Heat Pumps & Mini-Splits

Parent Q&A

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  • Hi All,

    Since installing our new heat pump about 8 mo. ago, we're now finding we have a mold issue that we have no idea how to cope with. We've seen signs of mold in three closets (along the baseboards and destroying a few clothing/cloth-covered items, in spite of keeping Damp Rid bags and leaving them constantly open to ventilate. More recently, I've had to toss an old book on an open bookshelf covered in white mold and found a few days ago a fuzz of mold on a basket also kept out in the open. So our mold issue extends beyond badly ventilated areas. I'm trying not to (fully) panic yet, especially with two small kids in the house, but what do we do?

    The heat pump settings are such that we can't run the dehumidifier function AND heat (dumb). Is there a better solution than running multiple de-humidifiers in several rooms at all times? Do we need to hire mold cleaners (who quoted one tiny closet measuring about 5x5' several months ago at $1,500+) as part of this? Is anyone affordable? Is there someone we can consult for structural changes that would reduce/eliminate the likelihood of mold throughout our house?

    What do we do? Heeeeeeeeelp!!

    It's hard to imagine a heat pump would have a significant impact on mold--especially in our climate--unless its drain were not configured properly or you had a water leak or something. Try opening windows during the day?

    A heat pump dehumidifies by (essentially) cooling the air, so that's why it can't both heat and cool at the same time, though I suppose you could do so by turning it to dehumidify and using space heaters, which would be cheaper than dehumidifiers.

    Measuring the humidity in various places is important--you can buy hygrometers off Amazon or another site for super cheap ($5 or so).

    If the humidity is high, you have to figure out where it's coming from and fix that. 

    Using an ozone generator (for use only in UNOCCUPIED SPACES) would definitely help with killing mold, but you really have to find/ fix the water source first. 

    I'm so sorry you are dealing with mold. It is truly insidious and can cause major health issues - so it is no joke. It needs to be dealt with properly or it can cause more issues down the line. When we were dealing with a similar issue, we researched companies and found Anderson Group International out of San Jose. They were recommended to us by multiple Water-Damaged Building experts. Repairs and remediation will be costly: you will need to address the cause of the mold, remove all affected materials, decontaminate, then repair. Please call them to help you. This is truly not something you should tackle on your own and ideally, you don't even want to be living in a home with that degree of infestation.

  • There are a few older postings on this, but I wondered what the latest information might be.  We live in a 30 year old condo with a forced air gas furnace in the attic, and want to switch to a heat pump.  We would love advice as to what is involved (e.g., do we need an electrician involved to also run higher voltage in), and even better, who we might trust to do it for us.  We're trying to be more energy efficient and all that, our gas furnace is aging and replacing it with another gas furnace seems climate unfriendly.

    Thanks a lot!

    [moderator note] Here is a recent discussion about AC that recommended heat pumps: Seeking alternatives to installing central AC

    My family needed to replace our furnace and went with a heat pump because we expect within the lifetime of any furnace/heat pump, air conditioning would become more and more necessary due to climate change. A heat pump was cheaper than furnace+AC and is better for the environment (and our electric bills now are pretty similar to our electric+gas bills before; just be sure to let PG&E know you’ve switched to electric heat so they raise your baseline for Tier 1 electric usage). You likely will need an electrical upgrade (we didn’t because by chance we had an extra electric panel in our house that we weren’t using). We went with Lennox through Costco. Their price was a bit higher than other vendors we talked to, but we got a huge Costco credit as cash back, and their system was much bigger (other vendors quoted us for heat pumps for our whole house that are meant for just a single room, which honestly is probably sufficient in the Bay Area). In the end, I’m very happy with the decision because electrification is an important climate change mitigation, and now we have AC!

    Hi Momima!  I work in the field of home efficiency and electrification and recommend checking out The Switch is On website (https://www.switchison.org/get-started) as a great resource to get started with this project -- you can look up contractors who are experienced with heat pumps and see the incentives that are available in your area.  We worked with Electrify My Home (https://www.electrifymyhome.com/) and are very happy with our system.

    I switched from old gas space heating to heat pump (also replaced my water heaters and turned off the gas!!!)

    Be sure you get a company that has experience with heat pumps.  The system(s) need to be designed for YOUR home layout.  I ended up with two separate systems for my 3 floor hillside house; one compressor for a mini-split ducted system for the middle floor and a wall unit for the basement.  The other compressor connects with three wall units for the top floor.  It was not cheap, but the result has been GREAT-- excellent heating, and the pleasure of having air conditioning.  Also no more outrageous gas bills.  The heat pumps are so efficient that my electricity didn't go up much. (Not true for my electric vehicle...) I used A1 Guaranteed in Sonoma. 

