# CB Classic Edge 750 Issues



## CB750 (Nov 18, 2016)

Hey Guys I'm looking for some answers to some issues I've had with my CB 750 pretty much since installation a year ago.  

The primary issue is that when properly working, the unit will not warm my house above 74 degrees.  Hot water reaches the radiator (boiler is set at 190) thru the supply but the return is luke warm.  The dealer installed the radiator between the furnace air return and the furnace itself NOT above the A coil.  Could this be the problem?  Our register temps are only in the low 90s so where is all that heat going?  My dealer insists that the radiator location is not the problem and that it is plenty big enough to handle our house size (3,000 sq. ft both floors).  I've inspected all the ductwork and found no holes and sealed up all the joints as best as possible.  

The secondary issue is that the boiler doesn't function very well when the bypass is shut (handle pulled toward the door) but does fine when it's open (pushed toward the back).  It runs constantly and struggles to keep up.  Most nights when I go out in the middle of the night the water temp is in the 150s.  I've cleaned it out as best as I know how. Cleaned reaction chamber, the chains in the back, and removed the two metal plates in the back.  The only thing I haven't cleaned are the holes in the sides of the furnace inside the firebox, not sure how to thoroughly clean those.  

I'm burning mostly  split ash that has been dead but still standing.

I really want to like my 750 but I'm spending more time trying to get it to function properly than I am cutting wood.

Any help would be greatly appreciated.


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## stee6043 (Nov 18, 2016)

Sounds frustrating and sounds like you have a really shitty dealer if they left you high and dry without ensuring you were completely happy with the setup.

That rig you have is designed to "only work" properly when the bypass is closed.  So it's not surprising you're not getting proper temps with the bypass open.  When you have it running with the bypass open it's essentially an overpriced burn-barrel.  Everything you paid for is in the downdraft mode.

When it is operating correctly (or the best it can be) are you saying you get 190 degrees at the supply side of your coil in the house?  And the return side is "luke warm"?  Have you measured both sides?  Most folks would expect to see 20 +/- degree temp drop through the coil.  This is a pretty typical setup.  If you're seeing much more than that my first thought would be that you're under-pumping.  If you have a multi-speed pump turn it up, if possible.

That boiler is way, way, way more boiler than a 3,000 sq foot house needs.  It would heat an airplane hanger properly setup.  And I would tend to agree with your dealer in that the location of the coil shouldn't really make that big of a difference. 

The fact that your boiler is not running with the bypass closed is a big, big problem.  If your dealer won't help you solve that they aren't worth the paper they used to invoice you.  Your return water temp might be contributing to your boiler not liking the bypass closed mode.  If you have really cool water coming back from the house it might be discouraging the gasification process.  These kinds of boilers want to run at a certain temp. I'm wondering if your dealer completely botched the plumbing or pump selection and that's what you're struggling with.

What is your pump and what size pex do you have?  How long is the run?  Elevation difference between house and boiler?  How deep is your pex buried?  Did you use thermopex?


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## stee6043 (Nov 18, 2016)

And one last suggestion...if you're burning wet wood that could also contribute to your troubles.  Buy a cheapo moisture meter from Harbor Freight.  If your standing dead ash reads above 20-25% moisture that might also be your trouble in burning with bypass closed.

Wood would not, however, explain your excessive temp drop at your coil.  I still lean towards a plumbing or pumping issue.

Another question - how long have you been running and are you sure you don't have air in the system still?  I would have assumed your dealer would have flushed your lines properly but if you have an air pocket in your coil that might also be contributing here.  Hooking up a hose and flushing water through the coil should be pretty easy...


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## The Weimar (Nov 18, 2016)

CB750 said:


> Hey Guys I'm looking for some answers to some issues I've had with my CB 750 pretty much since installation a year ago.
> 
> The primary issue is that *when properly working*, the unit will not warm my house above 74 degrees.  Hot water reaches the radiator (boiler is set at 190) thru the supply but the return is luke warm.  The dealer installed the radiator between the furnace air return and the furnace itself NOT above the A coil.  Could this be the problem?  Our register temps are only in the low 90s so where is all that heat going?  My dealer insists that the radiator location is not the problem and that it is plenty big enough to handle our house size (3,000 sq. ft both floors).  I've inspected all the ductwork and found no holes and sealed up all the joints as best as possible.
> 
> ...



Hi CB 750,
Welcome to Central Boiler Neverland, where once the product has been sold, the consumer finds himself alone in the void that is left after your check clears. Aside from that, is your "furnace" a pressurized system with the OWB plumbed directly into it? Or is the hot water from the OWB just passing through a separate 'radiator'? I have found that the two systems should not be plumbed together and that a heat exchanger should be used to heat the existing HVAC system with the hot water from outside and not be plumbed directly into the existing system.
Another "dealer'' problem I had was the undersized circulator pump that was installed on my Eclassic 2400, which led to not enough water circulating through the OWB itself leading to flame impingement (LEAKS) in the firebox itself and not enough heat in the house. How far away from your interior furnace is your OWB? The height above or more importantly below is also important.
As far as 150 degrees, Stee is on point with the wet wood. The gassifiers will only gassify if the smoke is dry meaning the wood not only has to be seasoned but it must also be dry.
Lots of possibilities but, lots of very knowledgeable folks that I have learned from here.


