Fitting a Webasto or Eberspacher Heater to a Boat | ButlerTechnikButlerTechnik Fitting a Webasto or Eberspacher Heater to a Boat | ButlerTechnik
Eberspacher Marine Webasto

5 thoughts on fitting your own Webasto or Eberspacher Boat Heater

How hard can it be?

I have a tool kit and I can take advice easily ….  so where’s the difficulty?

besides, I’m a practical guy (or gal) from a technical engineering background’

Many boat owners consider fitting their own Webasto or Eberspacher boat heater, and for very good reason.

There are some serious cash savings to be made sure, also isn’t it invariably so much easier to do-it-ourselves? It’s very inconvenient fitting in with your ‘local’ Webasto marine specialist – did I just say local? Just like Eberspacher approved dealers, there just isn’t one in every port, marina, or boatyard. Your time onboard is precious. Missed appointments and promises. Much tut tutting. Weeks passing by and still no diesel boat heater. Unfortunately a toasty new warranted heater system is seldom actually just a phone call away.

Where’s a decent factory-trained tradesman when you need them? You’re guaranteed of course to find one after the event – telling you where and how you did everything wrong eh?

It’s time you learn whether you’re likely to cut it as a self-installer. Yes, Webasto and Eberspacher heating systems definitely can be installed by a competent self-installer …. So we are going to cover the following areas:

(please note, I haven’t used the phrase DIYer)


… would you go up in a hot air balloon built by a DIYer?

Remember, on-board diesel fired heaters are potentially hazardous to life if incorrectly installed

Be honest with yourself. If you aren’t eagerly agreeing to the 5 points below leave the tools in the shed and reach for your wallet instead; fitting a boat heater can include working on safety-critical components and systems.

1. Do I have the time and required tools?

Okay, so not the obvious first question. Webasto diesel boat heaters aren’t a quickie fit. Eberspacher heater installations aren’t something to be rushed over. You need time to review your requirements (take the books to bed with you, there’s some great info to be found here for Eberspacher Airtronic marine heaters or here for Webasto boat heating ) A boat heater installation requires a plan.

Besides hole saws and power drills for mounting air outlets, screwdrivers and spanners for mounting the heater, what about electrical crimping tools? Not expensive, but if you haven’t got them it’s going to be a botched job.

Of course the professionals have much more, laptop diagnostic equipment such as these for Eberspacher or these for Webasto heaters, CO2 meters, fuel pump primers etc. Maybe at this stage they are probably not necessary.

2. Do I have the technical know-how – electrical?

Fitting a diesel boat heater involves working on your electrics. You’ve got to be comfortable with that thought.

Take a look at a typical wiring diagram for the latest Webasto EVO40 link or an Eberspacher D2 Airtronic electric diagram link.

typical electric

Do you understand exactly what this is about? The electrical wiring diagrams are not the easiest to understand –  but they are logical.

A few hints and pointers should certainly be available from your intended supplier. If your webshop guys aren’t answering their emails or can’t give simple quick answers for you, find another supplier. If they’re hard to get hold of before your purchase it’s not difficult to imagine how reactive they may be if you have any future queries

Remember, the electrical system is safety critical on your boat. If ever in doubt it’s crucially important to seek expert advice

3. Do I have the technical know-how – fuel systems?

Whether you’re connecting to existing fuel tank supply or fitting an additional tank all fuel connections are critical. Diesel is hazardous, it’s whole purpose is to burn, it needs to be treated with respect. Copper fuel lines are a requirement. Fireproof ISO7840 hose connections like these are essential. Consider, if there are leakages or spillages, will they flow onto hot surfaces, exhaust systems etc. Heater exhausts reach much higher temperatures than car exhaust pipes, always plan for the unexpected. Obviously all connections must be secure, protected and routed to prevent accidental damage.

It’s important also to wise up regarding maximum fuel line length requirements for your boat heater. These may vary between heater manufacturers. Also, your fuel supply, you need to be confident it is free from water and solids contamination, there’s no surer way of shortening the life of your boat heater than using poor quality fuel. Diesel suffers greatly from poor housekeeping and long on-board storage. Your fuel must also meet EN590 or BS2869A2 Gas oil standards

marine fuel system

Marine Heating fuel system

Once again, fuel systems are safety critical, if ever in doubt it’s crucially important to seek expert advice

4. Will I read the installation book thoroughly?

This is important. All the information you require for the safe and successful installation of your boat heater is either pre-supplied with your new heater or else easily and freely available online from reputable websites link

Both Eberspacher and Webasto have authored extremely informative installation guidelines for Marine heaters. They like having you as their customer. They wish most importantly for you to stay safe. Always read comprehensively the manufacturer installation manuals prior to deciding whether the self-install route is the correct choice for you. Make yourself aware of many aspects of installation. These will include permissible warm air ducting lengths, heater exhaust system requirements, combustion air sourcing and so much more before you take the plunge

Webasto marine exhaust

5. How and where can I buy a manufacturer guaranteed heater from?

Fitting a Webasto or Eberspacher heating system can be very rewarding – and not just with regard to your finances. The feel good factor upon hearing the exhaust burst into life for the first time  is always a joy.

Having fitted your own system you’ve also become more aware of your heater requirements should there ever be the need to service or repair your heater too. Your new diesel boat heater will have full OBD (on-board diagnostic) functionality should you choose to handle future maintenance and service work yourself also.

What a bonus, that’s future savings in the bag too !

Boat heater Size Chart in KW

How big will my boat heater need to be?

Remember, a carefully installed Eberspacher Airtronic or Webasto Air Top marine heater is an investment towards the long term passenger comfort of your boat. We’ve only touched on just a few aspects of how to safely install your Boat heater in this article. You may wish much more advice during the installation phase. Remember though, your planning is essential.

Choose carefully where you purchase your Webasto or Eberspacher boat heater from. Remember to ask if it’s a manufacturer dealer warranted heater. Confirm also exactly the level of warranty care and/or after-sales support that can be provided to you over the next 2-3 years of ownership

Happy Boating – stay warm inside