# Windhager People:  Boiler Temp Question



## velvetfoot (Dec 25, 2015)

For you Windhager pellet boiler people, have you fooled around much with the boiler set and external temperatures?  I currently have the set temperature maxed at 176 and external temperature at 161.  The idea is to increase the run time by increasing the time run at modulated output (<100%).  I'm thinking of decreasing external temp below 161, though not sure how low.

Opinions/Experience?


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## Sparky978 (Dec 26, 2015)

external temperature at 161.

Velvet
Is the 161 when your Ranco turns off your PB?


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## velvetfoot (Dec 26, 2015)

Sparky978 said:


> external temperature at 161.
> 
> Velvet
> Is the 161 when your Ranco turns off your PB?


No.  There are two temperature parameters you can set on my BioWin:  set and external.  Set is the boiler setpoint, which I don't believe is exceded (by much anyway).  The max set on mine is 176.  External is the temperature that the boiler shoots for.  What seems to happen though, is that the boiler continues to run even if the external temperature is met, although modulating itself down until it gets to the setpoint plus.  Mine actually shut off yesterday when it was at 181 and 30% for a few minutes.  I got to thinking about this again after reading nofossil's post about controlling a Froling's output (modulation) by modulating its return temperature.  My idea is to run the boiler longer at lower average output since I have overcapacity, especially now.  

I'm averaging around 2 hours, which isn't bad, but I'd like to increase it, without decreasing comfort too much.  

I might try to map the relation of % modulation, boiler temp, and exhaust temp.  I guess it'd be 3D.  Sounds like too much work.  Awww.. fuggedaboudit.


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## bdud (Dec 26, 2015)

I have my Biowin set at 167F for Max Value Offset Temp, 158F for Set Temp Ext Heating Requirement, the Johnson Controls A419 which controls my boiler on - off with the probe in the storage tank, is set for 170F.
With these settings the boiler goes into modulation mode 30% for quite a while. I kept the storage tank set temp high so if any one zone is calling for heat or water, the boiler keeps in modulation mode until that zones thermostat is happy. My highest average boiler run time last year was 3.56 hrs, ~ 2.5hrs average with 1.5hrs in the fall and spring.
I kept the Max Value Offset Temp at 167F thinking slightly more efficient boiler output - storage efficiency rather than using 176F.
I have never changed the Set Temp Ext Heating Requirement value, not sure if the boiler uses it in my scenario.


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## Tennman (Dec 26, 2015)

Proud to be a "Windhager people", but not sure what I'm doing is relevant to you. With extremely mild temps not expected to stay long I don't want to have to completely recharge sitorage so keeping boiler on. But I know that the larger the temp difference between stored and ambient, the larger the wasted energy leak rate. So lowered external temp to 125F to reduce pellet use. I'll be controlling the external set point to track weather extreme changes to minimize storage energy waste. I've presently set the boiler temp to 178. That big thermal battery gives us many options.


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## Sparky978 (Dec 26, 2015)

velvetfoot said:


> the boiler continues to run even if the external temperature is met,


It seems to me that the ext. heating set point doesn't control burner on/off. The on/off is only controlled by the Ranco on my storage tank. The boiler only goes into burnout when my Ranco reaches it set point of 180. So would lowering the ext. set point cause the boiler to go into a lower modulation sooner? Which I guess would give longer burn times. I increased my differential on the Ranco to get a little longer burn times.


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## velvetfoot (Dec 26, 2015)

Hey Tennman, bdud and I have tiny storage tanks compared to you!  But, and you want to make sure if I'm right, I believe with the external temp set at 125 and the boiler temp set at 178 (mine can't go above 176), with a continuing heat call, the temp of the tank will eventually reach 178.  The settings I'm talking about are on the boiler control panel.

bdud, unlike you, I'm still using a wood insert most of the time, but my pellet boiler, while not big at 15kW, is still too big when the insert is running.  It took about 2 hours to charge the tank with no zones calling (I believe) before I started my recent fiddling.  I want to retain the potential to heat with pellets only when the weather is cold, or recovering from setback: that's why I went with the 15 vs. 10 kW setting.

I have it set a `156 for external temp requirement right now. 

I'm also fiddling with the setpoint of the tank sensor to start the pellet boiler.  The bugaboo is not only getting a head start on heating the zones with whatever heat's left in the tank, but also to supply dhw.


