Tarm Solo 30 installed in parallel with an oil boiler

[tmchurch]

First, I am a newbie to this site, but I do have some engineering background.

Last month I had a Tarm installed with the Temovar valve, etc. My understanding is that the water is heated in the Tarm, is pumped over to the oil boiler where it is released into the house dependent on the thermostats for my two zones. My tarm has an aquastat at 160 for the Temovar (to start the circulation) and another set at 180 that I believe to be the feedback loop to tell the induction fan to start. My problem is that the temp gage on the Tarm shows 180 degrees, but my oil boiler keeps coming on, say once an hour or so. The temp gage in the oil boiler shows 160, and the aquastat for the oil boiler is set at a low of 120 and high of 140.

I want to be heating primarily off the Tarm, and have the oil start up only when the Tarm cannot supply the heat. The Tarm is clearly able to heat well. What may be happening here? I'd appreciate some control install help. Or at least the knowledge to challenge the installers.

 

[WoodNotOil]

Make sure the aquastat on the Tarm feed line that controls the circ between the Tarm and oil boiler is running continuously when the boiler is up to temp. If there is no heat demand the two should match. When zones are on in a parallel/series hookup the hot water from the Tarm mixes with the return water from the zones and the oil boiler temp will be lower than the Tarm temp until zones go off. This is one drawback of the parallel/series hookup.

Check that the differential on the aquastat is set to 5* and that it shuts off on a temp decrease not a temp increase. The Honeywell 6006 aquastats can be either NO or NC depending on which terminal you attach the circ line to. If you have a 6006 make sure the correct terminal was used. You may try having it circ water all the way down to 140*. Turn the oil boiler aquastat down as low as it will go or it may cycle on and off more than you would like.

Hope that helps a little.

 

[Toyman]

Just had the same problem with my solo 30,just got it fired up last week, you need to install another aquastat in the feed line from the wood boiler,a 4006a honeywell, and set it to 140* and wire it to the oil boiler this will keep the boiler from firing until it goes under 140* or you can keep lowering the temp on the oil boiler and raising it back up when the wood boiler is shut down, something they forgot to put in the piping diagram I got.
Hope this helps.