Advice on efficiency ratings when using a dual fuel system

[kevincol]

I live in Seattle.

I am purchasing a new house and am limited by the builder to the Bryant brand.

I am currently planning on purchasing the Evolution Series Heat Pump (model # 288ANA). It has a SEER of 19 and a HSPF of 9.0.

In Seattle, code requires an alternative heat source so I have to purchase a gas furnace. I have a variety of choices in the Bryant line, and have decided to go with the Evolution line because it offers a variable rate fan.

The house is 4300 sq. ft. so I have to have two heat pumps and two furnaces.

I have two questions regarding the choice of my heat pump and the choice of my gas furnace.

Given the fact that I will be getting a heat pump, is it a worthwhile investment to go with the 96.6 AFUE rated Bryant furnace or will the 80 AFUE be sufficient for Seattle. We plan on living in the house for more than 20 years, so I am trying to determine the potential reduced heat costs vs the increase costs of going with the 96.6 AFUE furnace. If I were only going to be having a gas furnace, it would be a no brainer for me to go with the 96.6 AFUE furnace, but since I anticipate that the the heat pump will cover a lot of my heating in the winter in Seattle, how can I realistically figure out the crossover point. I will spend the extra money on the 96.6 AFUE furnace if I can determine how soon I can pay that off in terms of energy cost savings.

The second question is the compressor type. Bryant offers two types of compressors. A scroll compressor and the reciprocating compressor. I am aware that the scroll compressor has less moving parts, thus should have more reliability, but I would like to get opinions from others on this topic.

thanks in advance.

- kevin

[hvac1000]

Go with the 96% unit. The cost is not that much more over 20 years. If you are going to be there 20 years I would also get the 410 refrigerant units. BUY the best you can afford and you will not be sorry in the future.

I would also check up on the company doing the install. You can buy the best equiptment in the world and it will turn to junk if installed incorrectly.

[dan sw fl]

Originally posted by kevincol
I live in Seattle. I am purchasing a new house and am limited by the builder to the Bryant brand.

I am currently planning on purchasing the Evolution Series Heat Pump (model # 288ANA). It has a SEER of 19 and a HSPF of 9.0.

In Seattle, code requires an alternative heat source so I have to purchase a gas furnace.

The house is 4300 sq. ft. so I have to have two heat pumps and two furnaces.

The second question is the compressor type. Bryant offers two types of compressors. A scroll compressor and the reciprocating compressor. - kevin

Why would a furnace be required as the alternate heat source? Strip electric should be all that is needed as
"an alternate soruce". Check Seattle code as to applicability for your situation.

Does Seattle have a significant number of hours at <~22'F? No. Alternate source would only be used if the heat pump fails. Heat pump failure would not be anticipated "for a decade".

I would use an 80% gas furnace due to Seattle weather and only if absolutely required by local code.

Life cycle cost needed ... send plans and windows specs. Contact info is in profile/credentials.

[Freezeking2000]

I would also go 80% since you will never need it unless the temps drop to 10 degres or less.

[kevincol]

Originally posted by dan sw fl

Originally posted by kevincol
I live in Seattle. I am purchasing a new house and am limited by the builder to the Bryant brand.

I am currently planning on purchasing the Evolution Series Heat Pump (model # 288ANA). It has a SEER of 19 and a HSPF of 9.0.

In Seattle, code requires an alternative heat source so I have to purchase a gas furnace.

The house is 4300 sq. ft. so I have to have two heat pumps and two furnaces.

The second question is the compressor type. Bryant offers two types of compressors. A scroll compressor and the reciprocating compressor. - kevin

Why would a furnace be required as the alternate heat source? Strip electric should be all that is needed as
"an alternate soruce". Check Seattle code as to applicability for your situation.

Does Seattle have a significant number of hours at <~22'F? No. Alternate source would only be used if the heat pump fails. Heat pump failure would not be anticipated "for a decade".

I would use an 80% gas furnace due to Seattle weather and only if absolutely required by local code.

Life cycle cost needed ... send plans and windows specs. Contact info is in profile/credentials.



I asked the same question to the builder and the said that I MUST have a furnace as that is code for new houses in Seattle. Unfortunately, I have two differing opinions on this thread. You say go with the 80% AFUE and the other person says go with the 96.6 AFUE furnace.

At this point, since there are two differeing opinions on this is the following:

1) At what temperature does a heat pump become ineffecient and needs to have an alternate heat source
2) What is the cost difference of having the electric heating coils kick in vs having a 80% AFUE or 96.6% AFUE furncace kick in.
3) Since I am forced to go with a furnace, the benefit I get is that I could choose what heating method I wanted based on prevailing rates for electricity vs gas.
4) Should I forget the heat pump and just go with an A/C? I have not price compared this option yet to see if A/C is cheaper than a heat pump (I don't know why it would).