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## velvetfoot (Dec 26, 2015)

Sparky978 said:


> So would lowering the ext. set point cause the boiler to go into a lower modulation sooner?


Yes.  I'm curious to see how pronounced it is.
Now, I'm not sure if it's less efficient when modulated down.
I figure the fewer starts the better, and if it just kinda of hanging out at 40 percent or whatever, there could be a chance that another zone would come on and take more of the boiler heat.
The Ranco on my tank controls the start but I let the boiler run until it shuts itself down.
Bear in mind our tank are probably similar to my 119 gallons, where Tennman  has 1000 gallons to think about!


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## Sparky978 (Dec 26, 2015)

velvetfoot said:


> The Ranco on my tank controls the start but I let the boiler run until it shuts itself down.


How does the boiler shut itself down without the Ranco opening up the call for heat circuit? Maybe your model is different than mine?


velvetfoot said:


> there could be a chance that another zone would come on and take more of the boiler heat.


At that time wouldn't the Max set boiler temp start dropping and increase the output %?
Yes I have the 120 gal. TurboMax tank.


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## velvetfoot (Dec 26, 2015)

Sparky978 said:


> How does the boiler shut itself down without the Ranco opening up the call for heat circuit? Maybe your model is different than mine?


The boiler shuts itself down depending on the "set" temperature on the boiler control panel.  Mine is set at 176, the max, but the temp on mine actually gets to 181.



Sparky978 said:


> At that time wouldn't the Max set boiler temp start dropping and increase the output %?


The max set boiler temp doesn't change-it is set in the parameters section in the service part of the control panel screen.  Yes, the boiler temp would drop and the percent goes up.


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## Sparky978 (Dec 26, 2015)

velvetfoot said:


> The boiler shuts itself down depending on the "set" temperature on the boiler control panel.


So at what temp on your Ranco does the start contact re-open to get ready for the temp drop in your tank to call for boiler start?


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## Tennman (Dec 26, 2015)

VF, to clarify, on our system the A419 turns the boiler on and off based on mid storage temp of 125-145F. 178F is being supplied to storage which when it warms mid tank water to 145F the PB shuts down.


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## velvetfoot (Dec 26, 2015)

Sparky978 said:


> So at what temp on your Ranco does the start contact re-open to get ready for the temp drop in your tank to call for boiler start?


It's not a matter of re-opening.  I have it arranged so that after the Ranco closes, which I have now at 120, a relay closes and keeps the demand for heat on until the boiler turns itself off.  There is a differential of 1, but it doesn't come into play at all.



Tennman said:


> VF, to clarify, on our system the A419 turns the boiler on and off based on mid storage temp of 125-145F. 178F is being supplied to storage which when it warms mid tank water to 145F the PB shuts down.


You have totally the opposite problem that I have.  You have too much storage and I have too little.  I'm trying to squeeze as much as I can into/out of my tank, and your trying to make do with the minimum, which is a lot compared to mine.


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## Sparky978 (Dec 26, 2015)

velvetfoot said:


> It's not a matter of re-opening. I have it arranged so that after the Ranco closes, which I have now at 120, a relay closes and keeps the demand for heat on until the boiler turns itself off. There is a differential of 1, but it doesn't come into play at all.



Ok, So you power a latching relay to keep the demand circuit closed which keeps the boiler running. After the boiler shuts down on its own how does the relay reset?


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## velvetfoot (Dec 26, 2015)

What keeps the relay latched is voltage sensed from the induced fan running, which is the best I come up with to check if the pellet boiler is running.  It also keeps the pellet boiler pump running until the fan shuts off, which I recall is 11 or 13 minutes.



























































































































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## Sparky978 (Jan 24, 2016)

velvetfoot said:


> The boiler shuts itself down depending on the "set" temperature on the boiler control panel. Mine is set at 176, the max, but the temp on mine actually gets to 181.



Velvet
I've been watching my system closely the last few weeks now that temps outside are colder. I notice that with the colder temps my zones are calling more and I'm getting much longer run times. I have never seen my boiler go into burnout until my storage tank sensor tells it to, which is set for 180. My "set" temp is set for 176 also and its has gone up to as much as 189 on the Biowin display but has never shut itself off. Is there something else that you do to make the PB shut itself down.