    I just got an email from East Bay Green Home Tour about a webinar on Oct 6:

    Dreaming of Air Conditioning, Replacing a Furnace, or Remodeling?

    Adapt to Climate Change with a Heat Pump! 4 East Bay Neighbors Show Their Heat Pump Systems.

    Register:  https://www.eventbrite.com/o/east-bay-green-home-tour-32572642533https:/...

    In this free, one-hour webinar, four East Bay neighbors will show and tell you about their heat pumps: energy-efficient systems that can heat, cool, and filter indoor air. Heat pumps can help you adapt to the hotter, smokier future we are facing, while also moving you off natural gas, which drives climate change. The four homeowners – plus heat pump expert Kyle Bosworth from EcoPerformance Builders – will respond to your questions about their heat pump systems, including ducted and ductless. Brought to you by the coordinators of the Bringing Back the Natives Garden Tour and the Green Home Tour.

  • We are considering replacing our central gas furnace with a ducted mini-split heat pump and wanted to hear how others' experience with ducted heat pumps has gone.  Does it provide enough cooling on the occasional hot summer days?  Is it noticeably noisier than a gas furnace?  

    We had a mini-split system in Brooklyn and it was excellent. Much quieter as the only fan that's on is the one that's in the room that needs the cooling. Our condenser unit was on the roof and we never heard it. Definitely provides enough cooling - though you need to have it sized for your building. I'd say it's far quieter than a gas furnace as you don't hear it click on, or the whurring of the wind through the ducts themselves.

    Which one were you considering specifically? Did you mean Ductless instead of Ducted?


    We installed a ducted Fujitsu heat pump system in our house (1400 sq ft) last year and are very happy with it!  It is not noisier than a gas furnace: I believe the fan/blower system is just a standard fan system, no different from the one that would circulate air heated by a gas furnace fire.  The compressor outside is as loud as an air conditioner (because a heat pump space conditioning system is basically an air conditioner with a reversible valve, allowing it to both heat and cool).  The compressor is outside our kitchen window and I don't notice the noise unless I'm listening for it (it's only running sporadically anyway, just like an A/C).  It keeps our house very comfortable, and also feels good to know that no longer burning gas is the right decision for the climate and air quality in general.  We like being able to pre-cool/pre-heat our house at times of day when there's excess solar on the grid.  It's a great decision, especially if you were considering installing/replacing air conditioning anyway.  BayREN may be able to connect you with rebates depending on where you live.  Feel free to reach out to me directly if you have further specific questions!

    I have a similar question!  I have a bid for a Mitsubishi pump with ducts for heating and cooling for our downstairs and minisplits for our upstairs bedrooms but it is quite expensive.  The system also requires an electrical upgrade.  Does anyone have experience with this sort of heating and cooling system? Thanks!       

    We installed a ducted mini-split heat pump in our house a few years ago.  We don't use the AC that often - probably a few days a year - but it is nice to be able to cool the house on those occasional days that are hot enough to warrant it.  (If it's only moderately warm we just use fans to save energy.)  We have not had any issues with cooling capacity.  It's worth noting, though, that the airflow from a heat pump is less powerful than from a furnace, so a cold room will heat less quickly than it would with furnace.  I assume the same would be true for cooling, but we've never had traditional AC to compare to.  Using a thermostat set point or scheduling it to come on in advance solves that problem.  We actually find that, with a gentler air flow, the heat pump is significantly quieter than a furnace.  We don't notice that it's on other than the house being a comfortable temperature.  The outdoor unit makes some noise, but it's not noticeable inside our house.  Overall, we've been happy with our heat pump.

    I can’t explain the mechanics of heat pumps but I can tell you my experience with ours. The noise is very similar to a furnace or air conditioner. It takes much longer to heat or cool your home so you want to want to turn it on before it gets too hot or cold. I have been told they are efficient. 

    We have a heat pump and love it.  We have one Fujitsu mini split wall unit and one ducted for our 1000 sq ft home and the ducted unit works better and is silent (quieter than a gas furnace for sure).  It also cools really well.   We've had it for about 6 years and super happy. We used Kevin Armstrong https://www.yelp.com/biz/specialized-heating-and-air-conditioning-castro... who did a great job and was far cheaper than the other 2 companies we got bids from.  In 6 years, we've had just one minor issue and Kevin came out on the same day (a Saturday!!!) to fix it. 

    We've have a ducted system  for 2 years and much prefer it to our old gas furnace for heating. It blows more gently and more moderately heated air so you don't get the temperature swings like with a furnace where it blows HOT, then stops and the house cools off (probably more quickly than it should with our old single pane windows), then HOT again. The fan noise is very quiet  (much quieter than the furnace) and so is the compressor--ours is pretty big and we never hear it (I think we set it up on some optional vibration absorbing pads). We have not used it much for A/C yet but now that we have MERV 13 filters, I think it will be helpful on hot, smoky days when you can't have windows open (new normal, sigh).