[kevincol]

Originally posted by hvac1000
Go with the 96% unit. The cost is not that much more over 20 years. If you are going to be there 20 years I would also get the 410 refrigerant units. BUY the best you can afford and you will not be sorry in the future.

I would also check up on the company doing the install. You can buy the best equiptment in the world and it will turn to junk if installed incorrectly.

Unfortunately, the builder requires met to go through one contractor. This contractor has been in business in the Seattle area since I moved here back in 1992 and they installed the current furnace in my existing house. If that qualifies them as a great contractor, I don't know. I am also limited to the Braynt line for this house. The heat pump that I selected (the best one they make) uses Puron. I don't know if that is equivalent to 410 refrigerant units.

[amd]

Yes, Puron = R410A

[seatonheating]

Originally posted by kevincol

Originally posted by hvac1000
Go with the 96% unit. The cost is not that much more over 20 years. If you are going to be there 20 years I would also get the 410 refrigerant units. BUY the best you can afford and you will not be sorry in the future.

I would also check up on the company doing the install. You can buy the best equiptment in the world and it will turn to junk if installed incorrectly.

Unfortunately, the builder requires met to go through one contractor. This contractor has been in business in the Seattle area since I moved here back in 1992 and they installed the current furnace in my existing house. If that qualifies them as a great contractor, I don't know. I am also limited to the Braynt line for this house. The heat pump that I selected (the best one they make) uses Puron. I don't know if that is equivalent to 410 refrigerant units.

I am a contractor in Seattle and that is a bunch of bologna, them telling you that you have to have a gas furnace....absolutely untrue.

Make sure that they are performing a heat loss calculation, designing the duct per Manual D. I don't believe that crap about "having" to go with that contractor. Builders can select whomever they want for you, they probably just have a loyalty to that particular one. But remember, that doesn't mean they are going to do it right. Got any questions, give me a call. # in my credentials.

[Irishmist]

You, my friend, are being fed the proverbial line of B. S.! You don't HAVE to do anything! It is YOUR house and YOU insist on the builder putting what YOU want in YOUR house. See a common theme? IT IS YOUR HOUSE! I would also ask to SEE whatever code requirements are being 'quoted.' And if in further doubt, ask to speak to the code enforcement officer yourself! Good luck. p.s. Dual fuel with Bryant evolution is an excellent system. It is what I have in my home. Heat pump with natural gas. And I would do the same exact thing in Seattle or anywhere else I lived. As long as I am paying the utility bill, I will put whatever I decide in my home!! All the best, John.

[dan sw fl]

Originally posted by kevincol

Originally posted by dan sw fl

Originally posted by kevincol
I live in Seattle. I am purchasing a new house and am limited by the builder to the Bryant brand.

I am currently planning on purchasing the Evolution Series Heat Pump (model # 288ANA). It has a SEER of 19 and a HSPF of 9.0.

The house is 4300 sq. ft. so I have to have two heat pumps and two furnaces.

scroll compressor - kevin

Why would a furnace be required as the alternate heat source? Strip electric should be all that is needed as
"an alternate soruce". Check Seattle code as to applicability for your situation.

Does Seattle have a significant number of hours at <~22'F? No. Alternate source would only be used if the heat pump fails. Heat pump failure would not be anticipated "for a decade".

I asked the same question to the builder and the said that I MUST have a furnace as that is code for new houses in Seattle.

At this point, since there are two differing opinions on this is the following:
1) At what temperature does a heat pump become ineffecient and needs to have an alternate heat source

2) What is the cost difference of having the electric heating coils kick in vs having a 80% AFUE or 96.6% AFUE furnace kick in.

3) Since I am forced to go with a furnace, the benefit I get is that I could choose what heating method I wanted based on prevailing rates for electricity vs gas.

4) Should I forget the heat pump and just go with an A/C?

I have not price compared this option yet to see if A/C is cheaper than a heat pump (I don't know why it would).



1. Heat pump may need back up at ~28'F depending on house construction, tightness and it's energy efficiency.
With a properly sized heat pump, the use of straight resistance heating as a supplement would be minimal
(< ~100 hours).

2. Seattle has 40 hours @<32'F, so it is not really a meanignful comparison when you are likely talking about a 40 year payback.

You need to provide your gas and electric rates to determine life cycle costs.

The other commenter likely does not have any idea on Seattle weather nor local electric rates.

3. Use an electric furnace. WA's electric rates are among the lowest in the whole country.

4. Initial cost of heat pump is more than A/C.
However, one must address Life Cycle cost which is the combined installation and operating costs over 20 years.

It is a "NO Brainer" for a WA residence
to recommend a heat pump.

Why do you need TWO heat pumps and furnaces?
Have you already determined through comprehensive analysis that a zoning a larger heat pump system would not be the most economical and provide the same level of Home Comfort?