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## velvetfoot (Jan 24, 2016)

Sparky978 said:


> its has gone up to as much as 189 on the Biowin display


Mine shuts itself off at 181.  I currently have the external temperature at 156 which leads to more modulation and longer runs.  I have a wood stove going but also do a couple of setbacks, so it's not running as hard most times, but the setbacks are a strain and need some oomph especially if we've been out of the house and not running the stove..  

I've never seen 189 for sure.  You can lower the set temperature (not the external temperature)-maybe that'd do it.  

I've been running the oil boiler a lot lately.


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## heaterman (Jan 25, 2016)

velvetfoot said:


> For you Windhager pellet boiler people, have you fooled around much with the boiler set and external temperatures?  I currently have the set temperature maxed at 176 and external temperature at 161.  The idea is to increase the run time by increasing the time run at modulated output (<100%).  I'm thinking of decreasing external temp below 161, though not sure how low.
> 
> Opinions/Experience?


If you have the boiler temp set a little lower than external demand, you'll get the result you're trying to achieve.
Ex.  Boiler at 170 and external storage demand @ 175.

The boiler "sees" 2 inputs and will stay running until bothare met in this scenario.


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## Sparky978 (Jan 26, 2016)

heaterman said:


> If you have the boiler temp set a little lower than external demand, you'll get the result you're trying to achieve.
> Ex.  Boiler at 170 and external storage demand @ 175.
> 
> The boiler "sees" 2 inputs and will stay running until bothare met in this scenario.



Is there a reason why when my Biowin gets a call for heat it doesn't kick in until the temp on the Biowin screen comes down to 165*?  Is there a setting that causes this to happen? My call for heat kicks in at 160* with a 20* diff.


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## velvetfoot (Jan 26, 2016)

I'm no expert but the highest boiler temp I can set is 176.  So, maybe after it went over 176 on the heat up, it won't let itself restart until it's cooled off 10 degrees.


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## Sparky978 (Jan 26, 2016)

velvetfoot said:


> I'm no expert but the highest boiler temp I can set is 176. So, maybe after it went over 176 on the heat up, it won't let itself restart until it's cooled off 10 degrees.


I've got my boiler temp set at 176 also. Maybe it's a preset differential. Would the "hysteresis" setting have anything to do with it? Doesn't Hysteresis usually deal with differential?


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## velvetfoot (Jan 26, 2016)

Yes, preset, I would say.  Not sure what the hysteresis does exactly-kind of like an anticipator, I imagine.
You don't let your tank cool off too much.  Where is your tank sensor located on the tank?


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## Sparky978 (Jan 26, 2016)

velvetfoot said:


> Yes, preset, I would say.  Not sure what the hysteresis does exactly-kind of like an anticipator, I imagine.
> You don't let your tank cool off too much.  Where is your tank sensor located on the tank?


My sensor is at the bottom of the tank. I have 5 heating zones and a DHW zone pulling off my tank so when they kick in especially lately with the colder weather i've noticed my tank temp has dropped into the 130's so I try to kick in on sooner to get it going. When it was milder out I had it kicking in at 150.  I've noticed these past few weeks sometimes that the water temp going up to my baseboards can be as low as 150's. You mentioned that you want yours to modulate for a longer period and thats what mine does and I like that but when I get that big demand I wish that it would stay at 100%. Am I missing something on the settings?


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## velvetfoot (Jan 26, 2016)

160 water going into the boiler is pretty warm, I think.  It wouldn't take long for the boiler to start modulating.  Although it does take some time for the boiler to get up to temp, and the zones could be draining the tank in the meanwhile.

If the system is plumbed so that the zones get first crack at boiler heat (before the tank), and multiple zones are pulling, then I can see most of the interaction being between the boiler and the zones, with the tank being left out of the mix.  I can see the zones being cool as the boiler warms up.  Also maybe the slugs of cool water in the zones have to work themselves out after the zones activate.  You have a boiler protection valve set for 140?  I can see that giving 150's while the boiler is warming up.

Perhaps you could set priority to on for the dhw zone, so that the heating zones are off when it's on.  Maybe stagger setback recoveries via thermostat so they don't all happen at the same time.  Then you could use a lower tank temp?


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## Sparky978 (Jan 31, 2016)

velvetfoot said:


> If the system is plumbed so that the zones get first crack at boiler heat (before the tank), and multiple zones are pulling, then I can see most of the interaction being between the boiler and the zones, with the tank being left out of the mix.


