Diesel heater fuel supply from CAV filter

rogerthebodger

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Both your pump types have valves. Which as I said act as their own nrvs. Not sure what you are arguing about.

It was your statement about positive displacement

Which most fuel pumps are not and in fact cannot be positive displacement as engines need a variable flow of fuel

Most reiary pumps do not need NRV but pups that act in to too and fro action do need NRV otherwise the puel just goes to an frow.

You cannot conclude the those with valves are positive displacement and the same with rotary pumps as you state centrifugal pumps
 

rogerthebodger

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All the heater fuel pumps are metering pumps. Driven by an electromagnet it pushes the amount that the heater is designed for.

No diaphragms.

This gyu opened one for you to see:

The ticking noise is the piston hitting the metal at the end of its stroke,

The piston has no diaphragm of O rings because of the close (honed) fitting between the moving piston and the body of the pump.

There will be a small fuel leakage back past the piston but not significates,

The case with a mechanical fitted to the engine block without any seal to prevent the backflow past the piston you would end up fuel oil in the sump or simple loss of fuel over time.

So if all heater fuel are metering pumps there should be some way of changing the feed to adjust heat output

Better ways for fine metering than with a crude pump lkw that as wear/leakage in the pump will cause change in metring over time
 

Refueler

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And I thought I could hang on by fingernails sometimes !!

From the video of course : "The ticking noise is the piston hitting the metal at the end of its stroke,
The piston has no diaphragm of O rings because of the close (honed) fitting between the moving piston and the body of the pump."

mmmm metered pumps are exactly that - metered by control demand ...
"So if all heater fuel are metering pumps there should be some way of changing the feed to adjust heat output" ... they do adjust flow by the pulses triggered ... or by simply arriving at user set temp and shutting off fuel till temp drops and needs raising up ...

Back on subject to where the fuel is sourced ??

I would like to hear reasons for and against use of the separate tank usually supplied with diesel heaters .... why would tapping off from the CAV filter be used instead ??
 

Refueler

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If you become too adept at adding fuel to get more heat, the heater itself will soon exceed its maximum allowable temperature and switch off.

And that's why greater heat production requires a larger heater (heat exchanger surface area and airflow rate).


I doubt that actual HE differs that much if fuel is constant and volume varied - as the diesel has a standard flame temp ... the heater will be using thermostat control .... switching on / off the fuel to regulate output temp. I agree that greater surface area for heat transfer though.
 

ChromeDome

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Talking heaters from the other side of the globe:

Even with a standard 22 ml pump you can enter the menu and change the pump frequency upwards - pushing more doses.
If you then switch to manual control and select the highest level (as opposed to leaving it on Automatic for the thermostat integrated into the control panel to decide the performance) you can get higher output for a short while.
The temperature sensor on the heat exchanger will sense something is wrong and shut it off.

Same result if you fit e.g. a 65 ml pump. First a lot of smoke, then overheat.
 

samfieldhouse

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So interestingly, it does appear that when starting the heater whilst the engine is running results in the heater shutting off and an Error 13 message which is...
This is an easy one just means the heater has not detected fuel. When you first install the heater or run low on fuel this code will show up.
Top up with fuel and restart heater it will self-prime and may require 10 restarts of the heater.


Both engine (2GM) and heater (2D) feed off the same CAV filter, so is the engine actually pulling fuel out of the heater supply?
Or creating so much vacuum in the CAV filter that the heater pump can't suck as well?
I don't understand the physics of that.
 

vyv_cox

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So interestingly, it does appear that when starting the heater whilst the engine is running results in the heater shutting off and an Error 13 message which is...
This is an easy one just means the heater has not detected fuel. When you first install the heater or run low on fuel this code will show up.
Top up with fuel and restart heater it will self-prime and may require 10 restarts of the heater.


Both engine (2GM) and heater (2D) feed off the same CAV filter, so is the engine actually pulling fuel out of the heater supply?
Or creating so much vacuum in the CAV filter that the heater pump can't suck as well?
I don't understand the physics of that.
I have started my Eberspacher D3L heater many times with the engine running. My fuel take-off is a T after the filter.
 

LittleSister

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If you mean the type of fuel pump below is not a true positive positive pump as the piston acts under spring thus the outlet is limited to the pressure excerpted by the spring. so it's more akin to a diaphragm pump which do have NRV on the inlet and outlet so will not allow any backflow as the OP wishes to install





shopping

Just to be clear - facet pumps are available both with and without Non-Return Valves.
 
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