Pensotti S1 18 Wicked High Flue Temp!

Matthew Grallert

Hello all
I just finished servicing a nice little Pensotti with a Riello F3. Old service records(my first time there)show a low combustion efficiency about 80% all hand written. They show a very high, in my mind, flue temp. Like high 550 to 630! Pump factory set at 180 im getting 12 to 12.5 co2 zero smoke. Lowered pump to 160 and made adjustments for zero smoke and 12.5 co2 got flue down to 530 even put a load on it still wicked high. What gives? Is this normal for the S1 18? Oh ya It's firing a .50 at 160psi.
Peace
Matthew

Norm Harvey

Here's this chart just for kicks.
http://www.pensotti-pna.com/riello BL and DK series oil boilers0001.pdf

But 530 flue temp I wouldnt say is "wicked high" Is all the cast iron visible in the flues after you cleaned them? An 1/8 inch of soot has an R value of something high, I cant remember what. but I would share your concern if I could see all the cast iron in the flues clearly, and still had a temp that high.

Though 530 isnt too bad.

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Matthew Grallert

Ya I would say the cast iron is visable of course there is sme left over stuff no soot though. This is a new customer for use and I think I am the first person to remove the burner and clean the chamber, were I found ash hard ash all gray was abkle to chip most of it away. Put I have never run across a temp that high except for some junky old furnaces. I'm use to mid 3's. The boiler I services next was a 25 year old single pass with a temp of 430 it doesn't seem fair.

Norm Harvey

Just a thought,..
Your well under the firing rate for that boiler by reducing the pump pressure. So over firing shouldnt be the issue. I was thinking,.. where are you taking your temperature reading? Is it very close to the boiler, or 16 inches down the pipe? Beyond that I'm stumped. I'll try to look up some efficiency results from some of my pensotti customers and compare. It wont be the same boiler model, but it may offer some insight.

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j novie

high stack temp

try checking the draft, you may be sucking the flue gas right up the stack. is there a barometric damper ??? may need to add some baffles to it. to slow the flue gas down a bit.

Matthew Grallert

no baffles with boiler I don't know if that boiler comes with them. I would think that they would help. There is a draft reg and not an extreme draft if I remember it's
-.02. after adjustment no big change in draft or temp.

Matthew Grallert

I did take the reading pretty close to the boiler before the draft reg. I dropped the firing rate from 70gph to just over 60 gph. I don't know whats goin on.

Pat_11

Hi Matthew my Pensotti (22years old firing .60) has cast iron baffles. I'll check the model # later this week (away travelling for work). Stack sounds a little on the high side. I agree you may have too much draft. I remember having to add two draft regulators to keep flame stable on some Pensotti installs with really large chimneys. Good luck.