When I run in "pellet boiler only mode" the zones can only get their heat from the storage tank.The PB charges the storage through the isolated coils then the zones draw off the storage. I've attached a rough sketch (nothing fancy) to show how my system is piped. By turning valves 1-5 I can run PB only, oil only or both.

QUOTE="velvet foot, post: 2048137, member: 208"]You have a boiler protection valve set for 140?

My boiler protection is set at 115* which fully closes the bypass at 133* so I can heat up my storage quicker.



velvetfoot said:


> Perhaps you could set priority to on for the dhw zone,


I do keep the priority switch in the on position so that DHW gets first crack at hot water.


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## velvetfoot (Jan 31, 2016)

Sparky978 said:


> My boiler protection is set at 115* which fully closes the bypass at 133* so I can heat up my storage quicker.


How is that working for you?  I have a 130 model which closes the bypass at 148.


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## Sparky978 (Jan 31, 2016)

velvetfoot said:


> How is that working for you? I have a 130 model which closes the bypass at 148.


No complaints.  As long as the boiler is protected it just makes sense to start putting the extra 15* into storage. It only comes into play at the start of the heating season and after a mid season cleaning because I never let my boiler temp get that low. Although with the price of oil Im starting to think about using that. Do you run your oil much?


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## velvetfoot (Jan 31, 2016)

Sparky978 said:


> Do you run your oil much?


I only run the pellet boiler when I'm 'experimenting', but I've been 'experimenting' a lot.


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## velvetfoot (Feb 5, 2016)

I tried setting the external boiler temp to 147, with the boiler set temp at 176.  A couple zones running, 66 & 68, about freezing outside.
It ran for 5hours 45minutes and then shut itself off at a boiler temp of 170.
I wonder if there is a duration that the boiler can run before it shuts itself down?


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## velvetfoot (Feb 6, 2016)

I set it back to 156, bumped up a couple zones a little, no wood stove, and let it run.  It turned itself off again after 6 hours.  My feeling is that it runs 6 hours and then turns itself off.
I recall Marc saying something about that in the past, but I can't get hold of him now.


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## heaterman (Feb 6, 2016)

velvetfoot said:


> I tried setting the external boiler temp to 147, with the boiler set temp at 176.  A couple zones running, 66 & 68, about freezing outside.
> It ran for 5hours 45minutes and then shut itself off at a boiler temp of 170.
> I wonder if there is a duration that the boiler can run before it shuts itself down?



What exactly is your external demand connected to on the Windhager?

This doesn't sound right. A loss of external demand should shut down the boiler regardless of where the boiler internal temp is set. 

All BioWins automatically cycle off for a brief cool down/cleaning period every 6 hours of run time. This is what your is doing. It's "seeing" demand from somewhere.


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## velvetfoot (Feb 6, 2016)

heaterman said:


> What exactly is your external demand connected to on the Windhager?


It is a latched relay connected to the buffer aquastat.  The boiler runs until the boiler shuts itself off.



heaterman said:


> All BioWins automatically cycle off for a brief cool down/cleaning period every 6 hours of run time.


That explains it!  What happens then is that the buffer tank supplies the load until the aquastat is triggered again.

Heaterman, 1) what lengths should be pursued to increase run time?  and 2) is it possible to connect to the BioWin with a 0-10volt controller to control boiler temperature (external)?


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## heaterman (Feb 6, 2016)

velvetfoot said:


> It is a latched relay connected to the buffer aquastat.  The boiler runs until the boiler shuts itself off.
> 
> 
> That explains it!  What happens then is that the buffer tank supplies the load until the aquastat is triggered again.
> ...



I don't know what you mean by "latched relay" ......aquastat? 
Where does it sense temperature and where is it connected to the Windhager?


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## velvetfoot (Feb 6, 2016)

I have a sensor for a Ranco controller 1/3 from the top of the tank.  When it goes down to 130F, a relay closes which remains closed until the boiler turns itself off at 181 or so. After the boiler turns itself off, the relay is unlatched and is free to close again when the temperature goes down again in the tank.  It's connected to the terminals on the Windhager that turn the thing on an off  .  

Would you be able to tackle those other questions I had:   1) what lengths should be pursued to increase run time? and 2) is it possible to connect to the BioWin with a 0-10volt controller to control boiler temperature (external)?


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## velvetfoot (Feb 7, 2016)

Sparky978 said:


> its has gone up to as much as 189 on the Biowin display but has never shut itself off.


