Estimating fuel costs for an oil fired boiler

[docbar99]

I have an oil fired boiler with a hydrostat 3250 Plus control and I am trying to find the best settings based on some parameters that I can measure. I have a micro controller that can log data to an excel file. I have 4 temperature sensors and a current probe to tell me when the burner is on. The 4 sensors are as follows 1- on the hot water pipe a few feet above the boiler. 2- just above the circulator on the pipe. 3- next to the thermostat. 4- outside the house.

Here is a sample summary report I can generate after 2000 readings, about 1.4 days test time.

I can't measure the amount of oil I consume but I can tell how long the burner is on for a given average temperature. The Riello burner has a rating of 0.62 GPH, with a particular nozzle. I was thinking that it is probably by running this test several times I could determine the Burner on the time for a given temperature. By using the Burn time * the 0.62 * some factor for average temperature I could get some result.

This graph shows the Burner on in grey and the Circulator water in blue. The contractor that installed the boiler left me with these settings. I am reading the Hydrostat manual and trying to optimize the settings.

Has anyone found a good way to improve the efficiency by adjusting the settings?

 

[Fitter30]

Nozzle size is based on 100lbs oil pressure but it's not not unusual to run a higher pressure up to 160lbs which uses more oil. This is all in the setup of the burner and a flue analyser. How many zones? Circulator hold on? Did they use a existing well for temperature? Is there outdoor reset since you have a outdoor sensor? Thermal targeting on? Brand and model number of the thermostats? Using boiler for domestic hot water? Most cast boilers want 135° - 140° return water temp so the boiler doesn't condense and cool return is hard on the cast sections could lead to cracking. Are the sensors just strapped to the pipe and insulated?

 

[Sponsor]

 

[docbar99]

@Fitter30 - Thanks for your reply. This is the same system you replied to about "optomizing the Hydrostat"
So it is a single zone tankless coil. The PRO- features I have turned on are "thermal purge =ON", Circulator hold off = ACTIVE",
Hi Limit Differential = 30 deg. HL =170, LL=140, ECO = OFF, Switch set to Zone.

The outside temperature sensor is not connected to the hydrostat, but connected to the data logger to see how weather affects my test results.

I am concerned about the returning water being too cold, but I am not sure where to measure. any suggestions would be helpful.

 

[Fitter30]

Looking at the graph and the temperature reading being average (post1) doesn't make any sense since boiler and pump is off for a long time. Would want to track boiler actual temp. Have any space heaters boiled runs 10-15 minutes and off for hours.

 

[docbar99]

Looking at the graph and the temperature reading being average (post1) doesn't make any sense since boiler and pump is off for a long time. Would want to track boiler actual temp. Have any space heaters boiled runs 10-15 minutes and off for hours.

@Fitter30 - Thanks for your support. Yes, the boiler is off most of the time probably because there is no one using any hot water during the day, and the thermostat is only set for 63 degrees so the heat demand is pretty low.
You mentioned that I should monitor the boiler temperature, how can I do that?


Can you tell me if my circulator sensor is on on the pipe leaving the boiler, or the the one returning to the boiler?

 

[Fitter30]

Put it on leaving water you don't have much load. Play with next winter. Outdoor reset would give you shorter cycles it would bring down supply temperature.