High anxiety on the first firing

[Old Timberguy]

Yippee! After a couple years of following forums, collecting components, and asking questions, I finally fired up my system last evening. Everything seemed to be perfect, good draft, only a little smoke on startup and a nice 6hr fire from an arm load of dry wood. It appears as if I got a 20 F degree rise in my tank, for which I had no expectations on since it’s all new to me.


There is a big “however”: I have concern that I'm not getting enough flow through my boiler to keep the temperature at a safe level. As recommended by a number of experts I installed a Caleffi high flow mixing valve, (140-F) between my boiler and the 500 gallon storage tank, using a Grundfos 15-58 circulator dedicated for this circuit only. I can’t find any tag on the boiler (which I purchased used), so I don’t know what the boiler is rated for, or what controls and circulator was originally used on it. I have a Honeywell Aquastat for circ control and a 24volt draft door control, and that’s it for this circuit. The boiler if physically quite small, but very well constructed. The former owner heated an average size home and garage with it.


So here is what’s causing my anxiety. As I carefully monitored this first firing I noticed the temperature climbing as the mass of the boiler heated up, I shut the draft down all the way and turned the circulator up to high speed but it kept climbing to almost 210 degrees. My first thought was the circulator simply isn’t big enough, even though rated at 17 gpm? Then I wondered if the factory installed check valve was impeding flow, and should be removed? Then I wondered if my Caleffi 140 degree mixing valve should have a lower temp cartridge because it was diverting too much flow on the return?


Unless I hear from someone telling me with certainty that this little circulator is just too small for the job, I’m going to remove the check valve before my next fire.

 

[BoiledOver]

Firstly, it would benefit you to provide more information about your system, specifically boiler name, temp gauges, pressure gauges, piping lengths, sizes, and such. Pictures maybe?

The 15-58 is not a high head circulator. How long, and what diameter piping is the boiler loop? In most cases, the 15-58 is a sound unit and will do its job effectively. The check valve keeps from getting a reversed ghost flow and I have kept mine on the boiler loop. FYI, my system is an Eko25 w/1,000 gallons of storage, about 50 feet round trip of boiler loop piping, a 15-58 on the boiler loop, and a Danfoss thermic valve to keep boiler temp above condensation levels. The piping for the boiler loop is 1" copper. The 15-58 is rock solid for this loop.

During my first full season of use, I experienced difficulties (due to false gauge readings) and thought I needed more from the boiler loop circulator. What it turned out to be was unreliable gauges. The tridicators (Honeywell) are turds. After springing for some good, reliable pressure gauges and a bunch of 12v digital temp gauges, all is well.

You must know what is going on in your system to run it to its potential, that requires accurate monitoring. Best of luck in finding a solution.

 

[Mike Fromme]

Do you have a gate valve on the bypass loop?

This is the mixing valve on my primary loop, but same idea; the gate valve is closed most of the way to limit flow through the bypass

 

[maple1]

We have no idea what you have for a boiler, and your whole setup - but I have a 15-58 on my loading unit & it handles things just fine on low speed. So something seems amiss.

I would firstly check/double check all your temps - redundancy is a must when it comes to that, I have too many temp & pressure guages on my system to count in my head right now. You should be measuring supply & return boiler piping temps, storage in & out, whatever you can measure. Other possible things off the top of my head are dirt in the Caleffi (teflon tape bits can upset things), and an airlock. A good IR temp gun would be handy.

 

[Old Timberguy]

Firstly, it would benefit you to provide more information about your system, specifically boiler name, temp gauges, pressure gauges, piping lengths, sizes, and such. Pictures maybe?

The 15-58 is not a high head circulator. How long, and what diameter piping is the boiler loop? In most cases, the 15-58 is a sound unit and will do its job effectively. The check valve keeps from getting a reversed ghost flow and I have kept mine on the boiler loop. FYI, my system is an Eko25 w/1,000 gallons of storage, about 50 feet round trip of boiler loop piping, a 15-58 on the boiler loop, and a Danfoss thermic valve to keep boiler temp above condensation levels. The piping for the boiler loop is 1" copper. The 15-58 is rock solid for this loop.

