What limits are best for running my KA-6 boiler?

Clousseau · Post by **Clousseau** » Sun. Dec. 15, 2019 9:17 am

Right now they are set at 150 low & 180 high. It is a single loop, one zone system, heating a log home of 2,000 sq. feet. I have burned 2880 lbs. of rice since 11/4, so around 40 days. That's 72 lbs./day. Generally leave thermostat at 70 degrees during day & 64 degrees at night. Live in the Berkshires - has been a cold November!

Thanks!

nepacoal · Post by **nepacoal** » Sun. Dec. 15, 2019 9:49 am

How long does the boiler run each morning to go from 64 back to 70. Seems like a daily setback that large would cause the boiler to run 2 or 3 extra hours to catch up each morning.

Clousseau · Post by **Clousseau** » Sun. Dec. 15, 2019 9:57 am

It does run for a long while to catch back up to 70 degrees. Sometimes 3 hrs. sometimes 4+ hrs. depending on outside temp. Should I be leaving it at 70 all night or maybe 66?

nepacoal · Post by **nepacoal** » Sun. Dec. 15, 2019 10:16 am

If it were me, I'd leave it at one temp, 70 or even 72. Running an extra 3 to 4 hours each day takes 30 to 45 lbs of coal to catch back up each morning (depending on your feed rate). I doubt you'd burn half that just leaving at 70. Try it for a few weeks to see what difference it makes.

Pacowy · Post by **Pacowy** » Sun. Dec. 15, 2019 10:21 am

nepacoal wrote: ↑
Sun. Dec. 15, 2019 9:49 am
How long does the boiler run each morning to go from 64 back to 70. Seems like a daily setback that large would cause the boiler to run 2 or 3 extra hours to catch up each morning.

The setback still reduces overall coal use, because the boiler only has to replace the btu's that have been lost, and fewer btu's are lost during the period when the lower temperature is maintained. Removing or reducing the setback will only increase coal use, all else equal.

I'm in the Berkshires, too, and I think the most likely cause is the "early winter" cold periods we've had plenty of. Does your maintenance periodically include a good cleaning of the heat exchange surfaces? Also, does your KA-6 have the secondary blower that runs all of the time?

Mike

Clousseau · Post by **Clousseau** » Sun. Dec. 15, 2019 11:09 am

Yes there is a small blower that runs continuously. The heat exchange surfaces, are they right above the fire? Also, what temp limits are being used for high & low settings? Noticed you have a HB Smith mills boiler in your home, oil fired? My father in-law worked for HB Smith for many years in the Shipping Dept. Had a new mills 4 section oil boiler & a 7 section mills coal boiler in my home went I built it in 1976. I went to a newer Series 8, HB Smith oil boiler. Wish I had not done that. The wood boiler, lasted 40 years, then I bought the KA-6.

lzaharis · Post by **lzaharis** » Sun. Dec. 15, 2019 11:34 am

Clousseau wrote: ↑
Sun. Dec. 15, 2019 9:17 am
Right now they are set at 150 low & 180 high. It is a single loop, one zone system, heating a log home of 2,000 sq. feet. I have burned 2880 lbs. of rice since 11/4, so around 40 days. That's 72 lbs./day. Generally leave thermostat at 70 degrees during day & 64 degrees at night. Live in the Berkshires - has been a cold November!

Thanks!

==========================================================================================
Bon Jour Mon Ami Monsier Clouseau,

Like you, I am burning the Anthracite Rice Coal to heat the home. I have a 225 foot+- single loop using fin tube baseboard-which I hate) and my boiler bypass valve is shut off as well. My Domestic Hot Water Coil is not in use as it has a hole in it after 3 full seasons of use, thank you keystoker.

My system has 54 gallons of water +- with the 225 feet of baseboard with the piping above the boiler, the 34 gallons of water in the boiler, and the 10 gallons in the steel compression tank

The home is exposed on the east and west sides and I have a small shelter belt facing north. My neighbors
south facing shelterbelt helps slow the wind down a lot as well.

I have my low limit set at 150 degrees Fahrenheit and the high limit is set at 170 degrees Fahrenheit with a 10 degree differential.

My hold fire timer is set to run 14 minutes every thirty minutes.

4 minutes at 0 minutes
3 minutes at 7 minutes
4 minutes at 15 minutes
3 minutes at 22 minutes

My boiler has the single combustion fan and it has worked very well. I need to purchase a spare stoker motor and blower motor when I can afford it.

