My tarm solo 40 has started knocking when It's loaded and really gasifying. The temp gets to about 180 and the knocking starts. I have to lower the temp, (turn off the fan) for it to stop. This happens when I have a full wood load. Does this happen to anyone else?
Tarm Knocking
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trehugr
Member
Really, I never heard of that. I've been reading that the Tarm should have thinner split wood, I'll try some bigger pieces.
My Solo 40 was doing the same thing also, you can also see your pressure spiking also. I thought had air in it, so I tried flushing it again and it seemed to help, but it does not knock as loud. I am not sure what it is, kinda of freaked me out when I first heard it.
I hope it isn't residue mercaptan from the propane tank. I did the best I could to flush out the old tank and there was no smell.
trehugr
Member
Ok, sounds like maybe 2 different things. I've had both things happen. The to much wood gas thing caused the boiler to puff out the stack and sometimes backdraft out the fan. Sort of like a rich mixture. The banging is due to air in the system. I call that a water hammer. It will make you say "what the %@$# was that 
! Find the air, purge it, and it probably won't happen again
! Find the air, purge it, and it probably won't happen againI doubt it's air. The knocking is steady, like someone knocking on a door. When I turn down the boiler heat control, it goes away. I have vents everywhere, taco auto vents at the high points.
Oh man my wife heard it now, she'll make my life miserable till I fix it. "It's getting louder, is it gonna blow?"
trehugr
Member
Wow, maybe it is an over abundance of wood gas. I would be curious to know if you find out what it is.
trehugr
Member
I vented the boiler. There is a manual coin vent on the top of the tarm. Surprisingly I did get some air out. The knocking was happening only at high temps with the fan on, just recently it started knocking at idle.
Hopefully it was air, I'll let you know.
Hopefully it was air, I'll let you know.
trehugr
Member
My wife had the same reaction to the knocking also. I am pretty sure it is air in the system. Mine acted exactly like yours, right at peak output it started hammering. I bled some air and it is not knocking as bad, but am still getting a slight knock. Good luck. DC
NHFarmer
Feeling the Heat
I have been up and running for a month and have had no strange noises.Are you burning hardwood?I have noticed that if I burn really dry pine it will gassify like crazy.I am thinking too much gas.Does the sound change at all if you adjust your secondary air?
I have a solo 40 and I get knocking when the tarm gets going. Not every
time but a couple times a week. Wife was surprised when she first her it.
Ethan
time but a couple times a week. Wife was surprised when she first her it.
Ethan
My Tarm knocked also. The issue is spot boiling. The cure is in the Thermovar. Check that your balancing valve has some restriction so that at least some of the heat generated will get out of the boiler.
Good point about the spot boiling (steam flashing). I'll keep that in mind. I think the problem was a slug of air in the boiler. I bled it out with the coin vent, and so far no knocking.
jebatty
Minister of Fire
I've had the knocking occasionally, wondered what it was (thought i might be spot boiling), have just ignored it, and all seems fine.
Next time it occurs I will try the manual "coin" vent at the top of the boiler, as the knocking is coming from the boiler. Actually, rather than a coin vent I installed a sink shutoff valve with a small piece of plastic tubing exiting through a side vent slot, so any venting with water will drip to the outside. I have automatic vents at other high points.
Next time it occurs I will try the manual "coin" vent at the top of the boiler, as the knocking is coming from the boiler. Actually, rather than a coin vent I installed a sink shutoff valve with a small piece of plastic tubing exiting through a side vent slot, so any venting with water will drip to the outside. I have automatic vents at other high points.
Yes, I was going to say the same thing... It's steam banging........ It happened to me the first time I ran my boiler because I had it set up so the circ pump wouldn't come on until the boiler water was up to temp... Well, let me just say that wasn't a good idea! 
jebatty
Minister of Fire
I think if the water was flashing into steam the pressure would have shot up and blew the prv. Plus the temp. @ 10-15psi would have to be higher than 212*.
I guess anything is possible though.
I guess anything is possible though.
The spot boiling can be in very small areas, one inch or more of surface area. In my Tarm it appeared to be near the left front corner above the main firebox. The temp gauge was indicating about 82°c. Obviously there are hot areas within the boiler.
The cure for mine was getting rid of the Thermovar since the one supplied was a 72°c. With a single return circulator very little heat was getting out of the system. Relying on a blend valve does not work well. These boilers really need a 4 way mixing valve so as they warm up you get a positive flow out of them. This way at high temperatures all of the water flow will go out to your storage or heat system.
The cure for mine was getting rid of the Thermovar since the one supplied was a 72°c. With a single return circulator very little heat was getting out of the system. Relying on a blend valve does not work well. These boilers really need a 4 way mixing valve so as they warm up you get a positive flow out of them. This way at high temperatures all of the water flow will go out to your storage or heat system.
I am in that transition phase at this time. I like the Laddomat 10. But I am sure there is something easier to get. Seems all the Tekmar that I have found are electronic control. I need to do some more searching at Honeywell. They must have a straight Thermo control. Danfoss, maybe but I have not found it yet.
Right now I am running mine with a manual control, AKA, the element is removed and I adjust the valves as needed. As far as testing has gone my efficiency is way up. No where near the claimed numbers
The key thing I have found is once the system has warmed up is to get full shutoff of the bypass.
I am going to do some machine work to my Thermovar so as it opens the return water it also shuts down the bypass. Simple job really. First I need to get the 63° element for it.
Right now I am running mine with a manual control, AKA, the element is removed and I adjust the valves as needed. As far as testing has gone my efficiency is way up. No where near the claimed numbers
The key thing I have found is once the system has warmed up is to get full shutoff of the bypass.
I am going to do some machine work to my Thermovar so as it opens the return water it also shuts down the bypass. Simple job really. First I need to get the 63° element for it.
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