Help with tekmar 260 settings

ak1000

Hi. First winter in a very old colonial house in the northeast, heating system uses oil fired Buderus g205 with a tekmar 260 control and an indirect water heater. Four zones, two of which are cast iron radiators and two fin-tube baseboards. Seem to go through more oil than should (4 or 5 gallons per day in heating season), even though thermostats are set fairly low most of the time. The oil company tech was not much help with answering questions. Does anyone have experience with fine-tuning tekmar260 to get more oil burning efficiency? Any suggestions are appreciated.

The outdoor reset is at 10, indoor room occ temp on the tekmar is 69 and indr boiler design is 68. There is an indoor sensor but the controller does not seem to be reading it.

STEVEusaPA

4/5 gallons, northeast, leaky house, is probably the best you're going to do. It's been the coldest winter in, I think, about 4 years.

ak1000

It has been a very cold winter. The house is actually decently insulated (no drafts that I can feel), and i run it at 60 when I'm not there and 65 when I am (it feels quite comfortable at 65) so do the outdoor design temp, indoor boiler design and occ room temp seem right? If my indoor room is set to 69 but the thermostats are never going over 65, should the indoor room be lowered? Is outdoor design temp of 10 right for the northeast or should it be lower?

Would there be any gain in getting the indoor sensor to work?

Hoffmann

Look up your county in this PDF

Presuming that the system was designed properly, you can use that as your outdoor design temperature. Add a few degrees as that PDF is 99% outdoor temps rather than the recommended 97%. What this means is that if your home was designed for -10 F weather, then the boiler doesn't need to be operating at design temperature until -10 F, so if the Outdoor Design temp is set to +10 F you're losing efficiency across the entire heating curve as the boiler target is always higher than it needs to be.

The indoor sensor will help the control fine tune the water temperatures which may lower the target and improve your efficiency. Sensor placement is important. On the tekmar/watts website you can look up the indoor sensor for a temperature vs resistance chart and test the sensor with a multimeter to see what temperature it is reading vs what you see with an IR gun - check the leads and splices for breaks if you're not seeing continuity.

A general rule of thumb with these sensors is replacement after about 10 years service. I don't know what the resistance drift is on these is but if significant enough you could get more accurate readings with new ones.