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HVAC guys new system

timinpatiminpa Member Posts: 2,250 ✭✭✭✭✭
edited September 2011 in General Discussion
So I got a couple companies coming to give me estimates for a new system, A/C and heat. I currently have an oil fired boiler system, it's a honeywell about 13 years old. I also have a wood burning firplace upstairs and a wood stove downstairs that are good heat in pinch, but definately not going to be an only source of heat.A/C is currently 2 window units.

I have 3500 square feet including a full finished basment that we use daily. Split level raised ranch.

Because i'm very rural, there is no option for natural gas. I'm in PA so humidity in the summer and fairly cold winters are factors.

My thought is a heat pump with added heating system. Supported by electric baseboard heat in several rooms (kitchen, living room, 3 bedrooms, family room, and possibly the upstairs bathroom as it is approx. 140 square feet)

I like this set up cause it makes me all electric, and I plan to back it up with a generator out back either now or in the near future.

A few questions?

1. Does the set up I want seem like a good idea? if not why? what would you recoment to go with?

2. What would be a ballpark guess for cost, I realize its difficult to say, but for a good Brand system with everything new and complete including removing the old system.

Thanks ahead for any/all feedback Tim


  • HandLoadHandLoad Member Posts: 15,998
    edited November -1
    Plan on a BEEEEG Generator!
  • nordnord Member Posts: 6,106
    edited November -1
    Bear in mind that resistance heat is about the worst choice you could make should you lose electricity. A generator would have to have a huge capacity to handle the load and it's terribly inefficient.

    Think of it this way...

    Any internal combustion engine is only about 30% (+/-) efficient. The the generator head will soak up a further percentage as will line loss. In the end you'll be lucky to obtain 20% efficiency from a gallon of fuel.

    Conversely you can obtain an oil or propane fired furnace or boiler in the 90% efficiency range. Even with the associated fans or circulator pumps the electrical draw would be minimal. Since a genset could easily run on propane it might be more appropriate to heat at high efficiency and run a much smaller genset at low efficiency while using the same fuel.

    Heat pumps are merely air conditioners in reverse. If you install an earth loop and use the constant soil temp as your heat sink, this is an efficient method of heating and cooling as long as line power is available.

    But when line power fails and you need to go on temporary power the story totally changes. While the heat pump remains efficient, your method of powering it will not. You'll need enough fuel to last through an emergency. Look at a 1,000 gallon tank and think of the 800 gallons that will go up as wasted energy from a genset and you'll begin to understand what I'm sharing.

    If you do decide to go with a genset then it will almost certainly be a diesel unit. You'll need to calculate your entire possible load and add a considerable cushion for items requiring high starting loads such as compressors and the like. Given the resistance load you propose and the general needs of a household you're talking about a very serious genset... And it's going to be thirsty!
  • UNIVERSITY50UNIVERSITY50 Member Posts: 1,705 ✭✭✭✭✭
    edited November -1
    Wow! that will be a lot of $$ replacing everything to new type systems. Our friend just put in GeoThermal last fall and could not be happier with the cooling & heating.
  • nordnord Member Posts: 6,106
    edited November -1
    But the question is running in an emergency! Resistance heat is 100% efficient from the standpoint of heat produced per KwH input. Geo-Thermal is even better as you're using "free" heat and really only running a compressor.

    But... This is predicated on commercial electric rates. Home generation isn't nearly as affordable. Think of a 25KwH genset drinking say 4 gallons of diesel per hour. That's 100 gallons of diesel per day. At today's prices the cost is $400 per 24 hours and a 1,000 tank of fuel will stretch for just 10 days. Even at half the burn rate of 4 gph this is very expensive!

    Take that same amount of diesel and call it fuel oil. Burn it in a 90% efficient furnace or boiler and everything changes. Perhaps one could get away with a genset burning only a gallon of fuel an hour or less. Even in the dead of winter with constant calls for heat you could go a very long time on a 1,000 gallon tank of fuel. Even longer if you used a liquid cooled generator and tied its excess waste heat into your loop.

    All the same we're talking of a very expensive project and the need to purchase a large quantity of expensive potential energy that will have to be stored and maintained.

    In my humble opinion it would be best to maintain minimal conditions during an emergency. Enough heat to prevent freezing and perhaps a warm zone in a living area. Enough cooling to keep a bedroom comfortable. Power to maintain freezers and enough power to assure domestic water. Do this with an eye toward thermal efficiency. The more usable energy you can wring out of a gallon of fuel the longer you can maintain yourself and afford to do so.

    Do the math.
  • MIKE WISKEYMIKE WISKEY Member, Moderator Posts: 9,752 ******
    edited November -1
    I've got almost 40 yrs in HVAC contracting, the most cost effective heating and cooling is forced air with air to air heat pump. you will have to remove your current heating system. I'd suggest 2 separate mulit speed systems (1 up & 1 down) with a l.p. back-up generator. While the generator isn't very efficienct operateing you normaly only use it for short periods (power outage), so one about 15 kw should do. Without knowing your particulars you would be looking at about $20,000 for a GOOD system (you get what you pay for). furnace=97% afue, h.p./18-20 seer & 14 eer; personaly I'd recommend a Bryant "Evolution" system.
  • timinpatiminpa Member Posts: 2,250 ✭✭✭✭✭
    edited November -1
    thanks guys for the input, I'm going to look into the geothermal heat pumps. We bought the house a little over a year ago and plan to stay for the long haul, so I'll invest some up front and hope it pays off over the years. I will back up only the utility room with generator, that will keep me with water, heat, etc. in a power outage. As for cost, we'll see tuesday morning. Thanks again!
  • Mr. PerfectMr. Perfect Member, Moderator Posts: 63,836 ******
    edited November -1
    Nord is spot on.
    Some will die in hot pursuit
    And fiery auto crashes
    Some will die in hot pursuit
    While sifting through my ashes
    Some will fall in love with life
    And drink it from a fountain
    That is pouring like an avalanche
    Coming down the mountain
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