CB 1200 Snap Disc/Convection Blower question

[eandbnorton]

So, I've got a question (or maybe a couple) about the convection blower. At what temperature does it come on? And at what temperature does it shut back off? The OM says "Snap Disc #1 (convection blower) 125*" and that's all it says with reference to temperatures and the blower. But does that mean the blower stays on until the firepot goes below 125*? I'm a bit confused.

Thanks

 

[jtakeman]

So, I've got a question (or maybe a couple) about the convection blower. At what temperature does it come on? And at what temperature does it shut back off? The OM says "Snap Disc #1 (convection blower) 125*" and that's all it says with reference to temperatures and the blower. But does that mean the blower stays on until the firepot goes below 125*? I'm a bit confused.

Thanks

The snap disks have different ratings. Depending on who makes them. Not sure about Quad's.

You switch should be close to this. Turn on(closed possition) temp would be 125ºF turn off(open position) temp would be like 110ºF or so. The switch is normally open. Or as some say close on rise.

Its not the firepot temp. It usually is the air stream or stove housing temp.

Hope this helps
jay

 

[eandbnorton]

Ah hah. That's where the problem is then. Because is soooooooooo cold right now (we got down to -3* last night) the convection blower is shutting down before the "green" light goes off because the air stream is colder than usual. Which means that the firebox temp is still reading over 200* when the convection blower stops. Hmmmm, could I replace the snap disc with another that can keep the blower on at a lower temp - lower than 125*? Maybe one that has a lower rating? That may mitigate some of my issues.

 

[DannMarr]

Try cleaning the disk. My issue with my castile insert was the opposite. It would not shut off, it would take over a half an hour to shut off at 60 degrees! My disk is rated 110-90 (110 would start and 90 would shut down). I cleaned the disk and now it shuts down in about 15 minutes at 90 degrees.

 

[eandbnorton]

Dann, how did you clean your disk? I'm not familiar with snap disks at all, so if you could "dumb it down" for me, that'd be great.

 

[SmokeyTheBear]

Dann, how did you clean your disk? I'm not familiar with snap disks at all, so if you could "dumb it down" for me, that'd be great.

With the stove off, cold, and the plug pulled.

Locate the snap disc, unhook the wires to it (normally two, if more than two make certain you mark which wire went where.

Remove the snap disc from where it is and with a cloth clean the switch where it went into the mount, also be certain that any dirt where it was mounted is also removed. Sometimes it isn't the switch that gets dirty it is the area behind the mount that gets covered with soot.

Reinstall the switch reconnecting the wires, plug the stove back in and try it out.

Note it is possible that a switch has a mounting gasket, if so make certain you have a replacement prior to attempting to clean the switch. Gaskets tear easily and are used to seal air paths.

 

[slls]

If it is that cold, why are you letting it shut down. Put the thermostat on 90 deg, set the heat to low , medium or high.

 

[CanadaClinker]

IMO the problem lies with the location of the snap disc that controls the convection blower. Especially with inserts, the 'lower back' part of the heat exchanger remains cool from fire place chimney drafts, or proximity to concrete in the fireplace (which requires 10 ft of it to give you an insulating factor of R10). This causes delayed startup and early shut down of the convection blower.

If Quadrafire would have mounted the snap disc nearer the 'top front' of the exchanger, it would be more immune to the external influence of the cool surroundings at the back of the stove and more influenced by the heat of the output of the exchanger.

Possibly putting a layer of non-flammable insulation between the stove and the surroundings will lessen the cooling influence on the stove (and snap disc location).

The other solution is to relocate the snap disc location to the upper front of the exchanger but that would void any warranty (unless you are out of the warranty period anyway).

My solution (which I posted before) for my stand-alone cb1200 was to make a 'timer' (controlling a relay) that is in parallel with the snap disc ...... which starts up the convection blower at 4 minutes from the time the thermostat calls for heat. It shuts off when the thermostat shuts of but by then, snap disc is in control and keeps my convection blower running till the temp of the air is around 93 degrees at the output of the front top of the exchanger.

Being that mine is a 'stand alone' (not insert), it is more immune to the permature shut off of the convection blower by the cooling off effect than the inserts would be I think. Having said that, the better solution would be to relocate the snap disc closer to the upper front of the exchanger (once your warranty is done).
IMHO.......cc ;-)

 

[DannMarr]

Canada, Very good idea. The snap disc is only mounted to the surface and not going through the wall, so it would be easy to relocate it. Another point, my wire connectors to the snap disc was very loose, so make sure the connectors are on tight.

 

[CanadaClinker]

Canada, Very good idea. The snap disc is only mounted to the surface and not going through the wall, so it would be easy to relocate it. Another point, my wire connectors to the snap disc was very loose, so make sure the connectors are on tight.

...... good point DannMarr....... loose connections become even looser when cooled off and can cause intermittent connections which are a real headache ...... just be careful while working around live wires (which these are)..... we can get all wrapped up in what we are doing and forget... best to unplug while we are in there...... cc

 

[slls]

IMO the problem lies with the location of the snap disc that controls the convection blower. Especially with inserts, the 'lower back' part of the heat exchanger remains cool from fire place chimney drafts, or proximity to concrete in the fireplace (which requires 10 ft of it to give you an insulating factor of R10). This causes delayed startup and early shut down of the convection blower.

