Central Boiler steam leaking from top, temperature won't drop

[jaycmw18]

Good morning,

First post on this forum, lots of good information here that has helped me thus far in troubleshooting my problem. I've owned a Central Boiler CL-5036 for 10 years and it's treated me well, with the occasional need to spray some WD-40 on the damper or remove build up around the door/damper door I haven't had to do much maintenance on it.

Nearly two days ago, I went came home and noticed steam shooting out from the top. I went out immediately to see what's going on and I noticed the water level had risen by about an inch. My temperature gauge reads 210, and when I opened the door to see what the wood was doing it was completely dead/smoldering. Checked the damper, it's flush and closed. Checked the door, and it appears to seal. I haven't loaded any wood in it for nearly two days and the same amount that was there when I noticed the steam remains - so it's not a draft issue/burning issue.

I checked the pipes in the house that come in and feed my heating system, and they were warm to the touch but not scolding hot. They still feel like water is moving thru them though? I'm not sure how to describe it, but it doesn't feel like a pipe with still water in it.

My local dealer has been closed all weekend and has not returned my calls to see what the problem is but it sounds like my water pump in the central boiler is bad. I had a spare temperature controller that I replaced just to see if that changed anything but it did not. I did not replace the temp sensor. What are your guys thoughts? Could it be anything else? If it's the water pump, how difficult is this to replace?

Thanks for the help!

 

[Armbru84]

I am not 100% sure how the centrals work as I have a Heatmor, but if your boilers hot and it's. It that hot in your house it seems like there is a flow issue or it's simply hot out. Which I doubt is the case! Are you getting much heat once the furnace kicks on in your house? Seems like it would not if you were getting no circulation.

 

[H-Ranch]

Sounds like a flow problem for sure. After 10 years the heat exchanger or other areas could be clogged. There was a member a few years ago that found a valve that had been turned off. Or it could be the pump as you say.

I don't know how the pump is plumbed on the Central Boilers, but if you do have to replace it now would be a good time to install quick couplers on either side of the pump - then the *next* time it can be swapped out in 5 minutes. I plumbed mine in the basement and keep a spare on hand for just such an emergency.

 

[jaycmw18]

I'm not getting much heat at all in the house, some heat, but not what it normally is. I have on/off switches for Wood/Oil and both are on at the moment so my heating system is trying to use wood first and it's not working all that well! I could turn it off to get full heat from the oil but I'm worried about my underground pipes freezing - seeing as it's snowing right now!

The hot water is working normally though, which is controlled by the same system. Out at the Central Boiler, the water pump sounds like it's running but I'm not sure if it's actually pushing water or not. My system has been steaming and at 210 degrees for nearly two days and the same couple of logs I put in two days ago, it normally burns thru 12-15 pieces every 10 hours or so. I don't know how it's staying so hot!

 

[jaycmw18]

That's what I'm thinking - it's the water pump. I kind of hoped there was something else causing this as I do not have couplers/shut off valves on the side of the Central Boiler. Which would mean I'd have to drain it completely before I can replace it. I'll double check my other shut off valves, and maybe turn the entire system off then back on and see if that does anything.

Thanks for the help/direction everyone! Hopefully a new pump will give me another solid 10 years!

 

[Armbru84]

It would be interesting to see if you turn the whole system off if the temp actually drops. Or purge in some cold water and see if it levels out or rises back up. I have left my furnace sit for 3 days over a weekend and the water at the boiler still drops 30-40 degrees over that time depending on outside temp.

 

[NSMaple1]

Sounds like either a heat exchanger blockage or pump problem.

Although we don't know much about your system.

Do you have isolation valves on the heat exchanger? Guessing not likely since none on the pump? Ideally there would be isolation valves, and hose bibs at inlets & outlets on both sides of the HX to allow for easy flushing. Whatever turns out to be the problem, it's sounding like cutting into the plumbing will be required, and a draining. So it's a good time to remedy those plumbing shortcuts & get it done right - could be a HX this time, and pump the next. Or vice-versa.

 

[Dogsout]

If you do have to cut to replumb, if you have enough room might I suggest installing a T fitting in the space where you install valves to isolate your pump. On the T put a close nipple, a ball valve and a pressure gauge. Next time you have any doubt, you can close your outlet pump valve to dead head the pump, and open up your valve on the T to the pressure gauge to check your pump for pressure. It is a good idea to dead head your new pump right away and get a pressure reading so you know what a good reading is when needed. This can also help some what when your pump is getting weak but still working. If you should see a steady slight drop in pressure it may be a good time to do a little preventive maintenance and change out the pump then.

 

[djones]

Ok, it sounds to me like your OWB has shut down and the oil boiler is taking over. Your oil boiler is circulating the water through your OWB and then back to the house , ergo the cooler temps at the pipes from the OWB. The pump at the OWB is going to circulate water as long as the power to the pump is on. If the temp is cold enough to freeze then do not shut the power to it off. The steam from the top of the boiler is probably from the pressure relief valve. Most valves are set at 30psi. The water level increase is probably from the excess heat of 210° causing expansion in the system. In my system, I have to lower the on /off limits of the oil boiler so that it doesn't override the OWB. You want the OWB to be the primary supplier of heat and then the oil boiler to be secondary. Check the temp of your water at the oil boiler and the pressure and be sure they are lower than the settings at you OWB. Your oil boiler also has a pressure relief valve on it and may have a higher setting then your OWB causing the OWB relief valve to open and dump pressure. One question that just came to mind is, do you have a closed loop system or an open loop system ? From the sound of your problem I assumed it was a closed loop system.

