Fitting a diesel fuelled, warm air heater, Part 2.

Day 1 on the boat

Day 1 of the installation work on the boat went pretty well, as is often the case some things I though would be tricky turned out to be straightforward and some things that should have been easy turned out not to be so, fortunately only one problem cropped up, that will take some time to fix but is easy to do and will not cost anything.

Fitting the trunking to the heater in its final position would be tricky so I ran the trunking first so I could fit it to the heater outside of the locker then move it in. There were two issues with the kit:

1. The documentation said you have to split the unit to remove the output grill before fitting the ducting, WRONG!. The grill now removes with a simple twist.
2. The duct to heater connection is very short and there is no jubilee clip supplied so it was down to the chandlery for one.

The hole in the bulkhead needed to be enlarged because as noted in the previous post it was previously used for the exhaust. Apart from holding a heavy corded drill at close to arms length through a small hatch to reach it (the arbor of the cutter was too big to fit on the battery drill) that turned out to be easy and the duct went straight through to the front of the cockpit locker without getting stuck on the fuel tank. Routing it through the below galley space was again straight forward although the fresh water pump and filter had to be unscrewed / bolted from their positions.

Unfortunately the hole for old warm air vent into the cabin was a different size and the new one needs to be moved an inch, in part to give sensible access to the sink waste water sea cock, that means a timber pad will have to go over the area to carry the vent and to cover part of the old hole, fortunately I have some Sapele left over from the headlining that will serve once cut to size, drilled, finished and varnished which I'll do at home.

Mounting the heater unit was straight forward with only a little filing required on the 2 holes I drilled at home. 

The unit mounted with all connections. I have not yet decided
if I will put some hose on the fresh air inlet to get it nearer to the
dome vent to starboard, doing so apparently makes the unit noisier,
 currently it is nice and quiet. The cables are deliberately not taken
directly outboard to avoid rising heat from the unit, a few more ties
around them and a fixing to the deck will be added.

Electrics were next, again straightforward although the 7m cable to the control unit, the longest available, was not quite long enough to reach its appointed place on the main electrical panel so the controller ended up on the bulkhead behind the chart table.

It is recommended that the power is connected to an unswitched supply, the stated reason is to preserve settings, time and date etc. held in memory, but the basic controller I opted for does not have any settings beyond a potentiometer to control power (or temperature with the optional sensor I don't have). A non-stated reason is probably to ensure that the power is not switched off before the unit had finished its shut down procedure to cool the unit and blow out any fumes, there is a warning about removing power whilst this is happening. [Update: confusingly another piece of documentation I found in 2023, possibly an update, recommended using a switched supply and turning if off if not being used for a while]

I don't like having power on non essential items when the boat is unattended, or indeed at sea, so I have installed a switch but independent of the main domestic switch. As the supplied fuses (on positive and negative lines) are 25 Amp, a toggle switch would be insufficient, so I used a basic (£4) 75 Amp battery isolator switch (with a removable key), that was installed by the main battery selector switches so its unlikely to be accidentally switched off prematurely. The downside is a minute or twos wait when starting the heater for the controller to connect to the unit.

To get the unit running, on the next visit I just need to fit the fuel tank and system and lag the exhaust - strangely the unit comes with 1 metre of exhaust but only half a metre of insolation, perhaps on the assumption that only the section before the silencer needs to be lagged although the documentation does not say any thing about that. So I had to get some "exhaust and manifold insulating tape" (£9.50 including postage for 15 metres of 2" tape & stainless cable ties) to do the job.

The standard 1 metre exhaust is sufficient but a bit more would be better and can be specified, although the £100 integrated exhaust and tubular silencer (that comes fully lagged) would, at two metres with the silencer a metre of that and not bendable, probably be too long with the unit where I have fitted it.

Day 2.

Initially every thing went very smoothly, I started by spending an hour or so refitting the fresh water pump and filter - it was too cold to comfortably work outside but it quickly warmed up and by afternoon it was a lovely winters day and I was working in shirt sleeves.

The fuel tank went in low enough to enable it to be filled from a 5 litre can, but probably not a 10 litre,  whilst still meeting the distance requirements vs the heater unit and fuel pump. 

The fuel tank fitted to the back of the life raft locker, rudder shaft
tube on the right. The tank is under the aft deck and does not
obstruct the  lazarette hatches. The cable hanging over the engine
exhaust is not normally there, it was being moved away from
the heater exhaust.

The tank is mounted on a board so that the mounting brackets can turn inwards, if they went outwards the upper one would need to be bolted through the support for the aft cockpit seat or through the coaming above the seat and the ones below would be out of easy reach.

The brackets were supplied bent and drilled at one end but not the other, unlike the pictures on the web site, this gives more flexibility but means you have to bend the very substantial brackets, doing that accurately and at right angles without a "bending machine" requires care and quite a lot of grunt. I did that at home, doing it on the boat would not be practical.

The fuel pipe and exhaust went on easily with, for the moment, just the supplied insulation. But when I put the power on everything was dead, power was at the connector by the unit and fiddling with all of the connectors made no difference. As it was early afternoon and I had a 2 hour drive ahead of me I rang the supplier, who asks for technical queries by email, I got a call back from an engineering type with commendable speed, he told me how to trick the system on and when it then started he was 99.?% sure that the problem was a connector on the control side - apparently they have had only a couple of duff controllers from over 10,000 units in service (mainly on lorries). I removed the controller from the 7 metre cable and used the short standard cable and things came to life.

