I've had my OWB online now for 15 years and have had a problem creep up on me. I have too much heat. LOL It started this year the opposite when I noticed on extreme cold days it wasn't heating as good as it used to. I attributed it a pump cartridge that had gone out years ago and the impeller had broken into pieces and were sent on down the line to the heat exchanger plate. I figured this year I would take it off and flush it because I though it might be plugging it some. With these warm temps this year, the house was staying warmer now even though the thermostat is set at 68. Lat night it was 83 degrees in the house and decided something is really wrong here. I went down thinking the 3 way zone valve had stuck open as it was still sending heat out to the house. Used the manual lever and moved fine. Took the head off and plunger moves up and down freely. I always put a few drips of oil on it at the start of the season. Put it all back and still the same. At this point I'll explain my system to give a better idea of what I have. Hot supply is coming in the lower copper pipe. When not called for it U's through the 3 way zone valve and isn't allowed to go through the plate heat exchanger. When heat is needed in the house it goes through the plate when the valve opens. I run the boiler pump 24/7 and use the existing oil furnaces circulator pump(which also runs 24/7) and baseboard heat to distribute the heat throughout the house. Waters never touches each other in the systems if you will. Green poly pipes are to/from the house. Last night before bed I decide to just turn off the circulator pump on the oil furnace to let the house cool down. I woke up this morning to find the house just as hot. Am I correct to assume that my Heat exchanger has died and is allowing the water to cross over now and the boilers pump is pumping it through the house. It's the only thing I can see as the pipes are warm 1 story up after 24 hours! I check my water every year as well and it's still in range. I've only had to add condiitioner once to bring it back. Can't turn wrenches now as I had shoulder surgery but want to see if you guys concurr with what I think has happened. Is this common? Thanks for any input.
I'm thinking it would be the 3 way zone valve. if the zone valve shuts the water off completely going to the plate exchanger when the thermostat doesn't call for heat, which I would think it would absolutely have to, then no water could pass thru the plate HX. also if the zone valve is not sealing properly then the low mounted plate exchanger would thermostatically heat the water in your copper lines and radiate up towards the 2nd floor. especially on warmer days that don't call for heat. also your furnace line should be pressurized, so if there is a leak at the plate exchanger, then the water pressure should drop. and I would think it wouldn't put out the heat like it should. but its just a guess at this point. please keep us posted on what happens. btw, your install is still impressive, no matter how many times I look at it.
That is what I can't figure out either. The existing oil furnace I tied into IS a closed loop pressurized running about 12 PSI with a self fill water fitting. OWB is open system and pump runs about 15PSI on the gauge. I just went out and double checked boiler water level and it hasn't changed. I've only added water to the boiler once in 15 years and it was just at the minimum. I too think it would over flow something but it isn't. I shut the valve on the green pipe in the upper left hand corner that runs to the oil furnace circulator pump and to the house. House is cooling down now. I too would think that the valve itself was the culprit if not for the fact that the pipes were all still too hot to touch AFTER 12 hours of shutting the oil furnaces circulator pump off. I have a hard time believing convection can travel that far and even have the return really warm. I do not have an IR gun to give temps to you. Went down and checked the green pipe now that the valve is closed and it is warm about 2 ft up but close to the valve at the ceiling it is cool(no heat to the feel) Maybe I have 2 problems? Zone valve and HX? The stove is higher but not as high as the second story of the house. This one has me scratching my head and I will post what I find but like I said, It will be a while as I can't physically do it at this time. I'll do the manual valve thing as long as nothing is leaking/running over. I'll probably wait till the end of the heating season. My plan is to take the HX off and pressure test. If okay I'll flush it out to see if I have any crud in there. If that all checks okay, I'll look at the valve itself in the 3 way zone valve. Can you take those apart or is it a sealed thing? I've replaced the head twice from lightning strike and power surge from electric company but nothing with valve itself. Thanks for the insight guys.
hmmm. this has me scratching my head too. I think the convection theory is more likely than having both the hx and the zone valve having a problem at the same time, but I've been wrong before. I think the only possible way to check to see if it is the zone valve is to install a valve between the zone valve and the plate HX. I understand your not turning wrenches until the end of the heating season. so I just hope you have a speedy recovery. now I'm really curious to see what the problem is.
Boiler is staying normal other than it's going a little hot now as there is no draw anymore. I had a little too much wood in there as it got warm so quick and no draw. I went into the garage and turned up the radiant floor and it kicked on. That drew it back down and is no holding fine as temp is getting cooler outside. Just going to have to keep an eye on things more but I'm off work so I can do that.
The oil furnace is one loop throughout the house via baseboard heat and up to the second floor, then back to the basement. I have a hard time wrapping my head around convection being able to travel that far AND come down on the return side. Time will tell I guess.
I agree, it seems unlikely. the only reason I suggested that it could be convection is that I have a friend who owns a 2 story building who heats it using only a water heater and convection, no pump. however his pipes are one inch. . . ? or 1.25 inches? I cant remember which. and it keeps the building at a comfortable temperature. however his temps may drop in colder weather but in warm weather they sky rocket. no one lives in the building so he just wants to save on electricity. also it doesn't need to stay at a consistent temperature, it just needs to keep the pipes from freezing.
Last year when the temperature started really warming up around the end of March we started getting "ghost flow" running hot water backwards through the system. Although we have an indoor unit in the basement it was mainly dumping heat on the second story zones. We have a 5 zone setup. Never experienced it when we had the OWB. We have a continuous pump running to circulate to the system and separate circulators for the heating zones now with a fully pressurized system vs a plate exchanger. Sounds like you are getting the same effect by heat getting through your HX and doing the same thing.
With no other clues, I am going to suggest the internals of your zone valve are shot. Is there a way to open it to find out? If not, it may be time to just replace it.
That is my question. Never had one apart to know. I'm wondering if when the impeller on the main pump died if a shard of it may have lodged in the valve keeping it just slightly open. I've looked online some but have not found anything yet. I always seem to look in the wrong area.
I asked the question in OWB forum and clean fire found me a PDF. It's a 562-5 Taco 3 way zone valve. Looks like I can take it apart and inspect. Either clean it or replace. Might even be able to just replace the internal stuff and not have to resolder everything...Hopefully.
This one? http://s3.supplyhouse.com/manuals/1249544647674/Taco_Replacement_Parts_List.pdf Does look like it is serviceable...
