Econoburn 150 aquastat setting

[pybyr]

Norm-- if I am remembering right, you have a Honeywell aquastat that you got from me (used but working spare on my shelf- had only been used by prior owner for a few years before they had someone change out that portion of their system) for cost of postage- because the prior/ original owner of your EBW had lost or wrecked the original.

I had not realized that the one that I sent you did not go above 180-- but, now that I think of it, that is probably because it had been on an indirect-tank water heater-- and probably the one spec'd and made for that use is not supposed to go above 180. __But__ if memory serves me correctly, from looking at the innards of several of these (including another used/ good one that I just pulled off the spare shelf to look at again) the ones that stop at 180 do so only because there's a little tab or clipped-on piece of metal on the 'dial plate' within the unit that hits up against the same little crimped "post" that points to the degree reading that you have spun it to.

IF you feel OK looking inside it (after all power is off), and find that the numbers do indeed go over 180, but there's a stop tab crimped on to block it going beyond 180, and IF you see and feel comfortable with pulling that crimped stop tab (that's on the edge of the dial) without bending anything else-- you may, I suspect, find yourself-functionally- with the same aquastat that you could go out and pay $100+/- for (if you have to buy one-try Patriot-supply.com- they should have it for less).

As far as max temp for this aquastat on an EBW- I would not go much over 190 anyways; I tried that early on and ended up having it trip the buzzer of the unit's warning too often; mine is set a fraction of a guess below 190-- these units have pretty crude readouts and, in my opinion, may not be too precise or accurate in their actual repeatability of the temperature at which they open/close electrical contacts (all the more reason to not push the high edge).

YMMV, but I hope I am remembering correctly, and that the above is helpful; I agree with I.H.W. that technically you should use only the precise OEM part, but, having been in projects where everything cost more/ took longer, I also know the desire to try to find a way to make things work as long as one is confident that the end result is safe and reliable.

 

[Huskurdu]

Can anyone tell me what your aquastat is set at on the output (top) of your Eburn 150? Mine only goes to 180 deg and I'm wondering how much better off I would be if I could raise it to 190-195? They aren't cheap and I don't want to waste a $100 if I'm not going to gain much. Any thoughts would be appreciated.

 

[in hot water]

Best to leave the factory installed one in place. The equipment has been tested and listed with that control. Warranty may be void if you change it.

Generally wood boilers over run that setting anyways as the temperature stratifies, or under low load conditions. While you would get a few more useable BTUs from higher temperatures it may nor be worth the risks.

hr

 

[ManiacPD]

What does the aquastat control?

 

[Huskurdu]

It's not the factory aquastat that came with it.
The aquastat shuts the induction fan off when a set temp is reached.
My thinking is that my max temp should be in the 190-195 deg range somewhere. This would pack more btu's in storage and coast longer betwixt burnings.
After reading Smurf's pm I'm thinking that the 100 bucks would be worth the added btu's in the tank, especially when considering that I'm using bb instead of radiant.

thanks all,
np

 

[Nofossil]

This is an interesting problem. I think that there are some conflicting goals:

1) You'd like the best possible efficiency. That's obtained with the lowest possible outlet temperatures.

2) You'd like quick response when you need heat and have just started a fire. That means circulating water as soon as the boiler has reached a usable temperature.

3) You'd like to be able to get storage 'topped off' with as high a temperature as you can safely get.

The ideal situation would be to change your outlet temperature depending on what's happening. Early in the fire when storage is cold, a much lower outlet temp might work fine, especially if you have radiant heat and don't need 180 for baseboards. This is consistent with objectives 1 and 2.

As you start to charge storage, you probably want to keep you boiler outlet a few degrees warmer than your tank bottom until the whole tank is up to a minimum usable temperature.

Then, you want to gradually ramp up the boiler outlet temp to stay a few degrees above the top of tank temp.

There are three tools available to affect boiler outlet: fan speed, boiler inlet temp, and flow rate. I don't know what others are doing, but my thought is that you want to keep boiler inlet as low as possible without risking condensation. You want the fan speed to be as high as the fuel charge can support, and you want to vary the flow rate through the boiler to achieve your target outlet temperature.