During my first full season of use, I experienced difficulties (due to false gauge readings) and thought I needed more from the boiler loop circulator. What it turned out to be was unreliable gauges. The tridicators (Honeywell) are turds. After springing for some good, reliable pressure gauges and a bunch of 12v digital temp gauges, all is well.

You must know what is going on in your system to run it to its potential, that requires accurate monitoring. Best of luck in finding a solution.




Thanks for the response, I’m feeling a little better about my circulator choice, but I still have some concern.

Unfortunately as I indicated, I don’t know much about the boiler. There is no name plate or info available from the home owner/seller, other than his word that it heated his house and garage, which I believe. My piping is 1 ¼” and 1” copper, the pressurized 500 gallon tank is about 4’ away and well insulated. I’m fairly certain the gauges are reading correctly because I was also using an infared thermometer on parts of the system. My Caleffi Thermomix is a 280 series with a 140 degree cartridge. Yes the gauge could be reading wrong i suppose, its a combo pressure/temp that came with the boiler. I’ve sent diagrams of the system in earlier posts, but for clarity the diagrams always lack dimension and real world obstructions. I will try to take a picture this evening and attach it to this post. Thanks again!

 

[BoiledOver]

Does the boiler have an electronic controller? Do you have a temperature&pressure relief valve on the boiler? Did it trip? If it has not opened to relieve either, maybe your tridicator (combo pressure/temp) is sour.

 

[Old Timberguy]

Do you have a gate valve on the bypass loop?

This is the mixing valve on my primary loop, but same idea; the gate valve is closed most of the way to limit flow through the bypass

View attachment 188623

I don't have a gate valve set up like yours. As far as I can tell from the instructions, my Caleffi mix valve shouldn't need any throttling down by me, it has a 140 degree fixed thermostat similar to what a car would have, opening automatically. Thanks

 

[Old Timberguy]

Does the boiler have an electronic controller? Do you have a temperature&pressure relief valve on the boiler? Did it trip? If it has not opened to relieve either, maybe your tridicator (combo pressure/temp) is sour.

There is no electronic controller, this is probably a 20 year old unit, not a gasifier, there are two controls: a honywell aguastat for the circ pump, set at 120 on, then a draft door actuator controlled by a 24 volt therm. Yes it does have a temp pressure relief on the boiler, just installed a new Watts 174A, and I did see a little weeping at around 25psi, just a few drops on the floor. Thanks

 

[Old Timberguy]

We have no idea what you have for a boiler, and your whole setup - but I have a 15-58 on my loading unit & it handles things just fine on low speed. So something seems amiss.

I would firstly check/double check all your temps - redundancy is a must when it comes to that, I have too many temp & pressure guages on my system to count in my head right now. You should be measuring supply & return boiler piping temps, storage in & out, whatever you can measure. Other possible things off the top of my head are dirt in the Caleffi (teflon tape bits can upset things), and an airlock. A good IR temp gun would be handy.

I do have a IR temp gun, and I was watching everything very closely last evening, my temp gun seemed to be giving low readings on the shiny new copper, but when directed towards oxidized surfaces and the boiler it self, I was seeing the high numbers. I could check the flush on the Caleffi, but I can already see a screw-up I have done there, I didn't Isolate it completely with shut-off valves, so I was hoping to avoid that till next year, 500 gallons of water! ):

 

[velvetfoot]

I think your Caleffi boiler protection valve would just start opening when the return temperature is 140 and be fully open at 157. What should a typical temperature rise be through a boiler, 20 deg? That'd be only 177, so I personally can't see why it can be the boiler protection valve (unless maybe it wasn't installed right?).

Where was the 20 degree tank rise measured and where did it start? Assuming that's a homogenized temperature, is 20 degrees a normal rise for a 500 gallon tank with that size boiler? How much wood was left when the boiler reached 210?

You would think with a cold tank there'd be no problem with keeping the boiler cool, quite the opposite. I would think with that cool water, return temps would be in the low 140's for quite a while.

