aquastat for Eko

[trumpeterb]

The Eko 40 package that I purchased from Cozy heat comes with a Honeywell Aquastat. As I looked at the installation manual, I could find no indication of where the aquastat is to be installeed. Does anyone know where to put this thing?

Thanks

 

[Dave T]

I believe the stat you are asking about is for the overheat loop..Do some searches on this site there are a variety of ways to run an overheat loop, overheat loops are needed and can not be overlooked..Dave

 

[Eric Johnson]

I put mine on the return line. My system pump won't work until the return temp gets to 160. That's what Dave suggested, and it works very well.

 

[trumpeterb]

Eric,
Do you have an overheat loop on your intallation as mentioned one reply before yours? I am unfamiliar with the overheat loop and didn't see one included on the drawing that Dave gave me.

 

[Eric Johnson]

Yes, I do. But I've never used it. The only time my EKO has ever overheated was when the pump failed. That or when the power goes out. For those occasions, I have a manual gravity-feed dump zone (a couple of cast iron radiators in the unheated attic above the boiler). My point is that you would need a pumped overheat loop to use an aquastat, and it won't do you any good if the pump fails or the power goes out. As long as you're pumping water, your boiler shouldn't overheat, even when all the zones are satisfied and the boiler is idling. At least mine never has.

 

[stee6043]

Perhaps I'm the only one....but I do not have an overheat loop with my EKO 40 setup. Since I stacked my 500 gallon propane tanks I have a pretty nice gravity situation with no pumping or sensing required. My top tank is above the top of my EKO. That being said....I also have a battery backup...

 

[Jeff S]

Eric,in a over heat setup such as yours,are the CI radiators always full of fluid or are they empty until the manual valve is opened ?Seems they would need to be full in order to thermosyphon properly .I'm concerned about freeze up if using only water.

stee6043,If I were to use a system similar to yours do you think a spring check between the boier and storage tank would prevent the thermosyphon action.

I'm working on my EKO25 project and could use any help I could get.thanks.

 

[carbon neutral]

Perhaps I'm the only one....but I do not have an overheat loop with my EKO 40 setup. Since I stacked my 500 gallon propane tanks I have a pretty nice gravity situation with no pumping or sensing required. My top tank is above the top of my EKO. That being said....I also have a battery backup...

I like this battery idea, is it a UPS like the kind sold for computers?

 

[jebatty]

My point is that you would need a pumped overheat loop to use an aquastat, and it won’t do you any good if the pump fails or the power goes out.

Not accurate. I have a gravity fed overheat loop consisting of baseboard finned material (about 32') installed on the ceiling of my shop. It is activated by an Automag valve triggered by an aquastat with a sensor in a well in the boiler, set at 210F. The aquastat is NC, completing the circuit to the Automag. At 210F the aquastat opens, shutting off power to the Automag which then opens, and the gravity fed loop is active. Same thing would happen on a power outage. But if power is active, my gravity loop also would be charged by the circ on the boiler, if that circ is active.

A person has to measure the risk of overheat against the extent of harm if it occurs. Not too likely, for sure, but if it did happen, boiling hot water being vented by the pressure relief valve would not be a pretty sight, and since I do not have automatic boiler water makeup installed, there also is the possibility of structural failure of the boiler as water boils off and the fire continues.The overheat loop is pretty cheap insurance against these risks. Total cost of the self-install was about $200.

And I did test the overheat to make sure it did its job by cutting power to the boiler when the whole system was up to full temp and then a fresh load of wood into high burn. The draft fan obviously stopped, water temp rose from typical boiler maximum of about 190F to somewhat above 210F, but not high enough to boil under pressure of about 20 psi. Then it held for quite a while before starting to fall.

Tarm and the experts say the overheat loop is necessary. I won't disagree.

 

[Eric Johnson]

A makeup water connection (with pressurized, city water) does change the equation somewhat. And I agree that you need some way to get rid of excess heat--preferably with a setup like yours with an Augomag, Jim.

My radiators are empty. It's a manual setup i.e., I need to vent them as they fill and then drain them when it's all done. You could fill the rads with a water/antifreeze solution as a one-shot deal, but then you'd have to make sure you recharged them after use. It's not an ideal setup by any means, but it works when you need it.

