What was the cooling load calc for AC?....I don't see how any dealer could recommend a heat pump either for a straight HP split system or in a dual fuel system...I assume for the attic area guest room/office, this space would not be used daily. Perhaps I misunderstood. Anyway, I would recommend a mini split HP. This living space should be well insulated. I have always understood that the Seattle area had moderate winters/summers. I would suggest a high eff 2 stage var speed furnace with a 2 stage AC condenser. I see no reason for a modulating furnace with a variable condenser whether AC or HP. While I like Trane/AmStd products, I would suggest a quote from Carrier Infinity or Bryant Evolution for comparison purposes.

IMO

Your gas rate is about $0.93 per therm which I think is higher than the current national average. I suggest getting quotes on a 80% and 95% efficiency furnaces. You would then need to calculate how much natural gas you used to heat your house in order to determine if the extra 15% in efficiency is a good investment.

Your electric rate is low for the first block of electricity, but then jumps up for the second block. Do you know how large are these blocks? The heat pump may be more economical to operate depending which furnace you choose and electric rate you are likely to be using for heating.

I don't think an 18 SEER rated AC is worth it for your climate. The prices start to jump up when you hit those levels.

@tigerdunes: you're correct, the finished attic is not used daily. It's a guest room and periodically used when we have guests and doubles as our home office which is typically used in the evening.

Why do you recommend against modulating furnace with variable condenser? Just that our climate in seattle doesn't warrant it or another reason?

@mike_home I looked this up on our energy company's site and saw this:

"Costs are based on average PSE residential rates for electric service ($.088594 per kWh [first 600 kWh] and $0.107172 [remaining kWh]) and natural gas service ($.97449 per therm) as of February 2013. Rates are based on usage of 1,000 kWh per month and 68 therms per month. These rates do not include the basic monthly charge."

the rates you listed in prior post do not correspond to the link you provided for comparison between nat gas and electric.

yes that's correct. Your climate does not justify full modulating high eff nat gas furnace and true variable condensers. I would get quote on 2 stage condensers and two stage var speed high eff furnace.

you did not list your AC cooling load.

IMO

@mike_home and @tigerdunes:

I looked at this again and verified these are correct and accurate for 2017. In case of natural gas, they gave the expected increase in 2017.

For electricity, the rates as of May 2017 are here and are:

• First 600 kWh per month: $0.097543
• Over 600 kWh per month: $ 0.116365

For natural gas, I found this PDF from May 2016 about their summer rates: https://pse.com/aboutpse/Rates/Documents/summ_gas_2523_res_2016_05_01.pdf

Which says:

• Base charge per month: $10.34
• Total charge (delivery + gas + other charges): $0.89952 per them

This other pamphlet is from November 2016 about winter rates: https://pse.com/aboutpse/Rates/Documents/summ_gas_2523_res_2016_11_01.pdf

• Base charge per month: $10.34
• Total charge (delivery + gas + other charges): $0.9017 per them

again, what was the cooling load calc for AC?...

I took a blend of your electric rate using $.105/kwh and 3 COP.

i used $1.00/therm that includes flat mthly fee for nat gas at 95% efficiency.

results below..

Cost per 100,000 btu of useable heat

Heat pump:$1.03

Natural Gas:$1.02

I see zero economic operating advantage for a heat pump. I will say that your nat gas rate is awfully high compared to mine but perhaps that's due to West Coast market pricing. It should be pointed out that av life of a furnace is longer than HP condenser.

IMO

heat pump life vs. furnace life. If the heat pump is properly maintained and you don't hire incompetent people to service it the heat pump 'could' last 20 years or more.

The furnace will probably suffer a few break downs in 20 years as well as a heat pump. I don't work on many heat pumps, the last one I saw was like 20+ years old.

With that said though, if you have natural gas available then you are almost always better to go with natural gas furnace... unless you have a solar panel set up or something like that.

Propane is probably a toss up. If you argue safety concerns of propane vs heat pump then a heat pump wins hands down.

A furnace has an easy life compared to a heat pump. The furnace gets to live indoors many times in conditioned space. The burner and its associated parts get summer vacations. The heat pump lives outside and has to endure the extreme of the weather elements while working summers and winters. It rarely gets a vacation.

You would need best matching evap coil and AC condenser. Postponable if air conditioning is not a high priority for your location. I would also include a pleated filter media cabinet. Certainly not a heat pump condenser.

IMO

Cooling is a priority. While it's mild here, there are times in mid to high 90s and given wife is pregnant we want it to be comfortable.

I'm at a loss why they'd recommend a heat pump then. This company is incredibly highly rated locally.

Are there factors here at play that may be causing them to recommend it? Noise? Or something else?

Also, what is a "pleated filter media cabinet" for? Is it the same as a air handler or something else?

The only reason I can think a HP condenser would be recommended is poor judgment and self serving to dealer's pocketbook. A whole house pleated filter media cabinet helps indoor air quality and protects both evap coil and var speed blower motor. Certainly better and more effective than 1" throwaway filters. Changeout is easy and filters last up to one year.

IMO

I think in the past the low electricity prices and mild winters in the Northwest made heat pump the popular choice for heating. But now that gas prices are low and many furnaces can achieve 95%+ efficiencies the heat pump is not as attractive. Your HVAC contractor may be very good, but he needs to run the calculations to determine what fuel is the most economical.

Efficiency is not a good comparison a heat pump is 100% efficient.

So realize efficiency has more than one meaning... a in some circles it doesn't mean what is spent to run the equipment. It means heat produced is not wasted by sending some of it up the flue as a by-product of the heating cycle.

