Heat pump needing natural gas backup?

rumiatNovember 12, 2011

I am replacing an old oil furnace with a heat pump. One company that has given us a quote is strongly suggesting having a hybrid system which uses natural gas as a backup. They say heat pump will not suffice for us when the temperature is lower than around 30, and that the heat pump air is much 'cooler' coming out.

A second company is telling us a heat pump will suffice just fine, with the backup being electric heat coils in the handler.

Of course, the heat pump by itself is pricing out quite a bit cheaper than the hybrid system, and will not require us to bring in a NG line (which would be free, just some drilling from the street).

My question is, do we really need natural gas as a backup for those lower temperatures?

Some specifics: I live in North Carolina, and while we have had some cold winter recently, they are nothing like those in the north. The house is 2200 square feet, split-level.

Thank you for any advice on this.

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harlemhvacguy

what are your electric and gas rates? electric back up or natural gas will both work just fine as far as keeping you warm it is just a matter of what is more efficient to operate.

    Bookmark   November 13, 2011 at 11:59AM
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david_cary

NC is a big state. I am a broken record because I say this all the time. Asheville vs the coast are worlds apart. I live in Cary and have a hybrid system and a heat pump. The hybrid is better and worth it for a few reasons but not for saving money.

I have more area than you heated with a hybrid system and the annual savings is just about what the gas maintenance charge is (but I needed the gas for other things). Cheapest run cost is usually heat pump but I know plenty of people with outrageous bills that hate their heat pumps. The quality of the install and the tightness of the house and then the unit itself. All are factors. My winter electric is about $200 a month for Dec/Jan and down to $150 for Feb/Mar. Other use is probably $80 so $500 a year or so. Then about $200 in NG for 5000 sqft total. Not bad but I know people with $500 a month bills for 3000 sqft. Last winter my gas use was only $120 because it was so warm (despite a really cold spell for a week or so).

Just a climate comment - we have not had a cold winter in many years. Talk to the old timers, NC used to be much colder. I had a 18 year old palm tree in my last house and they never used to survive more than 5 because of the winters.

    Bookmark   November 14, 2011 at 5:36AM
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tigerdunes

rumiat

Agree with above post.

Since you are replacing oil heat, I do think you would be better satisfied with a dual fuel system-high eff heat pump paired with 80% eff two stg var speed gas furnace backup.

IMO

    Bookmark   November 14, 2011 at 8:47AM
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harlemhvacguy

I have some customers that like it 65 degrees in there house in the winter and some that like it 85 degrees. It depends a lot on which one of those you fall in too.

    Bookmark   November 14, 2011 at 11:49AM
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neohioheatpump

When you get gas you will be paying the monthly gas service fee. I'm not sure what it is near you, but here it is $20 per month. Thats $240 per year. That can buy a significant amount of electricity.

Heatpumps work good but if your house is leaky, not so much. Ofcourse your heatpump will struggle during the extra cold weeks even if your house isn't leaky.

Just some things to consider.

    Bookmark   November 14, 2011 at 11:50AM
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ionized_gw

One thing that could tip the balance, obviously, is that if you bring in gas, switching to a gas water heater could save you money and eat up the monthly fee in the summer. The cost for the change-over could be significant, though.

    Bookmark   November 14, 2011 at 1:39PM
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saltidawg

Rumiat,

I must assume the cost of connecting up to gas is quite high. Why not replacing your oil furnace with a new oil furnace and use that oil furnace with your heat pump as a hybrid system?

I did that last year - replacing old A/C and oil furnace with a Heat Pump and new oil furnace. My utility costs are WAY down and the house is so much more comfortable.

    Bookmark   November 14, 2011 at 3:59PM
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tigerdunes

Certainly even with the cost of bringing a gas line to a residential home from the street, there should be a reasonable payback as opposed to way more expensive fuel oil.

And then there is the intangible of resale value at a later date. I certainly would not buy a home with oil heat.

I do think gas heat is worthy of consideration even in a dual fuel system if one's family is accustomed to oil forced air heat.

I would get rid of oil period.

IMO

    Bookmark   November 14, 2011 at 4:00PM
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saltidawg

tigerdunes is one of the most knowledgeable posters on this forum... he has forgotten more than I'll ever know about heating and air conditioning, BUT I must disagree on his logic here.

If your Heat Pump in North Carolina is going to be the source of heat MOST OF THE TIME then your expensive oil will only be used a relative small amount of time compared to your prior full time usage.

I am going to make up numbers here, but using oil as the backup might cost you (say) $600 in oil. Let's say using gas might cost you $300 for that backup heat.

In my case to connect to the gas line would have cost me many thousands of dollars... and that if I could get others on the street to share the cost by also agreeing to connect. The infrastructure for oil is already paid for and in place - oil tank, etc. Also, add the cost of safely and environmentally disposing of that old tank and its contents when you convert to gas.

