Diesel heater not producing much heat

[PaulRainbow]

The ducting hasn't worked loose from the heater, and there is no evidence of smoke in the exhaust fumes out the stern or fuel starvation, but there are indeed several meters of uninsulated ducting in the cockpit-locker / engine-bay space before it enters the cabin space. This ducting feels pretty hot for the first meter or so that is easily accessible, but by the time the air exits the two vents in the cabin it has obviously lost a huge amount of energy! The colder it is (i.e. at night and with the engine-bay no longer warm from a good engine run) the more heat will be sucked from the ducting before it gets to where I need it.

You'll lose up to 40% of the heat if the ducting isn;t insulated. But, i wouldn't insulated the first 2 or 3 feet, as it gets really hot and can cause the heater to shut down.

There is a third element that may be involved? After some time running (half an hour to an hour, maybe just fifteen minutes) the controller seems to run the heater cool for a while (i.e. a ventilation cycle, just like when cooling down to stop), or reduces the fan speed... then the heat comes back on...? I have no idea why all this is.

Possibly caused by the heater running hot and the overheat sensor limiting output.

Also I hate this controller (and its illogical and incomplete rubbish manual). I just wish Owen had fitted a basic ON/OFF switch with no thermostat - that is all anyone ever really needs out of these heaters on small or medium sized boats: ON for heat, OFF for no heat!

An ON/Off switch would make no sense at all, it would just run flat out all of the time. Which controller do you have ? There is a very basic rotary controller, with just on/off nad heat settings.

 

[Momac]

An ON/Off switch would make no sense at all, it would just run flat out all of the time. Which controller do you have ? There is a very basic rotary controller, with just on/off nad heat settings.

I say it does make sense . Use these heaters at full chat or not at all. Then you get no issues.

 

[PaulRainbow]

I say it does make sense . Use these heaters at full chat or not at all. Then you get no issues.

No issues with running ours on a digital temperature controlled timer. If we ran it flat out all of he time it would use more diesel and be too hot inside the boat.

However, if you wanted to run one flat out all of the time, just fit the basic controller, turn it to full and leave it there, just turn it on/off on the switch.

 

[Baddox]

Our Webasto heat output dropped so much it was only pumping out warm, not hot air. It was caused by a fuel blockage where the hose from the pump connects to the burner.

 

[Momac]

..... if you wanted to run one flat out all of the time, just fit the basic controller, turn it to full and leave it there, just turn it on/off on the switch.

That's what I do .

 

[Babylon]

An ON/Off switch would make no sense at all, it would just run flat out all of the time. Which controller do you have ? There is a very basic rotary controller, with just on/off nad heat settings.

He fitted the PU67 which has buttons all over it and a bizarre operating logic, with options to choose different temp sensors - controller, heater, remote, or override up to full chat, but which the crap manual tells you bugger all how to actually select and get to stick - then you hit the wrong button and can't do anything for a millennium while the bloody thing goes unto its shutdown sub-routine... then you repeat the bloody stupid thing all over again with the same end result!

I actually called him to find out about retrofitting a simple on-off rotary controller instead, but he insisted that I should persevere with the one he fitted - but because he lives up a Welsh mountain I could barely make out what he was saying, then the line dropped for good!

I just want a simple quiet life with a functioning heater....

 

[PaulRainbow]

He fitted the PU67 which has buttons all over it and a bizarre operating logic, with options to choose different temp sensors - controller, heater, remote, or override up to full chat, but which the crap manual tells you bugger all how to actually select and get to stick - then you hit the wrong button and can't do anything for a millennium while the bloody thing goes unto its shutdown sub-routine... then you repeat the bloody stupid thing all over again with the same end result!

I fitted a couple of those, wasn't keen. Not very intuitive or informative about what's going on. I stopped using them and fitted the simple one. The new digital one is vastly better.

I actually called him to find out about retrofitting a simple on-off rotary controller instead, but he insisted that I should persevere with the one he fitted - but because he lives up a Welsh mountain I could barely make out what he was saying, then the line dropped for good!

I just want a simple quiet life with a functioning heater....

Not a difficult job to swap timers. I'd call Owen again.

 

[Babylon]

My Planar output got progressively cooler over the course of a year. I stripped it down and found the heat exchanger well sooted up on the inside. Scraped it clean, put it all back together with new gaskets and, importantly, a sintered diffuser where the fuel enters.
One thing you can't get at is the sealed combustion chamber. All I did there was tap it with a small hammer to dislodge carbon and shake it out.

Well done, but that's a lot of technical work for a poor bloody consumer who really just wants to go sailing for more than a couple of hot weeks a year.

My new boat has a Bengco stove fitted against the forward bulkhead. It is ridiculously simple (a steel box with a flue) and designed to burn charcoal, but the vendors have been using small lumps of coal stashed under the floor, and it'll apparently also work with turf, wood... and paper printouts of the Planar PU67 instruction manual!

