Dump Zone for EFM520

A bit cold and rainy here in NEPA...it's soon getting to be that time. I get the feeling our coal friends to do the north will soon be striking that match if they haven't already. Calling for a low of 38 here on Saturday so I get the feeling I might be running the circulators Sunday morning. For those of you that remember me I always end up with fall/winter outfires due to reasons I don't always fully understand. This year has been a lot better and I have 7 ton in the bin sitting around just waiting for the 520 to do more then make domestic. Despite a more successful season this year I still "flirt" with that high limit cutoff depending on the daily weather so I've been thinking of installing a dump zone. The feed/air/timer seem to be doing well for me this year. The only thing is that the residual heat slowly starts to creep up and the occasional outfires I get I believe are related to high limit cutoff. I cleaned the whole unit a little while ago and the ash ring/dark spot seem to be great. I kind of just want this as a percaution. I'm expecting my first child this December and I don't want to have to worry about outfires at work while the wife is home with him.

My plan would be to use a strap on aquastat tied into my basement loop to dump cold water back into the boiler to drop the temp. Something I could throw on a switch and only active during those "troublesome" times. If that doesn't provide enough cooling I could always tie in other zones and/or run a loop out to the garage. Already have a tap for a return and a zone value headed out...just not connected.

My question comes as to where to put on the strap-on aquastat. My original thought was to put it on the main feed out to the zones. That only seems to start cooking when the boiler is getting to high temp. However, I thought tonight that once the circulator starts running that will always be getting hot water and won't shut down. Any suggestions as to where to tie this in? I believe I used all my tappings already. I have a aquastat in one of the tappings but that's for my low temp cutoff.

Thanks for the suggestions and advice!! Happy burning!

rocketjeremy wrote:
My question comes as to where to put on the strap-on aquastat. My original thought was to put it on the main feed out to the zones. That only seems to start cooking when the boiler is getting to high temp. However, I thought tonight that once the circulator starts running that will always be getting hot water and won't shut down. Any suggestions as to where to tie this in? I believe I used all my tappings already. I have a aquastat in one of the tappings but that's for my low temp cutoff.

My suggestion would be to use the aquastat now taped into the vessel wired to close on temperature rise set at say.. 205 for a signal to close a call for heat on that basement loop. Simple as a parallel hook up with the Tstat on that zone. I would also suggest that you seriously choke that flow as you don't need a great deal of cold volumes of liquid as to make the boiler temp fall so far that you get a call to hi fire. You just want to scrup off some idle fir heat - right??? That won't take a lot of flow.

Now strap on on the new aquastat very near the boiler on the supply and use it for boiler protection.

I agree with Sting, but I'd allow a little more room on the high side. Do you have a functioning mixing valve installed on the domestic hot water side?

Sting....yea that sounds like a really good idea. The boiler protection is only for a last resort so using the strap on aquastat for that and the well version for the dump zone probably makes the most sense. That way it's dependent on the overall boiler temp as apposed to the water in just one pipe. Probably would do a much more accurate job of controlling a high limit scenario. You're exactly right....I'm just trying to siphon off the idle rise if it compounds too much while I'm gone for the day and there is absolutely no demand.

Stoker...I do have a working mixing value in to control the domestic temperature. With the baby coming in December I'll be watching that closely to ensure that it's fully functioning.

Strap on aquastats need to be close to the boiler. Your largest BTU zone should be used for the dump zone. If you have access to an infired thermometer you could check how much the boiler differs to the pipe temp, these thermometers do not work well on shiny copper, they work better on dull black surfaces. Could you place a T fitting between the boiler and the pressure relief valve and insert an immersion well for an aquastat ? Just don't obmit the pressure relief valve.

