Other: Boiler tips (part 1 of 3)

Short, practical technician tips on other for boiler. Check each one against the manual for your exact model before acting.

Air separator location

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Place downstream of the boiler, upstream of the pump (hottest, lowest pressure water releases the most air).

Circulator pumps away from the expansion tank

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Tank can be on supply or return but the point of no pressure change must be on the pump suction side.

Eccentric reducers in hydronic piping

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Keep the top of pipe aligned when changing size so no air pocket forms.

Fan convectors pull heat from cooler water

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Kickspace/fan coils suit low-temp (condensing/radiant) loops where plain radiators won't.

Foaming boiler water fools the LWCO

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Clean and deaerate before commissioning.

Glycol systems need a transfer pump purge

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Recirculate from bucket back into the supply-side drain so the glycol is reclaimed, keep both hose ends submerged.

Never add air to an expansion tank with a compressor

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Bicycle pump only, check pressure every few strokes; over-pressure ruptures the bladder.

Never purge a hot boiler

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Cold fill water into a hot cast iron boiler can crack it; let it cool first.

Oversize flow-control valves on fast boilers

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Low-mass boilers that heat quickly may need larger flow checks to handle thermal expansion.

PRV has many names

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Pressure-reducing valve = boiler feed valve = fill valve; clarify.

Purge hose into a bucket of water

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Bubbles show when the air is gone; close shutoff downstream of the drain so flow is forced through the hose.

Purge valve = shutoff + drain in one body

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On systems with separate valves, close the shutoff downstream of the drain while purging.

Relief valve discharge pipe cut on an angle

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So nobody can cap or plug it; always pipe the relief to a safe spot.

Steam radiators work on hot water, not the reverse

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Don't put a hot-water-only radiator on a steam system.

Annual service requirement

Glow Brand · C95 & C140

The boiler must be serviced and inspected by a qualified technician every year in normal residential use. Demanding or commercial use may need more frequent service.

1. Schedule annual maintenance and inspection as described in section 14.2.
2. Note that skipping the maintenance schedule voids the warranty.

Anti-Legionella cycle

Glow Brand · C95 & C140 combi boilers in DHW Mode 1

Only active in DHW Mode 1. The control checks at least once every 168 hours (7 days) that the unit reached maximum control temperature. If not, it fires and starts the pump to raise the temperature above control temperature. Display shows 'ALEg' with the DHW sensor temperature, and the faucet icon blinks while the demand is handled.

Anti-legionella function behaviour

Glow Brand · DHW mode 1, storage tank with sensor

In DHW mode 1, anti-legionella can run if the tank does not reach 60°C / 140°F within 2 hours after first installation of a storage tank with sensor.

1. Confirm the tank reaches 60°C / 140°F within 2 hours after first start-up.
2. Use parameter 2.206 to enable or disable the function if needed.

Aquastat display reading in DHW mode 2

Glow Brand · DHW mode 2 with storage tank aquastat

With an aquastat tank and a DHW call, the display shows 864.8°F (462.7°C). This is normal and comes from the aquastat resistance, which can vary slightly with brand.

Before servicing the boiler

Glow Brand · C95 & C140 Glow Combi boilers

Basic precautions before any service work on the boiler.

1. Disconnect or shut off all energy sources: 120VAC power, water and gas.
2. Identify and mark wires before disconnecting them.
3. Do not bypass electrical fuses or limit devices except briefly for testing.
4. Wear proper PPE, including eye protection and safety footwear.
5. Only qualified service personnel should carry out these procedures.

Boiler location requirements

Glow Brand · C95 & C140

Install the boiler indoors in a dry location where the ambient temperature stays above freezing. Keep gas components away from dripping or spraying water.

1. Choose an indoor, dry location kept above freezing.
2. Protect gas components from dripping and spraying water.
3. Check the location against system piping, gas and electrical supply, condensate drain, and vent termination.
4. In an unheated area, keep the unit powered continuously so frost protection stays active.

Clean the condensate trap after the first few months

Glow Brand · Condensate trap maintenance

New components leave deposits after the first condensate passage that can affect trap operation.

1. After a few months of combi operation, clean the condensate trap to remove deposits and residue.

Combustion air contamination sources

Glow Brand · Combustion air supply

Air containing these chemicals or dust will damage the heat exchanger and void the warranty. Pipe intake air directly to the outdoors where possible.

