Indoor Wood Boiler

adamo141

Hello, I recently purchased a home with an IWB system a Kerr I forget the model, prev owners bought and installed in the '70s and never had any issues. For a majority of the winter it worked great! Until it started to Over heat/pressurize. I don't know much of anything about plumbing but it seems the circulator is working properly. I have mostly baseboard with 2 radiators left within the house. All of which have been purged of air successfully. The Wood boiler is plumbed to be ran either independent of my oil furnace or to supplement. Unfortunately the pressure gauge on my oil furnace is not working and I need to look into getting that serviced/fixed. Basically what happens is after loading with wood the boiler temp increases which in turn raises the pressure. The circulator kicks on and hot water is sent to the other circulator on my oil furnace which then sends it to the single zone within my house. Baseboards and radiators get warm. The issue is the wood boiler seems to on occasion over heat/pressurize causing pipes in my basement to snap crackle and pop, making an awful hammering noise. Water was coming out of my pressure relief valves and the wood boiler safety valve kicked on shooting water onto the fire (turned my water black temporarily).

It made sense that there was too much pressure so I drained about 2.5g of water from the wood boiler which dropped the pressure. Unfortunately I this was my last load of wood for the year and now that it's warmer I will not be using again until fall/winter. Does anyone have any ideas?

I have cleaned all of the areas of creosote that I can reach. I will be having my chimney cleaned this summer. Are there any other maintenance/servicing s that I can either do myself or have done professionally?

Thank you

Zman

It sounds like an issue with and expansion tank.
It might be a good time to get the whole system checked out.

cutter

You need to have about 12 psi of pressure on the boiler cold. And I would assume the valve between the boiler and expansion tank is open. Only put enough wood in the boiler that you think you will need to get your house up to temperature, don't overload the boiler. You can always put more wood in, its not a good idea to try and take wood out. Although I have done that when my boiler was hot and the circulating pump went out. A pair of fireplace tongs and a metal 5 gallon bucket comes in handy.
It would be a good idea to buy your own chimney cleaning equipment. You should clean that chimney more than once a year and using your own equipment would be a lot cheaper than having someone else clean your chimney. The flue pipe from the boiler to the chimney should be cleaned regularly also. I clean my chimney and flue pipe once a month during the heating season. When opening the loading door with a good fire going and you have excessive smoke coming back into the house that is a good indication that the flue pipe to the chimney needs cleaning.

Robert_25

It sounds like the draft controls on the wood boiler may need some adjustments, and your expansion tank is flooded. It would be good to have a pro check things out.

Also, those boilers are creosote monsters if you don't run them hard. Don't use the wood boiler in mild weather, burn seasoned wood, and have the chimney swept at least once per season...maybe more.

If your particular boiler has shaker grates, you may also be able to burn anthracite coal.

lchmb

and make sure the boiler is piped to spec's.. It should have a dump zone on it in case of a power failure or circ failure..

hot_rod

And a top quality, low level CO detector is a must!

cutter

lchmb said:

and make sure the boiler is piped to spec's.. It should have a dump zone on it in case of a power failure or circ failure..

It would be interesting to know how a dump zone or any other dump could be installed because of a power failure. A gravity dump would not work I feel because the system is not plumbed for gravity supply or return. From my experience if there is a circulator failure or power outage or control failure, A flashlight and a pair of tongs and a metal 5 gallon bucket is the solution.
If there is a better solution I would like to hear it.

cutter

Robert said:

It sounds like the draft controls on the wood boiler may need some adjustments, and your expansion tank is flooded. It would be good to have a pro check things out.

Also, those boilers are creosote monsters if you don't run them hard. Don't use the wood boiler in mild weather, burn seasoned wood, and have the chimney swept at least once per season...maybe more.

If your particular boiler has shaker grates, you may also be able to burn anthracite coal.

Don't scare the guy, I run my Buderus boiler all season from the start off cold till no more heat is needed, I'll light off to just get the chill off in the mornings and maybe fire it again before bedtime so it is not so cold in the mornings. I burn seasoned wood but clean the chimney and flue once a month. Not sure what you mean by run them hard but if you do not adjust that flue damper on the back of the boiler as you fire that boiler, a lot of heat will go up the chimney. A lot of wood can be saved by adjusting that damper as the draft damper closes. By adjusting the flue damper the flue pipe temperature will decrease tremendously. I have checked mine with a infrared gun with the flue all the way open and had a temperature of 700 degrees, a lot of heat was going up the chimney. Now by adjusting the flue damper as the draft closes as the water temperature rises the flue is never, well almost never over 400 degrees. When the water is up to 170, 180 degrees and the draft is closed or almost closed the flue damper is open just a little the flue pipe is around 200 degrees. Sure cuts down on the wood consumption. The flue damper needs to be opened to load more wood when the water is hot, even the draft needs to be opened manually, then closed.
I have been using a Buderus wood boiler since Valentimes day 1980 and have acquired a lot of experience since them.

hot_rod

cutter said:

lchmb said:

and make sure the boiler is piped to spec's.. It should have a dump zone on it in case of a power failure or circ failure..

