Am I flowing enough BTU's?

[JP11]

For some reason I was thinking it was 245btu rated, you're correct, it's 205. Yes.. with a full burn going, I can see a delta T of around 27 or 28. Even assuming i'm at the low end of my pump curve.. I'm up over 300k. Now, I'm not saying I run that for hours.. but peak burn.. yes.

I won't do it with a bunch of junk wood in there.. but load it up with the good stuff and it roars.

I could run the boiler in the + settings and get more BTUs out. Mine is seat at 60kw, rated power.

JP

 

[maple1]

Just found some specs for my loading unit that I hadn't found or seen before.

It is rated at 6.3gpm on speed 1, and 12.6gpm at speed 3. So I guess my doodle figuring from yesterday was in the ballpark.

 

[maple1]

Your math is based on the 10 gpm, which is at minimum head. If my head is 7 and I am only pumping 6-7gpm instead of 10-11, I am guessing it looks like trouble.

I'm not so sure. (Round in circles we go).

At 7gpm, and with temp in at 140 and out 185, that would be moving about 150,000 btu/hr. So your unit should technically be OK. But, once your bottom of storage starts rising above 140, your dT will narrow - and you might then start getting into trouble as your dT will be narrowing which isn't good if you've got any kind of fire still burning.

Another thing to try to take into consideration, is that the more flow you have - the more potential to mess up your stratification. But with your setup with the tall tanks like that, that shouldn't really come into play too much.

Does your boiler have any controls on board now that aren't being used? Was thinking you might try adding another circ in series in your boiler/storage loop, that would start pumping when your boiler got up to 185 or so, and stop when it was 160 or so. Or add a strap-on controller to control that - but can't really say if it would be worth it or not, overall.

 

[maple1]

For some reason I was thinking it was 245btu rated, you're correct, it's 205. Yes.. with a full burn going, I can see a delta T of around 27 or 28. Even assuming i'm at the low end of my pump curve.. I'm up over 300k. Now, I'm not saying I run that for hours.. but peak burn.. yes.

I won't do it with a bunch of junk wood in there.. but load it up with the good stuff and it roars.

I could run the boiler in the + settings and get more BTUs out. Mine is seat at 60kw, rated power.

JP

I think I would definitely put a Vigas on my consideration list if I were to do this all over again - sounds like very good bang for the buck.

 

[Boardroom]

I just finished my burn for today. The numbers are attached for anyone interested.
I was just using some old wood from dead elms that I cut off the property. I probably should have used some good seasoned stuff if I wanted better info as I never got up to full temp.
In my btu calculation I made the big assumption that the tank was split in even thirds.
I usually only heat my tank up about this hot as my available expansion doesn't allow much more.
As you can see my tanks stay stratified during the entire burn. I usually stop the burn when the bottom storage gauge reads about 70.
I just used strap on temp sensors for the boiler return and boiler output columns so I assumed the actual boiler was probably more accurate so used that in delta T.
This should be enough heat to supply me with DHW for about 3 days. I will try my next burn with better wood and see what happens.
Maple - I do have available controls on my boiler that would allow me to hook in another pump. It would be easy as pie.

 

[maple1]

That's interesting - and doesn't seem too far off what I experienced in my last burn.

I should add a couple temp sensors to my tank & do some data recording too, sometime - just for the heck of it if nothing else.

Also looks like you were pumping enough there too - might see something different with good wood the whole way through though.

 

[jebatty]

Your math is based on the 10 gpm, which is at minimum head. If my head is 7 and I am only pumping 6-7gpm instead of 10-11, I am guessing it looks like trouble.

I used minimum head because from your picture and description it appeared that your boiler pumped directly to storage, return directly from storage, 1.25" pipe, and assumed equivalent pipe length of 30 feet.