1. Avoid installing near laundry facilities, dry cleaners, chemical fertilizer or pesticide areas, farms with livestock, woodworking or refinishing shops, auto body or metal shops, refrigerant repair shops, beauty shops, pool or hot tub areas, photo or plastics labs, and concrete or construction sites.
2. Do not operate the boiler in an area under construction or renovation.

Crystalline silica in the combustion chamber

Glow Brand · C95 & C140

Some components in the combustion chamber may contain crystalline silica, a potential carcinogen. Improper service can cause exposure. Handling instructions and protective equipment are in Section 14.

1. Review the handling instructions in Section 14 before servicing the combustion chamber.
2. Use the recommended personal protective equipment.

Display symbols reference

Glow Brand · C95 & C140

Main screen icons shown on the LCD display.

1. Radiator icon: CH enabled; blinks when handling CH demand.
2. Faucet icon: DHW enabled; blinks when handling DHW demand.
3. Wrench icon: blinks when service is required.
4. Flame icon: burner is on and heating.
5. No flame icon: unit cannot start, lockout or blocking error present.
6. Frost icon: blinks when anti-frost protection is active.
7. OTC icon: outdoor temperature compensation is active.

Do not vent into a chimney or with other appliances

Glow Brand · All venting installations

Venting restrictions that apply to every installation.

1. Do not vent into an existing chimney or chase unless the vent is run through a vacant chimney using approved material.
2. Do not common-vent the boiler with any other gas appliance or vent stack.
3. Pipe the exhaust and combustion air intake separately.
4. Do not insulate PVC or CPVC vent in a conditioned space.
5. Do not terminate the vent over public walkways, near soffit vents, crawl spaces, or where condensate could cause a hazard or damage.

Domestic hot water scald protection

Glow Brand · C95 & C140

Water over 125°F/52°C can cause severe burns or death. Set the domestic hot water to the lowest temperature that meets user needs. 120°F/49°C is recommended to reduce scald risk. A tempering valve in the domestic hot water supply is recommended.

1. Set the domestic hot water temperature to the lowest setting that meets the user's needs.
2. Set 120°F/49°C or lower where possible to reduce scald risk.
3. Install a tempering valve in the domestic hot water supply.
4. Advise users that small children and disabled persons need supervision at hot taps and in bathtubs or showers.

Domestic inlet screen

Glow Brand · C95 & C140

A combined flow restrictor and inlet screen sits in the domestic water chamber. It twists out for cleaning. Never run the boiler without it, since debris can cause poor operation or malfunction.

1. Twist the grip to remove the restrictor and screen cartridge.
2. Clean or inspect the screen.
3. Reinstall the screen before operating the boiler.

Error display types and blink rates

Glow Brand · C95 & C140 combi boilers

Lockout shows 'Loc' top-left, blocking error shows 'Err', warning shows 'AttE'; the specific code appears large on the right. Backlight blink rate: lockout every 0.5 s, blocking error every 1 s, warning every 1.5 s. Lockouts 1 and 2 are hard lockouts and need RESET pressed and held. Blocking errors clear only after the fault is fixed. Warnings clear by cycling power or pressing RESET. User and Installer menus stay accessible during all three.

1. Press and hold RESET to clear a lockout.
2. Fix the cause before expecting a blocking error to clear.
3. Cycle power or press RESET to clear a warning.

Flue microfuse replacement

Glow Brand · Primary heat exchanger

Flue microfuse on top right of primary heat exchanger opens above 336°F (169°C). If it opens, the primary heat exchanger must be replaced.

1. Check the microfuse on the top right of the primary heat exchanger if an overheat event is suspected.
2. If the microfuse is open, replace the primary heat exchanger.

Hard water and domestic cleaning

Glow Brand · C95 & C140

Water harder than 50 ppm calcium carbonate needs a water softener before the appliance. Brazed plate heat exchangers can be cleaned with weak acid (5% phosphoric, or 5% oxalic if cleaned often), pumped at 1.5 times normal flow, preferably back-flushed. Rinse with clean water, then neutralize with a 1-2% sodium hydroxide or sodium bicarbonate solution before the final rinse.

1. Install a water softener if hardness is above 50 ppm calcium carbonate.
2. Clean the brazed plate with weak acid at about 1.5 times normal flow, preferably back-flushed.
3. Rinse thoroughly with clean water.
4. Neutralize with a 1-2% NaOH or NaHCO3 solution, then do a final rinse.