It isn't necessarily possible to do any or all of these things on a given system, but my thought is that this approach would be a good compromise between the conflicting objectives. Any thoughts?

 

[Huskurdu]

Do I have any thoughts???? I feel like Forest Gump when I read your posts.

I agree to some of what you are saying below a storage demand requirements aspect, but the implementation of required controls is more your area of expertise than mine. In other words, it would be too complicated for me at this time. I've acquired quite a bit of hydronics knowledge in the last 2 years off hearth.com and maybe in another 20 or so years I'll catch up to where you are now.......then maybe not...

Your #1 confuses me. I don't understand why you'd want the lowest possible outlet temps for the highest efficiency? Maybe the lowest outlet flue temp. My b/b seems to need 180 deg f water to acheive it's maximum water to air transfer efficiency. So why would you want only mediocre boiler outlet temps?
I have 1 boiler protection circ, 1 main circ that sends the over near the storage tank, 1 circ that I call the transfer circ as it transfers hot to the gas boiler in the house for distribution to the zones. As you know, when my Eburn reaches it's 150 deg setpoint, the main circ kicks on. If the house is calling for heat then the transfer circ is already on and sends the 150 somewhat-hot water to my gas boiler for distribution to the zones (b/b and dhw). At least until the boiler takes on too much of the cold return water and it tells the electronic aquastat to shut the main circ back off and run the boiler protection circ again. After a few cycles like this the main circ stays on and the house gets satisfied. This shuts the transfer circ off and the boiler then dumps that balance of the btu's into the storage (using the really cool close tees that your guys helped me with). My goal at this point is to keep the boiler running full bore until the tank is at it's maximum temp (your #3) and hopefully the wood boiler runs out of wood at exactly the same time....good luck with that guessing game! Currently my boiler tops out at around 175 degrees before the Honeywell aquastat shuts it down. That's why I would like to purchase, or steal, an aquastat that goes up to at least 195 degrees. This will work better with my b/b and pack more btu's into the tank.
After I insulate the house and the storage tank to an agreeable level then it will be time to look at how I get the induction fan on the boiler and at least the main circ to kick off when the boiler is safe to shut down. This will keep it from pulling heat from storage until the boiler gets below 150 and shuts the main circ off. This seems to be the main problem for all of you that have been at it for a couple years or more. I guess a timer would be a quick fix (or an alarm clock to wake me up to shut the system off...NOT).
I've got more room in my brain if you've got more data. I might forget how to tie my shoes after that though. That whole first-in-first-out mindset.

np

This is an interesting problem. I think that there are some conflicting goals:

1) You'd like the best possible efficiency. That's obtained with the lowest possible outlet temperatures.

2) You'd like quick response when you need heat and have just started a fire. That means circulating water as soon as the boiler has reached a usable temperature.

3) You'd like to be able to get storage 'topped off' with as high a temperature as you can safely get.

The ideal situation would be to change your outlet temperature depending on what's happening. Early in the fire when storage is cold, a much lower outlet temp might work fine, especially if you have radiant heat and don't need 180 for baseboards. This is consistent with objectives 1 and 2.

As you start to charge storage, you probably want to keep you boiler outlet a few degrees warmer than your tank bottom until the whole tank is up to a minimum usable temperature.

Then, you want to gradually ramp up the boiler outlet temp to stay a few degrees above the top of tank temp.

There are three tools available to affect boiler outlet: fan speed, boiler inlet temp, and flow rate. I don't know what others are doing, but my thought is that you want to keep boiler inlet as low as possible without risking condensation. You want the fan speed to be as high as the fuel charge can support, and you want to vary the flow rate through the boiler to achieve your target outlet temperature.

It isn't necessarily possible to do any or all of these things on a given system, but my thought is that this approach would be a good compromise between the conflicting objectives. Any thoughts?

 

[Nofossil]

The flue gas passes through internal HX tubes in the boiler before it gets to the flue. The colder the water is around those tubes, the more heat it will suck out of the flue gas. It's probably not a huge deal, but higher outlet temps probably always result in higher flue temps, everything else being equal.