I'm surprised that you get convection through baseboard, Jim. But it sounds like a good setup.

 

[stee6043]

stee6043,If I were to use a system similar to yours do you think a spring check between the boier and storage tank would prevent the thermosyphon action.

I'm working on my EKO25 project and could use any help I could get.thanks.

I guess it would depend on the check valve? I have a Grundfos 3 speed pump with integral check in my "overheat" circuit but I doubt it would stop flow. But again...I have a battery backup so I'm counting on not having to try it out!

 

[stee6043]

Perhaps I'm the only one....but I do not have an overheat loop with my EKO 40 setup. Since I stacked my 500 gallon propane tanks I have a pretty nice gravity situation with no pumping or sensing required. My top tank is above the top of my EKO. That being said....I also have a battery backup...

I like this battery idea, is it a UPS like the kind sold for computers?

Yes, I am using a "computer style" UPS by APC. But let the record show you have to get a pretty beefy UPS to support the boiler and a pump for any kind of time. The unit I have I obtained free and simply had to replace the batteries. But new it would have been $400-500 or so. The smaller UPS units wouldn't give you much time before the juice is gone. I believe mine is a 1500 model?

Lots of people on here rig up battery back up units with inverters and car batteries. Much cheaper I suspect if you can find a reliable way to switch automatically when the power fails...

 

[jebatty]

Lots of people on here rig up battery back up units with inverters and car batteries. Much cheaper I suspect if you can find a reliable way to switch automatically when the power fails…

There is the option of removing the internal UPS battery(ies) and replacing with deep cycle 12V batteries (100ah, for example); just have to wire to connections for internal battery. The you have the automatic switch-over. What I don't know though is whether UPS systems are designed for operation over several hours, over-heating issues, etc., as there normal use is just for a few minutes.

 

[carbon neutral]

I was just thinking about this some more and remembered when I first fired my boiler the pex I had was too small and didn't allow enough flow. The boiler came up to temp then shut off. Every six minutes it would go into its purge cycle where the fan would come on for a few seconds to keep the coals warm. Little heat if any was being taken from the boiler. So in a power failure wouldn't the boiler fire just go dormant? There would be an initial spike in temperature but without air you have no or very little fire. My boiler cuts out @80 celcious so I have a good margin to boiling point since I am operating @ about 20 psi. Is there really a need for these overheat loops since these boilers won't fire without power?

 

[DaveBP]

There is the option of removing the internal UPS battery(ies) and replacing with deep cycle 12V batteries

I'm not sure how properly the UPS battery charger could keep up with a larger bank of batteries if they were drawn down and needed more than a float charge, or a different type of battery than the sealed batteries that come with them. Different float charge voltage is used for the different types of batteries. It would bear some research but might not be too tough to do right.

Is there really a need for these overheat loops since these boilers won’t fire without power?

I don't think the draft fan seals completely when the power to it is cut off, at least it doesn't on my Tarm Solo. If you have a tall masonry chimney that is fully heated you might have enough natural draft to pull quite a bit of air through your firebox and keep a low fire going for some time. That could be enough to heat a lot of water long enough to cause problems.

 

[Eric Johnson]

IME, they overheat pretty quickly without some flow. There's enough heat stored in all that thermal mass to push water temps up well above the boiling point, even if you pull all the smoldering chunks of wood out and toss them into the snow.

 

[stee6043]

Lots of people on here rig up battery back up units with inverters and car batteries. Much cheaper I suspect if you can find a reliable way to switch automatically when the power fails…

There is the option of removing the internal UPS battery(ies) and replacing with deep cycle 12V batteries (100ah, for example); just have to wire to connections for internal battery. The you have the automatic switch-over. What I don't know though is whether UPS systems are designed for operation over several hours, over-heating issues, etc., as there normal use is just for a few minutes.

I'm not sure I'd feel comfortable adding bigger batteries to my setup. As it is the internal fans on the UPS kick on after only a minute or so of running on battery power. I'd bet the bigger batteries would eventually fry the insides.

 

[timberr]

Instead of using a UPS I bought this Power inverter w/ transfer switch and a deep cycle battary http://www.theinverterstore.com/the-inverter-store-product.php?model=pwric150012s , runs my system for at least 8 hrs (thats as long as I have tested). I provides true sine power. Best of all it works without you being at home.