Silent metering fuel pump TH-11
100 tick dose: 4.4 ml
The new super quiet pump is out and what a difference it makes. The normal pump is not that loud, in fact all diesel heater fuel pumps make some sound, but this new one is almost silent.
TH-11 Silent Fuel pump 12V, assy.4995
The TH-11 Silent Fuel pump is designed for the following AUTOTERM heaters with voltage of 12V:
We have had people use this pump on Chinese heaters with some success - but you do have to be able to adjust the pump/pulse rate of your heater as this Autoterm pump delivers at a rate of approx. 2 x the rate of a Chinese pump.
Personally we dont recommend this, we think your are better putting your money into a better heater - but if your pump is driving you nuts and you dont mind some mucking around and possibly some smoke from your heater - you can give it a go, but it doesn't come with a recommendation from us.
You can not hear it operating
We are pleased to say that with some tweaking and investigations, we can report this works well on our unit.
The old pump that came out is labelled as a "HD-20 22-12V".
To work out what frequency range the new pump needed to work at, we measured the delivered fuel of the old and new pumps in a syringe over 200 "ticks" of each pump. The new pump is capable of delivering a lot more fuel than the old one - if you install this pump on a chinese heater with the OEM pump above, you WILL overfuel your heater, and it will most likely pour out white smoke as a result/flood your unit, or otherwise be dangerous!
The old pump measured approx 5mL of fuel over 200 ticks, and the new measured approx 9mL (almost twice as much fuel delivered). We went into our advanced settings (google this to work out how - Pin 1688 on our model heater). The factory frequency for our heater was Low Limit -1.6Hz, High Limit 5.5Hz. We simply halved this to Low 0.8 (which is the lowest this model can go, luckily!), and High 2.7Hz. We did not change the fan settings, as these also affect the combustion fan, as well as the air blower fan - leave these as-is!
The heater started up first go (after blowing a bit more smoke than normal, due to my priming/measuring testing), and we have tested the temps at the exhaust and hot air to be within spec (~220 deg C exhaust max on high setting, 85 Deg C max on hot air outlet/piping). The exhaust temps drop a bit on the lowest setting - not sure if this is normal, or if further tweaking is needed to exactly match the delivery math.
Since the fuel delivery wasn't *exactly* double from old to new pump, halving the frequency has likely to have resulted in a slightly lean mixture, but various other sites report that this just means you will be blowing colder air through the exhaust (whether this is detrimental to the heater life span I do not know), but heater is running fine on low/high, and everything in between.
Highly recommend the pump - just make sure you do your own fuel delivery calcs if you want to use this pump, as it has much higher delivery capability than what the unit originally had!
Oh - and its also much quieter ;-)