[flashheatingand]

If you were going to install an hvac system for your Aunt Gertie, what would you choose? In most parts of the country duel fuel is worthwhile.

Sometimes, I think straight electric (with a heat-pump) is the way to go since there less components that can go wrong. Sometimes, I think 90% can be problematic with the condensate drainage and all. It's all good, as there are pros and cons with everything. But out of curiosity, what would you guys do?

 

[beenthere]

Dual fuel.

 

[flashheatingand]

80% or 90+?

 

[beenthere]

In my area, we recomend 90%plus.
But either is commonly installed.

Which is determined by venting restrictions.

 

[flashheatingand]

I almost always would recommend gas. But, lately, I am starting to wonder if electric with a h.p. is better in the long haul. I can't count the times I have gone on a service call in which the condensate line froze or their was some type of problem. Shoot, most service calls have to do with something failing on a gas furnace.

Do you think it's possible that money saved on gas gets squandered on service calls (ignitor, inducer motor, condensate drainage, h.e....etc.?) I certainly don't "know" what is right or wrong, but, thought it was food for thought.

 

[beenthere]

Most of those problems are caused by lack of regular maintainence.

Most places. The electric rate, will still cost more then routine maintainence does.

In this area. The electric rate is high enough. That a furnace saves enough on the heating bill. that a single service call won't eat up the savings from the furnace.

Its mostly an area thing. If gas an electric rate are close to same cost per therm. A service call for the furnace could eat up the savings, on a unit that the people never get maintance checks done.
But, the same thing happens with electric aux heat.
One call to restring a strip heater and the people lose a lot of the savings of having a heat pump.

How well the system is maintained, will effect how much of a chance there is of having a service call that eats up the savings.

 

[gene2]

It is a toss up at best. Fossil fuel rate changes are immediately affected by market rates. Electrical rate changes have a longer lag time usually.

Sixteen years ago, when I installed a hybrid system in my home it was cheaper. I had advised that that was the best way to go.

Earlier this year I had a client who used oil for heat & electric AC inquire about converting to all electric. Of coarse I said that was foolish but I plugged the numbers into Carrier's operating cost calculator at her request. This incorporates the cost of fossil fuels, electric rates, the climate zone & the required BTUH for heating/cooling degree days for the area in question.

Imagine my astonishment when the numbers came up saving several hundred dollars as all electric. Oil @ $4.00 gal, Electric @ $ .095 KWHR this past season.

To verify accuracy of the program, I plugged the numbers in for my house using $ 3.25 gal for LP & the same rate for electric. The calculated cost for my hybrid system was within $ 20 of my actual cost. The all electric calculation showed over $ 1200 LESS per year as all electric.

WTF? I started inquiries with my clients with similiar BTUH loads & all electric systems vs. hybrid & came up with cheaper all electric cost everytime. We all had similiar desired comfort levels, (Tstat settings)

I was taught when using Manual J to upsize 1/2 ton as fudge factor for cooling because of builders not actually producing the tight, well insulated house represented along with the rapid degrading of window & door seals. I have observed over my career that oversized for cooling heat pumps installed by others have produced lower auxilliary heat use.

I have been spec'ing 1/2 to 1 ton over Manual J when using a variable speed fan coil & thermistat with DeHum capabilites for a few years just for the increased heating of the larger unit, for heat reducing aux. heat use. DeHum allows the AC side to get to desired RH.

This what I'm going to install in my aunt's (2nd Mom) home 400 miles away. That' what will be installed when I upgrade my home next year.

 

[beenthere]

If your electric rate is stable and a lot lower then oil, or gas, it is often cheaper with a straight heat pump.

But, many areas have electric rates that can and do change monthly.
Might want to check the rate structure in your aunts home. Before you decide on an electric/electric heat pump.