NoFossil Control System does draft gauge

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Nofossil

Nofossil

Moderator Emeritus
Oct 4, 2007
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Lexington Virginia
www.nofossil.org
I found a pressure sensor that looks like it will give me the ability to measure flue draft up to about 1.5" of water with a resolution of 0.006" - since I don't have a draft damper, it will be interesting to see how the draft varies over the course of a fire. I'll be hooking it up tonight, should have graph tomorrow.

It will also measure positive pressure up to about 12" of water. Now I'm thinking about what else I'd like to instrument. Primary chamber pressure? Fan plenum pressure?

Maybe it could be combined with fan speed logic so that you could compensate for varying draft by adjusting fan speed to maintain the desired air flow through the primary and secondary chambers.

The same source has sensors that will measure higher pressures. It might be interesting to measure the pressure rise across a circulator to get a better estimate of flow (from the manufacturer's pump curve). Dang - I didn't have enough spare time as it is.
 
in hot water said:
Check out these direct sensors Grundfos has developed. Some of the solar control manufacturers are already incorporating the flow/ temperature versions into their pump stations. It is a rather unique sensor and has a lot of potential in hydronic as well as solar. Maybe it could be incorporated into your control platform.

http://net.grundfos.com/doc/webnet/directsensors/int/index.html

hr
Click to expand...

Very cool - especially the vortex flow sensor. Looks like this is new for them, with no established distribution network yet. They have a few scary words like 'proprietary bus', but if they come out with a standard off-the-shelf version it should play nice with the NFCS. The voltage and signal ranges look good. I expect it will be a bit more pricey than what I have now, but direct flow measurement with no moving parts would be awesome.
 
nofossil said:
I found a pressure sensor that looks like it will give me the ability to measure flue draft up to about 1.5" of water with a resolution of 0.006" - since I don't have a draft damper, it will be interesting to see how the draft varies over the course of a fire. I'll be hooking it up tonight, should have graph tomorrow.

It will also measure positive pressure up to about 12" of water. Now I'm thinking about what else I'd like to instrument. Primary chamber pressure? Fan plenum pressure?

Maybe it could be combined with fan speed logic so that you could compensate for varying draft by adjusting fan speed to maintain the desired air flow through the primary and secondary chambers.

The same source has sensors that will measure higher pressures. It might be interesting to measure the pressure rise across a circulator to get a better estimate of flow (from the manufacturer's pump curve). Dang - I didn't have enough spare time as it is.
Click to expand...

Cool!
since I don't own a draft gauge that would be nice. I had looked at sensors for higher pressure to monitor system pressure but they were PRICEY.
I run with make up water off so would be nice to monitor system for leaks.

There go a few more analog inputs. :grrr:
 
Don't want to hijack but I have a quick question regarding...

Nofo:... since I don’t have a draft damper...
Click to expand...

Is this the Barometric Damper many people have installed?

The Baro damper on my flue has deteriorated to the point that I need to replace it...Or do I??

I discovered some rust through on the bottom of my barometric damper yesterday when I was getting the tarm ready of this season...I'm not a fan of the baro damper in my installation because it would blow open in my first years of operation and kill my draft. I have a fairly short chimney less than 18 ft...so I am not so sure my setup would over draft under any circumstances.

Last year I ran with the baro damper blocked off with an end cap and I didn't notice any problems.

Is it ok to run with no baro damper? What should I be on the lookout for that would indicate a problem that needs a baro damper solution?

Thanks,
 
Nofo, I hope you have better luck in the differential pressure dept with the downdraft boiler than the garn.I was going to monitor the combustion analyser during a burn, when the effiency was the highest then record the diff pressure between combustion air inlet and flue, this differential would be maintained by a variable speed drive and 3 phase inducer motor. the problem came when the garn combustion started to pulse or puff, even slight disturbances of pressure caused meter output to be too erratic for control.
 
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