Keystoker K2 Coal Boiler Temperature

McGiever wrote:So you don't use or don't have an installed tankless coil in this boiler, only have indirect tank on a zone.

Was the indirect HW tank installed same time as the boiler or was that later?

Wdo have an indirect tank on a one. It was already there when we installed the boiler. We had an oil boiler prior to our coal boiler. We still have the oil boiler hooked up and only use it as a back up when we need to shut the coal boiler down. It has been set up this way since we installed our coal boiler 5 years ago.

anthony7812 wrote:maybe its not the boiler??? Im far from knowledgable (YET) about boilers but have you changed coal suppliers and notice a coal quality change?

We have not had any change in our coal, as we had it stock piled for the winter, but that is our next step, to try different coal. This was also suggested by Keystoker, so we are doing that next. I can only hope it is that simple, but am not very optimistic.

Have you tried isolating one (or more) of the homes zones for awhile to see if that brings the boiler temperature back up? Is your DHW leaking out to a drain somewhere? Is your homes hot water as hot as it should be? Try isolating the indirect HW tank zone for awhile also. Isolate the zones one at a time.

80 lbs. per day burning to a nice ash and seeing a good and proper flame leads me to think that plenty of BTU's are being generated. Somehow the load seems to be too much for the boiler though.

Is your flue pipe excessively hot?

lsayre wrote:Have you tried isolating one (or more) of the homes zones for awhile to see if that brings the temperature back up? Is your DHW leaking out to a drain somewhere? Is your homes hot water as hot as it should be? Try isolating the indirect HW tank zone for awhile also. Isolate the zones one at a time.

We have not tried isolating the zones, but will give that a try along with the new coal. Our hot water is as hot as is should be, and don't see any leaks, but will definitely try isolating the zones. Thanks.

alcm000 wrote:Just curious; when we cleaned the boiler, we did not clean every last speck of "dirt" off the walls of the inside of the boiler. How much of a difference would it make to wire brush every last section, except where you cannot reach? Does that have a large effect on the temp?

It works like this, you're burning 60-80 lbs or more a day and it struggles to recover after multiple zones come on. Where did the heat go if the boiler water didn't get hot?
Up the stack/stove pipe? Or are you heating your supply well water? It's going somewhere.

alcm000 wrote:Just curious; when we cleaned the boiler, we did not clean every last speck of "dirt" off the walls of the inside of the boiler. How much of a difference would it make to wire brush every last section, except where you cannot reach? Does that have a large effect on the temp?

It doesn't have to be squeaky clean, but you do need to brush all the surfaces. Just brushing the firebox around the flame is not enough, the area between the flame and the flue pipe is where most of the heat exchange takes place. You may need to reach up through the ash pit or through the flue opening to clean it properly.

Do you have any radiant heat in your house or underground piping?

How's the thermostat on the in-direct hot water tank? Do you have one of those black control boxes controlling everything? If so, is the priority switch for the in-direct hot water on? If you have minerals building in the in-direct hot water tank, the priority switch being on would be making the hot water tank priority, shutting down the other zones till the hot water reaches temp. I think I'd try isolating the in-direct hot water tank. If you have a priority switch, try turning it off to see if any changes. Maybe a different zone is on priority, and you have problems with that thermostat (Shooting in dark here). As Mcgiever said, the heat is going somewhere. If everything else is working as you describe, I'd be looking at the in-direct hot water tank. I know the Kaa-2 has to be run somewhat on the timer, in order to respond/recover fast enough. Not how it was designed to operate. But is how it has to be operated. You say you're running 3 groups of 7 pins. That sounds about right with 4 zones, plus hot water. I believe I'm running 3 groups of 6 pins now (Three zones, and no hot water). House temp is 73*. I'd say that little Kaa-2 is maxed out at your place. With these colder temps this year, you may be feeling it. I believe KEYSTOKER realizes the Kaa-2's limitations as well. That's why they re-introduced the Ka-4. I'm heating a little less than you. And I know I'm reaching towards the Kaa-2's limit during the colder temps. It's doing a great job at my place. But, I wouldn't want to add much more to the load. Oliver

alcm000 wrote:Yes, it was fine for our first three years. Nothing has changed in our home; same zones, water, and number of people. We have cleaned everything this year. We are heating approximately 1800 sq. ft.

The K2 is rated around 76-80K BTU's per hour net. You may have been right sized for the milder winters over the past few years and now with real winter returning you may be undersized. 1800 sq feet is a gracious plenty living space that the K2 is probably struggling to heat. Just using 45 BTU's per square foot times your 1800 sq feet comes to 81K BTU's required. And that's not including domestic hot water.

Try taking the load off by isolating the indirect hot water device and that should improve the loading and get the heat up to more comfortable levels. If that works you may want to consider an electric water heater for those times when the heating load is really high. Pipe it so you can turn it off and bypass it and go back on the boiler during more moderate weather.

I had a parishioner that had similar symptoms with a K2 they had installed when it got to the dead of winter and the temps dipped into the teens. We simply isolated the DHW function for the boiler and it brought temps up to comfortable again. It was a temporary thing as temps went back up outside the boiler did just fine.

Rev. Larry

Oliver and Larry are spot on.
Definitly get the HW set as Priority, that way it gets caught up faster and stays satisfied for a while and lets the room zones run uninterupted for a longer time. Not a good thing to have zones all fighting for too little heat.

But, if the boiler can not keep up in the occasional event of severe cold you must have a Plan B.
The idea of having the ability of switching on an electric or whatever alternative fueled water heater will go a very long way to allowing more room zones comfort.

alcm000 wrote:

McGiever wrote:So you don't use or don't have an installed tankless coil in this boiler, only have indirect tank on a zone.

Was the indirect HW tank installed same time as the boiler or was that later?

We do have an indirect tank on a zone. It was already there when we installed the boiler. We had an oil boiler prior to our coal boiler. We still have the oil boiler hooked up and only use it as a back up when we need to shut the coal boiler down. It has been set up this way since we installed our coal boiler 5 years ago.

Whoa, Old OIL Boiler...there is a source for re-thinking.

Depending on how the Isolation Valves are postioned, you may be trying to heat all that mass/pipes and water also.
We need more info...like pictures of piping arrangements of both coal and oil.

The answers got to where I was going before I posted.....my VF3000 is rated higher then that and it is heating about the same amount of space and hot water. I can tell you that it struggles and I would not go lower then a Leisure Line 110 the next time. I would suggest reading the balancing threads featuring the fabulous Sting. I slowed my flow down and installed a by pass line to make mine work in Maine. My son indicates the heat is working but struggles in these temps. Not a normal winter.

Kevin

What's the differential set at on the aqua stat??? Maybe try turning the high and low limits up. 170 low and 190 high with a differential of 10. Seems like the circulators are moving water away before it has had a chance to recover from the load??? The boiler temp should not be able to drop that far below the low limit. Something is moving heat out of the boiler when it shouldn't be it seems?

Here's your fix.............. The little Kaa-2 needs some help. "We still have the oil boiler hooked up and only use it as a back up when we need to shut the coal boiler down. It has been set up this way since we installed our coal boiler 5 years ago".

Here's your fix.............. The little Kaa-2 needs some help.

+1

My setup has an automatic kick in for the gas boiler. If it kicks in, it is cold outside or there is a problem.

Kevin