 

[Piker]

The mechanical aquastat does not control outlet temps... only the high limit of the boiler.

No fossil is correct, higher boiler temps result in higher stack temps... which means more thermal energy is passing through the heat exchanger and into the atmosphere. That having been said, I have been running my tanks up to between 190 and 200 every firing in order to get the longest cycle times. During this time of year when heat load is extremely low (except for when the wife has the thermostat on 82*) I can easily run the Econoburn on low fire to charge the tanks and meet demand. The boiler switches between the circs to temper the return water till it reaches 150... at 160 I drop the boiler into low fire, which effectively lowers the stack temps about 100* or more.

One thing about the guessing game concerning how much wood it takes to reach max temp... the more storage you have, the easier it is to gauge.

I use a timer to shut the boiler down... I added a relay though to turn the near boiler circ on in the event that I short change the burn time a little too much and an excessive coal bed is left. By leaving this circ running, you can prevent flashing water to steam around the firebox without disturbing the water in your storage tanks. This works EXTEMELY well as the burn times are fairly consistent from day to day providing your fuel source is fairly consistant, and there are no big fluctuations in outdoor temps. A three way light switch (single pole double throw) is used to run the boiler either through the timer or bypassed around the timer... both are mounted in the front panel of the boiler. You can generally guess accurately enough to leave just the right sized coal bed to get refired in the morning or the next day without lighting from scratch. If the coal bed is completely out, 30 seconds of a propane torch on a few coals around the nozzle brings the boiler back to life in a matter of moments with an intense gasification in less than 5 minutes.

cheers

 

[Gooserider]

Do I have any thoughts???? I feel like Forest Gump when I read your posts.

I agree to some of what you are saying below a storage demand requirements aspect, but the implementation of required controls is more your area of expertise than mine. In other words, it would be too complicated for me at this time. I've acquired quite a bit of hydronics knowledge in the last 2 years off hearth.com and maybe in another 20 or so years I'll catch up to where you are now.......then maybe not...

Your #1 confuses me. I don't understand why you'd want the lowest possible outlet temps for the highest efficiency? Maybe the lowest outlet flue temp. My b/b seems to need 180 deg f water to acheive it's maximum water to air transfer efficiency. So why would you want only mediocre boiler outlet temps?
I have 1 boiler protection circ, 1 main circ that sends the over near the storage tank, 1 circ that I call the transfer circ as it transfers hot to the gas boiler in the house for distribution to the zones. As you know, when my Eburn reaches it's 150 deg setpoint, the main circ kicks on. If the house is calling for heat then the transfer circ is already on and sends the 150 somewhat-hot water to my gas boiler for distribution to the zones (b/b and dhw). At least until the boiler takes on too much of the cold return water and it tells the electronic aquastat to shut the main circ back off and run the boiler protection circ again. After a few cycles like this the main circ stays on and the house gets satisfied. This shuts the transfer circ off and the boiler then dumps that balance of the btu's into the storage (using the really cool close tees that your guys helped me with). My goal at this point is to keep the boiler running full bore until the tank is at it's maximum temp (your #3) and hopefully the wood boiler runs out of wood at exactly the same time....good luck with that guessing game! Currently my boiler tops out at around 175 degrees before the Honeywell aquastat shuts it down. That's why I would like to purchase, or steal, an aquastat that goes up to at least 195 degrees. This will work better with my b/b and pack more btu's into the tank.
After I insulate the house and the storage tank to an agreeable level then it will be time to look at how I get the induction fan on the boiler and at least the main circ to kick off when the boiler is safe to shut down. This will keep it from pulling heat from storage until the boiler gets below 150 and shuts the main circ off. This seems to be the main problem for all of you that have been at it for a couple years or more. I guess a timer would be a quick fix (or an alarm clock to wake me up to shut the system off...NOT).
I've got more room in my brain if you've got more data. I might forget how to tie my shoes after that though. That whole first-in-first-out mindset.

np

This is an interesting problem. I think that there are some conflicting goals:

1) You'd like the best possible efficiency. That's obtained with the lowest possible outlet temperatures.

