Boilers, Radiant Heat & Snowmelt in Highlands Ranch, Colorado
Most houses in Highlands Ranch do not need a boiler. That's the honest place to start. The community was built almost entirely after 1980, the bulk of it through the 1990s and 2000s, under code cycles that already required insulation, house wrap, and a reasonably tight envelope. Those houses were designed around forced-air furnaces and ducted for it when they were framed. For most of them a furnace is still the right answer, and we do hydronics only.
So the work here is different in kind from Denver's pre-war brick. It's new radiant in finished-basement build-outs, snowmelt on the long driveways along the west and south edges, indirect water heaters, and boiler work in the custom homes plumbed hydronic from the start. If that's your situation, call (303) 908-5658 or use the contact form. If it isn't, we'll say so on the phone rather than after we've been out.
Why is a Highlands Ranch house different from a Denver house?
Age, and everything that follows from it. Denver's hydronic problems are old-building problems: cast iron radiators sized for 180°F water, converted gravity systems, boilers on shared masonry chimneys, single-wythe brick with no cavity to insulate. Highlands Ranch has essentially none of that.
That cuts two ways. Heat loads are lower, so equipment should be smaller. But the distribution is ductwork, not pipe, so hydronics has to earn its place in a specific room or a specific slab rather than take over the house. A boiler is not the automatic upgrade from a furnace — it's a different system, and swapping wholesale in a house that was never piped for it is rarely sensible.
What's the actual heat load of a 1990s Highlands Ranch house?
Lower than almost anyone guesses. Newer tight Front Range construction runs around 25 BTU/hr/ft²; older brick with some weatherization runs closer to 40. Highlands Ranch sits at the low end. A 2,400-square-foot house at 25 BTU/hr/ft² is about 60,000 BTU/hr on a design day — far smaller than what usually gets installed. Most boilers replaced in the Denver metro are two to three times larger than the building needs, because each replacement got sized off the nameplate of the last one and the padding compounded. Here that error is worse in percentage terms, because the true load is smaller.
The fix isn't clever. It's a room-by-room heat loss on your actual house — orientation, glazing, insulation, infiltration — before anyone picks a model number. More on why Denver boilers are usually too big.
Does the altitude derate matter more at 5,900 feet?
Yes — it's one of the few things here that makes the job harder rather than easier. Denver is 5,280 feet. Littleton is around 5,350. Highlands Ranch runs roughly 5,800 to 6,000 feet, rising as you go south and west.
Combustion equipment loses capacity in thin air, which is why manufacturers publish altitude derate tables. Six hundred feet above Denver is not a rounding error; it's a bigger correction applied to a smaller load. Derate once. Not zero times, which leaves you short on the coldest morning. Not twice, which is how a conservative load becomes a boiler two sizes too big.
Can I put radiant floor heat in a finished basement?
This is the most common real hydronic job in Highlands Ranch. These basements are big, below grade on all four sides, and cold in a way the thermostat upstairs never registers. A slab that heats the room fixes that in a way a duct run off the main furnace does not.
Two honest approaches. Pouring new concrete — an addition, a walkout, a slab coming out anyway — puts the tubing in the pour and gives you the best version of the system. Finishing over the existing 1990s slab means either rigid foam and a topping pour, or a plate system under a new subfloor. Both work; floor height usually decides it, since most of these basements have eight-foot ceilings and a beam to duck under.
One thing is not adjustable later: tube depth is permanent. Tube tied at the bottom of a 4" pour instead of held at mid-height raises the water temperature that slab needs by roughly 7°F for the life of the building. Chairs go at 18 to 24 inches for that reason — it costs almost nothing on installation day and can't be fixed afterward without demolition.
Low slab temperature is also why radiant pairs well with a condensing boiler. A condensing boiler only condenses when return water is below about 130°F. Above that it runs around 85% and you paid for efficiency you never see. A basement slab stays under that line all season. Cast iron radiators sized for 180°F never do — a Denver problem, not usually one here. More on our radiant floor heating page.
Will the floor actually feel warm?
Usually not, and that's the correct outcome. Radiant floors are not warm floors. They are floors that heat a room. A slab sized right for the load sits a few degrees above room temperature — noticeable in bare feet, not toasty. A floor that genuinely feels warm underfoot is usually one overcoming a load it wasn't designed for. More on what radiant floor heating actually feels like.
Is snowmelt realistic on a long Highlands Ranch driveway?