With the boiler external temp set at 170, things were more vigorous.  I just saw 190 on the display only it was after the boiler shut itself off.  It shut itself off at 181, the pumps runs as it always does for about 13 minutes, and then after it sat a little while, it rose to 190.  Maybe I should arrange for a longer run, but that would take more finagling.


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## heaterman (Feb 8, 2016)

velvetfoot said:


> I have a sensor for a Ranco controller 1/3 from the top of the tank. * When it goes down to 130F, a relay closes which remains closed until the boiler turns itself off at 181 or so.* After the boiler turns itself off, the relay is unlatched and is free to close again when the temperature goes down again in the tank.  It's connected to the terminals on the Windhager that turn the thing on an off  .
> 
> Would you be able to tackle those other questions I had:   1) what lengths should be pursued to increase run time? and 2) is it possible to connect to the BioWin with a 0-10volt controller to control boiler temperature (external)?



So the relay opens based on boiler temp instead of storage temp? If so, why? I mean how can that be?.......... does it have a sensor in the storage tank and on or in the boiler piping? 

Best efficiency is going to be the point where the boiler is reaching its  internal set point a little before the call for heat from storage is satisfied. You want it to be ramping down and "idling" at reduced output a little before the tank aquastat satisfies.
For example, external demand from storage set at 170 and boiler internal setpoint at 165-157*. 
The only caveat there is storage volume being not sufficient to provide a decent run time. Windhager likes to see around 1 start/stop cycle for every 1.5 hours. If you can get up to 2 hours between start/stop that's great. 

If your boiler is running for the 6 hour maximum run time I'd bet that it's spending a good part of that at greatly reduced firing rate unless it is matched very closely with your actual heat loss. Given that you are seeing temps 10+ degrees above the internal set point, something has to be keeping the boiler firing well past it's normal maximum temp setting of 176*. 
Running at 30-40% for extended periods (over half the burn cycle) is not the greatest for efficiency.  

Concerning 0-10Vdc control.........no, not that I am aware of. That would be a question for Marc.


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## velvetfoot (Feb 8, 2016)

When I've run it with load at 145, and to a lesser extent 156, it 'timed out' at 6 hours, never reaching its internal shutoff point.
I made several runs with no loads.
Have to think about it more.
Edit: See graphs below.


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## velvetfoot (Feb 8, 2016)

heaterman said:


> So the relay opens based on boiler temp instead of storage temp? If so, why? I mean how can that be?.......... does it have a sensor in the storage tank and on or in the boiler piping?


When the one sensor on the tank senses that the temperature the tank at a point 1/3 from the top is below 130, the boiler starts.  The boiler continues to run until it turns itself off, usually at 179 or so.  The sensor's controller is then released to turn on the boiler again when the temperature is below 130.  That's what I mean when I say it is latched.  I did it that way because I wanted maximum, consistent fill of the buffer tank.



heaterman said:


> Running at 30-40% for extended periods (over half the burn cycle) is not the greatest for efficiency.


Ah hah.  That's good info.  Now to figure out what to set it at. I'll try to make those charts look a little better tomorrow.


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## velvetfoot (Feb 8, 2016)

Unit is BioWin 150
Time interval:  15 minutes
No load other than tank

Legend: 
Blr - Boiler temperature as read at the console
In - ThermoMix In
Out - ThermoMix Out (return to boiler)
Bot - Bottom of Tank
Top - Top of Tank
% - Boiler Output


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## velvetfoot (Feb 9, 2016)

heaterman said:


> If your boiler is running for the 6 hour maximum run time I'd bet that it's spending a good part of that at greatly reduced firing rate unless it is matched very closely with your actual heat loss.


Yes, it was running a bunch at low firing rate.  That was with some load, not just the tank.  I made a chart of one, but I kind of lost it towards then end.  I'm logging this manually!

The trick is to pick a temperature that is works okay for high and low load days.  For me, the variables are if I have the wood stove on and the outside temperature. It might be nice if the boiler temp setpoint could be controlled based on outside temperature.  More boost in cold weather, longer cycle in warm temps.  Just thinking out loud.


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## Tennman (Feb 9, 2016)

heaterman said:


> So the relay opens based on boiler temp instead of storage temp? If so, why? I mean how can that be?.......... does it have a sensor in the storage tank and on or in the boiler piping?



