Humidifiers come up often in our conversations with homeowners across the Denver Metro area and it makes sense. Colorado is quite dry, according to my dry hands especially in winter, and unlike many parts of the country we’re actually trying to add moisture to our homes, not remove it.
This year though, with 96% of Colorado under some level of drought conditions, the conversation has taken on a new import worth talking about.
I recently sat down with my co-founder Xerxes Steirer, PhD the technical brain and Visionary for Just Heat Pumps to record a video podcast episode on this topic.
Here, I’d like to share the key takeaways in a way that’s useful when you’re making decisions about your home. Let’s get into it!
The Main Types of Humidifiers
As Xerxes puts it, “all humidifiers are not equal” and knowing the differences matters a lot for Colorado homeowners.
Here’s a quick rundown:
Bypass humidifier: The most common type we find in Denver Metro basements. It diverts air from the pressurized supply duct over a dripping wet evaporative pad and pushes humidity into your return duct. It is the lowest upfront cost (a few hundred dollars for the equipment, 24V connection, no big electrical work). The catch: it continuously flows water over the pad, with the excess draining away all the time it is operating.
Water-saving bypass: Same concept, but with a small recirculating pump that sends runoff back over the pad instead of straight down the drain. Cuts water waste roughly in half. Not much more expensive, and a meaningfully better choice.
Fan-powered humidifier: Similar to the bypass but with its own fan. Slightly more efficient in airflow, but same water waste story overall.
Steam-generating humidifier: The premium option. Uses an electric heating element to boil water and produce steam directly. Near-zero water waste because essentially all the water that enters becomes steam. The trade-off: significantly higher equipment cost (3x–8x a bypass) and requires a dedicated 240-volt circuit, which adds to the electrical scope. This is something to factor in if you’re planning on electrifying your home.
Standalone room humidifier: Don’t overlook these. A quality floor unit for a few hundred dollars gives you total visibility and control for one room or specific need. Just use distilled water Colorado tap water is mineral-heavy and will coat your air filter and surfaces with white calcium dust if you don’t.
The Water Waste Problem
This is the part of the conversation that is really important for our community. A standard bypass humidifier running at a normal 3–6 gallons per hour can send 10,000 to 25,000 gallons of water down the drain in a single heating season.
That’s not a worst case, that’s just how they work with heat pumps. Even the water-saving bypass can still waste 5,000 to 15,000 gallons per season.
Not only that it’s wasteful, but this shows up on your water bill too. And in a drought year like this one, with Denver Water restrictions back in place and water tables stressed across the state, it’s important to know what your humidifier is doing out of sight.
The steam generator is a whole-home option that gets waste down close to zero. It costs more upfront, but the ongoing water savings add up over the decade or two that humidifier will work in your home.
Why Heat Pumps Change Things
This is something we need to highlight as we install electrified heat pump systems across the Front Range: the traditional humidifier playbook was written for gas furnaces, and we can’t just copy-paste it for designing heat pump systems.
A gas furnace delivers supply air at roughly 120–140°F at the plenum, where a bypass humidifier is typically mounted. A heat pump delivers closer to 85 to 110°F, depending on outdoor conditions. That temperature gap directly affects how efficiently a bypass humidifier evaporates water from its pad, the capacity of air to hold moisture roughly doubles every 20°F, so the difference isn’t marginal.
At altitude, the evaporative physics shift further. Denver sits near 5,280 feet, where atmospheric pressure is about 12% lower than at sea level. Lower pressure reduces the energy barrier for water molecules to transition from liquid to vapor, which sounds like an advantage — but in a bypass humidifier, the heat source is the supply air itself.
If that air is already too cool to drive adequate evaporation, the lower air density at altitude also means less thermal mass per cubic foot moving across the pad. The net result is degraded evaporation performance relative to what the humidifier’s rated output assumes, which is typically established at sea level conditions.
Cooler supply air evaporates water more slowly, which means you get less humidity output than expected and more water going straight down the drain.
We’ve also seen heat pump coils corrode through in under three years from bypass humidifiers (yes, here in Colorado) shooting water into the supply duct rather than evaporating it properly. That’s an avoidable and expensive failure to build right into your HVAC system.
A steam humidifier sidesteps this entirely. It has its own heat source and doesn’t rely on supply air temperature or altitude at all. For a heat pump home on the Front Range specifically, that’s a big advantage.
What To Do If You Already Have One
Worth noting: roughly 9 out of 10 humidifiers we look at are either broken, not maintained, or both. So if you haven’t thought about yours in a while, here are the basics:
- Identify what type you have. Not sure? Send us a photo so we can help.
- Check if it’s actually working when the heat runs.
- Close the bypass damper in summer. Leaving it open wastes energy during the cooling season.
- Turn it off in spring when heating season ends. Don’t forget! Running your humidifier and AC at the same time can be a very expensive mistake.
- Maintain it annually. The evaporative pad needs regular replacement to avoid mold and mineral buildup.
- Lower your set point if you want to conserve water. Dropping from 45% down to 35–40% relative humidity is still comfortable and meaningfully reduces water flow.
A Simple Decision Framework
When a customer asks us about humidification, here’s how Xerxes and I talk through it:
First, what is your humidity goals and needs? Do you need whole-home humidification or just one or two rooms? Air sealing is often the best first investment because is can help humidity and also saves on energy while improving comfort.
A blower door test can show how much dry outdoor air is infiltrating your home. Tightening the building envelope keeps your heated and humidified air in and it saves on energy costs too. Every home is different, but it’s worth asking the question before adding high maintenance humidifier equipment.
Second, whatis the specific goal? Comfort while sleeping? Protecting a piano or wood floors? One specific room? If it’s targeted, a quality standalone room humidifier may fully solve it without the water waste of a whole-home system. And the current floor models are really nice, with wifi and sensors, and the ability to run distilled water, which avoids over mineralizing your breathing air from cool-mist type humidifiers.
Third if you do want whole home humidification:
- Tightest budget: water-saving bypass (avoid the standard bypass and get the recirculating pump version)
- Best overall in a heat pump home: steam generator, if the budget and electrical panel support it
You can see how it depends! But now you know what you’re choosing and why.
Wrapping It Up
Humidification in Colorado is more nuanced than it looks and with the drought situation being what it is right now, it felt like the right time to have this conversation as we kick off summer and hope our farmers get their crops enough water to grow. We’re not here to guilt anyone.
We just walk into a lot of basements, we see a lot of humidifiers quietly sending thousands of gallons down the drain. We wanted share our insights with you!
A big thank you to Xerxes for sharing his expertise on this one. We’ll keep these conversations coming. If you have questions about your existing humidifier, want to talk through options for your heat pump system, or just want to send a photo of whatever’s in your basement and ask “what is this thing?” reach out to us here. We love chatting through these with you!
Thanks so much for reading!
