Who burns year-round?

Are some of you summer DHW guys running straight off the coil or are you using it in conjunction with a storage tank. My off the coil only is not working very well

markviii wrote:

steevesj wrote:

markviii wrote:How tall is the chimney compared to the roof? What size is the flue? Are you using the recommended 8" pipe? How many elbows and tee's are installed between the boiler and the thimble?

The chimney stands about 6-8 feet high from the edge of the roof. There is 1 90 from the boiler then 1 90 that connects into the horizontal pipe that leads to the chimney. There is 8" pipe to the thimble but the chimney is 6" clay.

I think a 6" flue is marginal for your application. Have you adjusted the inlet damper according to Keystoker's instructions? You could be pressurizing the firebox with excessive combustion air.

How tall is the chimney compared to the roof peak?

I am not sure how tall it is but it is not near being even with it. I do have the air wide open so it definitely is putting a lot of air into the box. The coal didn't seem to be burning well unless I gave it maximum air.

coalmeister wrote:Are some of you summer DHW guys running straight off the coil or are you using it in conjunction with a storage tank. My off the coil only is not working very well

Right off the coil on the EFM.

coalmeister wrote:Are some of you summer DHW guys running straight off the coil or are you using it in conjunction with a storage tank. My off the coil only is not working very well

I have an 80 gal indirect tank set at 125 and the VF3000 stat is at 130. 1 on and 15 off in idle mode with reduced combustion blower speed. You would probably need to keep a much higher idle temp for the instant heating w/ coil only.

coalmeister wrote:Are some of you summer DHW guys running straight off the coil or are you using it in conjunction with a storage tank. My off the coil only is not working very well

I have an 80 gal indirect tank set at 125 and the VF3000 stat is at 130. 1 on and 15 off in idle mode with reduced combustion blower speed. You would probably need to keep a much higher idle temp for the instant heating w/ coil only. Have you tried the reduced combustion blower speed mod? This might smooth out your peaks and valleys nice so you can cruise along steadily at higher temps to do your instant heating. The only other thing I can think of to try is low flow taps + shower heads, give the DHW more time to absorb Btu's.

steevesj wrote:I am not sure how tall it is but it is not near being even with it. I do have the air wide open so it definitely is putting a lot of air into the box. The coal didn't seem to be burning well unless I gave it maximum air.

Unless you get excessive amounts of unburned coal in the ashes, I would back the air down. Read the Keystoker manual to see how they want you to set the baro and combustion air damper. Your chimney may also be contributing to the problem if the draft is lazy in warm weather...adding height to get the chimney over the roof peak is probably the only thing you can do to improve the draft.

qbwebb wrote:

coalmeister wrote:Are some of you summer DHW guys running straight off the coil or are you using it in conjunction with a storage tank. My off the coil only is not working very well

I have an 80 gal indirect tank set at 125 and the VF3000 stat is at 130. 1 on and 15 off in idle mode with reduced combustion blower speed. You would probably need to keep a much higher idle temp for the instant heating w/ coil only. Have you tried the reduced combustion blower speed mod? This might smooth out your peaks and valleys nice so you can cruise along steadily at higher temps to do your instant heating. The only other thing I can think of to try is low flow taps + shower heads, give the DHW more time to absorb Btu's.

I do have the blower rheostat which work very well, do you have your 80 gal tank set up on a zone valve? How much coal do you burn per day in the summer for DHW? I was trying to limit my residual losses with just the boiler "storage" - Thanks!

Wood'nCoal wrote:

coalmeister wrote:Are some of you summer DHW guys running straight off the coil or are you using it in conjunction with a storage tank. My off the coil only is not working very well

Right off the coil on the EFM.

What is your boiler temp set at and how many gallons in the boiler? My coil can't seem to extract the heat in real time as the temp doesn't go down much in the boiler while the hot water is running. Bet if I had a circulator in the boiler it could do it.

coalmeister wrote:Are some of you summer DHW guys running straight off the coil or are you using it in conjunction with a storage tank. My off the coil only is not working very well

I use a tempering valve set at 120. Summer boiler temps for me is 145-165.
I will be adding some type of indirect tank though. 2nd shower without some recovery time is a bit cool.

Pacowy wrote:Keystoker says the KAA-2 holds 24 gallons of water, so you might consider pushing up the low limit to improve performance on larger DHW draws. Also, even at maximum output, that boiler will make less than 2 gpm steady state. With a low-volume showerhead you might get away with multiple showers in a row, but the stoker would have to be set at/near maximum output. Mike

Yes, I should have mentioned I have low flow shower head. Reason I have lowered high limit is to reduce overfires and heat dumps. I will try though, I could probably set hi-limit at 170 with no problem.

My apologies, didn't intend to troubleshoot my boiler in this thread. I had intended to provide the OP information.

I set my boiler temp at 180 and I am now able to run off the coil although I over temp occasionally and trigger the dump cycle which uses a lot of coal as I am plumbed into my oil boiler. Not to mention it is close to the boiling point. Will have to tweak my feed & cycle timer.

Machinist wrote: Yes, I should have mentioned I have low flow shower head. Reason I have lowered high limit is to reduce overfires and heat dumps. I will try though, I could probably set hi-limit at 170 with no problem.

My apologies, didn't intend to troubleshoot my boiler in this thread. I had intended to provide the OP information.

The high limit setpoint will make no difference if you are using a tankless coil...the stoker won't fire until the aquastat sees that the low limit has been reached. You could have the low set at 150, the high at 170, and during a hot water call the stoker will fire at 140 degrees. Try 170 or 180 degrees for a low setpoint, 200 for the high, and a 10 degree differential. Set the 4006B at 220 degrees, as per Keystoker's instructions. If your boiler is overheating while sitting idle, you might have to back the timer off a little.

Machinist wrote: My apologies, didn't intend to troubleshoot my boiler in this thread. I had intended to provide the OP information.

Feel free to ask questions about your boiler and its performance. This thread was to get people to "check in", and say what works or doesn't with their summer boiler operation.

For the most part I am satisfied with the way it operates.

The boiler idles fine. It seems to me that there is lag time from idle to full fire at its current feed setting, maybe all feed settings. So if I use enough hot water to get to full fire, then stop using hot water, that is when it dumps heat. Also at that time the timer could come on feeding the fire needlessly.

This problem might be specific to the KAA-2 since there is not much water volume in the boiler.

Thanks for explaining that its better to raise lo-limit. ( keeping the minimum 20 degrees between lo and hi limit) Makes good sense. I'll try that when there will be no call for heat for a few days.