 

[NormanS]

Contact Owen. He will respond almost immediately. His philosophy with Autoterm (Planar) has always been to provide top level support.

Do not run on paraffin, you may burn it out. Might work with other makes but they are not allowed the same.

That's interesting. Mine is a different make of basically the same thing, an Eberspacher. My fuel supplier mainly services shipping, and the fuel still has a relatively high sulfur content, and was causing all sorts of trouble with a build-up in the burner. I changed over to using kerosene (paraffin) several years ago, burning about 100 litres per year. Since changing to kero, it has worked faultlessly. Presumably there is some difference in the construction materials used in the different makes.

 

[Babylon]

That's interesting. Mine is a different make of basically the same thing, an Eberspacher. My fuel supplier mainly services shipping, and the fuel still has a relatively high sulfur content, and was causing all sorts of trouble with a build-up in the burner. I changed over to using kerosene (paraffin) several years ago, burning about 100 litres per year. Since changing to kero, it has worked faultlessly. Presumably there is some difference in the construction materials used in the different makes.

That's useful to hear. The other thing my new-to-me boat (purchase shortly to complete) has is an old knackered Eberspacher with a separate fuel reservoir, currently filled with old diesel. I was going to just remove all of this, but it strikes me that if a diesel heater (Eber? Planar? Chineser?) can reliably run on paraffin, then I'd get a new one fitted and retain the dedicated reservoir.

In the meantime I'm off to Wickes in Southampton this morning to buy insulation for the old boat's ducting!

 

[PaulRainbow]

Well done, but that's a lot of technical work for a poor bloody consumer who really just wants to go sailing for more than a couple of hot weeks a year.

That's hardy fair or realistic. You cannot expect to run a blown air diesel heater without servicing it, especially if you run it for short periods on low settings. Every single make of blown air heater will do the same, build up soot and/or carbon.

 

[vyv_cox]

That's interesting. Mine is a different make of basically the same thing, an Eberspacher. My fuel supplier mainly services shipping, and the fuel still has a relatively high sulfur content, and was causing all sorts of trouble with a build-up in the burner. I changed over to using kerosene (paraffin) several years ago, burning about 100 litres per year. Since changing to kero, it has worked faultlessly. Presumably there is some difference in the construction materials used in the different makes.

I know that Owen runs his test Autoterm heaters on central heating oil (kerosene) without problems. Paraffin (Esso Blue!) is a lighter hydrocarbon that may cause problems.

 

[Babylon]

That's hardy fair or realistic. You cannot expect to run a blown air diesel heater without servicing it, especially if you run it for short periods on low settings. Every single make of blown air heater will do the same, build up soot and/or carbon.

I do appreciate that. I'd have it out in a trice for a clean and learn how to service it, but in the case of my own installation up inside the cockpit coaming but above the quarter-berth's GRP shell outer, the physical contortions involved to see it with mirrors and a mobile phone camera let alone get to it with knuckle-scraping tools are difficult and painful - hence my extra frustration.

Re reducing heat-loss from the ducting, I picked up a couple of rolls of 4" wide wool-based pipe-insulation at Wickes yesterday, and wrapped as much of it as possible: inside the rear of the cockpit-locker (1st photo) and inside the engine-bay (2nd one), but the section between the two of several feet has been left bare as that is behind and under the further reaches of the diesel tank and simply impossible to get to.

It is now early on a fairly nippy October Sunday morning on a mid-river mooring. Primary heat source is a flask of tea, main insulation is sleeping-bag, long-johns, heavy wool roll-neck jersey, wool beanie, alpaca socks... plus some vaguely warm-ish air is coming out the duct outlet in the cabin!

 

[Babylon]

It is now an hour or so later... lifted quarter-berth bunk cushion to get to fridge and plywood surround felt really warm... removed cushion further down and removed deep locker access lids... blast of hot air and both lockers really hot!! Same with the lockers under the starboard bunk! Slightly warmer air however is now coming from the outlet grill in the cabin... so I really mustn't grumble I suppose!

So, for the last 42 years since the boat was built and the circa 10m of thin plastic ducting installed, the first couple of hours of running the diesel heaters (this 2019 one and its expensive Eberspacher predecessor(s)) have only ever really been to heat the port cockpit-locker, the entire freezing cold engine bay, these two rarely-accessed under-berth lockers (which I now have to try to insulate as best I can), the area behind the fridge and under the chart-table cabinetwork (impossible to ever access), before finally getting to the ducting under the starboard bunk (to insulate that after another trip to Wickes).

