What to Know Before Switching to Whole House Heat Pumps | Ask This Old House

In this video, This Old House home technology expert Ross Trethewey teaches host Kevin O’Connor about heat pumps and how they aren’t a one-size-fits-all solution.

Heat pumps are economical to run and don’t use fossil fuels. But, they’re not the perfect solution for every home. Home technology expert Ross Trethewey teaches host Kevin O’Connor what to know about these appliances before making the switch.

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What to Know Before Switching to Whole House Heat Pumps | Ask This Old House

[jaycie]

Recommend to go watch the technology connections video.
You can do the calculations yourself (and he shows you several way to do it) and many pro's will either oversize the system to be on the cautious side or just copy what is there if it's the correct size or not.
A good calculation he showed worked was to figure the duty cycle of your current heater on the coldest days and divide the total BTU's of it by active time. In his case on the coldest Chicago day he furnace was only on 25% of the time. so with headroom a hest pump that was 1/3 the size of his current furnace would keep him warm with a margin of error.

[boborambow]

I’ve yet to meet a trustworthy HVAC company. It’s such a shame. I’ve also yet to meet someone who would actually take measurements such as the static pressure you are talking about. They all just come in and tell you heat pumps. Then say it will cost $15, 000 to install one. Then when you look up the model they recommend and see the whole sale price as 3, 000 you wonder, what am I paying for? Then it breaks down a couple years from now because they did a crummy installation. It’s sad to deal with and I feel for uniformed users. So I would say to watch that technology connections video as well!!!

[readyplayer]

I love our heat pump (ours is a multizone ductless system, vs. a whole house system using ductwork). It replaced electric baseboards and an in-wall cadet style heater. It's considerably more economical to run than the baseboards, and I love how quiet our system is vs. visiting a house with a furnace where you hear the furnace kick on. We also gained the ability to cool our space, which we didn't have before (we're in the Pacific Northwest, which has some of the lowest percentages of air conditioning in the country). It kept the house comfortable and cool several years ago when we hit 108 degrees, and has kept the house warm in the mid-teens during a cold snap. Our average winter temp is in the low to mid 30s, so we're very much in the heat pump sweet spot. This will be the 4th year since we had it installed, with essentially zero maintenance (I pop out the unit filters a couple of times a year and vacuum them). We kept our baseboards in most rooms as an emergency backup, but we haven't needed them once.

[LewHarriman]

Very complete overview checklist, Ross. Great job of informing homeowners. ...And yet as others have noted here... the consumer will have a VERY difficult time locating an HVAC service company that's willing (and able) to make calculations, much less accomplish relevant measurements (eg.: duct leakage and airflow). I dream of a day when an HVAC service tech shows up on site with modern digital (or ANY) gauges to take performance measurements of airflow, refrigerant pressures, subcooling and superheat, and then able to decode the results to make adjustments other than "...probably needs more gas", or for furnaces; "...You're gonna a bigger replacement furnace, this one's just too old." My own experience of 45 years here in Southern New Hampshire has shown me that HVAC measurement and diagnostic skills (and on-site time and willingness to use them) are sadly missing from our industry, no matter how much a homeowner might willing to pay for those services.

[thehvacgrapevine]

Great video!!!! Love the flow chart!!!

[janking]

Here in heating zone 4(SE PA), where you need both heating and AC, we have a ground source heat pump, 3 ton(36, 000 btus) in a old but tight, fairly well insulated, ducted system( I sealed the ducts). It does a terrific job year round, installed in 2008, minimal maintenance and one small repair. Backup resistance heat never goes on. My wife says the overall energy bill is much less than our former 4 ton ac( oversized) and high efficiency propane heater(90, 000btu- oversized). What made the most difference was air sealing and insulation, which let us use a small system at lower costs. House is 2200 square feet.
We are in a fairly competitive hvac market here,

[billspohn]

Great video! It's also important to consider how well the home structure itself gains and loses heat—this is the home performance subtopic in the world of building science. Blower door tests, thermal imaging, and smoke tracing can help measure and address home performance. The Building Performance Institute lists certified contractors who understand and practice these skills to make homes with heat pumps perform the best. Now, many HVAC contractors are practicing home performance tests and upgrades.

