leisure line 110 coal boiler dumping constantly

Recognize that only the water volume in the boiler is going to expand as a result of an overshoot condition. So it's only the boiler water capacity that needs the extra expansion tank volume. Said another way, the rest of the piping and radiators will only reach the high temperature design temperature, the boiler however can reach a higher temperature. Realizing this allows you to use a smaller expansion tank vs. a design that assumes all the water can reach the overshoot boiler water temperature.

I'm confused with what a larger tank has to do with controlling/preventing a dump from happening. The tank helps to regulate pressure, it will not bring the temperature of the boiler down, or stop it from rising if the fuel is putting out heat still.

I see the purpose of the dump zone as preventing very hot water from flowing through the radiator system. You could have 20 expansions tanks, but if the boiler has 220 degree water, 220 degree water is going to flow over those tanks and thorough your house.

Having a large expansion tank prevents the pressure release valve from releasing. The design criteria for the tank size is commonly set by a pressure rise no larger that 5 psi below the safety. Yes the water in the boiler will be very hot, but it's stationary. The very hot water is a result of an over-fire condition, e.g. the combustion blower was on stoking the coal fire and then just as the aquastat high set point is reached the circulator turns off because the room thermostat is satisfied. With coal, the boiler water will continue to get hotter. It has no where to go because the circulator is not running. You have two choices active a dump zone or let the expanding water go into a large expansion tank. If you store it in your boiler, it's available minus the boiler's radiation losses, for the next time the thermostat calls for heat. Yes, the initial water circulated from the boiler will be very hot but it will quickly cool as it reaches the distribution piping and/or radiation system. If you are using PEX for distribution piping you need to assure it doesn't exceed the pipe temperature rating. Many ways to do this, injection pump mixing at the boiler, mix some of the boiler return water to cool it, etc. Normally with metal supply piping you don't need to do anything special. Especially if you are using primary secondary piping with coal and some other conventional fueled boiler. Just make the primary loop all metal pipe. The primary circulator will mix the return water and cool it down to normal design conditions.

My boiler is almost going out on idle with rehostat all the way down and fan a 1/4 off running 18 sec on and 5 min off any more and it spikes in temp

I will add my 5 cents, I run a efm 350 stoker/ boiler so this may not help you at all but I have found that in low load conditions, such as a 50 deg day, that my fire would go out because the boiler water temp was at or above the high limit setting and not allowing the timer to stoke the fire to maintain the fire. what I did was remove the the wires on the aquastats tt terminals and set the low setpoint for 160 amg the high at 210 with a 10 deg diff. I also use a indirect water heater for my domestic use. Since doing this wiring change I have not had any out fires ,the only downside to this so far has been that if we use a lot of domestic hot water such as several loads of wash or several showers in rapid sucession we somethimes run a little short of domestic hot water. You might want to consider adding a hot water maker sort of tank to even out the bumps. Hope this helps Carl

sorry ,but I forgot to include this bit of info in my last post, I control all my heat zones with a 6 zone taco pump controller so I dont need to use the circulator output on the aquastat. Just wanted to clarify this point.
Carl

Ok I don't get this I have my stoker rehostat 3/4 off and blower almost on half. With 30 sec on and 5 min off and it seems like its almost going out from coallbeing burnt up . Should I increase more on rehostat ? It just seems. Coal is to wide as it is burning and if I go less on time it goes out. Any suggestions its a leasureline 110 boiler

How many times has it actually gone out on these settings? Or how many times has it gone out in the last few weeks? Maybe if you have time over the Christmas / New Years days you can spend some more time being vigilant with your stove to figure it out. Once you find a good setting it is little maintenance. I could understand the frustration coming home every day wondering if you have to re light the stove.

Turning the feed motor rheostat up a little would put more coal out during those 30 seconds, which would increase the width of the band of hot coals.

Its gone out 3 times so I think over holiday weekend ill try to watch close thanks

Well I've added more tehostat feed and turned fan up a little but still going out I don't think ill ever find the right settings for this boiler. I don't no what to do because its cold now and I can't trust it when im gone this has been going on for 3 months now since installed.

Have you spoken with Matt or Dave lately ????



Rick

Yes I've talked to them

klim1972 wrote:Yes I've talked to them

And they can't get you straightened out ???????




Rick

Ok now im going a little crazy icant get this boiler to idle down right now im trying 24 min off and 2min on that sound ok to anyone with feed 3/4 on and fan all the way down did anyone else have this problem with 110 boiler

What is your chimney draft? do you have a manometer installed, and what is the baro set at?

You have a combination of draft, fuel, and heat required to keep the fire..
Draft provides the air being pulled through the grates and coal bed.
Fuel provided by the pusher in the stoker.
Heat provided by the established fire, which keeps the fresh coal burning.

So, you need some draft to maintain airflow through the idling fire. How tall is the chimney, and what is the overfire draft?
Fuel: you control the feed rate.

Are you turning down your thermostats when you leave the house? if so, the boiler will go into a long idling period, while the house cools.
Maybe leave the thermostats set a degree or two higher than you have now, and see if the added thermostat calls will keep the boiler in
equilibrium.

Greg L