Boiler Care and Glycol

What does a yearly boiler care visit cover?

A yearly boiler care visit covers cleaning, leak checks, venting, water pressure, controls and the flame, all done by a qualified technician. Lochinvar's Knight Installation and Operation Manual for models 80–285 lists these service items in Table 12A:

• clean the condensate trap and refill it with fresh water;
• check for water, gas, flue and condensate leaks;
• confirm the flue and air pipes are sealed and in good shape;
• check system water pressure, piping and the expansion tank;
• check control settings, wiring and connections;
• clean and reposition the ignition and flame-sense electrodes and inspect the flame;
• clean the heat exchanger if the flue temperature runs more than 54°F above the return water temperature.

Other makers' lists differ, so the technician follows the manual for your model, including its high-altitude setup. CDC also advises having gas, oil and coal-burning heating appliances serviced by a qualified technician every year. Black Hills Energy's 2026 residential rebate form (read October 2026) pays up to $125 toward a boiler tune-up every 2 years for its Colorado gas customers; programs change, so check before you book the work.

Condensate is part of the visit. Lochinvar says the Knight's condensate is "slightly acidic (typically with a pH from 3 to 5)" and calls for a neutralizing filter where local codes require one. Pitkin County's Title 11 (effective May 2, 2026) does: all condensate from fuel-burning appliances must be neutralized before discharge. The neutralizer's media gets used up, so ask the technician to check it.

Why do some radiant systems use glycol?

Some radiant systems use glycol because part of the loop can freeze: snowmelt slabs, garages, and homes left empty for weeks. Caleffi's idronics article on heat exchanger applications (2021) explains that snowmelt-only systems often run entirely on antifreeze, while combined systems often put a heat exchanger between the snowmelt loop and the house, so most of the system runs on plain water.

The type matters. Lochinvar's manual says "NEVER use automotive antifreeze" and allows only inhibited propylene glycol made for hydronic systems, warning that ethylene glycol is toxic and can attack gaskets and seals. Dow's product page says DOWFROST inhibited propylene glycol solutions give freeze protection below −60°F; the right strength for your loop comes from the glycol maker's tables and the system designer, not a one-size chart. With an Aspen 1SW January average low of 9.9°F (NOAA NCEI 1991–2020 normals), a loop that loses circulation in a power outage can freeze in a cold spell; see heat during power outages.

How often should glycol be tested?

Glycol should be tested at least once a year and as often as the glycol maker recommends, according to Lochinvar's Knight manual. The same manual says freeze-protection fluid "must be replaced periodically due to degradation of inhibitors over time."

Leaks change the mix. Lochinvar notes that glycol may leak before water does, which lowers the concentration and the freeze protection, and that systems with automatic fill should have a water meter to show make-up water. Local codes may also require a backflow preventer, or a full disconnect from city water, on glycol systems. A technician tests freeze point and inhibitor level, then adds or replaces fluid; the amount has to include the expansion tank's water content.

What does the expansion tank do?

The expansion tank gives heating water room to grow as it warms and shrink as it cools, which keeps system pressure steady. Lochinvar describes tanks as open, closed, diaphragm or bladder types, and the Knight manual sets a minimum cold fill pressure of 12 psi.

A tank that has lost its air charge or is too small shows up as pressure that climbs sharply as the boiler heats. Lochinvar says that kind of rise "indicates expansion tank sizing or performance problem," and that a weeping relief valve may be caused by a waterlogged or undersized tank rather than a bad valve. PlumbingSupplyAndMore's hydronic expansion tanks (part of Upvalley Heat's ownership group) show the sizes and types a technician chooses from; checking the charge and replacing a tank are technician jobs.

Does water hardness matter for boiler care?

Water hardness matters on both sides of a boiler, but the two sides follow different rules. For the sealed loop that feeds radiant floors, Lochinvar's Knight manual asks for fill water under 7 grains of hardness and chlorine under 200 ppm, and tells installers in harder-water areas to consult local water treatment companies. Boiler fill water follows the boiler's own manual; no maker document checked for this page says anything about softened fill water.

Valley water varies. The City of Aspen's water FAQ calls its supply "very hard," 130–300 ppm (8–17 grains per gallon), changing with the season. Snowmass Water & Sanitation's 2025 report shows 74–104 ppm. Glenwood Springs, Carbondale and Basalt publish no hardness figure.

The domestic side is where hard water does most of its damage: scale builds in water heaters and in the hot-water side of combi boilers and indirect tanks. A softener such as SoftPro's Elite water softener (part of Upvalley Heat's ownership group) or a salt-free conditioner (part of Upvalley Heat's ownership group) at Quality Water Treatment is one way owners handle scale on that domestic water. Ask the boiler installer how the fill line is piped before treating it.

What can a homeowner check between visits?

A homeowner can look, listen and note, but leave the opening and adjusting to a technician. Lochinvar's owner list includes a daily look at the boiler area and its pressure and temperature gauge, and a monthly check of vent and air piping, the outdoor termination screens, the relief valve, the condensate drain and the air vents. If you are unsure what a reading means, stop there and call a qualified technician.

• Snow at the vents. Furnace makers set vent terminations at least 12 inches above the expected snow level, and each boiler manual sets its own clearances. After a storm, clear drifts from the outside pipes by hand or with a soft brush; if exhaust keeps icing or the boiler keeps locking out, call a technician.
• Drips. Water under the relief valve discharge pipe, at the manifold or around the tank is worth a service call, not a tightened fitting.
• Do not lift the relief valve lever yourself. Lochinvar warns of scalding water; operating and re-inspecting it is technician or inspection-agency work.

A boiler burns gas, so carbon monoxide rules apply. Colorado's 2009 law requires CO alarms within 15 feet of the entrance to each sleeping room in the homes it covers, including when a fuel-fired appliance is replaced under a permit; CPSC also advises one on every level. If an alarm sounds or anyone feels ill, get everyone outside to fresh air, then call 911. If you smell gas, leave first and call Black Hills Energy from outside; do not flip switches or use a phone indoors (Black Hills Energy). More in carbon monoxide safety.

Lift-line questions

Next runs

• Altitude: Boilers and water heaters at high altitude
• Radiant and snowmelt: Radiant floor heating
• Radiant and snowmelt: Snowmelt systems
• Folder: Radiant heat, boilers and snowmelt