If Quadrafire would have mounted the snap disc nearer the 'top front' of the exchanger, it would be more immune to the external influence of the cool surroundings at the back of the stove and more influenced by the heat of the output of the exchanger.

Possibly putting a layer of non-flammable insulation between the stove and the surroundings will lessen the cooling influence on the stove (and snap disc location).

The other solution is to relocate the snap disc location to the upper front of the exchanger but that would void any warranty (unless you are out of the warranty period anyway).

My solution (which I posted before) for my stand-alone cb1200 was to make a 'timer' (controlling a relay) that is in parallel with the snap disc ...... which starts up the convection blower at 4 minutes from the time the thermostat calls for heat. It shuts off when the thermostat shuts of but by then, snap disc is in control and keeps my convection blower running till the temp of the air is around 93 degrees at the output of the front top of the exchanger.

Being that mine is a 'stand alone' (not insert), it is more immune to the permature shut off of the convection blower by the cooling off effect than the inserts would be I think. Having said that, the better solution would be to relocate the snap disc closer to the upper front of the exchanger (once your warranty is done).
IMHO.......cc ;-)

The snap disc is where it is to assure that the whole heat exchanger is up to proper temperature before the fan comes on. The gasses come from the top to the bottom.

 

[CanadaClinker]

IMO the problem lies with the location of the snap disc that controls the convection blower. Especially with inserts, the 'lower back' part of the heat exchanger remains cool from fire place chimney drafts, or proximity to concrete in the fireplace (which requires 10 ft of it to give you an insulating factor of R10). This causes delayed startup and early shut down of the convection blower.

If Quadrafire would have mounted the snap disc nearer the 'top front' of the exchanger, it would be more immune to the external influence of the cool surroundings at the back of the stove and more influenced by the heat of the output of the exchanger.

Possibly putting a layer of non-flammable insulation between the stove and the surroundings will lessen the cooling influence on the stove (and snap disc location).

The other solution is to relocate the snap disc location to the upper front of the exchanger but that would void any warranty (unless you are out of the warranty period anyway).

My solution (which I posted before) for my stand-alone cb1200 was to make a 'timer' (controlling a relay) that is in parallel with the snap disc ...... which starts up the convection blower at 4 minutes from the time the thermostat calls for heat. It shuts off when the thermostat shuts of but by then, snap disc is in control and keeps my convection blower running till the temp of the air is around 93 degrees at the output of the front top of the exchanger.

Being that mine is a 'stand alone' (not insert), it is more immune to the permature shut off of the convection blower by the cooling off effect than the inserts would be I think. Having said that, the better solution would be to relocate the snap disc closer to the upper front of the exchanger (once your warranty is done).
IMHO.......cc ;-)

The snap disc is where it is to assure that the whole heat exchanger is up to proper temperature before the fan comes on. The gasses come from the top to the bottom.

......you are probably right slls..... that was probably the original design idea ..... however in real experiments that I have done (with my remote thermometer probe), other than the first fire of the day,.... after 4 min, I have at least 90 deg air temps out of the top of the exchanger that climb steadily up to 230 degrees which is where the stove peaks on low.

Before my modification, I was reading close to 300 degrees at the output of the exchanger before the fan would kick in. I surmised that the stove was waisting time (and heat) in not putting the heat into the room as soon as possible at 90 to 100 degrees .......as soon as when it was available.

My stove is in the corner of too large windows.... when this was all happening (with the 300 deg and no blower on yet), I could put my hand at the back of the stove near the window and everything was still cool because of the effects of the windows.... as I was saying, this is the same thing that I believe is happening to the owners of the inserts stuck in a cool concrete fireplace. ..... anyway, this has solved it for me...... cc ;-)

 

[slls]

The reason the back of the stove is cool, there is nothing there to get hot. Anyways, I like the surge of hot air when the fan kicks on.

 

[DannMarr]

I just tested what Canada mentioned. When the convection blower comes on at 110 at the snap disk, the temperature just above the heat exchanger is 15 hotter at 125. I like the heat surge, but would rather have the heat blow earlier into my living space. I guess it's a matter of preference. I will try it and post my results.

 

[eandbnorton]

My issue is that the fan turns off too quickly...in fact, before the green light goes out. Which means that the firebox is still over 200* . Aren't the heat exchangers supposed to essentially pull the heat from the firebox, through the system and then the fan blows the hot air out into the room? Well if the fan is kicking off too quickly, then the firebox just has to sit there until it cools down enough until the green light goes out. Not very efficient IMO.

SLLS, I'll try your method of leaving the t-stat on 80* or so and just filter the fan between low, med and high to moderate the room temp. Though I'd still like to fix the green light problem.

 

[DannMarr]

Pick up an IR Thermometer (Harbor Freight has them for cheap) and check the temperature at the disc. Check it when the convection blower starts and when it shuts down. Compare those readings to the rating of the snap disc. If the numbers are off alot, then change the snap disc.