Heat Pump ?'s

[PandaBear]

One of my coworkers' friend pulled out a functional and reliable HVAC and installed an NG heater + central AC in its place. The reasons is in the winter NG is still much cheaper than HVAC as electricity is because electricity is way more expensive than NG, and is charged at a tiered rate, so getting rid of the higher tier load by HVAC and moving it to the lower tier NG rate is a good deal.

 

[sleddriver]

Originally Posted By: NormanBuntz
I've had various brands of heat pumps for 37 years. Basically they are a compromise. They don't heat as efficiently as a furnace, and they don't cool as efficiently as a central air conditioner. Heat pumps only heat OK down to about 40 degrees. Above 95 degrees, forget about a heat pump really doing the job. You're lucky if you can cool the house to 75 degrees if it's 95 outside.
Not my experience at all. Summer solar heat indexes here are regularly 130°F. Plus, my HP must deal with a significant latent heat load. Lastly, mine is 26yrs old and barely a SEER 13, if that.

Sounds like you live in a very leaky, poorly insulated house.

 

[SHOZ]

Most heat pumps around me in the Midwest US are going in as ground water assisted heat pumps. The vertical loops work better than the horizontal. But the horizontal is cheaper to install. My electric coop loves them and will offer you a low interest loan to install and monthly payments with your bill.

 

[NormanBuntz]

Originally Posted By: sleddriver
Originally Posted By: NormanBuntz
I've had various brands of heat pumps for 37 years. Basically they are a compromise. They don't heat as efficiently as a furnace, and they don't cool as efficiently as a central air conditioner. Heat pumps only heat OK down to about 40 degrees. Above 95 degrees, forget about a heat pump really doing the job. You're lucky if you can cool the house to 75 degrees if it's 95 outside.
Not my experience at all. Summer solar heat indexes here are regularly 130°F. Plus, my HP must deal with a significant latent heat load. Lastly, mine is 26yrs old and barely a SEER 13, if that.

Sounds like you live in a very leaky, poorly insulated house.


Sorry, Bub. My house is 13 years old and has a High Energy Efficiency rating by Dominion Power. If you think a heat pump can make a house feel comfy at 25 degrees, then you've never had natural gas heat.

 

[sleddriver]

Originally Posted By: NormanBuntz
Originally Posted By: sleddriver
Originally Posted By: NormanBuntz
I've had various brands of heat pumps for 37 years. Basically they are a compromise. They don't heat as efficiently as a furnace, and they don't cool as efficiently as a central air conditioner. Heat pumps only heat OK down to about 40 degrees. Above 95 degrees, forget about a heat pump really doing the job. You're lucky if you can cool the house to 75 degrees if it's 95 outside.
Not my experience at all. Summer solar heat indexes here are regularly 130°F. Plus, my HP must deal with a significant latent heat load. Lastly, mine is 26yrs old and barely a SEER 13, if that.

Sounds like you live in a very leaky, poorly insulated house.


Sorry, Bub. My house is 13 years old and has a High Energy Efficiency rating by Dominion Power. If you think a heat pump can make a house feel comfy at 25 degrees, then you've never had natural gas heat.

Yo Bub...notice my reply only focused on your statement "above 95°, forget about a HP really.....". If yours doesn't cool any better than what you claimed, then something's FUBAR.

Simple thermodynamics tells us a HP won't make your house "comfy" when it's 25°F outside. Very, very rare to see those temps where I live however.

 

[Cujet]

Just a quick note. It's not the word Efficiency that we use to describe heat pump energy use.

It's COP or "coefficient of performance" . There is a very good reason for this. Resistance heating is almost exactly 100% efficient. That resistance element takes 100% of the electrical energy and converts it to heat. 1KWH converts to 3412 BTU

A heat pump can have a COP of 3 under certain conditions. In other words, it produces 3x more BTU per KWH than a resistance element. So under some conditions 1KWH can make 10,000+ BTU

To make matters more complicated, it's actually possible, in modern powerplants to convert 50% of natural gas energy to electricity. 7000BTU of nat gas makes 1KWH. Which with a heat pump, that 1KWH can produce 10,000 BTU!

If we used "efficiency" the above situation would be over 100% efficient.

I am, by no means claiming that a heat pump is more effective than direct natural gas heat. Clearly, a heat pump struggles in cold weather. And duct temperature is often only a few degrees over room temperature. People tend to find this uncomfortable when they want instant heat.

 

[DBMaster]

This is why a lot of areas in Florida requirement supplemental electric heaters (heat strips) to be installed in the air handlers of new heat pump installations. Heat strips are one of the commodities I manager for my employer. I asked an engineer why I have been seeing the sales if heat strips literally explode over the past few years. Apparently, a lot of new subdivisions are being built without gas lines.

 

[DBMaster]

My typing skills are going out the window. Areas in Florida REQUIRE (by code). I MANAGE for my employer. I really need to proofread my posts better.