I just posted a thread earlier (deleted it since it's irrelevant now) about my question to find a company for my HVAC. Well turns out that most of them were just using "rules of thumb" to quote systems. I found a company that did a manual J load calc and is the best of the bunch. They are also highly rated on Yelp and Angie's list FWIW.
So they provided me 3 options that I'd like to get advice on. Here is my original post re-written and with the 3 options to debate against. Would love advice!
I have a 1905 home in Seattle that is 2800 square feet finished space, with an unfinished partially heated basement. The house has a finished attic we use for home office a guest room when relatives come over.
There is existing 8" (?) duct work run all over the house by previous owner. Probably done within last 10 years (the ducts look really new). In the finished attic, there is no vent up there directly, but there is one in the staircase leading up to it. On warmer days, it feels probably at least 5 degrees warmer up there.
We have vents in every room but not ones that can be closed. Example: https://imgur.com/a/isdIg
Our existing gas furnace is a super old 40-50 year old unit that is 65-70% efficient. It's also way over sized at 165k BTU. Previous owner got it for free as he was a city contractor.
When it runs, it is so loud we can hear it and the vent noise. It also runs for very short periods of time. I've been told this is a classic sign of oversized and inefficient equipment.
We've had to do several repairs on the unit last few months. Given our high heating bills and our desire to get AC for the house, we are looking to phrase everything.
I know very little about HVAC and called several companies to come look at our house and quote something. The recommendations have been all over the map with equipment ranging from 40k To 80K BTU. One company was here for maybe 30 mins before providing a recommendation.
I had multiple companies come out and only one of them did a manual J calculation. So i'm much more confident to go with them and one of their options they provided.
I wanted input on how to select a system. I am also tech savvy and like the idea of being able to automate my home. I have an ecobee3 thermostat, but and I'm learning that variable speed or modulating systems wont' work with these smart themostats since they can't control them beyond on/off, or Off/50%/100%. I'm not sure if this is true or not.
company's recommendation
They said this to me:
Running a Manuel J off input from audit and what I get off your square footage and house volume. We're sitting at 45,292 BTU for max output needed. That could still be off some based on doing a true room by room load calc which is what we do before we actually move forward on a job. So we will be sitting between 40,000 to 50,000 for output. If we move forward with the job you will receive a full heat load break down using our software along with other documentation we use during start up of new equipment.
Their 3 proposals are the following:
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Gas Furnace with Heat Pump American Standard 4 ton Furnace (S9V2B080U4PSAA) with matching coil for A/C and exterior American Standard 18 SEER Heat Pump(4A6V8048A1000A). American Standard AccuLink Thermostat (ACONT850AC52UA) -- $17k
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Electric Air Handler with Heat Pump American Standard 4 ton Air Handler(TAM8COA48V21EA) with matching heat strip and exterior American Standard 18 SEER Heat Pump(4A6V8048A1000A). New American Standard AccuLink Thermostat (ACONT850AC52UA) -- $15k
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Electric Air Handler with Heatpump and Ductless in finished attic Mitsubishi Airhandler (MVZ-A36AA4) where current furnace is and install new ductless floor mount unit(MFZKA12NA) in upstairs finished attic (guest bedroom and office). Exterior Heat Pump will be a Mitsubishi 42K Hyper Heat (MXZ5C42NAHZ). Includes Mitsubishi MHK1 Thermostat. -- $17.7k
So basically Option 3 is Option 2, but mitsubishi since they are proposing a ductless up in the finished attic.
Advice on how to decide between these options? My initial thoughts were this:
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If I'm concerned with overall exterior footprint, the Mitsubishi is the winner since the heatpumpt size is much smaller than the American Standard.
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If I absolutely need cooling in the finished attic space (guest bedroom and office), then it needs to be a ductless unit so Mitsubishi is the only option that will work.
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If I'm OK with giving up on the last 2 points, then the gas furnace + heatpump option is better since it can handle subzero temps better (I'm in seattle, where it'll get really cold a handful of days a year, which snow).
How else should I debate this?
Note: If it helps, energy rates in Seattle are:
- Base Service Charge per day $ 0.1621
- First Block per kWh $ 0.0701
- End Block per kWh $ 0.1288
Natural Gas Rates are here
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