DH Hydronic Series – Diesel Hot Water and Air Heaters

DH Hydronic

The unique DH Hydronic Series consisting of the DH9, DH15 and DH30 diesel hot water systems provides fast hot water and optional air heating in the coldest of conditions in a super robust form.  Designed and assembled in Tasmania by Dieselheat, say goodbye to the hassles, risk (in boats) and cost of LPG and enjoy the benefits of hot water and air heating from one compact setup when free camping, sailing or off the grid.

The DH Hydronic series works by heating a tank of coolant using a diesel furnace and then using this to heat water via heat exchangers built into the tank. This coolant can then be piped to fan heads to allow optional air heating. The DH Hydronic series are a hybrid storage/instant on demand system, once pre-heated will provide instant hot water.

The DH Hydronic Series have the following features:

  • All 316 stainless steel, suitable for RVs and boats
  • Insulated tanks (DH15 and DH30) retains heat for efficient operation
  • Fast heat up time
  • Short term high flow rates to fill a sink or bucket
  • Continuous flow rate of approx. 2.5L/min allows long, hot, water-wise showers
  • Flexible installation arrangements allow installs in tight spaces for smaller Rvs and larger higher capacity systems for caravans or busses.
  • Integrated air heating (optional)
  • Includes Watermark approved tempering valve and fittings to ensure hot water is always delivered at safe temperatures

Advantages over Gas

  • Allows single fuel diesel or diesel electric installations.
  • Very safe, certified installers are not required.
  • Fast heat up times, from 7min to first hot water is quicker than gas storage.
  • Can provide hot water at very low flow rates like a dribble to rinse dishes, something an instant gas system cannot do.
  • First drop of water out of the system is hot, no long cold flow whilst the instant gas gets started.
  • Ideal for marine use where gas hot water is not suitable.

The DH Series comes in 3 sizes to suit all applications.

Comparison of Systems

DH9 Hydronic
DH15 Hydronic
DH30 Hydronic


Super compact, modular kit or pre-assembled, super fast heat up hydronic hot water

Compact, pre-assembled fast heat up hydronic hot water

Larger pre-assembled system where more hot water is needed.

Recommended uses

slide on campers, camper trailers, small motorhomes eg transporter, sprinter

caravans, off road trucks, larger motorhomes, small boats

large motorhomes, busses, off grid houses.

Furnace Options

Eberspacher D5E

Belief 5kW
Eberspacher D5E

Belief 5kW
Eberspacher D5E

Hydronic air heating compatible (optional)




Insulated Tank


10mm Fiberglass

10mm Fiberglass

Shipped As

modular kit or pre-assembled



Time to first useable hot water (from cold start)*




Time to fully heated*




Approx. regeneration time (ie time to reheat between showers)*




Length of time flow rates can be supported at temp rise of 30 deg.*

2L/min >15min
3L/min 9min
4L/min 3.5min
5L/min 2.5min

2L/min >15min
3L/min 13min
4L/min 6min
5L/min 3min

2L/min >15min
3L/min >15min
4L/min 12min
5L/min 7min
6L/min 5min

Long Term ‘Indefinite’ flow rate.*

2L/min @ rise of 30 degrees.

2L/min @ rise of 30 degrees.

2L/min @ rise of 30 degrees.

Recommended shower head flow rate

2.5L/min – 3.5L/min
Bricor Ultra Max

2.5L/min – 4.5L/min
Bricor Ultra Max
Bricor Elite

Up to 5L/min
Bricor Elite

Storage Medium

Coolant 9L

Coolant 15L

Coolant 30L

Required Space

300W x 280H x 280D
(assembled unit)

450W x 320H x 340D

630W x 320H x 380D

Approx. Dry Weight




Tank Construction

316 Stainless steel

316 Stainless steel inner and outer

*All values based on average ambient temperatures, actual results will vary depending on specific conditions.

The DH15 and DH30 can be set up with either a Belief (Chinese) or Eberspacher D5E (German) furnace. The DH9 is only compatible with the new Eberspacher D5E furnace.

Furnace Comparison

Eberspacher D5E
Belief 5kW


1.3kW to 5kW stepless

2kW or 5kW





Quietest option available due to better output modulation and quieter design.

Acceptable for hot water and occasional air heating, not recommended for overnight air heating operation.

Reliability / Service intervals*

Best in class
3000h+ service interval

Very good
1000h+ service interval

Fan Motor



Recommended Use

Combined hot water and air heating where air heating is needed overnight. Where a longer duty cycle is needed. Extended touring, live on board.

Primarily hot water systems where air heating use will be occasional. Recreational use.

*Service intervals are based on manufactures literature or our experience, they vary significantly due to fuel quality, dust ingress, how furnaces are used etc.

By adding in a Kalori fan head, the DH Series diesel hot water becomes an effective air heater, giving off up to 5kW of air heating from a range of Kalori fan heads.

kalori kuba fan head

Pair the DH9 or DH15 with a Bricor Ultra Max shower head to have super water-wise showers – only 2 to 2.5L/min. Great for a caravan or boat where water is limited.

bricor ultra max shower head

Pair the DH15 or DH30 with a Bricor Elite shower head for a more luxurious shower, whilst still only consuming 4 to 5L/min.

Backed by a two year warranty and with Dieselheat’s focus on great service, you will enjoy piping hot water, warmth and a good night’s sleep knowing that if you need help we have got your back.


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Two Year Warranty

All our products are backed by a two year warranty.

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0418 130 971

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Freight calculated on check out.