Please do not misunderstand, If I were moving into a new home I would prefer gas over oil - I just don't want to foot the bill to convert.

It would take me a decade or more to recover that up-front gas connection cost.

    Bookmark   November 14, 2011 at 8:54PM
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david_cary

Couple of issues. Electric resistance is cheaper than oil in most (?all) of NC - so why bother? On the wholesale market at least, oil is 4 times the price of NG (I suspect approaching 5).

I've never seen an ad anywhere for heating oil in NC. I think it is less than 1% of homes. Propane is much more common as a fuel of last resort. All electric is the most common.

A decade is not a bad payback period given the cost of money now. Also - most people in NC are not paying to get NG to the house and it sounds like the OP would not be paying. $10 a month is the typical monthly fee.

My thought would be if the NG is expensive to hook up, then just go all electric. Use some of the saved money to insulate the house better. Unless the OP is in the mountains.

    Bookmark   November 15, 2011 at 7:20AM
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bus_driver

At least one of the gas companies in NC has a flat $10.00 per month charge and the gas used is charged in addition to that. So there is $120.00 per year just to have gas available. Consider that if you have no other need for gas. Gas water heating is much cheaper than electricity. A portable generator will not fully power a heat pump. But the small generator will run a gas (or oil) furnace. Consider how to heat if there is a power outage.

    Bookmark   November 15, 2011 at 7:44AM
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saltidawg

bus driver,

"Gas water heating is much cheaper than electricity." Generally yes, however the advent of the residential electric hot water HEAT PUMP has leveled the playing field.

Last year I replaced an older A/C unit with a Heat Pump. I also replaced my oil furnace with a new oil furnace. I also replaced my electric hot water heater with a GE Heat Pump hot water heater.

For the first ten months of 2009 I paid $2700 for electricity. In the first ten months of this year, since the new equipments, I have paid $2000.

Additionally, I kept my home three degrees cooler this year during the cooling season and three degrees warmer during the heating season just beginning.

Also, for the first time in my 22 years in this house the entire house was properly cooled and comfortable during the cooling season.

Because of my ignorance, I did not use the heat pump "properly" during the past heating season - I used oil to heat almost exclusively - just as I had in 2009.

At the end of the year I will post 12 months worth of data.

However, replacing the old electric resistance heat hot water heater with the heat pump with resistance backup is saving nearly $50 in electric usage every month of the year. I believe this would compare quite favorably with gas - except it would cost me MANY thousands of dollars to bring gas in ...

    Bookmark   November 15, 2011 at 1:46PM
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ionized_gw

It must be tough to keep an oil burner going in an area where there are few and people are unfamiliar with them. That might be reason enough to get out of it. In the rural Northeast there would be no problem finding service or competitive oil delivery prices, but, apparently, you have few friends in NC.

    Bookmark   November 15, 2011 at 2:08PM
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david_cary

saltidawg - any noise issues with your HP hot water heater? There are lots of complaints that has scared me away from it - but of course it depends where you hot water heater is. Ours is in the laundry room on the 1st floor - bedroom right next door (although 2 walls separate).

The Heat pump hot water heater's usefullness is very climate and location driven. In my situation it would be great if it wasn't for the noise.

    Bookmark   November 15, 2011 at 4:38PM
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bus_driver

I received excellent oil burner training in the early 1970s from a very experienced man. And I now am down to just two oil furnaces on my properties. Now I know of only one oil company that also offers burner service. And their technicians are probably the best on oil in this area. Customers actually do not want oil when they call, they want heat. The oil companies are really in the heat business with respect to residential customers. Those that do not realize this are doomed. I suspect that few HVAC contractors now have a well-trained burner service person on staff.

    Bookmark   November 15, 2011 at 4:46PM
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saltidawg

David,

My unit is in the basement and thus noise is not an issue. If you locate it in a closet in a living area the noise could be a problem.

The thermodynamic performance properties have little or nothing to do with regional climate. The unit does extract heat from its surroundings but it is a very small BTU extraction in a basement which is a HUGE heat sink. The unit's operation makes absolutely no difference in ambient basement temperature, however it does reduce the humidity somewhat.

Operating the unit in a small service closet, in addition to being noisy, might also lower the closet temperature somewhat.

Here in MD the state gave me a rebate, the power company kicked in a few dollars, Montgomery County gave me a $250 Property Tax Credit, the state collected no sales tax, and Lowes gives service men and retired military a 10% price reduction... and last year it was eligible for the 30% Federal Tax Credit.

    Bookmark   November 15, 2011 at 4:52PM
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ionized_gw

"... received excellent oil burner training in the early 1970s..."

Finally, someone that knows how to use a Fyrite!

    Bookmark   November 15, 2011 at 7:52PM
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