Yes, but this can be completely misleading. Strip supplemental heat is 100% efficient and one of the worst and most expensive types of heat. Quality HP condensers by themselves without strip heat can have over 3 COP.

IMO

How do you find out the COP of a heatpump? Or is 3 COP a safe assumption?

TC

you seemed enchanted by the idea of purchasing a HP...you are not listening...HPs can (not always) be a good idea depending on climate and when nat gas service is not available...simply speaking, HP is not a good idea for your situation...

IMO

Misleading? now what ever made you think this industry was built on misleading people Tiger? LOL.

It's kind of like comparing a locomotive to an air conditioner huh?

The biggest difference from a heat pump to a general AC is that there are more controls on it and obviously the heat pump can produce heat as well as cooling.

Noise is a complicated subject... (how quiet is quiet? if you catch my drift)

Controls can prevent damage just as much as they can cause the system to malfunction / stop working. But typically the better the controls, the better everything works and in some cases the more reliable it is.

In a climate like Seattle (my estimation) is that there is probably a large heat pump base for that climate that are used in various areas where natural gas is not available.

A heat pump works best in a climate that is mostly above 32 degree OAT. The technology has vastly improved over the years and is much better today than even 10 years ago.

Anytime there are areas in which there is a heavy installation base these things will be offered more frequently. It can be what the dealer knows best and so they offer it along with natural gas as a back up or vice versa.

for OP

i would like to hear their reasoning with facts to back up HP recommendation. Show me.

btw, I have an 11 yr old Trane dual fuel system-high eff furnace with 15 SEER XLi heat pump. When installed, there was good economic operating leverage using my HP down to freezing and then switching over to gas furnace for lower outside temps. That leverage has long since disappeared. Two reasons, the continued march of higher regulated electric rates and the significant drop for market condition natural gas. For the past 3 heating seasons, I have used furnace exclusively, no HP use at all.

IMO

I don't think the 5 HVAC contractors are trying to fleece you. They are just not paying attention to what is happening in the energy markets. Fracking has caused the price of natural gas to drop, and 95%+ efficiency are very common. Meanwhile the contractors continue to quote what they have always quoted in the past.

If the HVAC contractors would learn how to do a simple energy calculation they would understand these concepts. But most either don't know how to do it, or don't want to do it.

Agree with Mike...maybe they are not educated in fuel cost comparisons and too lazy to learn. Eager to sell what they have always sold. Or could it be they are looking out more for themselves and not their customers?...

the savings between 80% eff and 95+% eff is a no brainer. this does not even take into consideration your potential savings for getting sized correctly. Of course high eff furnace will need to be in crawl space and vented properly to outside. You have crawlspace? Where is existing furnace located?

IMO

Vent though exterior wall...

The other issue to consider is the choices of 80% efficiency furnaces are limited. They are available but most are the basic single speed type.

The other issue to consider is the choices of 80% efficiency furnaces are limited.

I have no trouble finding 80% variable speed 2 stage gas furnaces with lifetime heat exchanger warranties.

Boy it's good to live near hydro-electric power. Your electric rates are over 40% less than what I pay in NJ (mostly gas-fired and old nuclear)

@freeoscar:

Given conversation, the electric doesn't matter since everything is already pointing to going wth Natural Gas being the winner... with your electric rates it seems that it would even be more pointed to go that direction.

what are your gas rates out there per therm?

About .72 per therm and $6 base service charge. Yes we obviously utilize gas over electric when given the option. But our household uses around 700kwh even outside of cooling season.

TC: they aren't trying to cheat you as the guys said. When I lived in Seattle, rates were so low that I had to call them since my first 2-month bill was $12. I thought it was a connection fee, but it wasn't.

Now, your rates are slightly higher than mine are here in the East.

When gas was more expensive a few years ago, the cost difference would have meant more than now. But your gas rates have probably gone down as the electric rates went up (still paying off those 5 nukes that never got built?).

The Seattle area has such a mild climate (for being that far north) that heat pumps work just fine. So its not a surprise that they get recommended now that they are more efficient. (And lets not start a war over the definition of efficiency.)

Another consideration perhaps. A heat pump will run year round in your location. An AC unit may only run 2-3 months in Seattle, if that much. Hopefully the AC unit will last longer from non-use. Which also means you don't really have to go with the higher SEER number since you are not going to see any ROI. 14-15 would be fine.

How important will a two stage, single stage or modulating AC unit be for my climate?

If you're just talking AC, then not really important due to climate. More important to your wallet. If your furnace has more than one stage (or in this case, blower speed), then a single stage AC will work with a variable speed blower. Any more stages of AC and you are talking simply about your comfort and not much else.

Once again, the Seattle climate is peculiar in that when it is hot in the summer, it usually is not humid eventhough so close to the ocean. The breeze comes from the mountains in summer when it's hot. Multi-stages in AC help with humidity extraction mostly which may not be something you need be concerned with.

A two speed AC might benefit you in the cooler times of the year if there ever is any serious humidity. A single speed AC will over cool much more under a low temp and high humidity situation.

A two speed AC will over cool too under this situation of low temp and high humidity, but it will be less than that of a single speed AC.

For your climate I don't know that there is really a wrong answer here. It comes down to what you want. Realize an air conditioner is sized for the biggest load. Which means a single speed AC system is oversized upwards of 90% of the time it runs.

No one in this industry is likely to tell you that, even though it is easily proven.

BTW: by saying 'sized for the biggest load', that usually means 'sized for the hottest day'. When a ManualJ calculation is done, one of the parameters is the hottest day temperature (and the desired indoor temperature on that day).