    One thing I don't like is the thermostat. It's even "dumber" than a basic furnace thermostat in that you can only set it in 30 min increments (instead of 15), it doesn't show current temperature, and it's hard to program. I think there is one other that I'm not remembering right now since I haven't used it since the Spring. It's more of an annoyance than anything else, but I'm curious, have other posters on this thread upgraded their thermostat to a Nest or anything else? I actually don't need a smart one, I just want an easy one. I feel like heat pumps can't use regular furnace thermostats but I could be totally wrong.

  • We need to replace our heating system and are looking for any recommendations for heating companies that install high efficiency heat pump systems.  If you have had one installed and are happy with the work and price, it would be wonderful to hear your experience (and the cost!). 

    Thank you!

    We just got a bunch of quotes and are currently installing a mini-split system with A1. Their proposal was the most cost competitive and they are very active in the decarbonization community. May want to contact the BayRen nonprofit as well for additional recommendations, they have been helpful.

    Great that you are considering a heat pump!  I work in the field of building electrification (policy, not the technical aspects) and this transition is so important for our climate!  I am in the middle of having a ducted mini-split heat pump installed in my house.  Our system was sold to us by Larry Waters at A-1 Guaranteed and I found him very knowledgeable.  We also got a quote from Hassler but didn't like their proposal as much because they recommended individual heat pumps in many rooms, rather than a ducted system (which we prefer for aesthetic reasons).  If you already have heating duct work in your house (we don't) Hassler may also have a good idea for your house.  The quotes were comparable.  Unfortunately I can't report on the work because the install hasn't started yet! 

    You may know this, but after completing the project be sure to contact PG&E to get on their "all electric" rate (you can still have gas cooking/water heating to qualify).  This will increase your Tier 1 allotment and reduce system operating cost. 

    Good luck! 

Parent Reviews

We swapped out our ancient gas furnace for an electric ducted mini split system and got quotes from a few installers and Hassler was definitely the most expensive.  We went with Kevin Armstrong who is a solo practitioner (chis ompany name is Specialized Heating and air conditioning (510) 886-5853). Kevin was recommended by the minisplit distributor company who told us that Kevin is the guy they call when people's mini split systems are installed incorrectly and Kevin fixes them.  He did a great job, was inexpensive and when we had a problem several years later, he came over on a weekend and fixed it quickly. We didn't have heating ducts prior to installing the mini split, so Kevin did all that duct work.  Six years later we're totally happy with what he did.  (And he was probably 30% -40% less than Hassler).

Atlas heating and cooling installed our mini split system. Reliable, good communication, good work and follow up when we had a few minor issues while it was under warranty. System is working well. I think the price was fair, too.

I’m having a Mitsubishi mini-split system installed right now, for just the two upstairs bedrooms. Cheapest quote from reputable installer (Nahman) was $18k. Others ranged up to $22k. I’m having ducts installed in the ceiling (from the attic space), rather than those big wall units, which I hate. But price is not much different for either. Mini-splits do both heating and cooling, meaning I could get rid of the baseboard heaters in those rooms, which is also nice. 

We've been getting estimates for a heat pump to replace our gas furnace, which would also provide cooling for "free" (the heating process is just reversed).  The mini split is a heat pump for one room only - you see them in hotel rooms mounted under a window or high on the wall. They are getting more popular and easier to find. Most of the major plumbing and HVAC companies can give you an estimate to install a heat pump or mini split now. As renewable energy becomes cheaper and more available, electric heating is going to be a lot cleaner than gas, and some cities like Berkeley are starting to ban natural gas in new construction. So electric heat pumps are the way to go for the future.

The City of Berkeley recently co-hosted an online "Green House tour" of local homeowners who have installed various appliances that don't use natural gas, including heat pumps, induction cooking, clothes dryers, etc. It's really informative - there is a video of one family in Lafayette that installed mini-splits in every room along with lots of other eco features. In all the videos, the owners walk you through their house explaining what they did, and why, how much it cost, who their contractor was. There is a list of the houses here: https://www.eastbaygreenhome.com/sites  - click a house to see what brands and contractors they used. To view the videos of each house, go on youtube and search "east bay green home tour"

We live in a 1500 sf house and just got our entire HVAC system replaced with heat pump system that takes advantage of the mild climate here to provide heat and cooling without relying on gas (all electric). It cost $16k, including entirely replacing the duct system in the house. Let me know if you want the name of our contractor.