Which stove, the AHS coal gun or the Axeman?

PostBy: Bob On: Fri May 04, 2007 4:26 pm

mwcougar wrote:when you take the heat shield off what do you use if anything to seal it back up?
cougar


My understanding is that no sealer is used. If the center hole that the motor/fan shaft passes through is enlarged the entire ceramic heat shield is replaced--a $43 part.
Bob
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea/Anthracite

PostBy: pret On: Wed May 09, 2007 9:16 am

Does anyone use their S-130 throughout the summer to heat domestic hot water? I read the post on not using the domestic hot water coil one can purchase for the S-130 but using an indirect hot water heater... but I'm having a hard time justifying the 1100 dollar difference.

If you are using the S-130 for domestic hot water, how much coal can I expect to use over the summer for a 5 member family - all small children under the age of 6.

mwcougar, you said your burning about 50lbs a day currently - two houses, I imagine most of your coal usage is due to domestic hot water??

Thanks fellas!

Pret
pret
 

PostBy: pret On: Wed May 09, 2007 9:51 am

Hey everyone!

Does anyone burn coal for domestic hot water through the summer? I live in Central Pa - Lancaster area, and I was planning on burning coal for my domestic hot water. I'm curious as to how much coal one would burn per day for a 5 member family - all children under 6yrs.

I read the post on using an indirect water heater rather than the hot water coil one could purchase for the S-130, but the difference in price is about 1100 bucks! Not sure it's worth it. Those tanks last maybe 13 years, and then it's another couple thousand dollar plunge for replacement. If I only burn 1/2 ton for domestic through the summer, at most 7 tons in 13 years is about the same money - give or take a couple hundred.

mwcougar, you mention that you're heating two houses and domestic for about 50 lbs a day currently. Temps here in central have been in the upper 40's at night, and in the 70's during the day for about the last 2 weeks. My heat has been turned off for about two weeks now. Are the temps that much cooler where your area? Would you say that most of the coal you're burning for heat or domestic?

Thanks tons fellas,

Pret
pret
 

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PostBy: Yanche On: Wed May 09, 2007 10:09 am

Burning coal for domestic hot water is all about controlling temperature losses. If the boiler is in your house any heat that is lost from the boiler jacket is good in the winter but bad in the summer. If you make domestic hot water with a coil in the boiler you need to have the boiler water hot enough the produce the on-demand water as needed. This is not a problem in winter but in summer you want to fire your boiler only enough as needed for domestic hot water production. Since it is an on-demand system the boiler water is hot all the time, i.e. you are burning coal all the time, sufficient to satisfy the aquastat setting. However, if you have an indirect hot water heater you only need the hot boiler water when you are heating the water was used from your domestic hot water tank. The coal boiler can be at idle for longer periods of time and in principle operate at a lower temperature. The well insulated hot water tank will hold the water hot longer than the rather poorly insulated boiler. There will also be less of the jacket heat loss into your house because the boiler is operating less frequently.

If the coal boiler is outside your house a hot water coil in the boiler is impractical. There will be to much heat loss in the piping from the boiler coil and it will take to long time for the water to get hot at the faucet. I have a indirect hot water heater because I have very acid well water, ph = 5.7. It has a stainless steel tank. I also need indirect because my boiler is not in my house. By lowering the auqastat setting for summer, my coal usage is about 25 lbs per day. Depending on the relative price of coal vs. #2 home heating oil, it may be cheaper to use oil for summertime domestic hot water heating. I have my oil boiler set to only fire when it needs to reheat the water in the domestic hot water tank. Yes, this is firing a cold oil boiler but it's summertime cold water, much more temperate and close to indoor summer ambient summer temperature.

Those that have the optional ash temperature controller should have the lowest summer coal usage because they can control idle conditions it just above what would cause the coal fire to go out. I'm looking to add one.
Last edited by Yanche on Wed May 09, 2007 11:27 pm, edited 1 time in total.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

PostBy: pret On: Wed May 09, 2007 10:57 am

Thanks Yanche,

The boiler will be in my basement. the S-130 will be going into a new construction, so lots of configurations are possible.

I could purchase an electric water heater for the summer months or maybe use a old electric water heater tank to store the hot water produced by the S-130.

I am purchasing the electronic control unit for the ash grate when I install the coal gun in the late summer - looking forward to the efficiency that will bring.

I'm already spending WAY TOO MUCH for the heating cooling system for this house, so I'm looking for ways to reduce the added $1000 here and the $1000 there for 'this or that'. I figure I can add the indirect water heater at a later date and try to make a used insulated water tank work for now.

