Heat pump

[Mike O'Brien]

I am looking for some advice on heat pumps.  I am inclined to be a DIY guy, in part because I am frugal (and out of work at the moment) and I also like to know exactly how things work and tinker a bit.  So a couple questions if folks have any thoughts:

• Can a heat pump install be a DIY project, or even a hybrid DIY install with experts doing the final pieces?  I know the refrigerants used in some models have massive Global Warming Potential (GWP).  I saw one the other day that had a GWP of 3800 - that seems ridiculously high.  Only experts should be allowed to handle that stuff.  But perhaps there is a way to do a bunch of the install myself and then have the expert do the final hook up?  Or are there decent options with CO2 or other low GWP refrigerants for the DIY homeowner?
• Our house is about 2000 square feet and has a forced air gas furnace. Does it make sense to use the existing duct work as opposed to installing a bunch of mini-splits?
• What are the best filtration systems to use with a heat pump?  This probably isn't the last smoke wave we will get.
• It seems like heat pump technology has evolved so that they work fine in Seattle temperatures.  Do we need to be considering a system with backup heat or are we beyond that?

Thanks for any thoughts you have on any of these questions.  As I discover answers, I will share them here too.

[Jill Eikenhorst]

Hi Mike!

You're former neighbor here :)

I've been working on our ductless heat pump (DHP) programs for a few years and recently had my own installed in my new home.

-DIY is possible, but complicated for several reasons (disclaimer that I've gotten a lot of my info from installers that I've worked with). The refrigerant is an issue. Some systems sold to DIYers are different brands with a special refrigerant line set up that are not as efficient and also lower quality. For the better brands (Mitsubishi, Daikin, etc) the system needs to be installed by a qualified installer to get the full warranty. Incentives also require that but you're not eligible anyway. I've heard of one company that will do hybrid DIY in Oregon, not aware of any in Seattle but there might be. You can do your own electrical work, if you're comfortable with that. My understanding is that the CO2 refrigerants are still a few years out for residential products.

-Your house is probably on the edge of DHP vs. central. The cost for a DHP might be slightly lower if you're willing to just do one on each floor and keep rooms open. Factors to consider: the condition of your ductwork, location of ductwork (is it in conditioned space or losing heat to a cold basement?), whether the existing system is effectively heating all rooms, if you would prefer zones, where you would put indoor/outdoor units of either system and the aesthetics of each. DHP are slightly more efficient but central heat pumps are very close.

-I really went down a rabbit hole once trying to find out what the filters on DHP are. They have a lot of marketing words but not much that is independently verified. I finally found a rating for a Mitsubishi of MERV-6, so it's not high efficiency filters. I'm still not clear whether the "Allergy Filter" provides more filtration. With a central system, I'm pretty sure you can get a HEPA or MERV-11+, but you'd want to confirm that with the system designer since the fan has to work harder to pull air through the filter. We've been using the DHP for the past week as well as a portable air filter in whatever room we're in. It's been acceptable but still feeling a little bit sore throat etc. It is very nice to have the cooling when we can't open the windows.

-No you don't need backup heat. We went with the Mitsubishi Hyper Heat which provides 100% of capacity at 5 degrees F. The non hyper-heat models lose capacity slowly starting at 47 degrees. Our installer also provided an alternate design of the non-hyper heat model that had 1 more head and higher overall BTU rating, so basically compensating with more capacity so it could handle really low temps. 

We've only had our system since June and used it once on a hot day and for the last week in the smoke, but so far I'm happy with it. The remote is hard to use, you have to learn a special DHP symbol language. I think I've got it down now. I'm sure the winter energy bills will be worth it!

Jill

[Kjell Anderson]

According to the EPA, “In wildfire smoke, most particles are less than one micrometer..."   https://www3.epa.gov/ttn/amtic/files/ambient/smoke/wildgd.pdf 

Relating that to ratings on filters, (https://nordicpure.com/pages/what-is-a-merv) it looks like you need MERV 7 to start filtering at 1micron (aka micrometer) and you need MERV 13 to get much below 1 micron. Do any of these systems allow MERV 13 filters?

