kc

where do you live?

what is your electric rate/kwh?

what is your cost of nat gas/therm?

post back.

I will explain this to you.

TD

I live in Kansas City Metro area basically the best place in the country to use Heat Pumps but Gas is cheap here too.

Rates if you have a heat pump are $0.07779/kWh from May 15- Sept 15 and $0.04556/kWh the rest of the year.

No heat pump $0.07779/kWh May 15-Sept 15 and $0.07026/kWh rest of the year.

Gas $6.59 per Mcf.

Average temp I think is around 58. Temps range from -10 - 100+

So my gas is $.659 per therm

In your area, your gas is dirt cheap. Here in Indy, we're twice that! But your electricity is cheap as well.

I'd bet much of your winter runs around freezing. Using your rates, a good pump at 32 provides 100,000 BTUs for 43 cents. If you had a 95% furnace, it would be 68 cents.

For me it would be 66 cents HP vs 1.33 95% gas. That's why my pump runs as much as possible.

For cooling, SEER is SEER.

Absolute system efficiency is not the issue.

The POCO charges by the kW-hr, not by the tons of coal used to generate the kW-hr. The losses are rolled into the electric rate you finally pay.

Decide what system has the lowest cost for your location based on the cost of gas per them and electricity per kW-hr.

Efficiency is the amount of energy delivered as heat compared to the energy consumed. Cost to operate is that times the cost of that consumed energy.
Electric resistance heat is 100% efficient but rarely the cheapest way to go because it's more expensive than gas/oil.

kcboom wrote: >>Most of the US electricity is generated by Coal fired boilers. A coal fired boiler has max efficiency rating of 80%. A large majority of US boilers are using lower BTU coal then what they were built for, decreasing the efficiency even more.The efficiency of coal->electricity conversion is around 40% absolute maximum, usually a bit less than this thanks to Mr Carnot and his laws of heat engines.

If you want to compare CO2 emissions for a given amount of heat delivered of say gas and a heatpump you have to know what your electrical generation mix is in the first place and how many kg of CO2 are emitted for each kWh of power delivered to your home and then factor in the COP of the heatpump. If you're interested in the cost of each kWh of heat delivered, you can do a similar calculation, but you only need to know the cost of each kWh delivered (and then, again, factor in the COP of your heatpump versus your furnace after accounting for the output efficiency).

Electric resistance heat is indeed 100% efficient, but that same electricity could give you 3x the delivered heat or more if it is used to power a heatpump - this is why heatpumps are touted as being "efficient". Really, all you need to know is the $ cost for each kWh of heat that makes it into your home - that's probably the most important metric for comparing systems in an apples-to-apples way (assuming you're not concerned with CO2 or anything else).

Paul.

The reason being, that resistive heat uses the electricity to make heat directly, whereas the heat pump moves heat from one place to another, and is not restricted to the amount of heat available from that consumption of electricity.

In other words, it extracts heat from the outdoors, concentrates it and releases it indoors. So it sounds a little like vacuum energy (getting more energy out than you put in, from an undetermined source) but it's just got a wider field. That thousand kilowatt hours of resistive heat, say produced 1000 btus, but the heat pump, using that same thousand kw/h scrounged 3000 btus from outside.

Heat pumps are less effective the colder it gets, but newer ones can work in much colder temperatures, so your gas backup heat would run less.