Why Heat Pumps are Hard in Multifamily

And why it requires almost an entirely different skillset than 1-4 unit residential.

At this point, we’ve spent years working on heat pump installations across a variety of buildings. And one of the questions that we always get from policymakers is:

Does your model work to make heat pumps possible for multifamily buildings?

My answer? Sometimes, if you get really lucky.

This article, which I’ve wanted to write for a long time, walks you through each one of those criteria, and how every one of them can make an installation more difficult.

1. Clearance

2. Electrical

3. Interior Walls

4. Condensate

5. Height

Preface: Can’t You Just Replace My AC?

In many cases, I can’t.

If you have a ducted air conditioning system, it was probably installed 25 to 30+ years ago. The fact of the matter is, air conditioning systems for multi-family units are oftentimes stuffed into as little space as possible, without any regard for how to replace the system afterwards. Refrigerant lines are oftentimes run inside the finished walls, and replacing them would require opening up interior walls and tearing up your living room space.

Example of an in-wall unit AC condenser. They don’t even make this anymore.

So what would be a relatively straightforward, non-invasive installation for a single-family home or a triple-decker ends up being a whole construction project in which parts of your walls are coming down in order to route refrigerant lines through. (And no, we probably cannot reuse those refrigerant lines from 20 to 30 years ago because the refrigerant has changed at this point.)

Condenser Location Limitations

Rooftops!

So sometimes you’ll have a condenser on the roof of your multi-family building. This usually happens when you don’t have a balcony to place the condenser, but your building was designed with air conditioning in mind anyways.

It may not surprise you to find out that working on condensers on the roof requires a completely different skill set than what contractors are typically used to for 1-4 unit buildings.

You’ll need to know:

• How to coordinate to get a crane on site

• A structural engineer, if there are substantial weight calculations

• How to get electrical and refrigerant lines through the roof in a leak-proof way

• How to snake a refrigerant line from the rooftop to your air handler in a closet somewhere, with the risk that you can’t even see the existing path because it’s inside finished space

This is very different than rolling up to somebody’s backyard and swapping an air handler in the basement. Very different. Commercial HVAC technicians are much more used to doing this type of work, but if they’re able to do commercial work, they’re probably not going to bother their time with lower-margin residential jobs.

Balconies

Suppose you’re lucky enough to have a balcony in your condo or multi-family unit. Well guess what? It’s not that simple either.

Balconies typically have space limitations because you don’t have massive balconies everywhere. Guess what? Heat pumps typically require a lot of clearance on the side from an electrical code standpoint. The disconnects need to be unobstructed, and they need clearance as well. Inspectors have flexibility to accommodate for reasonable limitations.

I feel like in multifamily settings, you’re going to have some inspectors who are going to be okay with 25 in. instead of the typical 30 in. that code mandates for service area next to the condenser’s service ports. But what if you have 20 inches? You’ll want to take super careful measurements, and ideally run it by inspectional services first. But in some towns, inspectors are difficult to reach outside of like, a single hour between 7 and 8 AM, and if you’re a contractor who wants to play it safe, you may just want to avoid balcony installations entirely.

The fact of the matter is, electrical code requires a lot of electrical clearance and is probably written with single-family homes and 1-4-unit homes in mind, with condensers on the ground. They are not written for balconies or multi-family. And from a fire safety standpoint, that makes sense.

Fire Standards

If you have a fire in a multi-family building, it’s going to spread faster, and other people are in danger. This is why multi-family ducted installations will require jacketed, specialized, extra fireproof MC cable, and mini split units are going to require extra fireproof duckt strip that’s 3x the price of standard tray cable.

If you are not familiar with this and you install the wrong type of wiring, guess what? You’ll need to replace all of it. (Yes, we’ve run into this before, and we learned the hard way.)

Electrical Limitations

Speaking of wiring and electrical, doing a service upgrade for a multi-family building or a condo is really hard. Perhaps it’s easier than I think, but I just don’t have experience upgrading service for multi-family buildings. My assumption is that if you don’t already have an air conditioner or spare electrical capacity in your unit, forget about getting a heat pump.

In a single-family home or a triple-decker, the electrical panel is typically in a basement, an unfinished basement that is really easy to connect to any appliances on the outside, such as a heat pump condenser. That is not the case inside a condo or a multifamily building. The electrical panel is usually somewhere in a finished space, like a living room, a kitchen, or a bedroom.

And guess what happens if you need to run a new electrical wire to that panel? Well, unless you want electrical conduit? Inside your finished space, you’ll have to open up your walls and drill holes through framing studs.

And the moment you do that fairly extensively, congratulations. Now you need to hire somebody to fix the drywall and to paint the walls. Sometimes people will get mad because the paint color that you choose is not the same color as the rest of the walls. You have to plan to actually paint the entire wall and not just the immediate space that you are working on.

This adds to the costs. This is, of course, assuming that it is even possible to connect an outdoor condenser to your panel, because you’ll need enough electrical capacity.

