Windhager People: Boiler Temp Question

[velvetfoot]

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.

 

[Sparky978]

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?

 

[velvetfoot]

Do you run your oil much?

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

 

[velvetfoot]

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?

 

[velvetfoot]

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.

 

[heaterman]

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.

 

[velvetfoot]

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.

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)?

 

[heaterman]

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.

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)?

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

 

[velvetfoot]

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)?

 

[velvetfoot]

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.

 

[heaterman]

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.

 

[velvetfoot]

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.

 

[velvetfoot]

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.

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.

 

[velvetfoot]

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

 

[velvetfoot]

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.

 

[Tennman]

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.

 

[velvetfoot]

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.

 

[__dan]

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.

 

[__dan]

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.

 

[velvetfoot]

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.

 

[__dan]

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.

 

[velvetfoot]

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

 

[heaterman]

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.

 

[velvetfoot]

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.

 

[__dan]

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.