Apollo C1 Diesel Coolant Heater — 5KW Parking Heater for Car, Caravan, Truck and Boat

• Warms your engine and your cabin at the same time 鈥 one unit does both jobs
• Full heat in 20–30 minutes with the engine off and the key out of the ignition
• Starts down to -40°F (-40°C) on a Kyocera ceramic glow plug
• 12V or 24V — the circulation pump, metering pump and harness all ship in the voltage you choose
• Draws about 3.5A at 12V while running, so a healthy leisure battery carries it overnight
• CE and RoHS tested, with certificate numbers you can look up

One Heater, Two Jobs — Engine and Cabin

The Apollo C1 is a 5KW diesel-fired coolant heater and engine preheater. It burns 0.30–0.61 L of diesel per hour and brings your engine coolant to 140–176°F (60–80°C). The engine stays off and the key stays out of the ignition.

You will see this type of 5KW unit sold under several names. Hydronic coolant heater, liquid parking heater, diesel water heater, engine preheater, car parking heater — they all describe the same machine. It is a diesel burner plumbed into your vehicle’s coolant loop.

Job one — the engine. Warm coolant means warm oil. Your oil flows on the first crank instead of sitting thick in the pan, which is where most cold-start wear comes from.

Job two — the cabin. The same hot coolant runs through the heater core you already have. Your dashboard controls, blower and vents work exactly as they do when the engine is running.

Will the Apollo C1 Fit Your Vehicle

The Apollo C1 suits engines up to roughly 6 liters, on any coolant circuit holding at least 4 liters (1.06 gallons) of fluid. Below 4 liters the loop heats too fast and the overheat sensor trips during startup.

Your vehicle	What to buy
Car, van, campervan, caravan, pickup, small boat — engine under 6L	Apollo C1 — this page
Heavy truck, coach, plant machinery, large boat — engine over 6L	12KW Apollo C3 coolant heater
No coolant loop, or you only want warm air blown into a space	diesel air heater
Hot water for a shower, sink or galley tap	diesel hot water system
Petrol or gasoline engine instead of diesel	Apollo GC5 gasoline coolant heater

12V or 24V? Pick by vehicle, not by country. 12V covers cars, vans, campervans, caravans, pickups and most boats. 24V covers heavy trucks, coaches and construction machinery.

Whichever you pick, the whole kit matches it. The water circulation pump, the fuel metering pump and the wiring harness all ship in that voltage. No converters, no resistors, nothing left for you to source.

Not sure which version your coolant circuit needs? Send us your engine size and vehicle and we will tell you before you order — info@vvkb.com.

Why Not the Cheap “Water Heater” — and Why Not the Webasto

Most cheap diesel “water heaters” on marketplaces are air heaters with a water jacket bolted on. They were never designed around coolant circulation. The heat exchanger corrodes, the pump fails, and the burner is calibrated for air rather than liquid.

The Apollo C1 was built as a coolant heater from the start. Combustion chamber, heat exchanger, circulation pump and fuel delivery are matched to one job — moving heat into liquid at -40°F (-40°C), season after season.

At the other end sits the Webasto Thermo Top EVO 5, whose US kits start around $1,260 and run well past that. The premium buys a European dealer network and more vehicle-specific mounting kits. The Apollo C1 delivers the same 5.2KW class output with free shipping. It carries CE and RoHS certificates you can look up by number, a Kyocera ceramic glow plug, and Tyco automotive connectors.

What It Costs to Run Overnight

The Apollo C1 draws about 3.5A at 12V once running — roughly 28 amp-hours across an eight-hour night. That is the heater’s 28W burner electronics plus the 14W circulation pump. On the 24V version the same 42W works out to about 1.75A, or 14 amp-hours a night.

Your own blower fan is the bigger load. A vehicle cabin blower on a high setting pulls 5–15A on its own, several times what the heater uses. Check its rating before you plan a full night of cabin heat off a single battery.

On fuel, the low setting burns 0.30 L/hr — about 0.6 gallons (2.4 L) over eight hours. The heater also watches supply voltage and shuts itself down before the battery drops too far, which on the 12V version means below 10.5V. That cut-out is protection working, not a fault.