rocketjeremy wrote:A bit cold and rainy here in NEPA...it's soon getting to be that time. I get the feeling our coal friends to do the north will soon be striking that match if they haven't already. Calling for a low of 38 here on Saturday so I get the feeling I might be running the circulators Sunday morning. For those of you that remember me I always end up with fall/winter outfires due to reasons I don't always fully understand. This year has been a lot better and I have 7 ton in the bin sitting around just waiting for the 520 to do more then make domestic. Despite a more successful season this year I still "flirt" with that high limit cutoff depending on the daily weather so I've been thinking of installing a dump zone. The feed/air/timer seem to be doing well for me this year. The only thing is that the residual heat slowly starts to creep up and the occasional outfires I get I believe are related to high limit cutoff. I cleaned the whole unit a little while ago and the ash ring/dark spot seem to be great. I kind of just want this as a percaution. I'm expecting my first child this December and I don't want to have to worry about outfires at work while the wife is home with him.

My plan would be to use a strap on aquastat tied into my basement loop to dump cold water back into the boiler to drop the temp. Something I could throw on a switch and only active during those "troublesome" times. If that doesn't provide enough cooling I could always tie in other zones and/or run a loop out to the garage. Already have a tap for a return and a zone value headed out...just not connected.

My question comes as to where to put on the strap-on aquastat. My original thought was to put it on the main feed out to the zones. That only seems to start cooking when the boiler is getting to high temp. However, I thought tonight that once the circulator starts running that will always be getting hot water and won't shut down. Any suggestions as to where to tie this in? I believe I used all my tappings already. I have a aquastat in one of the tappings but that's for my low temp cutoff.

Thanks for the suggestions and advice!! Happy burning!

Sounds to me you do not have enough span between you low temp set point and your high temp set point on the aquastat

Also the timer is running to much setting the hi temp in aquastat to override your timer making it skip fire cycle making the fire go out put a higher span between the low temp set point and high set point on the aquastat and set the Diff at
10 or 15 Move the timer to fire every hr instead of every thirty minutes that way it will not send the temp up to high and making the aquastat override the timer stopping the out fires and it you already have the timer on every hr then drop a minute off it

I have my settings on the triple aquastat at 160-180 high with a diff. of 15. I have never seen the stoker hit 160 when at idol. All the low on the triple aquastat does for me is keep the circulators from running if the water temp is to low. If I have the timer every 1/2 or on the hour for a 1 1/2 minutes the temps are up and I use a baro damper and the axemans are uninsulated to bleed off heat. Triple aquastats function off the low limit on oil burners, coal keeps on cook'in

AA130FIREMAN wrote:Your largest BTU zone should be used for the dump zone.

Normally -- YES

But

Well let me place a Caveat lector [ Latin phrase meaning "Let the reader beware."]

As I read this issue -- we have an idling boiler that will go out no mater how the owner tends - it gets too warm and its system shuts it off.

So my suggestion is simply to apply a small parasitic load to keep it working as the owner only has issues in the shoulder season.

Let me also say that 1) I agree with stoker-man that a dump-zone aquastat can/should/maybe set a bit higher BUT I normally install with an ODR that is set to limit hi boiler temps at 195 - therefore 205 is an over-temp - so that's where my head is at this morning. 2) As Fireman points out - Dump zones should be large but this is just a small sacrificial shoulder season load from a choked flow of a "larger" zone and it will be up to the operator to open this flow as the degree day load increases and the dump-zone becomes more important and the load needs the extra BTU's. 3) Coalberner's advice is appliance specific and I only assumed that the home owner was already doing this. My suggestion is a band aid to correct for (possible by advice) incorrect operation of the appliance.

Kind Regards even if Lisa thinks I am a jerk
Sting

AA130FIREMAN wrote:I have my settings on the triple aquastat at 160-180 high with a diff. of 15. I have never seen the stoker hit 160 when at idol. All the low on the triple aquastat does for me is keep the circulators from running if the water temp is to low. If I have the timer every 1/2 or on the hour for a 1 1/2 minutes the temps are up and I use a baro damper and the axemans are uninsulated to bleed off heat. Triple aquastats function off the low limit on oil burners, coal keeps on cook'in

