Release Valve Activating

I have a Van Wert Simplex Multitherm combination oil/wood/coal boiler. I've only been burning bituminous coal in it for a few weeks now, and am still trying to get the hang of balancing between keeping the fire good and hot, and also keeping it burning for long periods of time unattended. My problem is if I load it up to the bottom of the door in the morning it stays good and hot until I get home around 5pm, but during the day the release valve will activate. The furnace is set up so the water temperature maxes out around 220, but if it gets even a hair above that, the release valve activates for a minute or two. The furnace was set up for oil only, but after moving into the house recently we learned burning oil isn't the way to go with this particular furnace. Is there some maintenance that needs done to prevent this, or is there an adjustment on the furnace I should adjust for burning coal as opposed to oil? Also, is there a way to override the thermostat's controls and have the boiler circulate hot water throughout the house before it resorts to using the release valve? Any insights would be greatly appreciated!

Yes you need a dump zone. Pick your largest BTU zone and wire an aquastat paraell with the T-stat for that zone. You might also want to increase the size of the expansion tank.

That makes perfect sense. I'm new to all of this and didn't know something like that even existed. Is an aquastat something that already will exist in my current boiler setup and I just need to wire it in to the thermostat, or do I need to buy one and install it in my boiler somehow?

Water expands when it is heated, raising the boiler water pressure. That expanded water normally goes into your expansion tank. Your existing tank needs servicing (water logged?) or is too small. Was a larger or second expansion tank added when the second boiler was installed?

If your expansion tank is properly sized you don't need a dump zone. There are valid reasons for a dump zone but expanding water is not one of them.

Couple things. Upon further investigation and knowing what I was looking for, there is an aquastat wired into my largest zone. I'm considering it the largest because it contains 2 of the old cast iron radiators about 6ft long each. I'm thinking that has more heating power than the baseboard in the main level of my house. The aquastat is set at 220 degrees. I'm not sure what that setting even means, but that is where it is at.

It is possible my expansion tank needs serviced, I am not aware that has been done recently. In response to has a second tank been installed when the second boiler was installed, you might misunderstand, I only have one boiler, with a pretty sizable expansion tank up in the ceiling.

What does servicing the expansion tank entail? I'm guessing the entire system would need to be shutdown and cooled, which will have to wait as its our only heat source and it's still pretty cold here.

You will need to find a place to install an aquastat well 1/2" or 3/4" on the coal boiler. Then you need to find an aquastat that closes on temp rise so that it will turn something on ,either a thermostat or a circulator pump directly. The important thing is that the aquastat closes on temp increase. Enough expansion capacity is equally important. If you dont have the bladder type tank already , get one. While the old style does work, it requires monitoring .

You posted while I was responding. Sounds like you have the right aquastat, set that at 200 , too , it sounds like the old style expansion tank and probably it is waterlogged . to recharge find the shutoff for the tank ,turn it off then locate the drain and drain it . after most or all the water comes out just shut the drain and open the isolation valve. Then sometime this summer put in a new style tank, and inspect the fill valve/pressure regulator and replace if its old and crusty. Open beer drink vigorously ....

Regards,

Waldo

You might read this for Dump Zone information. Dump Zone hook up.
Can you post a picture of your expansion tank, modern tanks have bladders in them and older units require different care.
You might have some success filling in your location in the user control panel, upper left, assistance may be in your area.
Relief valves somtimes need servie also, often replacment.

Water expands when heated, this expansion goes into the expansion tank, if it still has air in it, older systems fill and drain from the bottom and hold air in the top. Newer units have a rubber diaphram that separates the air for the water and require less attention. If your expansion tank is full of water with no air the expansion squirts out the preasure relief. If your boiler is getting hot and making steam, no expansion tank will hold that, and you need to prevent your boiler form getting to hot, this is where having a zone valve or two open when the boiler gets to say 205 or whatever you want will help to prevent overheat situations, the house may get warmer but that is better than popping the relief. Lastly you may want to repalce the relief valve, if it has been active scale can build up on the seat and cause it to weep, or stick shut.

Check the expansion system, a dump zone on hand fired is probably a very good idea, and think about the relief valve. We save money with coal but you still need to service your heating system.

I notice the word furnace in your original post, this is a boiler, furnaces heat air, small point but it is better to use the proper words, some would say it's ony style points but .

I probalby used some incorect terminoligy in my post and misspelled at least five words

Sorry for not replying for a while, wife had a baby, and other things took precedence. Anyway, my expansion tank I'm guessing is an old style one, it seems to be just a simple steel cylinder. I have drained a little water out of it since, but the release valve still pops once in awhile unless my zones thermostats are set around 75 degrees. It looks like from the replies above, I should drain out all the water I can get out of it.