[billspohn]

On a personal note, with the benefit of new construction, we dialed in the design of the house and HVC system to be able to heat and cool our 2800 Sq ft home in climate zone 5 with a 2-ton air source heat pump without using any backup source of heat.

[apachestepside]

After plenty of YouTube videos and purchasing a vacuum pump/gauge setup and a few other tools, i successfully installed a wall mounted mini split in my garage office. Contemplating replacing my ducted a/c furnace with some sort of multizone heat pump system that uses cassettes. Waiting for my state to sort out all the rebates.

[ALAN-gnud]

The ultimate is a heat pump and a furnace. If it’s mild outside the heat pump runs but when it’s cold the furnace kicks in automatically

[generallyhelpfulsoftware]

In Southern New Hampshire, heat pumps are fine but here electricity is expensive and natural gas is cheap so, I wouldn’t recommend ripping an existing natural gas system out and going all heat pump. January is going to be very expensive in that case as the colder it gets, the more energy the heat pump needs to use. Against heating oil it’s more competitive especially at moderately cold temperatures, but this idea of ripping out an existing system seems limiting.

[GeorgeWashingtonLaserMusket]

If you can afford it, install a Geothermal system, it saves a TON of energy compared to the already efficient heat pumps and you can get real combo gains by using DualSun hybrid solar panels. DualSun makes a "Spring" series of panels (Spring2 is coming out soon) where water is pumped up to the roof then run on the underside of the panels to cool them off. The warm water can be used in cooler spring and fall months to boost the geothermal efficiency and to provide warmth in the winter too. If you want to keep it simple a large black tank of water in sunlight will get pretty hot even in the winter, "Thermal mass storage" works with sand and all kinds of other stuff too.

Finally you can go hardcore mode and tie in a generator (use a heat exchanger with the oil to keep the oil cool and get free hot water) or a "wood gasifier" syngas generator for emergency heat.

I like Geothermal because it uses a lot less power to run, if you accept most HVAC systems are over sized and shave off a half ton to a ton you can get even better energy savings.

I'm doing all of this with a buddies house, we got the geothermal installed, he bought normal solar panels so we're going with barrels painted black in his sunroom to collect heat which can provide passive boost in the winter, and we might be adding some solar heat collection in the backyard. A generator with a tie in to the geothermal system is next, then we're going to build a FEMA Wood Gasifier.

[qcsupport]

In temperate California folks who have ducted gas furnaces but no AC are getting interested in whole house heat pumps. The heat pumps will give them AC for the first time. I wonder if those older heat-only ducts now being used for cooling could lead to condensation issues.

[johndoe]

Good starting point to think about whether a heat pump is a good idea and make sure a hired pro is doing their job right.

[billdodson]

I wish Steve had asked What questions should a homeowner ask in order to determine if a contractor knows what they’re doing AND will be trustworthy/impartial in their recommendations

[sociopathmercenary]

Heat pumps are fantastic in the summer and during the shoulder season here in Ohio... But they certainly don't save us any money in January and February. $200 a month in July... $500 a month in January and February.

Planning to install a supplemental propane system for the winter.

Edit: This is with our thermostat set at 67° all year round and our electric rate is 11 cents per kilowatt

[robertm]

I'd like to put in a heat pump but I have yet to find an hvac company I'd trust to do it. Seems most won't do manual J and D calcs. Existing ductwork is leaky and in an unfinished attic. Floorplan makes it difficult to run new ductwork from half basement or garage without massive soffits. Multi zone ductless is probably the way to go, but expensive to install and questionable if it'll pay for itself in savings.

We have electric resistance heating but put in a high efficiency wood fireplace this year. Likely spend less than $1k/yr on heat with this setup, even running electric only at night.

[jefffrye]

What am I missing on the whole heat-pump fear? I grew up in the South around heat pumps my whole life and I do not understand why so many people are against them.

[energysaver]

This video mistakenly conflates energy savings with cost savings. They do not mean the same thing. The natural gas application has energy savings but in many cases does not have cost savings (positive, neutral, or negative), depending on electric and natural gas rates. I'd love to promote this video, but due to this error, we won't promote in our region.

[SurpriseFox]

Air to water heat pumps exist for people with hot water baseboard heat.