'Wet' Heating in Motor Boat

[rgsmg53]

Apologies if this specific question has been asked recently. I've been reading the many threads on here re boat heating (which are really useful) and have decided that a wet heating system will meet my needs best.

I want to fit a wet heating system to a twin engine motor boat which currently has no 'on the go' heating. I'm thinking of installing a wet diesel heater (eg Eberspacher Hydronic) powering a pumped flow and return circuit feeding radiators and also one coil of a twin-coil calorifier. The other coil of the calorifier would then be connected to one engine's fresh water cooling circuit (as the existing single-coil calorifier is already).

Is this possible? I can't see why not from a plumbing point of view but I may be missing something.

Does anyone have this set-up already and what is their experience of it?

 

[Paragon]

Have more or less this exact system on a 44' mono hull sailing boat and it works great. Hot water and heat from the same source, and quite economically too. I've got the Webasto ST90 "boiler" and it appears to be an effective and reliable unit, I did purchase it "refurbished" from fellow forumite and very helpful chap David of East Coast Marine. I installed the system myself using HepO2 piping and it's been very effective.

David is definitly the expert here and comes highly recommended by me, and I'm sure many other forumites.

 

[rgsmg53]

Thanks, Paragon.

I feel a PM to David coming on!

I had already decided that Hep2O was the way to do the plumbing.

Any advice on rads? Or have you gone for the 'finned pipe' approach?

 

[David2452]

Thanks, Paragon.

I feel a PM to David coming on!

I had already decided that Hep2O was the way to do the plumbing.

Any advice on rads? Or have you gone for the 'finned pipe' approach?

Finrads are not so good, the best rads to use are type 22, they are available in many sizes, the chalenge is finding space for them. As for your concept, that is exactly how it is done as a default and apart from the usual hot air systems I fit 8 or 10 wet systems a year to inland waterways craft with just that setup, but with more choice for radiator siting. I have a factory marine install manual for wet systems which would be very informative, if you would like a PDF copy just drop me a PM.

 

[Playtime]

I installed a Hydronic 5 on a 40' sailing boat using Hep2O piping and found it very straightforward. I used small matrix blown hot air units in each cabin as these can be hidden in the lockers/cupboards rather than radiators, space for which can be a problem on a sailing boat. The advantages of the small matrix units are that they can be individually controlled (off/slow/high) and the whole system heats up quickly as the required volume of water is lower than with radiators. The downside is that they are a bit noisy when all blowing on high. The Eberspacher boiler has been faultless in 5 seasons.
One tip - look at the kits for inland waterway craft; they are usually much cheaper than for marine craft. You will have to replace a couple of parts (eg transom exhaust fitting - needs to be stainless not black painted steel) but it still works out way cheaper.