Tarm Lo-Limit and Operating Temp Controls?

[Rory]

First, I should say that I've been lurking here for a while, and have picked up a lot of good info, though lots of things seem to float over my head a bit. My plumber's in my basement right now, finishing up the install of my new Tarm Solo 30. I built a 670 gallon tank that we heated up last week.

My question involves the Lo-limit and Operating Temp knobs. The Lo-Limit Thermostat says to set it at 190F, while the Operating Thermostat says to set it for an operating temperature of 180 - 190. It seems that the Lo-Limit is at the upper end of the operating range, and it's not really clear what either one is doing.

Can anyone explain?

 

[NHFarmer]

The low limit should be located in the smoke chamber and the settings you have should work fine

 

[nporter]

Rory I had the same question. My installer had mine set at 190°C and it would shut off in the middle of a burn. Understandable once I clued into what it was trying to do. I now have it set at about 80°C on the Lo-limit knob. It works fine at that setting. Shuts off the fan when the temp drops to that level.

Good luck!

 

[NHFarmer]

The operating thermosat is looking at the water jacket temp while the low limit is looking at the smoke box temp.

 

[chuck172]

The low limit that you're referring to is the stack temperature, I'm sorry, smoke box temperature low limit which uses the long probe that is inserted horizontally in the smokebox. The knob you set is under the top cover of the tarm. It's a black dial.

 

[jebatty]

My question involves the Lo-limit and Operating Temp knobs. The Lo-Limit Thermostat says to set it at 190F, while the Operating Thermostat says to set it for an operating temperature of 180 - 190. It seems that the Lo-Limit is at the upper end of the operating range, and it’s not really clear what either one is doing.

The Lo-Limit thermostat control is under the top cover in the control area. If you have storage, Tarm recommends setting this at 190F (90C). It monitors a probe inserted into the top right of the smoke chamber above the hx tubes. When this area cools down to the setting, its shuts the boiler down (turns off the draft fan). It operates on the assumption that if this area of the boiler falls to 190F, the fire is out, no heat is being produced to move to storage, and its time to put the boiler to bed.

The Operating Thermostat is on the front panel and turns off the draft fan when the boiler water reaches the set temperature, and then when the boiler water cools a bit (about 5 degrees), it turns the draft fan back on again to bring the boiler back up to the set temperature. It will cycle the boiler in this manner. When it turns the draft fan off, this is the period when the boiler is said to be idling.

 

[nporter]

On my Solo30 the lo-limit knob is on the front of the boiler just under the operating thermostat. It appears different than the manual shows that came with the unit this fall.

 

[Rory]

Mine agrees with the illustration. I got the last of the old model, the new ones have an outer door and cost about $750 more. Perhaps you have the newer model.