Monday, 8 September 2008

Bitter disappointment - no veg oil for Carrie :-(

It's been a downer day today. All my plans for running my boat on used veg oil have come to nothing. I brought Blackbird up the Wolverhampton 21 locks to Dixon St bridge where 'Diesel Veg' have their business, converting diesel cars and vans to run on veg oil. They are a lovely team, friendly, enthusiastic for a challenge, serious about what they do and their standard of work. But having had a really good look at my engine and how it runs and my fuel pump and calorifier, they decided the conversion just wouldn't work properly.

Here are the problems we looked at:
- We had intended using the main fuel tank for veg oil and installing a 20l extra tank for diesel to start the engine and flush through before stopping it. Because the fuel tank is below the waterline, the veg oil would be too cold, encouraging sludging. Therefore, we decided we could install a small tank for the veg oil inside the engine room and continue to use the main tank for diesel. No room in the engine hole but wall-mounted space available in the engine room itself.
- My fuel pump was a problem, as I'd known it might be. It's a Lucas CAV pump and these often break down with veg oil. It would have been better with a Bosch pump apparently. We were going to add a whole new fuel filter and lift pump to help overcome the problem.
- I was going to have a purge alarm fitted to ensure I always switched back to diesel before stopping the engine as the veg oil would thicken and cool overnight and be impossible to de-gunk in the morning.
- Filtering the waste veg oil. The oil has to be filtered down to 1 micron - much finer than my efforts to filter with muslin. Diesel Veg sell an electric filtering system but I learnt today that it's a 240V pump. The guys said I could maybe manage okay with a filter 'sock' they could provide me with, that could drain through overnight.
Each problem was sort-of being overcome until we hit the real stumbling block - temperature.
The team were looking to heat the veg oil via the calorifier pipes to lessen its viscosity as it entered the engine but the temperature just wouldn't get high enough for this to happen. Chugging along at 4 miles an hour wouldn't do it and the calorifier heats the water to about 60 degrees only. In a car, you'd be at the right temperature in a few minutes. They were reluctant to do the conversion, knowing it would be very unreliable and highly likely to break my fuel pump and I had to agree.

I'm gutted but would defintely recommend Diesel Veg for converting a car or van as they were so motivated, friendly and professional. Check out their website:


Simon said...

that's really rotten, you were so enthused about it (not to mention having done all those bloody locks to get there). Have there been any other canal boats converted to veg oil successfully?

I'm still looking at electric propulsion, but it's not an easy answer itself, and possibly not practicable for the way I use the boat at the moment...

Alan said...

Hi Carrie,

I'm sure these people know their stuff, and I'm in a field I'm ignorant of, but, even so....

Assuming you still have a BMC 1800, it should easily be possible to get the temperature of the pipes feeding your calorifier a lot hotter than 60 degrees C.

If you are limited to that temperature, it's likely to be because the engine thermostat is a low temperature one, so as soon as a pre-set low temperature is reached, heat starts getting dumped into the canal via your skin tank, and the calorifier feeds get no hotter than the thermostat temperature.

The default thermostat in a BMC is about 70 degrees, but it's a doddle to swap to one which will allow the calorifier to heat hotter, before the stat opens, and heat is again dumped into the cut.
(I've recently swapped an approximately 70 degree stat to one of around 80 degrees, in anticipation of installing a calorifier).

I feel it can't be that simple, because I'm sure the people you talked to know this.

But just to exaggerate the point, if you replaced your engine thermostat with a total blockage, that never let water to the skin tank, then your calorifier feed would quickly reach boiling point, even at canal speeds, (definitely!).

As I say, I don't really understand, but can't see why you can't easily generate a higher temperature to heat the veg oil.

I'm missing something, I guess ?


Carrie said...

Hey, thanks both for your comments. Simon, I havn't heard of any boats running on waste veg oil. Seems there's less chance of gunkiness with new oil but I didn't want to go down the burning food route ;-). By the way, coming back down the locks I didn't get any help but isn't it amazing how many multi-crewed boats like to give you advice. "Why don't you just jump down onto the roof?" was a favourite as I bow-hauled out of the locks coming down. This in the pouring rain with my dog waiting to get back on board. I never get given advice by sngle-handers as they respect everyone has their own coping methods!

Alan, you naughty man, you've raised my hopes again!!!
Do you mind if I use your suggestions to re-contact Diesel veg? They may be experts in their field but they didn't know anything about narrowboats and spent ages getting to know the engine room! Would the temperature stat change be at all risky? I mean would I risk burning my skin on the hot tap?
Yours, in the usual state of ignorance,

Alan said...


No problem at all with you at least passing my thoughts to Diesel Veg. (I think I prefer "Veggie Might"!).

Your engine certainly will not mind.

But you are right, if you allow it to heat your calorifier into the '80s', and you have no other control, then you could get some very hot water out your taps.

The way this is normally solved is to have a thermostatic mixer valve on the water being drawn from the calorifier, such that if forces mixing in some cold, and what comes out of your taps is never hotter than a preset value. Obviously if you already have such a valve, no issue, but if you don't one could be fitted.

A benefit of increasing the water temperature in your calorifier, is that it's heat you can use, rather than warming the cut. If you end up using less of your hot water, and more of your cold, then of course the hot will last longer before it runs out.

I'm sure you would think me a "naughty person" as we don't have a calorifier at all, so all my spare engine heat is wasted. The trouble is that as only occasional leisure boaters, it would take a very long while to recoup the cost of retro-fitting a calorifier to a boat that's never had one. I reckon at least £300, and probably £400. Should I do it, or does the environmental cost of manufacturing all the bits I'd need, actually outweigh the fact that I could get some hot water without burning gas. I really don't know!

Carrie said...

Well, I did give em a ring and they said fine, but that doesn't get around the old Lucas fuel pump and it coping with waste oil. But they did promise to do a bit of research on the pumps for me. Of course they'd sell me a conversion kit to do-it-myself but don't want to risk their reputation on a failed job if they did the fitting. Still having a think about it.....
- Carrie

Sam said...

Hi Carrie,
I hate to add to your worries, and it may well be that it doesn't apply to Straight Veg Oil, but this discussion:
Suggests that the O-rings and seals in the BMC 1800's C.A.V. pump swell when exposed to Bio-Diesel. And the writer still hadn't found suitable non-reactive replacements.
Sorry to bring this up just when the heating issue was solved, but I don't want you to end up with a dead engine.