Pellet heater vacuum problem

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New Member
Jun 8, 2024
So we have a ziegler & brown pellet heater (I think a rebranded Chinese one). The blower fan motor died and we have replaced the original blower with the best fit replacement we could find where we are (not an identical one to the one that died). Since then we have had a problem with the heater maintaining vacuum when it gets to heating.
- ignition phase no problems, auger drops pellets nicely and flame ignites as usual
- blower fan comes on when "heating" phase starts, auger and pellets stop, "V" for vacuum symbol on control panel turns off
- fire in the burn pot dies out due to lack of pellets without any other alarms going off.

Things we have done
- swapped the vacuum switches from an identical heater in another room: the other room heater works fine with the vacuum switch from the dud heater, dud heater is still dud with the different vacuum switch (so prob not the switch)
- bypassed the switch using some wiring on the circuit board: no problems and auger/vacuum stays on (we didn't leave this on long term, just enough to test the theory).
- attached a syringe to the vacuum hose to create a vacuum: works, need to keep pulling plunger back to maintain the vacuum
- sealed up all leaks we can find both on the air intake and exhaust (had a slight leak in the flue)
- cleaned the exhaust system and flue
- messed around with the air intake baffle to try to alter the air intake to see if that changes the issue - this leads to the vacuum continuing enough to run the heater for some time, but then turns off and the fire dies out

So far we're working on the theory that it is either - as the air in the burn chamber gets hotter the longer the heater stays on this is affecting the vacuum enough to make it switch off, stopping the flow of pellets OR the new blower fan has somehow altered the amount of air the fire needs to burn/maintain vacuum through the intake and we need to find a sweet spot with the intake baffle (damper?) to get the balance right.

Is there anything we might have missed?
It sounds like the stove has hidden ask traps that need to be cleaned
Try the leaf blower trick ( search for it on this site)
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Reactions: ARC
Since the issue started when you purchased the new blower that would be your issue.. It is creating to much air flow to create a vacuum. Their should be specs on your old blower or online for CFM, RPM, and rotation this needs to match as close as possible
You also could swap out the blower with the second heating unit to see if its the blower, but seems logical the replacement blower is the source of the issue. Stay warm.
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Reactions: johneh
What he said