Fine, learn me heat pumps

To drag this out of the rant thread and into a full conversation, I'm making a thread. 

I have gone looking for literature and just gotten confused.

I was under the impression a "heat pump" was similar to say a turbo, in that some central air systems come built with them, some can have one added on, and some just  can't.

So I went digging and researching to not sound like a total idiot when I call my HVAC friend or the company whose done the HVAC work at my house for the previous owners.

I'm now more confused than when I started.

It looks like "heat pump" and "air conditioner" are, and can, be used completely interchangeably EXCEPT when referring to two entirely different things. 

I have a Trane XB13. Actually trane xb13 4ttb3036b1000ba.

Tranes website and "user manual" had this packaged under AC and heat pump, the dealer paperwork has it just listed as an AC. (Bunch of people on OLD hvac forums say they wouldn't sell the XB13 when it was new because it was a cheap POS).

I'm doing some testing right now but so far results are inconclusive.

I switched the thermostat to heat, and set it for s couple degrees warmer than the house currently is. After 45 minutes or so I'm only seeing half a degree temperate difference between a wall and a duct.

ANYWAY

My questions are:

1 is there something like an aftermarket add-on heat pump that could be added to the system? If so, any ideas what that might run?

2, if not, are there any good quality 3-3.5 ton units with heat pumps I should be looking for and is it going to cost me one kidney or both to swap them?

3 would it be a better use of my extremely limited dollars to replace the 25 year old 80% efficient oil furnace with something more modern and more efficient? Or maybe to swap to an LPG boiler and get a tank installed?

Using last winter as a guide, I'm expecting to spend $4000-5500 to heat the house this winter with my oil boiler and the wall radiant heat. That's not only beyond my ability to afford, but berkeleying Highway robbery as far as I'm concerned. Yes, I'm still hung up on the pellet stove at the last house costing me under $700 to heat all winter. 

I already have the furnace set to 65 and am getting complaints because "it's freezing", despite my repeated "layer up buttercup" mantra. 

So what do I need to know about heat pumps, furnace replacements, whatever to get my heating bill to a more reasonable amount this year and in the future? And why the hell do all the manufacturers hide their system prices?

I don't think I've ever seen an add on Heat Pump. 

A heat pump has a reversing valve to allow the system to pump in the other direction and the entire system is designed for that. To convert an a/c to a heat pump would probably cost more than a new unit. 

If I was in the market for a new system, I'd probably be looking at Goodman systems. 

I can't answer your specific questions, but I'm sure somebody will be along soon that can.

I can do the basic concept. A heat pump is essentially a fairly efficient AC unit that can be reversed. So operating one way it cools your home & when reversed it heats your home.  Problem is it is essentially extracting heat from the outside air to heat your home. This means when temperatures get down near freezing they become very inefficient heat sources and thus generally have a second stage heater such as an electric resistance heater which is not much more efficient at producing heat.  So in colder locales, they might only be used for AC.

In reply to secretariata (Forum Supporter) :

Heat pumps are usually good down to the low 30s and high 20s. Some of the newer high-efficiency units are good into the teens. 

They hide prices to make money, duh. Most people don't know the actual cost (retail or wholesale) and just eat it because things always go out at the coldest/warmest and anything to get rolling is shelled out. 

I looked into the heat pump option for my system and it's an additional control board and the rest of the system can handle it. It will depend a LOT on the unit you have. Make friends with an HVAC tech that does this on the side, likely they will tell you straight. Helps if you can fix his car.

secretariata (Forum Supporter) said:

I can't answer your specific questions, but I'm sure somebody will be along soon that can.

I can do the basic concept. A heat pump is essentially a fairly efficient AC unit that can be reversed. So operating one way it cools your home & when reversed it heats your home.  Problem is it is essentially extracting heat from the outside air to heat your home. This means when temperatures get down near freezing they become very inefficient heat sources and thus generally have a second stage heater such as an electric resistance heater which is not much more efficient at producing heat.  So in colder locales, they might only be used for AC.

I'm good with it not working or switching to a backup system when it gets below freezing. 

Right now I'm burning $3/gallon oil on days where a heat pump would be just fine, which I'd really rather not be doing. 

In reply to RevRico :

What I know...not claiming to be an expert... 

I bought my house 10 years ago.  It is an all electric house.  It has heat pumps; two.  One does the living/kitchen area.  The other, on a separate thermostat, does the sleeping areas of this 2500 sq ft ranch.  Said another way, one does the south side of the house, the other does the north side of the house.  Outside I have two large units that look like AC units. In my crawl space (more like a 4ft tall unfinished basement) I have two big boxes that are plumbed to all the duct work.  I think they are called air handlers.  I believe that within these units there is also what my thermostat calls emergency heat.  This is the supplemental heat for when the outside is reallllly cold.  

Should be noted that I live just one mile from Lake Erie at the top of Ohio.  This puts me in a similar if not slightly colder climate than your Pittsburg-ish local.  

At the closing of my house they have you sign a lot of paper.  One paper was, "and here's your one year home warranty that the seller paid for."  I figured it wasn't worth the paper it is printed on.  Sure enough, the first night we spent in the house (about 30 days after taking possession) the one unit stopped delivering AC.  The home warranty replaced the outside unit to the tune of $1800 and no expense to me.  About 6 months later, or the first night using heat, the remaining old unit quit supplying heat.  That outside unit too was replaced by warranty for $1800.  What I have are Goodman units.  I have done nothing to them in those 10 years.  

I have heard (and it seems true) that the air coming out of the register of a heat pump'ed house is colder than the air coming out of the traditional furnace heated house.  I have been told that heatpump houses don't really like the heat turned down during the day and the cranked back up when you return home.  This is because the lower register temp makes the house hard to quickly raise the temp.  Keeping the themometer at a steady temp seems to work best.  We are not cold in the house and we keep it at 69 degrees.  The downside is my 1973 home is not that well insulated and the whole back of my house is glass.  In our worst winter month my electric bill can be $400 but that is also my sole utility (no gas bill too.)  I really need more attic insulation and really should get that done.  

The only user input required of me is I have to set the thermostat to AC or Heat and a degree setting.  If set to heat, the supplemental heat (emergency heat) kicks on by itself, requiring no input.