I decided that continuing on I would have got home very late, particularly if I did the 2 hour test and burn in, and having missed lunch (the café was unexpectedly closed) I wanted my dinner so headed home after about 6 hours work.

Day 3

Was an easy day apart from grovelling in awkward places. I quickly found the problem in the long control cable connector and did a short test run. All that was left to do was re fit the control to the panel (serious grovelling going head first into the quarter berth - at least for those like me who are no longer very flexible), lagging the exhaust (I should have worn gloves dong that to avoid the itchy fibres and dirty hands) and securing cables etc. It was then off for a relaxed lunch whilst the 2 hour run in / test completed and I was home nice and early.

The duct is protected from being crushed by cans etc. in the locker.

Having done all that I think we can be assured of a nice warm spring and autumn so that I'll not need to use it! 

Update June 2022

The heater worked well and was a huge benefit on my 2022 attempt to get to St Kilda fuel consumption was modest and drain on the battery usually about 1.6 amps once it got going. I have decided to leave the boat on the mooring for much of next winter so upgraded the system to include a remote temperature sensor and a "comfort" controller. I also replaced the simple on off switch with a selector switch so that I can run the heater from either of the service batteries independently of which is in use for other systems.

Update December 2023

I had to take the heater out to fix a problem and managed to drop it a few inches which broke the Vermiculite fire brick that the silencer was fixed on, to improve the angle to the exhaust outlet on the transom, to  make it a bit more sturdy and to give more clearance underneath I redesigned the mounting:

The view from what will be the outboard and (hidden) side
with the unit upside down, the air inlet will hang down clearing
the exhaust.

All done apart from securing the cables etc - I left the fitting
and plastic conduit I needed at home 😒

Fitting a diesel fuelled, warm air heater, Part 1.

A poor picture looking aft in the locker (for some reason the
flash did not activate, it is easier to see when expanded). The
small pipe is the gas line, the hole in the bulkhead took the
exhaust. The drilled hole in the frame was the main support
for the heater.

Sancerre came with a long defunct "Eberspacher" diesel fuelled warm air heater, last years very cold cruise has convinced me it is a good idea to have one (or at least to take the electric heater for use in marinas!). The Eberspacher heater is rather expensive, and some cheap Chinese made look-alikes have a rather dodgy reputation, so I took a middle path and went for a Russian (now Latvian) made "AutoTerm" (previously Planar) which has had some good reviews and is more sensibly priced. 

Unfortunately, it is not a direct replacement, the Eberspacher had been mounted in the port cockpit locker, right next to the Gas line, almost impossible to get at, mounted on a rather fragile piece of ply and taking its air from a rather smelly locker, since I got rid of the bladder tank and sorted out a few other things it is not as smelly now but I do keep diesel cans in there so it will always have some niff.

Also having put the new large fuel tank in this locker putting the heater in there with it would not be a good idea. 

The other side of the bulkhead, the gas locker on
the right. Unfortunately, the hole originally
for the exhaust is not large enough for the
60mm output duct.

Although a little cramped, a better location is the Lazarette which already has a good-sized dome vent for the air supply. The only component to be re-used will be the exhaust vent on the transom. 

Most of the old fuel supply was removed some time ago, but not the first part, whoever installed the bladder tank ran the heater fuel supply pipe down the breather for the tank from a point well below the level of the fuel filler, that meant if you filled the tank up into the fuel filler pipe, diesel leaked out through the entry point. And from the breather itself which no longer ran up to the original vent fitting, all of that was fixed with the new tank.

I am leery about using the main tank to also supply the heater, even though the newly installed fuel sender is as accurate as they get, there is always the risk of letting the heater use rather more than intended. More importantly putting a T piece in the fuel line leaves open the possibility of syphoning diesel out of the tank if there is a fault in the heater. And if a T piece is used there is a risk of introducing air into the engine supply which inevitably would happen at an embarrassing moment when the engine was needed. 

A separate 7.5 litre fuel tank is the answer and in theory holds enough fuel to operate the heater for between 32 and 75 hours. That fits well immediately in front of the rudder tube, biased to starboard to help filling and to keep it clear of the engine exhaust. The mounts will be bolted through the back of the life raft stowage space. Filling directly from a 10 litre can would be problematic even with a funnel but its fine from my 5 Litre..

The forward four (of five) M10 bolts securing the drogue plate.
Two of these will provide a convenient mounting point for the
heater just requiring a couple of holes to be drilled in the
provided mounting plate, one bolt will probably have to
replaced with a longer one.

The fuel pump (that has to be below the lowest fuel level) and the fuel line, are mounted on a timber strip (the remains of the Teak capping piece on the galley surround recently removed) running out and up to the port side near to the heater. 

Each visit to the boat requires 3.5 - 4 hours of travel and with the boat out of the water I can't stay on board so as much of the assembly as possible was done at home.

With limited space to fit the silencer I opted to mount it vertically and close to the heater which gives more flexibility in routing the exhaust to the vent. It would probably be self-supporting but better safe than sorry and to avoid potentially warranty issues by not following the instructions I mounted it to a block of Vermiculite fire brick fixed to the mounting bracket, that will prevent conduction taking heat directly to the mounting bracket and will shield the fuel line which will route behind the block.

In retrospect, having seen this mounted in the boat I, would have spent a bit more time building a frame that would have allowed the silencer to be mounted horizontally but still close in, that would have given a better lead to the exhaust outlet (update: I did that in December 2023, see part 2 of the thread).

I'm now waiting for some decent weather to go down and start the installation. 

Continued here.