Thanks again Yanche for your time and expertise


Pret
pret
 

PostBy: Yanche On: Wed May 09, 2007 2:28 pm

I understand how an extra $1000 here and an extra $1000 there can really add up. Kind of hard to justify the 10,000 lb GVW trailer I just bought for hauling coal!
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

PostBy: pret On: Wed May 09, 2007 2:42 pm

Yanche wrote:Kind of hard to justify the 10,000 lb GVW trailer I just bought for hauling coal!


Totally! I've already have $19000 in the heating and cooling and still have to purchase materials for radiant floor heat. Probably another $4K. Sounds ridiculous, but it's going to cost very little to heat and cool this place when it's all said and done!

Justified? I don't know... but it's pretty cool!

Pret
pret
 

PostBy: MXer On: Wed May 09, 2007 5:51 pm

My motto is "Do it right the first time" If your going to do the indirect - do it now. I'm installing an indirect unit with a lifetime warranty, so I sure hope I get more than 20 years out of it. I have an electric hotwater heater for the 3 or 4 hot months out of the year we get here in central Pa. You have to factor in the $$ saved for electricity to heat the water. For my family, it runs $40 - $50 a month.
MXer
 

PostBy: Rex On: Wed May 09, 2007 7:05 pm

pret wrote:
Yanche wrote:Kind of hard to justify the 10,000 lb GVW trailer I just bought for hauling coal!


Totally! I've already have $19000 in the heating and cooling and still have to purchase materials for radiant floor heat. Probably another $4K. Sounds ridiculous, but it's going to cost very little to heat and cool this place when it's all said and done!

Justified? I don't know... but it's pretty cool!

Pret


Just purchase a tank less or on-demand hot water heater and be that much more money ahead.
Rex
 
Stove/Furnace Make: D.S. Machine
Stove/Furnace Model: Circulator 1500

PostBy: mwcougar On: Thu May 10, 2007 8:37 am

Hi Pret

yes most of my usaged right now is domestic hot water. oh but the mornings have been brisk here around 35 degrees. I supply water for 3 adults and 4 young ones under 4 years old. i have the aquastat around 165 right now. mine is hooked up outside and i loop through my oil boiler inside which has the domestic coil. this is a rental unit so i need back up. if this was in my house i would do it alittle different. Yanche idea about a tempurature adustable aquastat is a good idea that reads outside temp and adjusts itself. I would experiment more with dropping the temp but i am soon going on a big ride and would hate to lose hot water while i am gone and have the oil boiler heating the coal boiler right now. also Yanche you can buy the fuji controller on Ebay with a solid state relay for around 100 dollars. I can send you the program if you want when you are ready. I am thinking of buying one for back up . these things do work great.

cougar
mwcougar
 
Stove/Furnace Make: ahs 130 heating 3700sq ft

PostBy: gaw On: Thu May 10, 2007 7:37 pm

Just a little food for thought about an indirect water heater and an internal coil/instant heater. The question worth knowing is just how cold the boiler will get while maintaining a fire. The fire can only idle along so low and it is always giving off some heat. Unlike an oil burner there is always some heat output from a coal stoker. I am not using a boiler that is built with this sort of sophistication so my experience may be totally irrelevant but I have noticed during warm weather with the low limit set at 140 I always have at least a 150 reading on the boiler gauge and this is just from the fire required to maintain itself (enough fire to stay lit) as far as I know. Obviously I am not standing there 24/7 to see if it has to run to satisfy the aquastat when there is no demand.

A good experiment would be to turn the aquastat down to about 100 and then see just how low the boiler temp will go when lit. If you are going to maintain at least 120 to 130 degrees no matter what the aquastat setting then an instant coil type heater may be the most economical choice.

Hope this makes “cents”
gaw
 
Stoker Coal Boiler: Keystoker KA-6
Coal Size/Type: Rice from Schuylkill County

PostBy: Yanche On: Thu May 10, 2007 9:17 pm

gaw wrote:Just a little food for thought about an indirect water heater and an internal coil/instant heater. The question worth knowing is just how cold the boiler will get while maintaining a fire. The fire can only idle along so low and it is always giving off some heat. Unlike an oil burner there is always some heat output from a coal stoker. I am not using a boiler that is built with this sort of sophistication so my experience may be totally irrelevant but I have noticed during warm weather with the low limit set at 140 I always have at least a 150 reading on the boiler gauge and this is just from the fire required to maintain itself (enough fire to stay lit) as far as I know. Obviously I am not standing there 24/7 to see if it has to run to satisfy the aquastat when there is no demand.

