UFH condensing oil boiler short cycling

[Johntheo5]

Yeah, might be something like this?.

2-Pipe Versus 4-Pipe Buffer Tank Configurations

In the following article, HeatSpring instructor John Siegenthaler discusses 2-Pipe Verses 4-Pipe Buffer Tank Configurations. Read on to learn more about… The importance of a properly sized buffer tank for both wood gasification boilers and boilers fueled by pellets/wood chips The primary...

blog.heatspring.com

 

[markmorrison1957]

That's it - a two pipe buffer is less hassle I think but no disadvantage to a 4 pipe system

 

[Johntheo5]

Did a few sums on the above and assuming the buffer is fully recharged after each burner run then the times might look like something below,
and because you still have the 21L boiler HEX "buffer" then I did the calcs based on installing a 25L external buffer which gives a total buffering effect of 46L (21+25).
36 kw burner. all times in minutes
Heating Demand 3kw no ext. buffer ONtime./OFFtime/Cycletime 0.89/9.77/10.66 With ext.buffer ONtime/Offtime/Cycletime 1.46/16.05/17.51
Heating Demand 12kw no ext. buffer ONtime./OFFtime/Cycletime 1.22/2.44/3.66 With ext.buffer ONtime/Offtime/Cycletime 2.01/4.01/6.02
Heating Demand 30kw no ext. buffer ONtime./OFFtime/Cycletime 4.88/0.98/5.86 With ext.buffer ONtime/Offtime/Cycletime 8.02/1.60/9.63

In all cases above it extends all the times by a factor of X1.64.

 

[markmorrison1957]

Is it a fair assumption that with or without a 25L buffer the percentage of time the boiler is firing during each cycle time for whatever heating demand remains the same?
The only way to reduce fuel consumption is downsizing nozzle?

 

[Johntheo5]

No, not really, the only way to reduce fuel consumption is to reduce your heat demand, you might save 3or 4% with reduced cycling but that's it.