Help needed on refitting an old boiler, specifically I need an automatic damper.

[MrDan27611]

Hi guys, relatively new to the site. I'll give a hopefully quick background and get to my question.

Middle aged, married, 3 kids, in NC all my life, second generation on the family farm, moved into the big house 3 years ago next month and still getting things up to snuff. Tractors are my trade. I'm also a poorly functioning machinist, blacksmith, gunsmith, welder, pilot, woodworker, nerd.

Specifically to this site I am rehabbing a 20 year old OWB that was defunct in the house I'm in now. The original boiler was used for most of my childhood, burned in a fire and was replaced by the boiler that is there now. After about 1-2 seasons the new boiler was superseded by an LP boiler and never used again. Effectively it's 20 year old new, in place, and mostly plumbed. For a quick overview here is where we redid the underground lines.

Redoing the underground pipes on my wood boiler - YouTube

The system is one 500 gallon boiler with another 500 gallon storage tank located in the house for a total of 1000 gallons.

I'm already two months into the refit and currently have the system up and running heating about 4700 sq feet plus domestic hot water. I have added Johnson electronic controls, an electronic flue damper, and a induction blower.

What I need help with is I need a damper for the induction side so that I can shut off air both in and out when there isn't a call for heat. Leakage allows the fire to stay lit, it just doesn't burn hot. I control creosote with how much wood I load vs. the demand for heat. Basically I try keep the fire going most of the time, when it's going. Today it's going to be in the 60s so I fired it last night and will operate off of the heat stored in the 1000 gallons until tonight.

So what I'm looking for is a normally closed, 110 volt controlled electronic damper that will survive blocking a wood fire (read not made from tin), that fits a 1.5" round opening, which is the size of my blower motor air channel. I can fab up whatever I need to bodge it together, I just need some brand names and suggestions on the damper itself. Any suggestions?

 

[CrappieKeith]

Can I see a pic?

 

[Felman]

Would a barometric damper work? When the blower blows, the BD would open with the suction, when the blower stops, the BD closes.

 

[MrDan27611]

Can I see a pic?

I'll have to take one when I get home and upload it. It's nothing dramatic. Small blower has a 1.5" round opening. That fits to a temporary solution which is a plumbing check valve which then goes into and through the door ending in a cut piece of 1.5" cast pipe which is open to the fire box. The intent is to replace the check valve with a powered damper valve so there is a positive open and close. Currently the check valve is opened by air pressure, closed by gravity. Neither one is strong enough to overcome any creosote so I'm having to clean it about once per week. It does work though, amazingly enough considering I know the designer of this system (me)

I'll upload pics when I get home.

 

[MrDan27611]

Would a barometric damper work? When the blower blows, the BD would open with the suction, when the blower stops, the BD closes.

Good idea. That's effectively what I have now, except what I'm using isn't adjustable after install like a BD. However I adjusted it by canting the connection a few degrees giving it just the right amount of gravity to close it. The issue is that eventually it clogs up due to creosote and soot and the fan pressure isn't enough to overcome the resistance. The thought is that a powered damper will have a positive open and close. The creosote isn't that bad, but it's more than none so I have to have a solution.

 

[Felman]

i meant a BD connected to the combustion blower"s air intake

 

[MrDan27611]

i meant a BD connected to the combustion blower"s air intake

Ahh, I see now. I don't that would work. I have to stop the smoke before the blower because :

A. The blower isn't sealed so the smoke would just flow out of the motor itself
B. The creosote would gum up the fan blades till it locked up the motor, or at least added enough weight to throw things out of balance causing a premature failure.

Yep, gotta seal it off downstream of the motor/fan.

Dan

 

[MrDan27611]

Here are pics, I hope.

View attachment 205572View attachment 205573View attachment 205574

 

[loadthestove]

On my homebuilt owb I had, I used the throttle plate from a fuel injected engine with a continous duty pull solenoid and a spring return to close it. I used an aqua-stat as the control.
Also to reduce the cresote problem try moving you blower farther away from burn chamber its simply,,just use a longer pipe and move blower back away from firebox.

 

[mtfallsmikey]

On my homebuilt owb I had, I used the throttle plate from a fuel injected engine with a continous duty pull solenoid and a spring return to close it. I used an aqua-stat as the control.
Also to reduce the cresote problem try moving you blower farther away from burn chamber its simply,,just use a longer pipe and move blower back away from firebox.

i'd really like to see a pic of that, sounds interesting...

MrDan: The check valve is a nice try, but probably not enough air from the blower to open it..????

 

[MrDan27611]

MrDan: The check valve is a nice try, but probably not enough air from the blower to open it..????

Actually it works fairly well, when it works. The air was a bit much before, more of a blast furnace than a boiler fire. The check valve dampens that a bit and creates a nice positive pressure. It does open about 30% of wide open with air pressure, when it opens.

Dan

 

[loadthestove]

i'd really like to see a pic of that, sounds interesting...

I have looked but dont have any pics,I sold the OWB back in the summer.I used a throttle plate assembly from a toyota camary,and the solenoid I used was the same one used on a Hardy OWB.As mentioned I used an aquastat as the controller.when the stat called for heat the solenoid would open the butterfly in the plate and allow air flow.when the heat cycle was finished the return spring would close the plate.

 

[Windwalker7]

This is what I got on my Shaver. It works awesome.

Maybe you can do something like this?


http://www.arboristsite.com/firewood-heating-wood-burning-equipment/110817.htm

 

[jackel440]

I have a build thread of my gasifier on another site that shows how my blower is isolated from the burn chamber and secondary burn chamber.I used a Belimo damper actuater to trurn a shaft which opens a door to allows the fan to blow air into my stove.It is turned on by a relay from the furnace controls.The same relay also sends power to my blower.When the stove is to temp.The relay opens ,and the power is cut to the fan and damper.The damper is spring return.which closes the door in tha air box.This allows no draft into the fire box.Plus in case of a power outage the damper will close and there is no chance of the stove running away.Which would cause a boil over situation.
<iframe width="420" height="315" src="http://www.youtube.com/embed/3A3IAgtgWxU" frameborder="0" allowfullscreen></iframe>

Here is a link to the box before mounting on the boiler.The fan mounts to the bottom of that square tube on the bottom of the box.There is an cover that is not on there.The camera is actually shooting from the side that got welded to the back of the boiler.
There is an idea for you:msp_thumbup:

 

[MrDan27611]

Jackel,

That's not what I was asking for, that's better! I found your postings detailing your build and read through the entire thing up to where you got it working. I haven't had time to read the post warm house comments yet but I'll get to them.

I must be pretty slow but I could not see the pictures. I could see the little guy with the camera icon, but no clickable link. Maybe I have to register or something. I'll have to figure that out. Anyway, awesome build. I too thought I was a welder until I had to weld pressure vessels. I learned some humility that time. I'll be taking a look at your actuator to see if I can make it work.

 

[jackel440]

Yes there are tons of pics of the build on that site.you will. Have to register to see them all.great site if you are into OWB.