Holistic Quality Indicators
Here's how we vet contractors. Now, you can vet your own contractors, too!
Executive Summary
In no particular order:
Permits: do they pull permits & do inspections?
Sizing & Design: is the heat pump sized correctly in the first place?
Aesthetics: does the line sets & equipment placement blend in/make sense?
Technical Competency: is the heat pump installed correctly?
Service & Reliability: are they nice? Do they respond to calls & email?
Setting the Scene
We’ve all been there. The HVAC salesman is trying to convince you to shell out a ridiculous price, and when you push back, they say
You’re paying more, but you’re paying for quality.
What does that even mean? Are they right? Is this person just trying to make more money via. the standard 10% sales commission? What does “quality” even mean??
This article exists to answer that question (in, admittedly, a very detailed manner). Here’s what we look for.
Permits and Inspections
Contractors should pull permits. Unfortunately, cities don’t really make it easy to figure out which permits you, the homeowner, should expect a contractor to pull.
We solved that problem by calling every single town and getting that info for you:
Ductless:
Ducted:
Unfortunately, cities also sometimes make it difficult to schedule inspections, as I talk about here in our letter to Mass Save. Nonetheless, you’ll still want it done so you know the installation is up to code.
Sizing
The goal of this step is to avoid oversizing the equipment relative to the size of your house. The easiest way to think about this is that oversizing is like buying a Ferrari to drive to the grocery store. You simply don’t need it for that.
Ask how they calculate thermal load.
Ask when they calculate the Manual J/precise thermal load.
Ask how they think about insulation & ductwork.
Ask for their consideration on heating vs. cooling load, based on the house.
This is what a really detailed, floor-by-floor Manual J looks like:
It’s great if you get this, but in reality, most contractors won’t do the Manual J on the spot. For the average homeowner, it’s better to ask for them to break down their thought process for thermal load calculation, because you’ll want to see them consider things such as the following edge cases:
2nd floor of triple deckers, or any multifamily/condo unit in which the space below & above a ceiling is occupied (which means it’s already heated/cooled) - this requires much less cooling & heating load.
2nd floor spaces above unconditioned garage space. Heating load may be greater.
On equipment: our stance is that everyone should get a variable speed (inverter) condenser, as it dramatically increases the chances that sizing would be done within the acceptable minimum/maximum heating & cooling output of the equipment.
Design
IF you have pre-existing ductwork:
The biggest design question we face in LC installations is whether you can reuse the ductwork or not. Maybe you have central air with an AC. Maybe you have a furnace that connects to ductwork.
Either way, you’ll definitely want to confirm with an in-person walkthrough with an experienced tech before the actual installation. The biggest risk is ductwork that is too small, because that leads to (1) suboptimal airflow, and (2) high duct pressure, which adversely impacts fan/coil/compressor life. This usually happens when ductwork is sized only for heating1, and we’ve seen this a bit less when it comes to ductwork sized for both AC and heating.
Our recommendation: confirm that an experienced tech will look at your ductwork before the installation. Ask them what they think.
Also, ask for references.
IF you don’t have ductwork at all:
Congratulations, you may be in a better spot. You could get ductless wall units in each room, or you could opt for ducting in the attic & ductless on the 1st floor, if you’re in a standard colonial SFH. This is a bit easier, but you also may want to consider…
Aesthetics
This is where you should ideally ask for past references. How are the exterior line covers? How are the interior line runs? Is the contractor good at hiding interior line runs in the basement / up closet space?
This is good:
This is bad:
Good installations will pretty much hide all line set on the inside, meaning that you’ll only see the wall units. Like so:
Technical Competency
WARNING: THIS IS ABOUT TO GET REALLY TECHNICAL.
I’m going to quote the great Nate Adams here, of Nate the House Whisperer, who has spent years going deep into the weeds on installation quality & building science.
This excerpt is from a Q&A he hosted on the MCJ Slack in February 2024:
Kit:
Let’s say you’re talking to a potential contractor.
What are the technical questions (besides a standard Manual J calc) you’d ask to ensure your installer correctly installs the equipment? (E.g. asking about commissioning, expecting an installer to know why it’s important to pull a vacuum below 500 microns)
Related to #1, for heat pumps that fail in under 5 years due to poor installation, what are the main mistakes that are made?
Nate:
For the first part, there are three big pieces to a good install:
Low duct pressure - the pressure inside the ducts should be as low as possible for fan life, compressor life, and coil life. The two easiest ways to reduce it are to downsize the equipment and to upsize the ductwork that connects to the unit, both supply and return.
Brazing with nitrogen - unitary split systems need to be connected in the field. Soot from brazing can add a lot of acid in the refrigerant which can substantially reduce compressor life. It's a simple fix: flow a few psi of nitrogen while brazing so soot can't get into the connections.
Deep vacuum - new refrigerant lines still have some contamination in them (water is a contaminant to refrigerant). The best way to get it out is to put it in a deep vacuum. Atmospheric pressure is about 750,000 microns. You for sure want to get below 500, preferably below 100 microns. That vaporizes contaminants and sucks them into the vacuum pump.
Those are 3 things to ask about when talking to contractors, and also critical install details. Not tackling those 3 could lead to constant equipment issues and failure in 5-10 years. Following those can lead to 15-20 year lives.One more key issue for installs: surge protection. Modern equipment is very sensitive to voltage fluctuations, so it's best to have a surge protector on both the indoor and the outdoor unit. The ICM493 is the consensus product for the outdoor unit.
Kit’s Response to #2:
I agree with everything Nate said, but I want to point out that some contractors are opting for pressing instead of brazing to connect refrigerant lines. We’ve heard that you can achieve a higher quality with a perfect braze, but press fitting is a lot harder to mess up, which means that the quality floor with press is higher.
Here’s the gold standard research from ASHRAE that confirms that press fitting is okay:
This is like, really building science-y, so we don’t anticipate every homeowner to ask about this. But we do vet our contractors against these things, and we won’t strike a bulk deal with a contractor until we’ve personally done walkthroughs at 2 or 3 installations, and ask them how they do their work/commission/etc.
Service & Reliability
Toughest to tell, to be honest. You can’t see their admin staff. (I mean, we can b/c we vet really deep for bulk deals. But the average homeowner can’t.) I think this is vibes, to be honest. Do they respond to emails? What’s your impression of the person walking through the house?
This is one thing that’s really tough for a consumer to tell since it’s a 1-time, non-repeated decision. Laminar Collective has better observations on this b/c for us, it’s an iterated repeated game.
Other Considerations
Price, of course! We think a properly functioning market should route buyer volume to high-value contractors. That is, contractors who offer a combination of good price & quality.
The market is not uniform; some people will be more price sensitive, and others will pay a premium for convenience. Taking off the rebate upfront matters to some people, and others would happily do the paperwork themselves.
Conclusion
Okay, that was a lot. I’ve given up on making this article a homeowner-friendly article, but hopefully it’s something that energy coaches/advocates, or sustainability managers (& other fellow researchers) can dig through.
Long story short: we spend a lot of time thinking about quality, and that’s just from me (Kit), not including Hannan (who got an EPA 608 license to know more & to get access to supply houses). This summarizes what we know.
Furnace heat tends to be at a higher temperature, which means low airflow still delivers the same temp. Heat pumps deliver a more consistent, slightly lower temperature heat, which means you’ll need more air.