Full Specifications

Specification	Details
Brand	Vvkb
Model	Apollo-C1
Type	Diesel coolant heater (hydronic parking heater)
Fuel	Diesel, up to B10 biodiesel blend
Heat output	5.2KW full / 2.5KW partial (17,700 / 8,500 BTU/hr)
Voltage	12V or 24V
Working voltage, 12V version	10.5–15V
Fuel consumption	0.30–0.61 L/hr (0.08–0.16 gal/hr)
Electrical draw, heater	18–28W
Electrical draw, circulation pump	14W (pump supplied in 12V or 24V to match the heater)
Standby current	Under 1.0 mA
Coolant outlet temperature	140–176°F (60–80°C)
Minimum coolant volume	4.0 liters (1.06 gal)
Minimum coolant flow	250 L/hr (66 gal/hr)
Circulation pump flow	About 900 L/hr at 0.1 bar
Heat exchanger volume	0.15 liters
Operating pressure	0.4–2.5 bar (6–36 psi)
Coolant line inner diameter	20 mm
Metering pump	228 ml/hr at 1 Hz, supplied in 12V or 24V to match the heater
Dimensions	8.4 × 4.2 × 6.6 in (214 × 106 × 168 mm)
Net weight	6.4 lb (2.9 kg)
Operating ambient temperature	-40°F to +140°F (-40°C to +60°C)
Storage temperature	-40°F to +248°F (-40°C to +120°C)
Mounting	3 × M6 bolts, up to 30° tilt and 90° rotation
Exhaust pipe	φ24mm, 20–39 in (500–1,000 mm) run
Combustion air intake	φ25mm, up to 16 in (400 mm)
Fuel line limits	Tank to pump max 4 ft (1.2 m); pump to heater max 19 ft (5.8 m)
Certification	CE (EMC 2014/30/EU and LVD 2014/35/EU), RoHS (EU) 2015/863
Warranty	1 year, extension available

What’s in the Box

Everything a standard installation needs ships with the heater. You supply the diesel from your existing tank and the coolant already in your vehicle.

Main components

• Apollo-C1 heater unit
• Water circulation pump with bracket — 12V or 24V to match your heater
• Fuel metering pump with bracket — 12V or 24V to match your heater
• Digital controller with wireless remote
• Wiring harness

Installation accessories

• 3 m coolant hose
• Stainless steel exhaust pipe (φ24mm)
• Combustion air intake pipe (φ25mm)
• Exhaust muffler
• Fuel filter
• Fuel standpipe
• Elbow connection fittings
• Mounting brackets
• Clamps, nuts and hardware

Installation — the Four Details Behind Most Callbacks

Most Apollo C1 complaints trace back to four installation details, not to the heater. Budget 2–4 hours and get these right the first time.

1. Mount the heater at or below the low point of the coolant loop. Air collects at the high point. If the heater sits up top, an air pocket forms in the heat exchanger, heat never reaches your heater core, and the unit short-cycles. Bleed the system fully before the first run.
2. Feed fuel from a standpipe, not a tee into the vehicle fuel line. Tapping the engine feed is the single most common cause of support calls on this class of heater. Fit the included fuel standpipe into the tank and angle the metering pump 15–45° upward. Keep tank-to-pump under 4 ft (1.2 m) and pump-to-heater under 19 ft (5.8 m).
3. Give it thick cable and a clean ground. Long thin wiring drops voltage, the glow plug under-heats, and you get ignition faults that look like a dead heater. Run the supply straight to the battery or busbar and scrape the ground point back to bare metal.
4. Keep the exhaust run to 20–39 in (500–1,000 mm). Fit the muffler at least 8 in (200 mm) from the heater. Keep the outlet 0.8 in (20 mm) clear of brake lines and wiring, and point it down or up to 20° rearward. Never point it toward the direction of travel.

Watch the full walkthrough: Apollo C1 diesel coolant heater installation video.

Spare Parts and Service

Every wear part on the Apollo C1 is sold separately, and you can change all of them with hand tools. That is the difference between a heater you own for ten winters and one you throw away in year three.

The replacement glow plug, fuel pump, burner and gasket set, combustion blower, control panel, ECU and exhaust pipe are all stocked. Browse the full range of diesel heater spare parts.

