Hello to everyone as I'm new to the site. I'm having some issues with my OWB and would looking for some form of direction. It's a Aqua-therm 275ss and for some reason (after using it the last three years without problems) it seems that the fan is to be turning on and off a lot. I was told that it could be a sign of the pump going bad or the lines are air locked. Either way how do I figure out the problem with out too much trial and error? This morning was -20 F with the wind chill so I'm trying to nip in the butt before it gets to out of hand. Any help is appreciated.
I don't know anything about that boiler, but more info would likely be needed for someone who does. Like, temp data to go along with when & how often the fan comes & goes. E.g., boiler temp? Is the fan shutting off because the boiler is up to temp or is it doing it before it should or when it shouldn't? Water temps in the house? Other signs of things not being or working right?
You could be correct. Thanks for the response.... So I have the boiler set to kick the fan in at 150F and shut off at 170F as this is how it was set up when I bought the house. This part seems to work fine and starts/stops when it is set up to. The part I do notice is that the temp seems to drop faster then usual making the fan kick in way too much. A normal day the boiler full of wood could go easy 12 hours, now it starts/stops so much I can barley get 8 hours when full. For some reason I feel as if the pump isn't circulating the water fast enough and when It finally does move the water that the temp drops so much it needs to start the fan again. I have felt the lines in the house and they're hot to the touch and I can feel vibrations from what I assume is the pump running, which I guess doesn't necessarily mean that its working correctly. (This part is why I was told the pump is the problem.) The pressure of the boiler when cold is about 2 psi. The manual states this should be around 12 psi when cold however when I do this the pressure rises above 30 psi and the boiler dumps the fluid. Normal running pressure is 18 psi when hot which is what I get only when I have it at 2 psi cold. (This part is why I was told the system is "air locked" and the air needs to be removed from the system.) I hope this information is more than needed to get it fixed and running right again. Thanks to all for looking... Kilbourn.
About the only help I can offer is that with the cold snap going on, wood usage is higher. What used to last 1/2 day gets used up sooner. Especially if your house is poorly insulated. Remember the wind and how fast it'll cool the house down...with that in mind, it is not what you refer to as a normal day. The OWB I have is a non-pressurized system with only a circulation pump on it. The aquastat controls air inlet (dictated by water temp) which is non-induced. A very simple and effective system with high reliability. One circ pump replaced in 10 years usage. Being a non-pressurized system, I don't have to worry about air lock in the lines as when it was filled or topped off, I just add it from the basement in a backfeed manner. I wonder if you OWB water level is good or not? Leak?
That's what I was thinking, water level is low and that's causing the pressure to be low as well since the pump is circulating air and water. since the weather is colder than usual the wood consumption doesn't sound that odd. Are you burning the same kind of wood as before, of possibly a softer wood that will burn faster? Also, can you dial up your max temp another 10 degrees or so, which would give more "off time" as the water cools back to the low temp before triggering the fire again. One last thing- are you running the right mix of water/anti-freeze specific to your boiler?
Hate to say it but it doesn't sound like you have an issue at all... You stated you would normally get 12-hours from a load. You said it was -20F this morning...now you're getting 8-hours out of a load? That doesn't sound wrong at all to me. With the temps we're seeing in NH this week I'm noticing a higher wood consumption as well, perfectly normal.
It sounds like your pressures are right where they need to be and the blow off valves are working correctly. Do you have drain valves at each zone? If so, crack them open and see if it pushes any air out. You may be low on water, so open the drain at the bottom of the boiler and see if your auto fill valves opens and refills it. Otherwise, your stove might just be working overtime to keep up to temp in this weather. Checking the strength of the pump can be done by emptying the return line into five gallon buckets and seeing how many gallons it filled in a minute.
So this is a pressurized OWB? Can you confirm? If so - those pressures don't sound right, at all. Yes, it should be more like 12psi low. And shouldn't rise to blow-off when hot. Getting air out will only make that worse - air can compress and can absorb expansion to some extent, water can't. That part sounds like an expansion problem - like, maybe waterlogged. Has the boiler always been this way? What do you have for expansion? Is there an expansion tank? Does it have a bladder? How is the OWB connected to the house system? The original post didn't sound too out of whack, with increased wood consumption and fan action for very cold weather. But you opened the door to possible other issues with that last post, along with also seeming to confirm the fan is working as it should be. Any other info? Also - feeling pipes by hand isn't a very good method to trace issues with heat distribution. Usually accurate temp measuring at all ins & outs is part of it. An IR temp gun can be useful if it is a good one, and used properly. They don't measure shiny surfaces well so a blotch of flat black spray paint might be needed on some surfaces.
Thanks for all the responses!! I understand it's cold out and it will run more often but I guess I failed to say that it's been like this even when the temp was above 0 F. I think increasing the shut off temp isn't a bad idea. This is a closed system and no auto fill is hooked to it, so a water hose is the way it gets filled. The mixture mostly looks like ( I'd hate to say) car antifreeze/water mix. I had a bladder tank hooked to it and it seemed to have a hole in the bladder so I replaced it with a new one. They ran lines in the garage and that is higher than the boiler which makes me believe it's the only place air could sit if at all. As far as the wood I try to keep 20 full cord spilt and stacked at all times. All is red and white oak with very few black locus and no soft wood. I hope this answers some questions. I know the expansion tank it to be set at 12 psi empty and 60 psi at full temp. I didn't think to check the pressure in case the new one has a pin hole. I will update the results when I get back home.
Now we're going in even more directions. I hope that water hose is not turned on all the time. You shouldn't really need to add any water over the course of a winter, especially with a closed boiler. Once it is set up, that should be it. What made it seem to have a hole in the bladder? There is a procedure to follow when installing an expansion tank to make sure it is doing what it should be. Starting with - did you check the air pressure in the new one out of the box? Before it was hooked up to anything? Actually, even before that - is picking the right sized one. And 60 psi? That is an 'out there' number for a heating system pressure. Not sure what you meant by what you said though? But I couldn't make sense of it, relating to a heating system. Full temp pressure should be a few pounds less than your blow off pressure - which sounds like 30 from the above, but I like mine to be below 20 at all times. And nowhere near 60. Were you the owner when it was originally installed? Sounds like it might actually have some antifreeze or glycol in the system?
^^^this^^^ Going from 2 to 18 psi and popping off is a waterlogged symptom Unless you're making steam, which would be really bad!
.....Thanks to everyone for the replies. I still don't know what is the issue but it seems to be heating the house so I guess until something fails I'll just let it do its thing. Thanks Kilbourn!
