19 February 2021

Heater project - getting started

The engineer has been thinking about whether it is possible to install a diesel heater on Nahani for years. He's looked at other people's boat heaters, visited the suppliers here, wrestled mentally with the issue of where to put the burner and how to pipe the heat into the cabin.

In 2021, we decide to get more serious. Everything on the back shelves and the floor is taken out of the shed, more than once, so that we can think about where to locate things, and look under the floor to see where heating ducts could go. We look at the pros and cons of the Eberspächer and Wallas systems. The engineer leans toward choosing the Wallas, because it's designed for boats rather than RAVs and caravans, but there is a problem. The Wallas uses ducted air. After much consideration and a visit from Dieslheat to inspect the boat, we all reluctantly agree that there is no way that you can get the big air ducts forward into the saloon from aft in the shed where the burner will go, .

We settle on the alternative, which is an Eberspächer with hydronic heating. We think that the smaller pipes carrying the circulating fluid will fit under the floors of the shed and the head. The Dieselheat guy also tells us that we can connect the heater system to the hot water as well, with ball valves that can be used to direct the heating fluid to either the saloon outlets or to the hot water tank. That means that if we stay out of the marina for an extended period not only can we heat the boat but we can also have hot showers without having to run either the engine or the generator. That's a very attractive option which clinches the decision to go with the Eberspächer hydronic option.

The next problem to solve is where to locate the exhaust. This involves making a hole in the boat somewhere, either in the hull or on the deck. After extensive thought and consultation with the guys at Dieselheat and with Steve, who built Nahani, we decide to bring the exhaust up through the scuppers and into a pipe which will raise it well above the waterline. The pipe will have a 180 degree curve at the top to prevent water coming in from above, and will be able to be plugged if you were sailing in heavy seas to prevent sea water ingress. The engineer buys the requisite bits of pipe, and works out a way to make the exit through the scuppers watertight.

Dieselheat deliver all the gear to the RYCT in multiple large cardboard boxes, which are temporarily stashed in the car because we can't make a start until our guest departs. After a bit of post-guest R&R, the project starts with the removal of everything in the back on the shed, and putting it into  the guest bunk.


The boxes are opened and their contents distributed around the boat, along with lots of tools.

Chart table

Saloon seat


The engineer makes multiple trips to "Map 11" (Moonah and Glenorchy) to purchase additional requirements such as more hole saw blades - it takes 3 blades and a borrowed high-powered drill to cut a circular hole through the stainless steel ring frame that forms Nahani's scuppers.

Next issue is to work out where to put the valves which adjust the flow of heating fluid between the heating system and the hot water. Dieselheat suggest that most people put these right at the heater itself. This solution is so much better than the underfloor options we were considering. The engineer had planned to try and keep the option open to reconnect the feed from the engine to the HWS, but now realises that all will be cleaner and simpler if there is a straight connection from the diverter valve to the HWS. The installation plan is getting better all the time.

First irreversible step is cutting the hole in the scuppers, which was the first thing the engineer did, earlier this week. Second step is taken today when the exhaust pipe is locked into position, with appropriate sealant to stop water ingress.

The engineer is still busy beavering away in the back of the shed, where he is mounting the heater, the header tank for the circulating fluid, and the diverter valves that switch the flow between the systems. Here he is, happy in his work.



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