Also, I wanted to ask, my boiler's temperature seems to always gravitate to around 220 degrees. When it is that high, and the thermostats open, water going through the baseboard sounds like Niagra Falls in there. It is much quieter when the boiler reads between 180 and 200. My domestic hot water is supplied by the same boiler (no hot water tank, one is on the way in the spring), and when the boiler temp is that high, the hot water from the faucet will scald. Its almost more steam than water at that point. Is there a way I can turn the boiler's temperature down, at least down to around 210 or 200? I like that it is nice and hot now, when a zone calls for heat, the temperature in the house jumps up in a matter of minutes and we've been keeping the house at 75 degrees for the baby, but I'm wondering if maintaining such a high water temperature is causing me to burn much more coal than I need to be. Burning through the coal isn't such an issue this year as I'm burning bituminous coal I got from my father in law for around $37 a ton. Due to the messiness, though, I'd like to switch over to anthracite next winter, and don't want to unnecessarily burn through it quicker than I have to.

Another thing my father in law noted, which may or may not hold any water was that I might want to consider capping my barometric damper because he suspected I was getting draft feeding back down through there and not letting the fire calm down when the draft control would try to seal it up. I think I've answered that myself though, from reading different posts on the forums here, I definitely don't think I want to cap that when burning coal, it seems you want to do that more so for burning exclusively wood where creosote buildup and possibly fire in the chimney is a concern.

I have a Van Wert Simplex Multitherm and can post pictures of various components if anyone needs to see any of that.

Matt328 wrote:Another thing my father in law noted, which may or may not hold any water was that I might want to consider capping my barometric damper because he suspected I was getting draft feeding back down through there and not letting the fire calm down when the draft control would try to seal it up.

I agree, I don't think this to be the case. I think a major part of the over heating could be due to the nature of the bit coal's burning characteristics. I recently burned bit coal in my furnace for about a week. I noticed that in the first few hours after loading, it would go nuclear and be very difficult to cool down. Cutting combustion air supply would make it angry and it would puff back at me. SO, I was often caught in the middle of running it too hot and at the same time preventing puff backs.. Then after the volatiles burned off it would run cooler but then not quite hot enough. So basically, I learned that bit coal has an inconsistent and unpredictable burn cycle I'm glad to be back to feeding her anthracite again

Does your boiler have a combustion fan that ramps up the fire when the water temp is low?? If so, you must have an aquastat that senses the water temp, and turns the fan on and off to maintain the target temperature.

OR, maybe our boiler has a temp sensor that uses a very small chain to lift and lower a draft vent flapper valve??

OR is your fie and temperature control only by manually opening and closing the combustion air control in the ashpan door??

Turn the temperature down on the dump zone, to say 210* so it will keep the water temp below 220.

And with a baby in the house, you MUST add a tempering valve to the hot water from the boiler,
You don't' want your child getting a bad burn !!

Greg L

I have the 2nd option, the temp sensor with the chain going to a flap on the draft. It seems to have an adjustment on it but is just in the form of a knob with arrows for warmer and cooler. It is turned all the way to the cooler direction already.

Make sure that the air flapper is seating properly so it IS shutting off the air..

Then look for other sources of combustion air, like leaking or missing rope-gasket around the ashpan door, or the loading door.

AT what water temp does the thermostat completely close the air flapper ? Is there an adjustment for the lenth of chain that
moves the flapper?? if so add a fe links to the chain to let it close at a lower temp.

Greg L

The air flapper is seating properly, I mean its not making a perfectly airtight seal, but its seating as good as they do. The rope gasket around both the firebox and ashpan doors is present, although might could use replacing. Still though they are in good enough shape, I doubt much air if any is getting in through there.

I was thinking about adding a link or two to the chain, as you said that would cause the draft flapper to close earlier. I'm not exactly sure what temperature it closes at, I would have to sit and watch it as the temp rises.

Is the length of that chain the main thing that controls my firebox's heat output? I would have imagined some kind of electronic sensor somewhere, but given that the flapper and the firebox and ashpan doors are the only openings, I guess I answered my own question.

I'll try adding a link or two and see how that goes. I have had the temperature for the dump zone set at 210 degrees, but that only seems to slow it down for a bit, then it powers right through that. The end result there is my basement (dump zone) just gets up around 85 degrees, and the boiler still goes up to around 220 before it calms the fire down.

The reason that you hear the water when the dump zone activates is because at 220 degrees the water is partly boiling and you are hearing the hot water/steam mix rushing through the piping. Maybe I missed it but your water temp low setting could be at 140 with a high setting of 160. That would give you almost 60 degrees before you get to the dump zone at 220.