It would be interesting to know how a dump zone or any other dump could be installed because of a power failure. A gravity dump would not work I feel because the system is not plumbed for gravity supply or return. From my experience if there is a circulator failure or power outage or control failure, A flashlight and a pair of tongs and a metal 5 gallon bucket is the solution.
If there is a better solution I would like to hear it.

I'm told a piece of large diameter fin tube piped like this can be an effective dump loop.

Most fan induced wood fired equipment revs down quickly. Unless it has a door gasket or other air leak.

lchmb

What Hot rod said Cutter. You may be there when it fails but I'm not always around... I like them piped to manufacturer spec's to cya...

cutter

hot rod said:

cutter said:

lchmb said:

and make sure the boiler is piped to spec's.. It should have a dump zone on it in case of a power failure or circ failure..

It would be interesting to know how a dump zone or any other dump could be installed because of a power failure. A gravity dump would not work I feel because the system is not plumbed for gravity supply or return. From my experience if there is a circulator failure or power outage or control failure, A flashlight and a pair of tongs and a metal 5 gallon bucket is the solution.
If there is a better solution I would like to hear it.

I'm told a piece of large diameter fin tube piped like this can be an effective dump loop.

Most fan induced wood fired equipment revs down quickly. Unless it has a door gasket or other air leak.

Hot rod, I remember seeing that in Idronics #10, I am a little skeptical of that design. Idronics #10 did not give any design information either. What makes that thermosyphon work,Hot water is lighter that cold water and if the piping is sloped upward to the large fintube and the fintube is sloped upward a little and there is enough fintube to cool the water the slightly the colder water will go downard back to the boiler.
What you have is basically an old gravity hot water loop? Am I correct? The boiler room air temp would not be so cool as to be able to cool that loop a lot. that last sentence is just my thought.

hot_rod

I have not personally tried an over-heat loop like that, but I have seen thermosiphon at work in solar collectors and water heater loops.

If your mechanical space is 80F and the loop and boiler is 180F or generally over 200F at runaway condition, you have plenty of ∆T to make the energy move from fin tube to room.

Another option is a 12VDC circ and a car battery. With ECM pumps like the Laing/ B&G Eco, that would buy you hours worth of over heat pumping. A small "battery tender" would keep it charged.

I have owned and installed quite a few wood boilers of all brands, the only run aways were the ones where the doors warped and they would not starve air when the fans shut down.

A bucket under the relief discharge save glycol, by the way

ChrisJ

I'm curious @hot rod why is a low level CO detector a must with a wood burning setup?

I thought these were primarily required for very clean burning appliances such as natural gas or propane because you will never smell the appliance venting into the structure, though CO levels can skyrocket.

I'd expect to smell, if not even see (smoke) a wood burning device long before CO levels were a concern. No?

Zman

You can get high CO levels on both ends of the spectrum. As you make the mix more rich and the O2 drops, you get it on the more efficient end. You can also get high CO when the mix if running very inefficiently. I have seen it a few times with boilers, car engines are a good example as well. Very inefficient, by design, very high CO as a result.

ChrisJ

Zman said:

You can get high CO levels on both ends of the spectrum. As you make the mix more rich and the O2 drops, you get it on the more efficient end. You can also get high CO when the mix if running very inefficiently. I have seen it a few times with boilers, car engines are a good example as well. Very inefficient, by design, very high CO as a result.

You've seen a wood burner, or car engine produce CO from running too lean?

My experience has been both produce other very noticeable things as well, usually smoke and even burn your eyes something awful.

But, this is why I asked. Often, there are things we don't realize are possible.

Solid_Fuel_Man

On my personal wood boiler I have a main circulator which supplies all zones. I have a modine as a dump zone with it's own circulator for redundancy of main circ failure. As @hot rod eluded to, I use a more conventional design with a UPS on the dump circuit. In a power failure it will run for several hours on the battery.