I have my stoker adjusted to 7 threads out.

The coal ash is very fine with a thick bed of clinkers that falls off the end of the fire bed and breaks apart when it drops into the 4 gallon pails I use for the coal ashes.

In my case the home is a very leaky old school house that was turned into seasonal a home.
I still have the original mercury thermostat that was mounted on the dining room wall when we moved in 41 years ago.

I have found that the system works well with these temperatures and If house gets colder I just bump up the thermostat a little.

My tile lined chimney is now 19 feet tall with the stainless steel chimney extension and it has improved on how much draft I have as well.

Having replaced the damaged 67+ year old ash pit door on my fully exposed chimney with a new insulated one has made very big difference in how much coal I have burned so far this year.

If you change your high and low limit temperatures and the hold fire times to what I have adjusted my timer to fire and unplug your secondary fan you will use less coal.

On the warmer nights lately (with no wind) I have only found that I have a gallon of coal ash when I check the 4 gallon bucket I use for my coal ashes.

nepacoal · Post by **nepacoal** » Sun. Dec. 15, 2019 11:42 am

Keystoker recommends starting at 180 HL and 160 LL. If you've done a heat loss and know you have extra radiation, you could lower your LL. If you don't have any extra radiation, you could raise your LL. Many raise the LL to 180 and the HL to 200 during the heart of winter when it's zero with high winds...

From the manual:
TRIPLE AQUASTAT/Low Water Cutoff- Controls temperature of boiler and domestic hot water. It should be set at about 180º on high (Hi) and low (LO) maybe set at 160º for winter and 140ºin summer. A 20º minimum must be kept between HI and LO settings.

Post by **Rob R.** » Sun. Dec. 15, 2019 12:45 pm

Clousseau wrote: ↑
Sun. Dec. 15, 2019 11:09 am
The heat exchange surfaces, are they right above the fire?

Yes, but the most important area to clean is not easily seen or accessed. Take a look at this cross sectional view of the boiler to see the other passages that need to be cleaned.

https://www.keystoker.com/product/boilers/

The aquastat temperature really depends on how your system is setup. I assume the boiler runs up to the high limit setting on long heat calls - as long as you are getting adequate heat out of the radiators, there is no reason to change. If you are running a tankless coil and are happy with the output, the low limit setting is fine also. As for the setback, it is not causing you to burn extra coal - but it might make for a cool morning a the coffee table. I would not set it back more than 5 degrees.

Pacowy · Post by **Pacowy** » Sun. Dec. 15, 2019 5:21 pm

Clousseau wrote: ↑
Sun. Dec. 15, 2019 11:09 am
Yes there is a small blower that runs continuously. The heat exchange surfaces, are they right above the fire? Also, what temp limits are being used for high & low settings? Noticed you have a HB Smith mills boiler in your home, oil fired? My father in-law worked for HB Smith for many years in the Shipping Dept. Had a new mills 4 section oil boiler & a 7 section mills coal boiler in my home went I built it in 1976. I went to a newer Series 8, HB Smith oil boiler. Wish I had not done that. The wood boiler, lasted 40 years, then I bought the KA-6.

I'm not a "fan" of those secondary blowers. Especially during the shoulder months, it seems like they spend most of their time blowing unneeded air through dead ash, ultimately cooling the boiler and delaying the response to a call for heat. I know it can be difficult to idle that type of flat/inclined stoker; a long time ago I suggested increasing the bed thickness (using the adjustable bar) as a way to reduce the duration and frequency of timer cycles, but I never heard whether anyone ever tried that.

Thanks for the reminder that I need to update my profile. In Dec 2016 we sold the house that was heated by the Smith boiler mentioned in the profile. That one was a Mills 350, understood to have been installed in the 1950's, that had made enough steam to heat the approx. 12000 sf uninsulated masonry building for decades. When we bought the house, the gas burner in it was junk (basement had flooded), and it sat new to a disconnected oil burner. We took that stuff out and powered the boiler with a reconditioned old school EFM 85R conversion stoker, burning approximately 35 tons/year of buckwheat. From that experience we fully endorse the legend of vintage HB Smith boilers as powerful, durable and efficient heating machines.

The house we're in now also has a Smith boiler, but it's gas-powered and only about 10 years old. It does the job without fuss and bother, for which we are appreciative. But that Mills 350 was something else...

Mike