Jill - can you share more about the ductless heat program? 

Thanks!

Kjell

[Jonlin, Duane]

Kjell,

MERV 13 filters are extremely unusual for very small units, which is why we exempted small units from the new filtration rule going into the 2018 Seattle Mechanical Code.

DJ

Duane Jonlin, FAIA Energy Code and Energy Conservation Advisor City of Seattle Department of Construction and Inspections P.O. Box 34019, Seattle, WA 98124-4019 P: 206.233.2781 |  duane.jonlin@seattle.gov

As stewards and regulators of land and buildings, we preserve and enhance the equity, livability, safety and health in our communities. SDCI’s offices are closed to in-person services until further notice. Visit the SDCI website and read our Building Connections blog for service change updates. Thank you for your continued flexibility and patience as we provide online services to help reduce the risk of spreading the COVID-19 virus.

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[Allan Montpellier]

I purchased MERV 13 filters for my air handling units.

 

Allan Montpellier, PE, LEED AP PRINCIPAL

PAE d: 206.596.8615 | m: 617.877.9516

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From: seattle-home-e...@googlegroups.com <seattle-home-e...@googlegroups.com> On Behalf Of Kjell Anderson
Sent: Wednesday, September 23, 2020 4:35 PM
To: Seattle Home Electrification <seattle-home-e...@googlegroups.com>
Subject: Re: Heat pump

 

According to the EPA, “In wildfire smoke, most particles are less than one micrometer..."   https://www3.epa.gov/ttn/amtic/files/ambient/smoke/wildgd.pdf 

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[Jonlin, Duane]

But, they need a 2-inch frame, right?

Duane Jonlin, FAIA Energy Code and Energy Conservation Advisor City of Seattle Department of Construction and Inspections P.O. Box 34019, Seattle, WA 98124-4019 P: 206.233.2781 |  duane.jonlin@seattle.gov

As stewards and regulators of land and buildings, we preserve and enhance the equity, livability, safety and health in our communities. SDCI’s offices are closed to in-person services until further notice. Visit the SDCI website and read our Building Connections blog for service change updates. Thank you for your continued flexibility and patience as we provide online services to help reduce the risk of spreading the COVID-19 virus.

---

From: seattle-home-e...@googlegroups.com <seattle-home-e...@googlegroups.com> on behalf of Allan Montpellier <Allan.Mo...@pae-engineers.com>
Sent: Thursday, September 24, 2020 5:51 AM
To: Kjell Anderson <kjella...@gmail.com>; Seattle Home Electrification <seattle-home-e...@googlegroups.com>
Subject: RE: Heat pump

 

CAUTION: External Email

I purchased MERV 13 filters for my air handling units.

To view this discussion on the web visit https://groups.google.com/d/msgid/seattle-home-electrification/MW3PR16MB38049B9498EB59BF7588F5C5B5390%40MW3PR16MB3804.namprd16.prod.outlook.com.

[Allan Montpellier]

I found some for my house that fit in the 1” frame.

 

Allan Montpellier, PE, LEED AP PRINCIPAL

PAE d: 206.596.8615 | m: 617.877.9516

Get connected

From: Jonlin, Duane <Duane....@seattle.gov>
Sent: Thursday, September 24, 2020 8:34 AM
To: Allan Montpellier <Allan.Mo...@pae-engineers.com>; Kjell Anderson <kjella...@gmail.com>; Seattle Home Electrification <seattle-home-e...@googlegroups.com>
Subject: Re: Heat pump

 

But, they need a 2-inch frame, right?

 

Duane Jonlin, FAIA Energy Code and Energy Conservation Advisor City of Seattle Department of Construction and Inspections P.O. Box 34019, Seattle, WA 98124-4019 P: 206.233.2781 |  duane.jonlin@seattle.gov