the dehumidification of an Heat/Energy Recovery Ventilator ? Can you also say a little more about where these ar cost efective in the north (heating climate).tedd

4. 
   Ron_Schroeder | Oct 01, 1999 07:51pm | #8

   *Tedd,A heat pump is an air conditioner that can reverse its freon flow to also heat, so it performs both heating and A/C functions. A heat/energy recovery ventilator is only a heat exchanger not a heat pump.The economies of heat pumps (in the heating mode) depends upon there efficency at the operating climate, the cost of electricity and the cost of equipment and installation. A heat pump shouldn't cost more than about $600 more than an A/C unit (about $300 for the heat pump and about $300 for the air handler since there is no furnace to blow the air). Of course with an earth coupled heat pump, you also have the added cost of the ground loop. In my house I have an earth coupled heat pump and an oil fired boiler. With the costs of electricity (high) and oil (low) I use the heatpump for cooling only since it is more efficent and quieter than a conventional A/C unit and I heat with the baseboard and radiant oil system. The heat pump will easily heat the house but at a higher operating cost here (Long Island NY). In Columbus OH I would use the heat pump only because of the lower electric rates even tho it is colder there.RonRon

5. 
   The_Tennis_Court_Builder_...on_t | Oct 03, 1999 11:00pm | #9

   *Ron,My electric backup heat pump is the worst heat system in every regard I can think of. Yes I do get a/c in the summer but that it unbelievably expensive too. I think fossil fuel with superinsulation, thermal mass and some passive solar along with some Fred L. sealing ideas and a little Gene Leger mixed in is the way I'm headed with the update of my place....I tell b allmy clients that heat pumps are a total joke and marketing "big business" sell job to the masses.near the stream,aj

6. 
   Ron_Schroeder | Oct 04, 1999 04:43pm | #10

   *Jack,Just out of curiosity what are the fuel costs in your area? I am suspecting that propane or oil may be the lowest cost fuel for you. Electricity may only be the best choice with an earth coupled heat pump. Some of the worst comfort heating systems that I have ever seen were heat pumps but they were improperly sized or improperly ducted. The most common installation fault is too much airflow followed by wrong duct placement. The airflow should be about 400CFM per ton. More than that will feel drafty and cool. I have seen other instalations that were very comfortable but another choice would have been more cost effective.I am a big fan of superinsulation and haven't built a wall in a heated structure under R25 since 1974. Even the shed behind my garage is a true R 25.With superinsulation, as we both know, since the amout of energy need for heating can be so small, electric resistance heat can often be the least expensive when the equipment and fuel costs are added togeather. It doesn't cost much to put in a dozen feet of electric baseboard and it may only need to run a few hours a year.Ron

7. 
   The_Tennis_Court_Builder_...on_t | Oct 16, 1999 04:57am | #11

   *right on ron...

2. 
   kirk_ | Oct 16, 1999 04:57am | #12

   *
   If the code says my home needs a certain BTU/hr furnace, what is the equivalent heat pump rating to satisfy this? I see them advertised by "tons" or SEER ratings. What is all this in terms of kilowatts? Thanks in advance for your help. Kirk