Pulse pumps

[MtB]

The pulse pumps I have on the Whispergen and the Webasto run at widely different click rates, with the webby being far slower. Does this mean the Whispergen is using a lot more fuel than the Webasto? 

In particular, can the pulses be counted to work out the exact fuel consumption? Do all pulse pumps deliver the same volume per click or do they vary from appliance to appliance? 

I ask because my perception from tank-filling is that the webby and the Whispergen consume fuel at roughly the same rate, yet the webby clicks about 20% of the speed of the Whispergen. 

[RLWP]

2 minutes ago, Mike the Boilerman said:

Do all pulse pumps deliver the same volume per click

Why would they?

Richard

[MtB]

On 17/12/2017 at 12:33, RLWP said:

Why would they?

Richard

 

I just wondered if there was an industry standard given neither of mine has the volume per click marked on it. 

Users being users are bound to sometimes fit new ones, how do they select the right one? The old thread about them mentions red ones and silver ones and seems to assume they deliver the same volume per click and are interchangeable. Hence my question.

 

[cereal tiller]

12 minutes ago, Mike the Boilerman said:

The pulse pumps I have on the Whispergen and the Webasto run at widely different click rates, with the webby being far slower. Does this mean the Whispergen is using a lot more fuel than the Webasto? 

In particular, can the pulses be counted to work out the exact fuel consumption? Do all pulse pumps deliver the same volume per click or do they vary from appliance to appliance? 

I ask because my perception from tank-filling is that the webby and the Whispergen consume fuel at roughly the same rate, yet the webby clicks about 20% of the speed of the Whispergen. 

Had to Spec a Genset for a New 50 Foot Motor Yacht @ 20 Years ago ,looked at the Whispergen and it was Super Quiet But the Electrical Out put was considered Inadequate for the Specification and the Wasted Heat in Mediterranean  Climes meant that Fuel Consumption was regarded as too high.

It worked out at something like 4 IMP. Gallons per 24 Hours. Opted for a Conventional Cocooned AC. Generator instead.

 

Edited December 17, 2017 by cereal tiller

[RLWP]

1 minute ago, Mike the Boilerman said:

 

I just wondered if there was an industry standard given neither of mine has the volume per click marked on it. 

Users being users are bound to sometimes fit new ones, how do they select the right one? The old thread about them mentions red ones and silver ones and seems to assume they deliver the same volume per click and are interchangeable. Hence my question.

 

If they are the same as the Facet pump, there are a range of pumps with different deliveries. So your initial question fails - they don't have the same delivery per click

They are meant to deliver fuel on demand at a particular pressure, how they go about it doesn't really matter

Richard

[MtB]

On 17/12/2017 at 12:44, RLWP said:

If they are the same as the Facet pump, there are a range of pumps with different deliveries. So your initial question fails - they don't have the same delivery per click

They are meant to deliver fuel on demand at a particular pressure, how they go about it doesn't really matter

Richard

 

I disagree. The Whispergen one in particular fuels at a particular volume per click. The microprocessor varies the click rate to control engine speed. I assumed (incorectly it seems) the Webby did the same. It certainly has two different click rates corresponding with high and low hot air output. I don't think my 26 year old webby is sophisticated enough to be metering the fuel input other than by varying the click rate of the pulse pump, having seen the innards of it. 

[RLWP]

7 minutes ago, Mike the Boilerman said:

 

I disagree. The Whispergen one in particular fuels at a particular volume per click. The microprocessor varies the click rate to control engine speed. I assumed (incorectly it seems) the Webby did the same. It certainly has two different click rates corresponding with high and low hot air output. I don't think my 26 year old webby is sophisticated enough to be metering the fuel input other than by varying the click rate of the pulse pump, having seen the innards of it. 

Then you know far more about it than I do. Most ones I have come across use the stroke of the pump pushed by a spring to trigger a solenoid to take a new gulp of fuel. They deliver fuel at a (more or less) constant pressure

Your microprocessor controlled one needs more research - good luck

Richard

[NMEA]

Definitive answer, even Webasto PUMPS give a different dose per pulse dependant on the pump and there are six different models of pump. Even the latest AT EVO PUMPS deliver a different dose than earlier models. This is just another reason why the YouTube videos of a so called service done by amateurs are useless as the datum for any heater service is pump calibration and burn rate.

[MtB]

On 17/12/2017 at 15:20, NMEA said:

Definitive answer, even Webasto PUMPS give a different dose per pulse dependant on the pump and there are six different models of pump. Even the latest AT EVO PUMPS deliver a different dose than earlier models. This is just another reason why the YouTube videos of a so called service done by amateurs are useless as the datum for any heater service is pump calibration and burn rate.

 

Ok thanks for the definitive info. So there is no consistency from one pump to the next then. 

Consequently I have another question. Is the volume pumped per click the same all the time (for a given pump and calibration), or does it vary according to the hydraulic resistance it is presented with as Richard holds? 

Ok and another. Do pulse-pump-fed appliances vary the fuel rate by any method other than by changing the click rate?

Thanks and duly greenified.

[RLWP]

Not hydraulic resistance, rate of use of fuel. And it seems like I'm talking about a different kind of pump

Richard

[MtB]

On 17/12/2017 at 15:40, RLWP said:

Not hydraulic resistance, rate of use of fuel. And it seems like I'm talking about a different kind of pump

Richard

 

I think we must be! 

On the Whispergen it clicks about 7 times a second in "fuel bleed mode", during which the fuel pipe must be disconnected from the burner, so it is pumping out of an open ended pipe with no restrictions, and it pumps glacially slowly, about 1cc every 10 to 20 seconds I'd say. 

There is nothing in the burner as far as I can determine to restrict or modulate the flow of fuel to the flame either so I conclude the fuel rate is modulated by varying the click rate, or pulse rate. (The fuel hose goes directly from the pulse pump into the burner assembly so there is nothing in line for the electronics to use to control fuel flow other than by changing the pulse rate.) The pulse rate during running varies very slowly between about 5 and 14 clicks per second according the load and is shown on an electronic display. The presence of a display stating the pulse rate leads me to believe it delivers a fixed quantity of fuel per pulse and needs to be known.

Perhaps on the old Webasto it is as you say, a constant pressure device. It still isn't obvious why or how the pulse rate changes between high and low settings if not electronically as there appears to be nothing inside the burner to physically modulate the fuel flow rate. 

Edited December 17, 2017 by Mike the Boilerman

[NMEA]

No the Webasto is a solenoid dosing pump, all evaporator heaters are solenoid dosing pumps, the fuel rate is regulated by the ECU. Earlier heaters had two levels but more modern ones are stepless. As a rider the larger Webasto pressure jet heaters ave an internal high pressure pump but as those are rarely seen on narrowboats it is of not really of relevance to this discussion.

[NMEA]

The hydraulic resistance is not really a variable and does not affect the pulse rate. Well I guess it might if you tried to pump engine oil instead of diesel.

[Detling]

Perhaps the Webasto ECU monitors the flame temperature or exhaust temperature and changes the click rate to suit it's readings. My thermotop when starting clicks slowly while the jet engine noise builds up, then clicks like mad for 30 seconds before slowing to it's normal rhythm.

[NMEA]

No, the thermotop is programmed to reduce to half rate when the returning coolant reaches a set temperature. Also a faster pulse during start up, the air motor matches the pump rate to ensure a constant fuel air ratio.