I appreciate your advice and knowledge. Thank you very much.
I just started reading this and agree lose the tankless coil and get a indirect and a honeywell 4006 aquastat to cold fire the boiler when a call for heating from the house or the indirect calls for heat. you will see your oil bill drop doing this! why waste the energy of having the boiler maintain 180 degrees? Just my opinion I have converted my parnets to this same set up.
If your going to cold fire a boiler.Some evaluation should be done.
The burner needs set up to burn clean, not just an eye set up.
And some times a thermal bypass needs added to temper the water.
Most baseboard systems don't hold enough water to effect the boiler.
Cast Iron rad systems generally need a thermal bypass.
A boiler is less efficient when the water temp is at 180*, then when the water is at 140*.
The colder it gets outside, the warmer the boiler stays between heat calls.
OK, so if I understand this correctly, the tankless coil gets capped off, and the indirect is used as a new zone to provide domestic HW. My existing combination of baseboard and radiant heat zones still operate as is---and I'm guessing indirects don't need to be at 180 to be effective.
The end result should be that my boiler operates less frequently for DHW, but will operate the same for heating needs but only when called on. Since I supplement my heat with my wood stove, I am thinking I should see less oil use than I have in the past.
I just got my electric bill last night...it is up to $.18 now...ouch.
Very good advise so far. If I could step in and add that an outdoor reset used on the boiler if you're going indirect or electric for your hot water would dramatically decrease fuel usage. A Heatmanager form Beckett or HW+ from Intellidyne would also save money and both come with a 10% savings promised or your money back. I personally use outdoor reset.
I can personally vouch for the savings potential of an ODR. Can't speak for timers, but in europe I understand they use them alot. The only thing I might caution against is modifying the wiring on the aqua-stat. If doing so might void UL approval I wouldn't and haven't done it. I have seen it done in the field many times though and it seems to operate properly. Just my own personal feeling regarding liability etc.
Letting tankless coil boilers go cold isn't always easy on them. Too much possibility the coil gasket will start leaking. There is also the likelihood of increased scale accumulation in the boiler flueways, especially in a pin-type boiler. Better to lower the aquastat to about 120 and use a relay for the indirect that will start the burner with the circulator. The high side of the aquastat then comes into play. Maintaining some boiler temp provides faster DHW recovery, especially if the boiler is not oversized. After the hot water call is satisfied the boiler temp will drop back to the low setting.
You can use a Beckett AFG with outside air kit instead of the Riello BF. This does reduce considerably air infiltration. It takes almost 1400 cu ft of air to burn one gallon of oil. It has to come from somewhere and if that somewhere is the house outside air comes in to replace it. In winter that air is cold and requires fuel to bring it to room temperature.
The only thing I might caution against is modifying the wiring on the aqua-stat. If doing so might void UL approval I wouldn't and haven't done it. I have seen it done in the field many times though and it seems to operate properly. Just my own personal feeling regarding liability etc.
Its just the low limit that you by pass, not the high limit.
The only thing it does. Is stop the aqua stat from maintaining temp, and shutting the circ off if the water temp drops below the low limit setting.