He is not running a AA boiler EFM run completely different Then AA do your setting may work in the winter time But not in Summer time on a EFM you need a longer span between the low temp set point and the high set point on the aquastat
running a efm. Also running the timer on to many minutes every 1/2 hr will & can set the high limit on the aquastat to override the timer That's why I like the timer set to fire every hr for 2.5 minutes with the low temp set point at 160f and the high temp set point at 200f the boiler water temp will stay all day at 180 f Winter setting is 170f low 200f high always with a 10 diff timer gets set back to 1.5 minutes every hr boiler water will stay between 180f to 190f with 3 teeth
feed rate 6 lbs per hr. SummerTime it is 2 teeth feed rate 4 lbs per hr with buckwheat . My unit runs 2 to 3 times in 24 hrs in winter for 40 to 45 minutes cycle times Summertime 9 minutes 30 seconds on the timer in 24 hrs no insulation on boiler just the Jackets with the back ones off to keep an I on the coil area . Use 2.5 tons in winter heating second week of Oct. to second week of April Summer time 3/4 to 1 ton ton from May to Oct. works for me heating a 1948 coal ash cinder block Ranch Bottom to Top of roof line 1500 Sq ft basement copper finned baseboard T -stat set at 68F First floor 1640 Sq ft 10 cast iron Radiators T-stat Set at 70F overshoot + 2 Degrees 72F

You probably wouldn't get away with 160/180 in the Winter either, and forget about the warmer days. I'd say most outfire problems are caused by too much feed/air for the season, and aquastat settings not far enough apart. The timer setting comes in third.

Thanks for all the great advice and points to consider. I appreciate the extensive support of you guys considering I go through this every year. I LOVE this boiler when it works but I HATE it a good percentage of the time. She's been running great for 2-3 days. Nice ash ring, dark spot in the center, etc. Maybe she got a little warm but that's nothing a quick tap of hot water didn't fix. Came home at lunchtime today for a doctors appointment looked fine. Timer ran, nice fire, moved on. Came down just now to check it because I was reading the post and thinking about it....completely out.

For the record my settings are 140 low, 210 high, 10 diff, timer 2.5 every 30, 5 feed, 6 air. With the exception of the timer being 1.5 then those were my settings all summer long....when outfires were just a distant memory.

Also for the record...I'd currently like to be in the bottom of a nice aged wooden barrel owed by a man that goes by the name Jack.

Outfires are annoying but I would say that just a little tweaking here and there should cure them. I burned 9 tons last year and had only one outfire. It was a freaky warm day in late Winter and I left the feed at 11 when I went home and it was coasting at 220/230 all day with no demand.

stoker-man wrote:You probably wouldn't get away with 160/180 in the Winter either, and forget about the warmer days. I'd say most outfire problems are caused by too much feed/air for the season, and aquastat settings not far enough apart. The timer setting comes in third.

He is Talking about a Axeman boiler completely different then a EFM and most of all the other stoker boilers made
The type of coal he is using will also play a factor in out fires to dirty and some coal will not hold a fire period.
Not having enough air will be a big problem to in Summertime letting the temp in the chimney drop to low will cause the draft to drop not letting the temps stay up inside the chimney will drop the draft in the chimney and the fire will go out
stick a probe thermometer in the chimney pipe and adjust the air setting up and down you will see the temps go up and
drop down inside the chimney not enough air to keep the temps up in the chimney will kill the draft in it putting the fire out Lots of things can cause a out fire all can be fixed with some small adjustments you Just need to know what ones and do one at a time until you find the problem stopping the out fires

P.S. the only time I have out fires is when I leave the coal run out of the bin

Not having enough air will be a big problem to in Summertime letting the temp in the chimney drop to low will cause the draft to drop not letting the temps stay up inside the chimney will drop the draft in the chimney and the fire will go out

I use a draft fan in my flue for this problem in warmer weather, as I run my stoker year-round for DHW. Never had an outfire.

P.S. the only time I have out fires is when I leave the coal run out of the bin

X2

You probably wouldn't get away with 160/180 in the Winter either

I wasn't clear enough. I was commenting on what AA130FIREMAN said about his AA and meaning that he probably would have trouble with the 520 even in the Winter at such close settings.