A good experiment would be to turn the aquastat down to about 100 and then see just how low the boiler temp will go when lit. If you are going to maintain at least 120 to 130 degrees no matter what the aquastat setting then an instant coil type heater may be the most economical choice.

Hope this makes “cents”
I don't have the data to make a knowledgeable recommendation. I believe the answer will be unique to the AHS and/or A-A boiler design. What we are trying to answer is "What is the most economical operation mode for summer production of domestic how water?" The boiler produces very little heat when the combustion blower is not running. So with the proper control system it could approach the ideal of a truly on-off boiler like oil or gas units. The data point that's missing is how small the coal fire is possible when there is no need for heat. Only those with the optional Fuji thermocouple ash probe can answer this. I don't let have one. Let's assume with no heat demand the long term boiler water temperature is really low, say 75 degrees. This might be a reasonable possibility, it's only an 11 inch round fire box surrounded by 27 gallons of water. A barely burning coal fire would not make much heat. Now the Fuji controller is a fancy unit adapted by AHS to measure ash temperature with a thermocouple probe in the ash. The controller can predict future temperatures, it's called fuzzy logic. The idea is this based on past measurement of temperature overshoot. Basically you turn off the combustion blower before the desired set point boiler temperature is reached. The coal fire dies down but the continued heat input allows the desired set point to be reached. There is no temperature overshoot. I don't think the factory programs the Fuji controller in this way but it is capable of such operation.

Now lets assume the purpose of the Fuji controller in summer mode is only to keep the fire from going out. Let's further assume there is an indirect hot water heater and the thermostat in the hot water heater calls for heating. The combustion blower comes on heating the boiler water. But the circulating pump doesn't come on until the boiler water comes up to aquastat set point. The domestic hot water tank get reheated and everything shuts off. Boiler water cools and the Fuji controller continues it's job of keeping the fire from going out.

Now the next step... All hot water heaters have snap action thermostats, on or off. What if the indirect hot water heater thermostat is replaced with a Fuji like fuzzy logic controller. Now you can turn off the boiler's combustion blower early and let the circulation pump transferring the boiler water heat to the hot water heater tank and run greatly reducing the boiler water losses.

Hopefully E-bay will have Fuji controllers cheap enough for me to install several and I'll live long enough using coal heat to answer my initial question.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

PostBy: Bob On: Thu May 10, 2007 10:01 pm

Yanche wrote:Now the Fuji controller is a fancy unit adapted by AHS to measure ash temperature with a thermocouple probe in the ash. The controller can predict future temperatures, it's called fuzzy logic. The idea is this based on past measurement of temperature overshoot. Basically you turn off the combustion blower before the desired set point boiler temperature is reached. The coal fire dies down but the continued heat input allows the desired set point to be reached. There is no temperature overshoot. I don't think the factory programs the Fuji controller in this way but it is capable of such operation.


The only input to the Fuji controller is from the thermocouple probe in the ash. It seems to me that in order to implement a control system to avoid overshoot you would also need to sense the boiler water temperature and the rate of change of the boiler water temperature. As I understand it that would be three separate inputs being monitored. According to the specs for the PXR3 series controller there is only one input.

A Fuji PXR3 controller can be purchased on Ebay for $70 plus $5 shipping. The solid state relay can be purchased for $10 plus shipping.
Last edited by Bob on Thu May 10, 2007 10:04 pm, edited 1 time in total.
Bob
 
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea/Anthracite

PostBy: Rex On: Thu May 10, 2007 10:04 pm

""What is the most economical operation mode for summer production of domestic how water?"


lol, electronic controllers, electric blower, electric combustion blower and yet another electronic circulation pump along with coal cost.. damn get yourself a 40 gallon electric water heater and be done with it. :roll:
Rex
 
Stove/Furnace Make: D.S. Machine
Stove/Furnace Model: Circulator 1500

PostBy: Yanche On: Fri May 11, 2007 6:57 am

Don't confuse operating costs with equipment costs. Sure an electric hot water heater is simple and relatively inexpensive. But operating costs are high. If your electricity is produced by a coal fired plant 2/3 of the Btu in the coal is lost in making steam and getting the electricity to you. So heating water with coal directly will be 1/3 the cost. For those of us with an expensive AHS boiler, we want to know if it is economical to operate it through the summer. The answer is not obvious. If the boiler is in your home and you A/C your home you now have the large extra heat load of the boiler losses to remove. But if you could substantially reduce this heat with a fancy electronic controls summer operation might be ok. Is all the complication worth it for heating domestic hot water? Certainly not. But high end AHS installations have most of what's needed already.
Yanche
 
Stoker Coal Boiler: Alternate Heating Systems S-130
Coal Size/Type: Anthracite Pea

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