I have an indoor wood boiler in my basement which has an automatic draft which is controlled by an aquastat, when the water temperature reaches 180 degrees the draft closes. It works the same as an outdoor wood boiler. The wood boiler loop is ran through the oil burner and I turn the oil burner down to 160 high and 140 degree low temperatures on the oil burner aquastat. The oil burner rarely ever kicks unless the outdoor temperature is below 15 degrees. When it is this cold should I turn up the temperatures on the oil burner aquastat for it to be more efficient? I don't want to turn the oil burner up to 180 degrees because the fire will just smother. Any suggestions? Normally the return temperature of the water from is baseboard heat is between 155-160 degrees. As per the baseboard It is Weil McLain slat fin. The house was built in the late 1980's. It has r19 insulation in the walls, Andersen dual pane Windows, and it also has house wrap on all the exterior walls. The ceilings have r38 in them. As per efficiency, it meets all of today's irc building codes for insulation with the exception of low e glass windows and thermoply insulation on tub walls. Any suggestions? Are there any formulas on effiency?

So where do you liive?

2x6/R19 doesn't meet IRC 2015 anywhere north of the warmer edges of the Gulf coast states, US climate zones 1 & 2 in this map:

http://www.greenbuildingadvisor.com/sites/default/files/images/DOE%20climate%20zone%20map.preview.jpg

R38 only meets current code-min in zone 3 & further south.

Current code-min for zones 3 through 5 is 2x6/R20. That may not seem like a real difference until it's understood that R19s only perform at R18 when compressed to 5.5" in a 2x6 stud bay, whereas R20s perform at R20. See TABLE N1102.1.2 (R402.1.2) INSULATION AND FENESTRATION REQUIREMENTS BY COMPONENT

https://up.codes/viewer/utah/irc-2015/chapter/11/re-energy-efficiency#11

The temperature the baseboards need depends on how much baseboard, and your actual heat load. At 180F EWT (entering water temp) or 170F AWT (average water temps) a typical baseboard puts out about 500 BTU/hr per foot of lenght. At an EWT of 140F /AWT 130F it's down to about half that. See:

https://www.slantfin.com/images/stories/Technical-Literature/ratings_fineline30_r.pdf

Without knowing how much baseboard or your actual heat load (which has to be calculated/estimated with a Manual-J or at least an I=B=R load calculation) there is no way to know what your water temperature requirements are. But with design load per foot of baseboard ratio it's fairly straightforward. eg:

If the actual heat load at that temp is 25,000 BTU/hr, if you have less than 50' of baseboard you'll need that 180F temperature or more (at least 1% of the time) , since 25,000/50' = 500 BTU/hr per foot of baseboard. But you won't need more than 140F if you have 100' of baseboard.

If the oil boiler is able to keep the place warm with a high temp of 160F, leave it there. Most hydronic heating systems have enough baseboard to keep the place warm with 140-150F EWT (though there are enough exceptions to prove the rule. :-) ) Turning the boiler temp up reduces rather than increases it's efficiency, as long as it's not short-cylcing at the lower temp. (Minimum burn times of 5+ minutes, 10minutes is even better, and fewer than 5 burns per hour is where it wants to be.)

I live in Pennsylvania which is zone 5a

As per the baseboard, it is Weil McLain High Trim baseboard.

https://www.weil-mclain.com/products/high-trim-baseboards

Zone 1- upstairs - kitchen/living rm/ dining rm/ bathroom 1 & master bath-
23,580 btu/hr- average infiltration

Zone 2- upstairs- 3 bedrooms
10,885 btu/hr- average


Zone 3- basement - below kitchen, dining & living room. This is all sticker framed and above ground.
Average- 35,841 btu/ hr
3 big old cast iron radiators with btu rating of 30,000 btu
- heat loss calcs were figured for bath room, hallway, foyer area which are not heated so it should be pretty close .

Back half of basement where wood stove is
29,213 btu/hr- average
This area is 4' underground/ below grade and 4' stick framed wall.

The load numbers seem suspiciously high- how were they calculated? Adding it all up I get about 100,000 BTU/hr, which would have to be a truly gian-normouse mostly code-min house!

For comparison purposies, I live a zone 5A location with an outside design temp of +5F with insulation valves and window performance well below code min in a house with 2400' of above-grade space and ~1600' of mostly below-grade insulated basement that stays above 65F all winter, and my whole house heat load at +5F is about 36,000 BTU/hr.

We still don't know how many feet of baseboard there is for zone 1 or zone 2. Or perhaps those are the 170F AWT specified for the amount of baseboard in those zones, and not heat load numbers?

How was the BTU rating of the radiators determined (and at what temperature)? Take a look at this document to estimate the output at 170F AWT, or just report the square feet EDR:

http://www.columbiaheatingsupply.com/page_images/Sizing%20Cast%20Iron%20Radiator%20Heating%20Capacity%20Guide.pdf


The ratio of load to radiation or baseboard is what determines the needed water temperatures to cover the load. See the nomograph in that radiator sizing document to figure out what temperature the radiator zone needs. The W-M baseboard emits ~650 BTU/hr per running foot at an average water temp of 170F (which is about what you get with an entering water temperature of 180F. It'll put out about 350 BTU/hr per foot at an AWT of 130F, which is about where it will be with 140F entering water temperature.