[Isaac Zachary]

Originally Posted by JSH

$5,000 to $7,000 sounds about right for a new NG furnace. My parents just replaced theirs and it was about $10,000 installed for a 97% efficient furnace for their 1000 sq ft home

Do they live in a mobile or modular home? One HVAC technician I talked to said that the units for mobile or modular homes are actually more expensive than the ones for traditional homes.

What was the BTU of theirs?

Originally Posted by JSH

You would likely spend a similar amount for a heat pump that would go in the same space.

Yes. Interestingly, I can find forced air heat pumps that are designed to replace a mobile home furnace. They are around $4,500 and up for just the unit itself, and apparently come precharged with refrigerant. I'm not sure how much other stuff I'd need if I were to DIY.

Originally Posted by JSH

How large are the temperature swings in your home. You said you turn off the heat at night - how cold does it get. What is the temp you heat your home to during the day when you are there?

Heat pumps can vary temperature fine but they are slower to heat up a cold room than a gas furnace because for a ducted system a furnace puts out air at 150F to 160F while a heat pump is 105 - 115F

Not that it has to be this way, but what we've done is this:

• 45 °F at night while we sleep. We used to go down to 40 °F but then the pipes would occasionally freeze. Unless it's below 0 °F outside, the house usually never actually gets that cold inside.
• Then up to 65 °F an hour or two before we wake up. If it's well below 0 °F then the house will have reached 45 °F and takes a couple hours to get back up to 65 °F.
• Less importantly, we turn it back down to 45 °F when we're out of the house. Usually, it doesn't drop down below 55 °F or so during the day.
• Occasionally we bump it up to as much as 68 °F if we're just hanging out on a holiday or if someone is sick.

Electric rates are the same regardless of time of day or day of week.

Originally Posted by JSH

We are shifting our temperature a max of 10 F which works fine. If you are heating from 45F in the morning to 65 - 70F and then turning off the heat again when you go to work then on again at night when you are home I doubt a heat pump will work well for you.

But we could go to 55 °F to 65 °F instead of down to 45 °F. As far as comfort is concerned, even 60 °F to 65 °F would be fine. Really, we use 45 °F because it's not uncomfortable and because it seems to save us money.

My heat pump is set on a program:

• Mon - Thur 62F at (9 pm), warm to 67 in the morning (4:30 am), drop to 65F at 6:00am, heat to 72F at 3:00 pm, then 65F at 5 pm.
• Friday we are home so it is 69 from 6 am to 3 pm
• Sat / Sunday it is 69 from 6am to 9 pm (no peak electrical rates on weekends)

Originally Posted by JSH

With a heat pump as a primary heat source you would also need back-up heat for at night when the outside temp drops below the heat pump rating. (assuming you heat at night) A small electric heater would do that.

That would be the question there. Last couple of nights have shown us that at 10 °F/nights and 35 °F/days outside a 1,500W heater isn't quite enough to keep the house warm at night, but it does warm up the house enough by mid morning, before noon. But in a worse case scenario a small electric heater would be more than enough to heat our room. The main thing would be keeping the pipes from freezing and figuring out how to eat breakfast in the cold.

Originally Posted by JSH

DIY you would likely need to go with a 36,000 BTU ductless in your kitchen / living room and then a smaller 24,000 BTU unit on the other end of the house in the master bedroom. That would likely cost as much as a furnace or singled ducted heat pump

A 4 ton 48,000 BTU forced air unit starts at around $4,500. I guess that would suffice. With dual systems I'm afraid the bathroom would be hard to keep heated without putting vents in the wall. Ducted heating also, inefficiently, spills heat to under the trailer which helps keep pipes from freezing.

Originally Posted by JSH

Realistically just replacing the furnace is likely your best bet in your climate.

Yeah. I'm afraid you're right.