Queries: about plumbing the fuel supply to diesel heater

[NealB]

Over the winter, we had a diesel heater fitted to our 'new' Westerly Falcon (bought by us a year ago).

It's been fantastic ... we've been delighted with it.

However, we launched today, which has prompted a few queries, if anyone can offer an opinion, please.

- the fuel line is T-eed into the engine feed, between the tank and the first filter / water separator. Is this good practice? It means the heater is getting diesel that hasn't been through the water separator, and it also means that any air drawn in at that T will affect fuel supply to the engine. Wouldn't it be better to plumb the heater line into one of the currently plugged 'out' connections on the the CAV water separator body?

- I was pleased when, soon after launch, the old Volvo 2003 fired up instantly (not really a surprise, as it started and ran faultlessly all last season). I was therefore was rather dismayed when, after about twenty minutes, it started to shake, splutter and eventually stopped. I cracked open the bleed screw on the filter on the engine block, and got loads of bubbles whilst manually operating the lift pump. After bleeding, she fired up again, and ran fine till I switched off after half an hour. Is it safe to guess this was likely to be air that got into the system whilst the heater was being plumbed in, and now that it's bled, there should be no more problems?

Thanks!

 

[lw395]

It should work fine.
Personally, I'd prefer to have a completely independant feed from the tank.
You could fit a small inline filter to the heater line. This might help you see any air that's moving around the system.
I like to see shut-off valves, just in case a pipe gets damaged, or you need to take the heater out for servicing etc.

 

[NealB]

Thanks lw395, that all sounds sensible. The 'to do' list continues to grow.

 

[PaulRainbow]

- the fuel line is T-eed into the engine feed, between the tank and the first filter / water separator. Is this good practice? It means the heater is getting diesel that hasn't been through the water separator, and it also means that any air drawn in at that T will affect fuel supply to the engine. Wouldn't it be better to plumb the heater line into one of the currently plugged 'out' connections on the the CAV water separator body?

Perfectly OK to fit it to the CAV outlet, bad idea to have it how it is currently.

I was pleased when, soon after launch, the old Volvo 2003 fired up instantly (not really a surprise, as it started and ran faultlessly all last season). I was therefore was rather dismayed when, after about twenty minutes, it started to shake, splutter and eventually stopped. I cracked open the bleed screw on the filter on the engine block, and got loads of bubbles whilst manually operating the lift pump. After bleeding, she fired up again, and ran fine till I switched off after half an hour. Is it safe to guess this was likely to be air that got into the system whilst the heater was being plumbed in, and now that it's bled, there should be no more problems?

Thanks!

Almost certainly air from the heater installation, in which case it will be fine now.

 

[Allergy]

It should work fine.
Personally, I'd prefer to have a completely independant feed from the tank.
You could fit a small inline filter to the heater line. This might help you see any air that's moving around the system.
I like to see shut-off valves, just in case a pipe gets damaged, or you need to take the heater out for servicing etc.

+1 for the independent feed from the tank. However, I have a separate tank(25litre outboard tank) and I use white diesel(filling station).

 

[NealB]

Thanks Paul.

 

[jiris]

This issue has been discussed extensively recently. A few ideas emerged and as far as I can tell, the winner solution was a T feed from the engine return fuel line. Very safe and and simple. Any solution involving the suction part of the fuel system presents some degree of danger of getting air in the engine fuel line. It is not entirely wrong, but it has to be done really properly and a non-return valve on the heater line is highly recommended.

 

[lw395]

This issue has been discussed extensively recently. A few ideas emerged and as far as I can tell, the winner solution was a T feed from the engine return fuel line. .....

I wouldn't do that.
Either the heater sucks fuel from the tank into the return connection unfiltered, or it has to suck fuel through the entire injection system.
The best system IMHO is an independent standpipe for the heater. With its own filter.
Teeing off the feed side is OK if you have shutoffs in the right places to minimise the potential grief of bleeding both engine and heater.

Bearing in mind, in my experience, bleeding heaters can be quite a performance, as they can lock you out due to too many failed starts.

 

[scottie]

The conservative answer is separate supplies

Other installations may work ok most of the time but problems don’t usually occur tied up in the marina or at the most convenient times

 

[Fr J Hackett]

I have done two installations both worked for years without problems: one with a direct feed from the main tank using Ebbers diptube the other from one of the spare outlets from the CAV filter. in both cases I included the traditional in line filter to the Ebber.

 

[vyv_cox]

I installed my Eberspacher nearly 20 years ago, with a T after the primary filter. It and the engine have always run faultlessly. At the time I used a plastic T, which a man from Eberspacher told me later is bad practice. It would be preferable to take the feed from the CAV filter but as the heater is rarely used now is a job waiting to be done.

 

[PaulRainbow]

My Eber was fitted to the CAV head in 1988, it's standard practice for all the Eber fitters i know. No need to interfere with the tank or the return system and the fuel is filtered to the same degree as for the engine.

Oh, forget the talk of two lots of bleeding, if the engine runs out of fuel, or you change the filters, the fuel to the Eber does not drain back, when the engine is bled the heater carries on working. Also, if you work on the heater and have to bleed it, it does not let air into the engine circuit.

 

[pvb]

The single advantage of having the heater supplied from a separate pick-up pipe on the tank is that you can arrange for the pick-up pipe to be shorter than that for the engine, so there's no chance that the heater will use all the fuel and leave you unable to run the engine.

 

[VicMallows]

One slight issue to be aware of is that if the diesel level in the tank when full is HIGHER than the heater, then occasionally I find that diesel can leak past the pump. This does not really cause a big problem, but results in lots of smoke and 'howling' next time it is used until the excess fuel is burnt off (particularly if it has been unused for quite some time). I get this problem occaisonally on my Sadler29, but only if the tank is nearly full .

This problem will be the same whatever type of draw-off is used for the supply (mine is tee'd after the primary filter). The solution if really concerned would of course be an inline isolating tap.