Shipping, returns and warranty terms are set out on our help centre page. Technical questions before or after purchase go to info@vvkb.com and reach a person who has the wiring diagrams.

Frequently Asked Questions

Will the Apollo C1 flatten my battery if I run it all night?

Not on a healthy battery. The heater plus its circulation pump draw about 3.5A on the 12V version, or roughly 28 amp-hours across eight hours. On the 24V version the same load is about 1.75A and 14 amp-hours. Each ignition cycle adds a short high-current burst while the glow plug fires. The load that catches people out is the vehicle’s own cabin blower, which can pull 5–15A on a high setting. Run the heater from a leisure or house bank rather than the starter battery when you plan long overnight sessions. The heater also shuts itself down when supply voltage drops too far — below 10.5V on the 12V version. It will not drain the battery past a restart.

My coolant loop heats unevenly and the heater keeps cycling on and off. What is wrong?

Almost always an air pocket, not a faulty heater. Air collects at the highest point of the circuit. If the Apollo C1 or its hose runs sit above the low point, that trapped air stops coolant moving through the heat exchanger. The unit then heats a small volume of fluid very fast, trips its overheat sensor, and cycles. Mount the heater at or below the low point of the loop. Bleed the system with the cap off until no more bubbles appear, then run a test cycle before you close everything up.

Can I use the Apollo C1 to make hot water for a shower or sink?

No, and this is worth being clear about before you buy. The Apollo C1 controls coolant temperature for an engine circuit, not potable water temperature for washing, and it has no calorifier or tank. If you want hot water at a tap, buy the diesel hot water system instead, which is built for that job. Plumbing a coolant heater into a domestic water loop is the mistake behind most disappointed reviews of this product class.

It tries to start three times and then quits. Is it defective?

Almost certainly not. On a fresh installation the fuel line is empty and needs priming. The Apollo C1 runs three automatic ignition attempts to pull fuel through and build pressure. Wait five minutes and restart. If it still fails after three or four attempts, check for air leaks between the tank and the metering pump. Confirm the pump is angled 15–45° upward.

What do the flashing fault codes mean?

The status light flashes in groups of five. A long flash is 1, a short flash is 0, and there is a three-second gap between groups. The five you are most likely to see: 01101 is a failed ignition, usually air in the fuel line on first use. 11110 is overheating, which points to low coolant or restricted flow. 10010 is an open glow plug circuit. 10110 is a circulation pump fault, which also appears if nothing is wired to the pump circuit. 00011 is undervoltage. The full fault code guide covers the rest, and the complete table is printed in the manual in the box.

Does it work with my existing dashboard controls and heater core?

Yes. The Apollo C1 heats your coolant to 140–176°F (60–80°C) and pushes it through the cooling circuit you already have, including your heater core. Your dashboard temperature dial, blower speed and vent selection behave exactly as they do with the engine running. The heater’s own controller manages the burner and the coolant pump; your vehicle handles air distribution. No second heater core and no dashboard modification is needed.

How long does the glow plug last, and can I get parts later?

Plan on replacing the glow plug every two to three years with regular winter use. Carbon buildup is what kills them early. Running the heater at full output for five to ten minutes before shutdown burns off residue and extends its life. Replacement Kyocera glow plugs, part number 9812HD50P005, ship from stock. So does every other wear part: fuel pump, burner and gasket, blower motor, control panel and ECU. You can see the whole range on the diesel heater spare parts page.

Can I run biodiesel or a winter diesel blend?

Winter and arctic diesel blends work with no adjustment at all. Biodiesel is supported up to B10, meaning a 10 percent FAME blend. Pure biodiesel is not compatible because it shifts the air-to-fuel calibration and causes ignition failures. When you switch fuel types, run the heater for about 15 minutes so the new fuel fills the lines before you rely on it.

How does it compare with a Webasto Thermo Top EVO?

Both are 5.2KW class diesel coolant heaters that plumb into the vehicle cooling circuit the same way. Webasto gives you a wider dealer network and more vehicle-specific brackets for European vehicles, and its US kits start around $1,260. The Apollo C1 ships free and carries CE and RoHS certificates with numbers you can check. It uses a Kyocera ceramic glow plug, and every spare part is sold individually. A repair is a part, not a new heater.