DIY Home Improvement Forum banner
1 - 9 of 9 Posts

· Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I own a 2400 sq foot house in the Mid-Hudson Valley of NY. Winters vary greatly from almost none to lots of snow and down to 10 below (Rarely that cold any more. Twenty years ago I saw 30 below.)

We built the house in 1990 with energy efficiency in mind. When our AC unit was installed the installer said it should last around 12 years. It’s older than that now. We have a blown hot air propane furnace, also fairly old, and a relatively new propane hot water heater. During the summer our electric costs are high because of the AC. I installed solar panels (on the ground, not roof) a few years back. That was supposed to decrease our electric costs by around 70% but I don’t think it has.

Can a heat pump replace both the furnace and AC? Does it make sense to replace them with a heat pump? I’d like a ballpark figure what it might cost and payback in decreased electric and propane costs.
Thanks,
Al
 

· Registered
Joined
·
17,845 Posts
What do you pay for electricity and propane?

HP is normally cheaper to run than propane furnace.

The problem is, the typical heatpump in new york state without fossil fuel backup needs a lot of electric backup and your electric bills would skyrocket if you pulled the plug on propane entirely.

Unless you have cheap electricity, go dual fuel, a heatpump backed up by propane.

You can buy a propane furnace and get a heatpump instead of a/c, the furnace takes over when it is too cold for the heatpump to keep up or propane is cheaper, whichever happens first. (heatpump efficiency and capacity drop as it gets colder outside)

Another option - heatpump, air handler, and ahigh efficiency propane water heater designed for heating connected to a hydronic coil in the air handler.

The latter allows you to supplement the heatpump with propane heat instead of shut it down and switch to 100% propane. Often, a heatpump is still provides more economic heat than propane and oil when it can't keep up.

Now, there are fancy heatpumps that maintain full capacity down to very low temps - in which case you can pull the plug on propane, but they're super expensive and loaded with electronics.
 

· Red Seal Electrician
Joined
·
1,595 Posts
I have a ~10yo York heatpump in an older home. It replaced a forced-air oil furnace, and uses the existing ducting.

Any savings to be experienced with heating are when the outside temps are below room temperature, but above freezing.

When the unit can't keep up due to demand, and cooler outdoor temps, it kicks over to electric (toaster coil) or gas backup - and you pay. In winter I'll burn wood instead, and run the heatpump on fan-only to spread the heat out.
 

· Registered
Joined
·
17,845 Posts
^They don't switch over to electric entirely below freezing when set up properly, they continue heating and the electric is used to supplement. The bills can still get really high supplementing with straight electric.

Only if the backup is a fossil fuel furnace upstream of the coil is it necessary to shut the heatpump entirely.

The thermal balance point is not always freezing - it depends on heat loss vs capacity of the particular heatpump.

Every application is different and it takes doing calculations to determine i getting a hp is a good idea.
 

· Red Seal Electrician
Joined
·
1,595 Posts
^They don't switch over to electric entirely below freezing when set up properly, they continue heating and the electric is used to supplement. The bills can still get really high supplementing with straight electric.

Only if the backup is a fossil fuel furnace upstream of the coil is it necessary to shut the heatpump entirely.

The thermal balance point is not always freezing - it depends on heat loss vs capacity of the particular heatpump.
Agreed - freezing is just a ballpark. Model/technology, sizing, and how 'tight' your house is are factors. Mine won't 'pump heat' much below 5-8*C.

About the only time I let the 10kW coil come on is if nobody's home during the wintertime.
 

· Registered
Joined
·
2 Posts
Discussion Starter · #6 ·
We should be able to keep the propane furnace for many years. That would be our backup. Basically I'd be replacing the AC. That should get rid of a good bit of our electric bill and it should help with the heat. If we have to replace the AC unit that would probably cost several thousands of dollars.

Thanks for all your replies,
Alan
 

· Registered
Joined
·
17,845 Posts
A load calc should be done to determine balance point of different heatpump sizes.

There's a lot that goes into a dual fuel application, much more sensitive to selection and proper installation than straight a/c.

I do think it's worth getting a heatpump instead of a/c when the heating fuel is propane - saves in the milder weather.

Just don't assume a new unit will cure high cooling bills - bad ductwork, poor attic insulation, etc can contribute.
 

· Registered
Joined
·
7,423 Posts
Can a heat pump replace both the furnace and AC? Does it make sense to replace them with a heat pump?
l
I wouldn't install a conventional heat pump in your climate.
Geothermal, yes....but that is big bucks.

Heat pump mfg. claim that heat pumps can work efficiently down to 0°.
I haven't seen any that do.

Stick with fossil fuel heat.
 

· Registered
Joined
·
17,845 Posts
I wouldn't install a conventional heat pump in your climate.
Geothermal, yes....but that is big bucks.

Heat pump mfg. claim that heat pumps can work efficiently down to 0°.
I haven't seen any that do.

Stick with fossil fuel heat.
Conventional heatpumps are installed well north of new york state. Capacity slowly drops off as it gets colder out but they can supply heat with a cop of 2 or higher well below freezing - still better than going straight electric.


If an a/c is being installed anyway, it can be well worth the extra money for a basic heatpump instead on oil or propane in new york.

There are many hours during the heating season above the typical thermal balance point in a northern climate. and one can save compared to propane which would get kept for backup.

Propane is very costly.

-------------------------

Yes, there are actually models which can maintain full capacity well in cold weather, the best ones can do it down to 0F or below, they're specifically engineered to do so, use inverter compressor.

The mitsubishi zuba is one of them. Lots of $$$ and loaded with electronics.
 
1 - 9 of 9 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top