 

[Old Timberguy]

I think your Caleffi boiler protection valve would just start opening when the return temperature is 140 and be fully open at 157. What should a typical temperature rise be through a boiler, 20 deg? That'd be only 177, so I personally can't see why it can be the boiler protection valve (unless maybe it wasn't installed right?).

Where was the 20 degree tank rise measured and where did it start? Assuming that's a homogenized temperature, is 20 degrees a normal rise for a 500 gallon tank with that size boiler? How much wood was left when the boiler reached 210?

You would think with a cold tank there'd be no problem with keeping the boiler cool, quite the opposite. I would think with that cool water, return temps would be in the low 140's for quite a while.

Now you have me doubting myself, Its a very simple install on the Mix valve, but it could go in backwards, and that would certainly explain things, so that will be the first thing I double check when I get home from work. Unfortunately I still have a job that take 9hrs of my day When i noticed the temp climbing I shut the draft down completely, it had been burning for about 1hr at 1/4 open. once it leveled off 2 more hours later, I went to bed, when I got up for work at 6:30 there were still a bed of embers with a boiler temp of 160. Yikes! that's probably 11hrs., Thanks

 

[Mike Fromme]

I think your Caleffi boiler protection valve would just start opening when the return temperature is 140 and be fully open at 157. What should a typical temperature rise be through a boiler, 20 deg? That'd be only 177, so I personally can't see why it can be the boiler protection valve (unless maybe it wasn't installed right?).

Where was the 20 degree tank rise measured and where did it start? Assuming that's a homogenized temperature, is 20 degrees a normal rise for a 500 gallon tank with that size boiler? How much wood was left when the boiler reached 210?

You would think with a cold tank there'd be no problem with keeping the boiler cool, quite the opposite. I would think with that cool water, return temps would be in the low 140's for quite a while.

The only problem I've had with my boiler has been related to the return protection valve. When it's not doing what it should be doing it causes confusion. Especially sense it might be allowing partial flow which makes temp readings be 'correct' at various points in the system.

My thermostat valve in my danfoss mixing valve wore out over time. Only Symptom was the boiler temp being slightly higher then normal. The temp reading on all the pipes throughout the system were wher they normally were... My first thought was the pump or air lock. When it finally stopped working the boiler quickly got to its set point way too quick..still thought partial air lock as the other temp readings were same as always. Basically enough flow was getting through to warm the pipes and the top of storage, but not enough to cool the boiler. After a couple hours of head scratching I pulled the thermostat out of the danfoss, closed the gate valve on the bypass completely and the boiler temp quickly dropped.

Now all that to say --- I can create the same symptoms if I completely open the gate valve on my boiler bypass loop. For whatever reason the thermostat doesn't stop flow through the bypass and the boiler reaches its set point if the gate valve is not throttling flow through the loop.

Ihave no idea if the Caleffi valve works the same as the danfoss. Just something to keep in mind.

 

[maple1]

You said you read temps, but you didn't post any.

And on the temp readings on copper, spray some flat black paint where you want to measure. IR guns don'tlike shiney surfaces.

Pictures are a must, me thinks. But you should be able to find the problem with use of the IR gun, seems like something rather up there on the wonky scale.

 

[Old Timberguy]

You said you read temps, but you didn't post any.

And on the temp readings on copper, spray some flat black paint where you want to measure. IR guns don'tlike shiney surfaces.

Pictures are a must, me thinks. But you should be able to find the problem with use of the IR gun, seems like something rather up there on the wonky scale.

Thanks for the suggestion, black paint, and I was so pleased with the shiny new copper.I will attempt to take pictures and post those along with temp readings next opportunity on Thanksgiving. And yes it will be something wonky, perhaps I'll find a mouse that thought my old boiler looked like a safe home.): thanks!

 

[woodsmaster]

Air bubble in the piping, or restricted flow somewhere. Check valve shouldn't make much difference.

 

[woodsmaster]

Try loosing the bolts on the out flow side of the pump just enough to break the seal and see if you get any air out. Warning, you may get wet. LOL