Thursday, January 13, 2022

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 😒

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