VF, I'm following for my education. HM is the expert, but I find it odd that your boiler is turned on by the low setpoint on your storage and turned off by a high temp limit in the boiler. Not pretending to be a controls guy, but isn't it more common for the boiler to manage a low to high temp of your storage (hopefully HM will chime in). On our BioWIN the two "external heat demand" terminals control boiler start and shutdown based on desired storage high/low setpoints. Maybe your method was used because of the small storage volume? I can imagine with small storage thermal mass temps would have large and rapid swings. Doubt I'm contributing much useful, but wanting to understand and optimize our boiler also.


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## velvetfoot (Feb 9, 2016)

I'm not saying my way is better,  but it seemed to be the right thing to do at the time.  I'm depending on the boiler itself to shut itself down, just like my typical oil boiler. My oil boiler has a separate aquastat (that can be replaced if it goes!).  The pellet boiler doesn't have that, but shuts itself down at 180 or so, even though there still is call for heat-for safety.  So, the pellet burner turns on based on tank temperature, and turns off based on the safety turn off temperature.

I fill up the tank the same way when I have the oil boiler running, but that's more like a bull in a china shop.  I think it runs for about 45 minutes and storage goes to 185 or something like that.

I feel I get the most thermal filling of the tank (120 gallons) this way.  Otherwise, I'm stuck with the 30 degree setback if I use one sensor, and trying to cut it close to the safety cutoff if I use one or two tank sensors.  Sometimes the pellet boiler turns itself off a little earlier, based on, I don't know, temperature change rates (?), so that has to be taken into account.  So now, instead of the 179 tank temperature I would've gotten with "my" method, I'd have to set the tank controller to 176 or so to be 'safe'.

My only concern is am I putting undo wear on the boiler's (unreplaceable) relay or whatever that turns things off?  I mean, there are plenty of other electrical doo-dads in the boiler that can go south, right?  It operates maybe 4 times a day, or whatever.

My goal is to fill up the tank as much as I can every time either boiler runs.


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## __dan (Feb 9, 2016)

velvetfoot said:


> My only concern is am I putting undo wear on the boiler's (unreplaceable) relay or whatever that turns things off?  I mean, there are plenty of other electrical doo-dads in the boiler that can go south, right?  It operates maybe 4 times a day, or whatever.



That's one thing you don't have to worry about, unless you or your contractor are buying parts from old farmer's barn and basement cleanouts, intentionally driving quality down to the dirt by refusing to pay for standard suitable parts.

Modern manufacturing and engineering standards / practices result in products that are very heavily tested and validated. Depending on who makes it, even a four dollar relay could have millions in prior development factory engineering, testing, validation, before RTM, releasing to manufacturing / market. Failures then could be grouped into early (burn in, first use /install), improper useage / bad implementation in the field, lightning strikes, water damage ...

The manufacturer already knows how many cycles of normal  operation the part is rated for, and for some parts, do you think they want the liability or negative impact to business that early known failures will bring. Think Firestone tires, GM's ignition switch, Tata airbags, the Challenger Space Shuttle, Chipotle, the list goes on. Point is, engineering knew of the failure mode in advance.

So for parts manufactured millions of copies in advance, aircraft and car parts in particular, the electronics and electrical are very heavily validated to not failure during the expected lifetime. The average company cannot survive their early failed parts coming back to their docks or attorney / CEO's office. I would group boiler controls in with this group. Even Ebay has been very reputable in a good way in my experience, very good sellers.


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## __dan (Feb 9, 2016)

The latching relay. Unless you have a factory wiring diagram telling you to do this, I cannot see why you would want to.

The boiler, internally and hidden from you, has its own fire control "latching relay" where, when the call for heat circuit is dumped by the Energy Tank aquastat, it continues to run in a programmed shutdown cycle, burning off the remaining fuel, purging heat / flue gas.

It seems the Energy Tank would be too small to run heat loads off it. It is never used for ride through heating of the house when the boiler is off. It can only serve two purposes, DHW production including or especially when the boiler is off, and as a dump zone for boiler excess heat when the boiler is commanded off (the heat call is dumped).

I would revisit this with the factory wiring diagram. I cannot imagine the factory showing anything other than an aquastat with a standard operating range differential. It makes no sense to dump the heat call only after the boiler high operating limit is tripped. The heat call is dumped when the tank aquastat temp is sufficient to achieve DHW production and nothing more.