2) You'd like quick response when you need heat and have just started a fire. That means circulating water as soon as the boiler has reached a usable temperature.

3) You'd like to be able to get storage 'topped off' with as high a temperature as you can safely get.

The ideal situation would be to change your outlet temperature depending on what's happening. Early in the fire when storage is cold, a much lower outlet temp might work fine, especially if you have radiant heat and don't need 180 for baseboards. This is consistent with objectives 1 and 2.

As you start to charge storage, you probably want to keep you boiler outlet a few degrees warmer than your tank bottom until the whole tank is up to a minimum usable temperature.

Then, you want to gradually ramp up the boiler outlet temp to stay a few degrees above the top of tank temp.

There are three tools available to affect boiler outlet: fan speed, boiler inlet temp, and flow rate. I don't know what others are doing, but my thought is that you want to keep boiler inlet as low as possible without risking condensation. You want the fan speed to be as high as the fuel charge can support, and you want to vary the flow rate through the boiler to achieve your target outlet temperature.

It isn't necessarily possible to do any or all of these things on a given system, but my thought is that this approach would be a good compromise between the conflicting objectives. Any thoughts?

Well, as NF said later, the lower the input and output temperatures, the more efficient the boiler will transfer heat from the fire to the boiler water, and the less heat you will have going up the stack... This is basic physics of heat transfer; the greater the temp difference between two objects, the more readily they can transfer heat.

From your descriptions, I would say that your biggest problem is that you are using baseboard that requires 180* water for useful output - this leaves very little margin in your tank for useful storage. However I'm not sure you'd gain all that much advantage from adding just a few more degrees of temperature into the storage tanks. IMHO you might be better off to look at seeing what you could do to improve your radiator setup so as to lower your operating temperature on that side... Upping your tank temps is only going to get you 10-15* more storage, if that, and will have you bumping up against your safe operating limits. Lowering your radiation temperature could get you as much as a 60* effective benefit if you could get the working temp down into the 120* range.

Obviously the optimal would be to try to retrofit infloor radiant, but that would probably be hardest to do... Next best might be flat panel rads. Least effective, but probably easiest would be to add more baseboard, or switch out what you have for BB that will run effectively at a lower temperature ( White-Rogers claims to have some lower temp baseboard, and I think SlantFin might as well - haven't tried either so I don't know how really good either is...

Hope this makes sense,

Gooserider

 

[Huskurdu]

Nofossil, I finally understood what you were talking about after I went to bed last night. The greater the temp diff between the water and flue gases the greater the heat transfer. I'm not a hard core 'use-as-little-wood-as-I-can' type of guy. I sleep just as well killing a few extra trees. They're plentiful here and they screw up my Dish reception. So a perfect heat transfer is not one of my goals at this time. I'm more interested in creating more 'coasting' time between burns.

Piker, I think the system that you have is more in line with what I need to do. Relay's are cheap and 'fairly' easy to install. I could handle that. I like your idea of a switch to go from a normal operation to a timed operation. The 'low fire' that you speak of is effectively turning the induction fan down to the slower setting correct? I can see that slowing the flue gas through the heat exchanger and sucking more of the heat out of it. This would probably create more 'coasting' for me. Right now I'm doing about 1 big load/day for heat a dhw. The 500 gallons storage is not enough for my usage at this time. 1000 gallons would be more in line. The problem is that during the coldest part of the winter I'll make just enough heat for my demand. I won't have any extra to store. I need more insulation in the house, garage, and around the storage tank I guess. That should be my next big concern.

Goose, Yes, the b/b is my weakest link at this time. I can't say that the house ever was cold last year...but I'm sure I would be much happier with some radiant installed. Or maybe a couple of those big ugly cast iron radiators.... That would be so cool! I like the idea of new lower temp b/b, but I'm sure no improvements are going to be in the cards for a while as money is going to be a continued problem for another year.

You guys are awesome, thanks for the input. np