Opening Up Interior Walls

I talked about this a little bit previously, but if you are working with mini-splits, then it’s more than just the communication wiring and the electrical wiring that you have to figure out. You have to wire and connect actual copper insulated refrigerant pipes into your house. Usually, that means that you will have interior line cover, which some people are okay with, but other people don’t like the looks of it.

The bundle of wires & pipes that connect everything. Usually under a cover.

Guess what? If you have a ducted system with an air handler or condenser that is so specialized to your building that nothing else fits in it, you don’t have any other choice. I guess you could forego AC if your air conditioner breaks?

Condensate Drainage

All heat pumps, mini-splits, and air handlers will produce condensate of some kind as they dehumidify interior spaces during the hot, humid summers. The water has to go somewhere. Typically, this ends up going outside in a normal single-family home or a triple-decker. It falls straight into the yard. Or in this case of a commercial packaged rooftop unit, onto the rooftop:

If your heat pump is in a balcony, then now you’re thinking about water potentially dripping onto other people’s balconies. If your neighbors are chill, this is not a big issue, but I’ve run into cases before in condos where people are very, very sensitive about where you drain the condensate. They do not want it to drop on their balcony, and therefore now you are opening up another wall to drain the water into a condensate pipe that may or may not be there previously.

Multifamily condo units usually do not have a lot of exterior wall space, and when they do, they typically have that wall space dedicated for windows. This means that routing a condensate drain line into the outside isn’t very simple, and usually this requires the use of a mini split condensate pump. Each mini split condensate pump costs approximately $300.

Height Limitations

What if you want to avoid some of these problems and route the refrigerant lines outside, like you would in a 1-4-unit building? Well, you can’t do that because these are multifamily buildings, and they oftentimes are really tall. Once you get above two to three stories, it’s not really safe to have somebody go up on a ladder that high. In some cases, you just don’t have ladders, cherry pickers, or scissor lifts that go that high.

Will Window Unit Heat Pumps Solve This?

For all of these reasons, New York City has decided to make window unit heat pumps, and I totally agree with their decision. Other cities have followed suit, including Boston & cities around Boston.

Hat tip to the awesome guys at Wirecutter, like Thom Dunn!

We’ve actually installed 3 of these in Boston late summer. We found them incredibly, incredibly convenient compared to the alternative of trying to figure out line run / condensate routing 4 stories off the ground.

For a window unit heat pump to work, you will probably need a window that opens up and down, not from side to side. I find that in a lot of condo scenarios, you do have a lot of windows that open up side to side. We are about a year away from products hitting the market that can ostensibly work with side-to-side windows, but we’re not quite there yet.

Multifamily Is Not Low Hanging Fruit

So there you have it. It’s not easy. There’s a lot of stuff you need to consider that you wouldn’t need to for a Colonial SFH, or a Cape house, or a triple decker. And if you’re a contractor, you honestly may feel like you’re better off just working on the standard single family homes you know.

I know there’s an equity component in the sense that renters often live more in multifamily. I know this well - I used to live in New York & I paid a CRAZY amount for electric baseboard heating. The first bill I had was so high that I immediately started turning the temperature down in the middle of winter & opting for the sweater instead.

There. I lived right there.

Window unit heat pumps would have paid for themselves in like, 3 or 4 years. And I think this is what we all hope to see with multifamily.

I can see air-to-water potentially playing a role here. If there’s a network of boilers heating a 5 to 10 unit building.. you can stick a bunch of Althermas or Ecodans in there & potentially call it a day.

But for buildings that can’t install a window unit heat pump? Yeah, I don’t know. I mean, I guess if you really wanted to know if you’d be a good fit..

The Silver Lining

If you have a multifamily / condo unit, and it’s super straightforward to install a heat pump, chances are, it’s probably easy for almost every unit in the space to install a heat pump. This lends itself really well to bulk deals.

In Summary, We Can Do It If…

• You have balcony space that is big enough for us to have reasonable electrical & service clearance. That, or your condenser is on the rooftop, but 5 to 10 of your neighbors are willing to get in on this deal. That way, we can get a single crane to lift all of these old units off and all the new units on all at once.

• Your electric panel can already support existing AC, and we can simply repurpose your breaker slot for the heat pump/you don’t need an electrical upgrade.

• The electrical panel is really close by to your ideal condenser location, or otherwise you’re OK with interior electrical conduit (like, a 1-inch metal pipe).

• You are okay with the possibility of refrigerant lines running on the interior, or alternatively, you are low enough on the first or second floor that somebody can actually access the exterior using ladders and stay safe.

• You are okay with the disruption that comes along with potentially opening up walls, and the possibility that the paint finish on the wall is not going to be perfectly matching, or alternatively, you are willing to pay for the entire wall to be painted.

• Your neighbors are chill enough for us to drip water on the side, or alternatively, the condensate drain pipe is accessible and easy enough to get to.

If all of these things are true, then your building may be a very good candidate for heat pump installations. If your unit is a good fit, then chances are a lot of other units are also a good fit, so you should probably get in on a bulk deal to lower the cost.

Otherwise, I would recommend using the Midea or Gradient window unit heat pumps. If you can’t do that, then I’m sorry, you may be out of luck!

From my days in New York. Lots of multifamily here!