Any Suggestions To Get Pellet Boiler Temperature Up

[velvetfoot]

I'm wondering if there's a way to get the pellet boiler temperature up, and thinking there might be parallels with wood boilers too.
I'm thinking it'd be nice to get it to 170 or so and keep it there while the baseboard zones heat up but not sure this is possible or even desirable for that matter.
I set the buffer tank heat call to 160 and the launch temps for the circ and zone pumps to 145. The boiler protection valve starts opening at 130 and is fully open at 148. I've also turned down the pumps speeds. Maybe bump up the launch temps more?

 

[jebatty]

I don't recall any details of your system or the rated btuh capacity of your pellet boiler. It is possible that your system may be demanding more btus than your boiler can deliver, and therefore temps are lower than you expect or want.

 

[velvetfoot]

I don't recall any details of your system or the rated btuh capacity of your pellet boiler. It is possible that your system may be demanding more btus than your boiler can deliver, and therefore temps are lower than you expect or want.

That's more than likely true, but I should still be able to increase the boiler temperature at the expense heat delivered. I understand that baseboard delivers more heat at higher temperature-thinking 160s instead of 140's, 150's. But it is indeed linear (see chart I made in an old thread below), so, I guess the same amount of heat is being delivered over a period of time at a lower temperature.

I'm playing with the launch temps of the pumps now. I have the boiler pump at 165 and the circs at 155. However, every time the boiler pump turns off, the boiler modulates down, then modulates up when the boiler circ comes back on. The modulating isn't instantaneous, so there's lost heating potential there. I have succeeded in keeping the boiler temps up though, but as you indicate, maybe to no avail.

I think I'll switch to 15 kw mode, up from 10 kw and see how that works.

 

[bdud]

I am not sure why you are concerned about the boiler temp. Are you able to maintain or reach the temp you have set on your room thermostats?
If you cannot reach those temps then increase the temp that your boiler will reach, mine is still set as 167F.
If your room thermostats still do not turn off and your boiler is continually running, then change the switches on your Windhager to a 150.
I think heaterman made those recommendations on another thread of yours.

 

[velvetfoot]

I think heaterman made those recommendations on another thread of yours

That wasn't me.

My boiler has always been set at 176-it just never approached it, not even in the 160's, until the end when zones and tank were satisfied maybe 7 hours later. I just changed it to 15kw and I think I'm going to like it better. Part of the problem was recovering from a pretty big overnight setback, as well as the lack of power.

Yours is set at 167: Does it stay in that vicinity for the duration of a cycle, or does it approach it gradually, modulating downward as it does? I don't recall what kind of emitters you have, but my baseboards do like the higher temperature.

As I said, I think I'm going to like the 150 setting. Also, not do as deep an overnight setback.

None of this was an issue until I decided to test it in the cold weather and not use the insert at all. Next thing I'll be complaining about short cycling.

 

[bdud]

That wasn't me.

Sorry my bad.
My buffer aquastat is set to 170f I think. The boiler temp I think might even reach 174f and it modulates down as it approaches 167f and stays at 30% for quite a while. If any zone is on, the buffer tank does not reach the 172f set temp. I have baseboard radiators on 5 zones and I don't have much setback overnight, 68f upstairs and 66f downstairs after about 11.30pm, 70f to 72f in the morning with 66f & 66f during the day, 70f & 71f in the afternoon. The buffer aquastat calls for heat at 140f.

 

[velvetfoot]

Thanks for the details; they're helpful. I'm going to go with a less aggressive setback.

Now, when you say you have the boiler set at 167, do you mean the max set boiler temperature, or the external heating requirement (to use Windhager's terminology)? I'm familiar with heaterman's tip of putting the external max several degrees below the max set boiler temp and the modulating, etc, mostly to extend the cycle. I'm not sure what changing the set temperature does, overshoot, etc.

 

[bdud]

My Windhager "Maximum value ofset temperature" actual value is 167f, max is 176f.
"Set temperature ext. heating requirement" actual is 158f, max is 176f.
These are the default values it shows in my manual.
Not sure what the "Set temperature ext. heating requirement" is used for or where the sensor is supposed to be located and wired to the Windhager.
I use the aquastat on my buffer tank to turn on the boiler.
Correction from above

My buffer aquastat is set to 172f I think.

The buffer aquastat calls for heat at 147f.

This is set at 170f and my boiler turns on at 140f.