In conclusion the entire installation has been ridiculously flawed from the outset. All these deep and largely inaccessible areas act as massive heat-sinks - themselves continuously cooled by the cold water outside the hull - and only roughly 40-50% of the approx 10m of uninsulated ducting is accessible to wrap a thin spiral of wool bandage around.

It would take an engineer a while to work out the inefficiency of the whole system, but I reckon the cabin air space is only benefitting from 10% of the energy available at the heater in the first hour or two of operation, then maybe only 15-20% or so thereafter. What an incredible waste!!

 

[NormanS]

Are you sure that there's not a leak in the ducting in some of these hot locker spaces?

 

[Boathook]

It is now an hour or so later... lifted quarter-berth bunk cushion to get to fridge and plywood surround felt really warm... removed cushion further down and removed deep locker access lids... blast of hot air and both lockers really hot!! Same with the lockers under the starboard bunk! Slightly warmer air however is now coming from the outlet grill in the cabin... so I really mustn't grumble I suppose!

A blast of hot air would seem to indicate that air is escaping from the ducting. I would expect the lockers to get slightly warm but not to your description.

 

[PaulRainbow]

Lockers with uninsulated heater ducting will get pretty hot. My current boat came with a 4kw Webasto to heat the saloon and cockpit (we keep the cockpit vent closed) and a 5.5kw Webasto for the the cabins, heads, dinette and galley, no insulation anywhere.

The storage spaces beneath the saloon sofas got hot. I insulated all of the ducting from the aft Webasto, the lockers barely get warm now and the heat output to the saloon is significantly improved.

The ducting to the forward cabins etc ran under storage in the guest cabin, which got nice and hot (the storage, not the cabin so much). It then ran under the floors to the rest of the forward areas, nice warm bilges, not so warm cabins and heads. After insulating all of the ducting the heat output has been transformed. I replaced the 5.5Kw Webasto with a 4kw Planar because i wanted a 7 day timer and the Webasto one was nearly half the cost of the planar heater. Unless it's really cold the 4kw Planar heats our 45ft motorboat, if it's really cold we run the Webasto as well for a short while.

The main point of the above, insulate your ducting or lose a significant amount of your heat and waste money.

 

[Babylon]

Lockers with uninsulated heater ducting will get pretty hot. My current boat came with... no insulation anywhere.

The storage spaces beneath the saloon sofas got hot. I insulated all of the ducting from the aft Webasto, the lockers barely get warm now and the heat output to the saloon is significantly improved.

The main point of the above, insulate your ducting or lose a significant amount of your heat and waste money.

This now absolutely makes sense to me.

At a rough guess, by not insulating (or able to access to insulate!) my ducting I've been losing: 15% of the heat energy in the cockpit locker, 25% in the engine-bay, 10% in each of the two lockers under the quarter-berth, 5-10% behind the fridge, 5-10% behind/under the chart-table cabinetwork and 5-10% in the locker under the starboard bunk before the first duct outlet - that adds up to 80-90% loss - then what goes on forwards through two more bunk lockers before reaching the outlet in the forepeak area is so little heat that it's not even worth losing!

Maybe there is a break in the ducting somewhere (I can only finish the job properly by emptying the remaining areas of clobber, checking and insulating where I can - not easy on a 27 footer where routing space and access is very tight), but my conclusion over this weekend is that there is nothing wrong with the Planar heater at all!

 

[fredrussell]

I hate to say this, but I ran my 4kw Chinaspacher with no insulation on the 3 metre run of heater outlet (75mm) pipe, and output was hot enough that you couldn’t hold your hand in directly in front of cabin outlet with heater on lowest setting. I’ve since insulated it all and it’s made a noticeable difference, but I strongly doubt you’re losing that much heat through lack of insulation. At I wild guess I would say you’re losing 10 to 20% max.

 

[PaulRainbow]

This now absolutely makes sense to me.

At a rough guess, by not insulating (or able to access to insulate!) my ducting I've been losing: 15% of the heat energy in the cockpit locker, 25% in the engine-bay, 10% in each of the two lockers under the quarter-berth, 5-10% behind the fridge, 5-10% behind/under the chart-table cabinetwork and 5-10% in the locker under the starboard bunk before the first duct outlet - that adds up to 80-90% loss - then what goes on forwards through two more bunk lockers before reaching the outlet in the forepeak area is so little heat that it's not even worth losing!

Maybe there is a break in the ducting somewhere (I can only finish the job properly by emptying the remaining areas of clobber, checking and insulating where I can - not easy on a 27 footer where routing space and access is very tight), but my conclusion over this weekend is that there is nothing wrong with the Planar heater at all!

You can lose up to 40% by not insulating the ducting, 80-90% loss isn't likely.

Where does the heater draw its air in from and how long is the inlet ducting ?

What size (diameter) is the ducting ?

Why do you have 10 meters of ducting on a 27ft boat ?