As noted earlier, some storage capacity for excess heat must remain at this time. The tank must not be at max temp when the heat call is dumped. If it is, the boiler will have run a few minutes more, for nothing, at the end of every cycle.


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## velvetfoot (Feb 9, 2016)

There is plenty of room for excess heat storage after the call for heat stops, usually around 179.  As I've said, the boiler pump runs for about 13 minutes after.  It goes up a couple or three or four degrees.  This is a pellet, not cord wood boiler.

This is only partially about dhw.  It's more about getting 2+ hours of runtime per cycle, and extending the time between starts.  At 120 gallons, it's good for some heating time when it is fully charged and the house is up to temperature.


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## __dan (Feb 9, 2016)

One thing I am sure of, I still don't understand exactly which problem you are detecting. Any and all of the recommendations I have been thinking of, I had anticipated and given some thought to years earlier. Such as reset of the load's water temp. Even for conventional baseboards, as the boiler equipment packages started to come with modulating fire burners, resetting the load independently complements the burner modulation. The problem with that solution being the added cost in a competitive bid market. I cannot sell the added work if it's 2K more and the competition meets the customer demand for the lowest price quote.

So there's nothing specifically about your install, but something specifically about a reference install, if I was to do them in volume all the same.

As I still don't understand the problem, I would start with the basics, like pellet consumption. I would SWAG if you have a standard conventional house and pellets only for heat and HW all year, I would guess four ton for the year would be great, a conventional system that is working well. If you're over that, I would SWAG that there may be a problem that could be found and fixed.

No one ever looks at their boiler for runtime. That;s the first I've ever heard of it. Typically they only know if it's working or not, leaking or not, horrible on fuel or not. That's why I cannot sell P/S pumping with reset controls. There are no buyers with an extra 2K. That's how I see the problem anyway. I don't know if you have a system that is working very well, you have heat with low fuel consumption (my guess is this is the present state), or if there is something on its knees begging and weeping to be fixed (mostly everyone else).

Hard to believe I still don't know what the problem is, but knowing that would be the first step. The possible solutions have already been anticipated and standardized solutions implemented many times.


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## velvetfoot (Feb 9, 2016)

Who said there was a problem?   I'm obsessive.


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## heaterman (Feb 9, 2016)

Rather than a 0-10Vdc control, you'd be farther ahead letting a Tekmar outdoor rest control manage the water temp in your storage. 
Simply connect the output leads from it to the xx connections on your Windhager board and watch what happens. Set minimum water temp at 125 - 130 on the Tekmar.


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## velvetfoot (Feb 9, 2016)

heaterman said:


> Rather than a 0-10Vdc control, you'd be farther ahead letting a Tekmar outdoor rest control manage the water temp in your storage.
> Simply connect the output leads from it to the xx connections on your Windhager board and watch what happens. Set minimum water temp at 125 - 130 on the Tekmar.



I actually have an Tekmar on/off model that's just laying around. I'm not sure how to hook it up, ie, what you're driving at.  Plus, I forget how it's wired.
You're not saying to use it control at what tank temperature the boiler starts (colder outside, higher start temp)?

I'm still under the impression that as complete a thermal fill is desirable. So, if the reset is to control the boiler shutdown, I don't know if turning the boiler off when the tank isn't 'full' is desirable.

If you could expand a little, it'd be great.


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## __dan (Feb 10, 2016)

velvetfoot said:


> Who said there was a problem?   I'm obsessive.



Well if you called me with this problem, I would take the business phone out to the middle of the road and spend several hours running it over.


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## velvetfoot (Feb 10, 2016)

heaterman said:


> Rather than a 0-10Vdc control, you'd be farther ahead letting a Tekmar outdoor rest control manage the water temp in your storage.
> Simply connect the output leads from it to the xx connections on your Windhager board and watch what happens. Set minimum water temp at 125 - 130 on the Tekmar.


I took a picture.  The 10 v. external heating demand terminals are intriguing:


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## heaterman (Feb 15, 2016)

Intriguing possibly but they are not going to help you get what you're after, which is longer run time if I'm not mistaken?

I would get rid of your "latched relay" and use a normal aquastat with adjustable differential in your buffer tank. run the set point on that at 180 and the boiler at maximum (176*) You'll get longest possible run time from that configuration.


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## velvetfoot (Feb 15, 2016)

heaterman said:


> Intriguing possibly but they are not going to help you get what you're after, which is longer run time if I'm not mistaken?