 

[jaycmw18]

I do have valves at the heat exchanger, both for the two inlets and two outlets. I just don't have valves at the other side where the pump is within the boiler. So if it is a blockage in the heat exchanger that would be ideal.

Good idea to put in the T and a pressure gauge if I do have to cut into it. I will do that if it comes down to doing that.

I'm going to shut down the system meanwhile and wait a little while to see if the temp drops and if firing it back up does anything at all.

 

[jaycmw18]

Ok, it sounds to me like your OWB has shut down and the oil boiler is taking over. Your oil boiler is circulating the water through your OWB and then back to the house , ergo the cooler temps at the pipes from the OWB. The pump at the OWB is going to circulate water as long as the power to the pump is on. If the temp is cold enough to freeze then do not shut the power to it off. The steam from the top of the boiler is probably from the pressure relief valve. Most valves are set at 30psi. The water level increase is probably from the excess heat of 210° causing expansion in the system. In my system, I have to lower the on /off limits of the oil boiler so that it doesn't override the OWB. You want the OWB to be the primary supplier of heat and then the oil boiler to be secondary. Check the temp of your water at the oil boiler and the pressure and be sure they are lower than the settings at you OWB. Your oil boiler also has a pressure relief valve on it and may have a higher setting then your OWB causing the OWB relief valve to open and dump pressure. One question that just came to mind is, do you have a closed loop system or an open loop system ? From the sound of your problem I assumed it was a closed loop system.

I am not sure if it is a closed loop or open loop system. If a closed loop means the water used in the boiler is separate from the house water system (drinking/bathing) then it is a closed loop.

 

[jaycmw18]

I checked the water pump that is inside, that I can isolate with the shut off valves. The taco water pump is extremely hot to the touch, I imagine this is not normal?
I attached a picture of my system inside, showing the heat exchanger and water pump

 

[djones]

A closed loop system is one where the water is maintained within the heat system and has no open outlet or fill pipe. An open system has a stand pipe that allows for overflow and filling of the system. The water is always separate from the domestic (potable) water. The oil boiler and the OWB just heats the heat exchanger inside the oil boiler. Another question, the pipes going to and returning from your OWB, are they both cool or is one hot and the other cool ? If you have 210° at the OWB and no fire, then the oil boiler is doing all the work keeping that water hot. If you have 210° water in your OWB but it is not coming back to the house then you have a circulation problem probably caused by the OWB circulation pump. Is your pump on the OWB or in the house near the oil boiler ? If you have no isolation valves then you have my sympathies.

 

[jaycmw18]

The two front pipes in the picture feel slightly cooler than the two in the back (going into the heat exchanger). None of the 4 are hot to the touch.

 

[djones]

Tap lightly on the temp gauge at the OWB. If the temp gauge says 210° and is cool to the touch then there is something wrong there. If it is digital then look for a reset or turn the power off and wait 5 minutes then turn it back on. 210° is definitely not cool to the touch.

 

[djones]

Is there a pressure gauge and temp gauge on your oil boiler? If so what are the readings ?

 

[djones]

According to central boiler, your hi limit setting for your model boiler should be 185° or above. I would check to see what your max setting should be for the PEX pipe you used and adjust accordingly. Had your OWB been running normal before this incident? My basic theory is when all else fails, go back to the beginning and start over. Is your temp gauge reading 210° or is that the setting you have chosen for it ? Try resetting your basic thermostat settings and see what happens. Is there still steam coming out of the top of the boiler? I see in the Central Boiler info package that they refer to the systems as pressurized or non pressurized. Pressurized would be the closed system and non-pressurized would be the open system. Do you recall which one you have?

 

[djones]

The 2 shut offs you have at the heat exchanger for the OWB will isolate the circulation pump for you but you will still lose some water that you will have to replace. if you have a pressurized system you will not lose that much, but if you have a non-pressurized system you will lose everything in the OWB down to the pump. You can try plugging the fill pipe to create a vacuum when the pump is removed and save some water, if it is non-pressurized.

 

[H-Ranch]

I checked the water pump that is inside, that I can isolate with the shut off valves. The taco water pump is extremely hot to the touch, I imagine this is not normal?
I attached a picture of my system inside, showing the heat exchanger and water pump

I'm going with odds on the heat exchanger by the photo and the age. I would guess that the performance has been slowly degrading over the years and it is finally plugged to the point that it can't flow enough. The pump may be hot just from deadheading against the blockage. The higher fill level, steam, and cool pipes seem to indicate the temperature reading is correct at the OWB, but it's a good practice to check the simple stuff first anyway.

 

[jaycmw18]

Tap lightly on the temp gauge at the OWB. If the temp gauge says 210° and is cool to the touch then there is something wrong there. If it is digital then look for a reset or turn the power off and wait 5 minutes then turn it back on. 210° is definitely not cool to the touch.

I replaced the temperature controller with a new one yesterday and it still reads the same temperature. I did not replace the probe however, so it could be that maybe?