On some lots it's the most sensible thing you could do; on others the number stops the conversation. It comes down to square footage. The larger lots on the west and south edges have long approach driveways, some steep enough that shoveling isn't the real alternative — not using the driveway is.
Snowmelt is a heat plant with a driveway attached. Design load is roughly 126 BTU/hr/ft² at the reference condition of 5°F air, 10 mph wind, and a 38°F surface, per the Uponor Snow & Ice Melting Manual. Put that next to the 25 BTU/hr/ft² the house needs and the problem is obvious: a 900-square-foot driveway can want more heat than the home it serves. Sometimes the right answer is melting the tire tracks and the walk to the door instead of the whole slab — a legitimate design, not a compromise. Details on our snowmelt page.
Timing is not negotiable. Tubing goes in before the concrete pour — there is no version added later. Tubing, under-slab insulation, and 6x6 W1.4 mesh are base scope, and the loops go on 100 psi air, held through the pour, gauge visible. If a rebar boot goes through a loop, you find out while the truck is still there and not the following January. That makes snowmelt a summer and fall conversation — same reasoning as installing a heated driveway in summer.
My house was built with a boiler — what goes wrong first?
Some custom homes here were built hydronic, and they're now twenty to thirty-five years old — the age where the original boiler is at or past the end of its service life and the near-boiler piping starts telling on itself.
What we look at: whether the system was ever sized to the building or just to the last piece of equipment; whether there's a proper air separator and a working expansion tank; and what the water looks like. We'd rather re-pipe the primary loop correctly than hang a modern boiler off arrangements it can't work with. If we find something ugly, we'll tell you what it is and what it would take to make it right, without a running commentary on whoever was there before. More on the boiler page.
Why does the circulator keep failing?
Water quality, most of the time. Magnetite — Fe₃O₄, the black iron-oxide sludge that forms in any system with steel and oxygen in it — grinds down to particles around 5 microns and never settles out. Modern permanent-magnet circulators pull it straight onto the rotor. Per ADEY, roughly 70% of circulators returned to manufacturers fail on water-quality issues.
The check takes five minutes: draw a sample. Healthy system water is slightly gray with a faint metallic smell. Black and gritty means the sludge is already circulating, and a new pump dropped into that water is on the same trajectory as the last one. Here's the whole check.
What happens to the water heater when the heating equipment changes?
This one catches people, and it applies here even though the chimneys are different. Denver's version is a masonry stack; the Highlands Ranch version is usually a shared B-vent serving the furnace or boiler and the gas water heater together. The physics is the same: pull the larger appliance off a common vent and the water heater is left driving that whole stack on its own draft hood. When it can't, combustion gas — carbon monoxide included — spills into the house.
The check is the Seven Times Rule: the largest common stack must not exceed seven times the area of the smallest draft-hood outlet. A 12×12 chimney is 144 in². A 4" water-heater flue outlet is 12.56 in², and seven times that is 87.9 in². 144 is not 88, and it isn't close. Any equipment change that alters a shared vent has to account for what's left behind — that's the water heater nobody talks about.
Who permits this work, and does the HOA get involved?
Highlands Ranch is unincorporated Douglas County, so permits and mechanical inspections go through the county. One jurisdiction, no ambiguity about who's coming out — unlike Littleton, which straddles three counties and where the answer depends on the address.
Separately, most of Highlands Ranch sits under HOA covenants and a metro district. That generally doesn't touch a boiler swap or a basement slab, which are interior. It can matter for anything visible outside — a driveway replacement for snowmelt, an exterior vent penetration, a manifold enclosure. We don't know your covenants and won't guess at them. Check with your association before the concrete work is scheduled, not after. The county permit and the HOA approval are separate things, and having one doesn't get you the other.
Where do you work?
We're based in Littleton and work the south metro: Highlands Ranch, Lone Tree, Castle Pines, Castle Rock, Centennial, Parker, Ken Caryl, and into Denver. No storefront and no office in Highlands Ranch — we're a service-area contractor and everything runs out of the truck.
If we're booked past when you need us, or if the honest answer is that your forced-air house should stay forced air, we'll say that on the phone. Call (303) 908-5658 or send details through the contact page: what the house is, roughly when it was built, and what you want fixed.
Related reading
— Ryan Van Inwegen, licensed hydronic contractor (LIC00254926), ByDesign Hydronics & Air, Littleton, CO
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