It's intriguing, and I have a 0-10 v. controller laying around, but I'm not sure it's worth the risk, for as you say, possibly dubious rewards.



heaterman said:


> I would get rid of your "latched relay" and use a normal aquastat with adjustable differential in your buffer tank. run the set point on that at 180 and the boiler at maximum (176*) You'll get longest possible run time from that configuration.


I might, but I'm pretty sure I'm getting the most run time this way.  Besides, there's no guarantee that the tank would hit 180 each time. If the boiler aquastat shuts things down at 181, or whatever, and the tank is still calling for heat, the boiler will start again after it cools to 160 or so.  Then if it makes it to 180 on the tank, it will shut off the boiler again after a short while.


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## bdud (Feb 15, 2016)

velvetfoot said:


> It's intriguing, and I have a 0-10 v. controller laying around, but I'm not sure it's worth the risk, for as you say, possibly dubious rewards.
> 
> I might, but I'm pretty sure I'm getting the most run time this way.  Besides, there's no guarantee that the tank would hit 180 each time. If the boiler aquastat shuts things down at 181, or whatever, and the tank is still calling for heat, the boiler will start again after it cools to 160 or so.  Then if it makes it to 180 on the tank, it will shut off the boiler again after a short while.



You could lower the boiler output temp and have the boiler controlled by the tank aquastat set at a higher temp as heaterman said. I have boiler water temp at 167F and the tank aquastat at 170F. I get ~3hr average run times when it is real cold, ~2hrs back in November. If any one heat zone is calling for heat, the boiler will not turn off. You just have to find your own sweet spot.


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## velvetfoot (Feb 15, 2016)

I forget, where is your tank aquastat located?  The Ranco has a 30 degree differential, which is also a factor.  170 at the top isn't awesome, in my opinion.


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## bdud (Feb 15, 2016)

I think it is about 1/4 - 1/3 way down the tank. I have a 25 degree swing, I replaced the mechanical aquastat with the electronic one. As long as your home is heated adequately with whatever you set your boiler to, it does not matter what that temp is. I personally think, maybe rightly or wrongly, with a lower tank temp I have a less heat loss from my tank / boiler / piping. European - English boilers do not run as hot as ones in the US. My house is nice and warm at 66 - 72F with the way it is set.
YMMV


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## heaterman (Feb 15, 2016)

velvetfoot said:


> It's intriguing, and I have a 0-10 v. controller laying around, but I'm not sure it's worth the risk, for as you say, possibly dubious rewards.
> 
> 
> I might, but I'm pretty sure I'm getting the most run time this way.  Besides, there's no g and idle as long guarantee that the tank would hit 180 each time. If the boiler aquastat shuts things down at 181, or whatever, and the tank is still calling for heat, the boiler will start again after it cools to 160 or so.  Then if it makes it to 180 on the tank, it will shut off the boiler again after a short while.



The boiler will not shut down if there is still external demand present. It will reduce firing rate but stay on while that demand is there along with a differential temp on its supply/return. 

Mine has a constant external demand because of the type of heating system I have. When it reaches my internal set point (whatever I have that set at) it will just ramp down the firing rate. About the only start/stop cycle is the 6 hour cool down & self clean period. Right now it has 7336 hours run time and 1659 starts.  4.42 hours per cycle average since start up.


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## velvetfoot (Feb 15, 2016)

heaterman said:


> About the only start/stop cycle is the 6 hour cool down & self clean period.


So, a majority of that time it's more than 30%?


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## heaterman (Feb 16, 2016)

The firing rate will typically be 30-50% depending on weather. The only time I see output around 60-70% is at outdoor temps <10*.
Outdoor temp today is 25* and the boiler is running between 30-40%. Boiler and system temp are sitting at 162* with a 165 internal set point.
My boiler is a 210 or, 72,000btu max.
I have no heat storage other than the water capacity of the system which is around 75 gallons.
System flow and boiler flow are constant but variable rate depending on the TRV's, zone valves, DHW etc etc.


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## velvetfoot (Feb 16, 2016)

More or less constant flow.load is probably the way these things like to operate, vs.  setback recovery, varyable building aux supply (wood stove), etc.  As I said here or somewhere else, with both zones on recovering from setback and the tank manually turned off, it came up to temp quickly and modulated very nicely at its set temperature at 70% or so, as I recall.  I'd like to emulate that with my fabulous tank bypass concept, detailed elsewhere.


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