I Just Had My First Ever Out-Fire in the AHS S-130 Coal Gun

lsayre wrote:

McGiever wrote:By deepen...do you mean, lower or thicker?

Raise, lower the fire position, thicker, thinner size of the fire.

Thicker is what I should have said. Am I taking it in the right direction to accomplish that goal?

Raising the PID setting (SV) will cause for a longer running ashing time period and will make the fire thicker but could also move the fire some lower at the same time.
The effect really depends on how long the firing cycle time is. But running over time it will have an averaging effect. Today it is to hit 50* but after tonight and into the coming days temps, you should get some noticeable changes in the fire.

Every install is different, some basics principals are universal and some are variable due to the individual heating loads of each system, etc.

McGiever wrote:Raising the PID setting (SV) will cause for a longer running ashing time period and will make the fire thicker but could also move the fire some lower at the same time.
The effect really depends on how long the firing cycle time is. But running over time it will have an averaging effect. Today it is to hit 50* but after tonight and into the coming days temps, you should get some noticeable changes in the fire.

Every install is different, some basics principals are universal and some are variable due to the individual heating loads of each system, etc.

My first guess is that each firing cycle (as generated by a single zone calling for heat) generally runs our boiler for roughly 15-20 minutes. That's what I see in taking it from 165 to 180 degrees with a zone circulating. Does this sound typical?

I just had 3 of my 4 zones calling for heat (only the garage not calling) and the boiler ran for 46 minutes to go from 165 degrees to 180 degrees in order to satisfy this call. I had previously determined that the BTU output of my boiler was about 70,000 BTUH by running a measured amount of hot water (measured for flow and temperature) and having the boiler pull against it. I will now try to verify the BTUH of my boiler by using these three calling zones.

Total water capacity of the boiler plus all 3 zones = ~45 gallons = ~375 lbs. of water
Total length of the baseboards in all 3 zones = 116 feet
116 feet x 550 BTU/ft = 63,800 BTUH as my constant boiler load during this 46 minutes
46 minutes = 0.77 hours
375 lbs. of water x 15 degrees of rise divided by 0.77 hours = 7,305 BTUH's

63,800 BTUH of load + 7,300 BTUH of heat gained against this load = 71,100 BTUH of boiler output

This seems to confirm that my boiler when using Stockton pea is capable of delivering an output (averaged over 46 minutes) of about 70,000 to 71,000 BTU's per hour.

lsayre wrote:116 feet x 550 BTU/ft = 63,800 BTUH as my constant boiler load during this 46 minutes

Is this a constant? The BTU given off at 165 is much less than rated output.

franco b wrote:

lsayre wrote:116 feet x 550 BTU/ft = 63,800 BTUH as my constant boiler load during this 46 minutes

Is this a constant? The BTU given off at 165 is much less than rated output.

You are right in that the baseboards are probably rated to deliver around 450 BTUH at 160 degrees and around 600 BTUH at 180 degrees. Their output is not the constant that I presented. I agree that I cut many corners and made many loose assumptions in order to greatly simplify this process. Only trying to ballpark it. It is very likely that the boiler was putting out far less than 71,000 BTUH at the start of the 46 minutes, and far more than the 71,000 BTUH (that it averaged) at the conclusion of the 46 minutes.

Here is another observation I just completed:

Two zones fired the boiler for 27 minutes, taking it from an observed 160 degrees to 180 degrees. These two zones have a nominal combined heat load of 44,000 BTUH. They plus the boiler have a nominal capacity of 325 lbs. of water.

Total water capacity of the boiler plus 2 zones = ~39 gallons = ~325 lbs. of water
Total length of the baseboards in these 2 zones = 80 feet
80 feet x 550 BTU/ft = 44,000 BTUH as my (ahem, presumed) constant boiler load during this 27 minutes
27 minutes = 0.45 hours
325 lbs. of water x 20 degrees of rise divided by 0.45 hours = 14,445 BTUH's

44,000 BTUH of load + 14,450 BTUH of heat gained against this load = 58,500 BTUH of average boiler output for 27 minutes

Less time required here (27 minutes vs. 46 minutes) means that the boiler had less time to ramp up to full heat during this cycle and that for these 27 minutes it only required on average 58,500 BTUH instead of on average 71,000 BTUH.

If for the first (46 minute) test it started out delivering perhaps 45,000 BTUH and ended up delivering say 95,000 BTUH, the average would be about 70,000. And the average gain in output woiuld be about 1,090 BTU's gained per minute of firing.

If for this test (27 minutes) it also started out delivering the same 45,000 BTUH and it cut off while generating about 72,500 BTUH the average would be about 58,500. Again assuming 1,090 BTU's of heat output gained per minute of firing, then 27 x 1,090 + 45,000 = ~74,400 BTUH at the end of firing.

Admittedly a lot of conjecture, loose rounding, and ballparking it here, but 74,400 BTUH at termination of firing for 27 minutes by one guesstimate is pretty close to 72,500 BTUH at termination of firing for 27 minutes by another guesstimate.

I just timed a single zones call for heat as firing the Coal Gun for 17 minutes.

So far I have observed today that:

A single zone calling for heat fired it for 17 minutes.
Two zones calling for heat nearly simultaneously fired it for 27 minutes.
Three zones calling for heat nearly simultaneously fired it for 46 minutes.

What are your aquastat settings? Differential? Does it always run when a zone calls for heat?

coaledsweat wrote:What are your aquastat settings? Differential? Does it always run when a zone calls for heat?

Low limit is 180, and differential is 10 degrees (though zones generally knock it lower). Fires at 170 though.

My boiler does not always run on heat calls from T-Stats. It runs off the low limit and its differential.

High limit is 200.

Dump zone activates at 215.