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## CB750 (Nov 18, 2016)

The Weimar said:


> Hi CB 750,
> Welcome to Central Boiler Neverland, where once the product has been sold, the consumer finds himself alone in the void that is left after your check clears. Aside from that, is your "furnace" a pressurized system with the OWB plumbed directly into it? Or is the hot water from the OWB just passing through a separate 'radiator'? I have found that the two systems should not be plumbed together and that a heat exchanger should be used to heat the existing HVAC system with the hot water from outside and not be plumbed directly into the existing system.
> Another "dealer'' problem I had was the undersized circulator pump that was installed on my Eclassic 2400, which led to not enough water circulating through the OWB itself leading to flame impingement (LEAKS) in the firebox itself and not enough heat in the house. How far away from your interior furnace is your OWB? The height above or more importantly below is also important.
> As far as 150 degrees, Stee is on point with the wet wood. The gassifiers will only gassify if the smoke is dry meaning the wood not only has to be seasoned but it must also be dry.
> Lots of possibilities but, lots of very knowledgeable folks that I have learned from here.



Thanks for all your suggestions.  I'll have to look at the circ. pump and see what size it is and if the speed can be increased.  The pump would make sense.  The line to the house is thermopex buried about 1-2 feet under ground with a run of about 50 feet to the inside furnace.  The elevation is only a few feet if any.  And this doesn't go into a pressurized system.  
Thanks again


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## stee6043 (Nov 18, 2016)

CB750 said:


> Thanks for all your suggestions.  I'll have to look at the circ. pump and see what size it is and if the speed can be increased.  The pump would make sense.  The line to the house is thermopex buried about 1-2 feet under ground with a run of about 50 feet to the inside furnace.  The elevation is only a few feet if any.  And this doesn't go into a pressurized system.
> Thanks again



Hmm....for what it's worth I think your frost line is 32" in Ohio.  If you ever leave your house unattended for a "significant" period of time your pex depth could be problematic.

I would think a 50' run with minimal elevation change should be manageable for just about any standard circ pump.  Unless it's a three speed set to low I'm going to bet you're pump isn't the problem.

I'm currently leaning towards 1.) wicked wet wood or 2.) air pocket in plumbing/heat exchanger.  Issue one could be ruled out by running for a day or two on only fresh pallets or other scrap, dry wood.  Issue two could be addressed with a propertly placed hose connection and a quick flush.


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## The Weimar (Nov 18, 2016)

I think that Thermopex is pretty well insulated but 2-3' of cover won't cut it. Call your local water Dept and ask them what the required depth is for a water service installation and you will have the answer.
Wet wood will kill the gasifiers performance, get some dry stuff. I had the same problem my first year, what a nightmare.


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## Mike Fromme (Nov 18, 2016)

It's the wood... It is always the wood with new gasification boiler owners.




(Paragraph four, original post... 'standing dead')


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## stee6043 (Nov 19, 2016)

Mike Fromme said:


> It's the wood... It is always the wood with new gasification boiler owners.
> 
> 
> 
> ...



I don't disagree that the OP may have a wood problem but wet wood does not explain "190 going into the coil, luke warm coming out".


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## woodsmaster (Nov 19, 2016)

Mike Fromme said:


> It's the wood... It is always the wood with new gasification boiler owners.
> 
> 
> 
> ...





Mike Fromme said:


> It's the wood... It is always the wood with new gasification boiler owners.
> 
> 
> 
> ...


 I doubt it's wet wood if it's dead ash. I've been burning it for 5 years now in my gasser. live ash is only 30% moisture at most. all the dead standing ash i've been burning is 26% or less the day it is fell, most being 22% or less.


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## hondaracer2oo4 (Nov 20, 2016)

I echo others comments here. 

1. Unplug pump from boiler and allow it to reach its 190 set point. Remember that a good 3-4 inch hardwood coal bed is required to really operate correctly. Slowly build up your coal bed over a few hours with small splits while brining the boiler up to temp. After you have established your coal bed add your larger splits. These splits should be in the 4-6 inch diameter range. Do not operate the boiler in bypass mode for longer than 5-10 mins to initially start the fire. 

2. Once the boiler has reached 190 and shut down plug your pump back in. Now go into your house and use an Ir thermometer, meat thermometer taped in insulated to the incoming and outgoing pipes or any other way you find to consistently check the return and supply temps on either side of the water to air hx. Then turn up your thermostat to call for heat kicking the fan on the indoor unit. The temp difference between the incoming and outgoing line should be less than 20 degrees different. If it is greater than 20 degrees the water is moving to slowly through the exchanger causing it to lose to much temperature to quickly. This is caused by either a pump on the owb pushing the water to slow, a large air bubble in the water to air exchanger allowing only a small quantity of water to exchange it's heat or three a bad boiler temp return protection device installed inline in the system. I believe cb requires this in their installs so you need to see if that is sending the hot water back to the boiler instead of to the heat exchanger. 

How big are your wood splits? I agree the people that are new to gassers think that their wood is "seasoned" ad ready to go but it's ussually 30% + which won't work unless you have a really good coal bed going.


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## brack86svo (Nov 20, 2016)

Wood is your problem. Had the same issue with my 350 in March when I got it. I recently cut and split some standing dead ash and it was over 35% water content. You need well seasoned wood and small splits. Get yourself a moisture meter, split some of your stock, and see what the moisture content is. You can pick them up online for cheap.

You really should have storage with a stove that big. I learned in just the month of March alone, that I needed storage.

Look up "taco circulator sizing" and read their PDF. You need to calculate what size circulator you should have, vs what the dealer installed. Not all dealers are bad, but there are those out there for just about anything you can buy.

You could also have an air bubble like hondaracer said.


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## brack86svo (Nov 20, 2016)

Also.... Is you heat exchanger mounted in the return plenum? If so, pulling heat through the air handler blower can cause premature failure of the blower, due to the heat.


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## hondaracer2oo4 (Dec 15, 2016)

What happened to this guy?


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## Mike Fromme (Dec 15, 2016)

hondaracer2oo4 said:


> What happened to this guy?


Probably found some dry wood.


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## hondaracer2oo4 (Dec 15, 2016)

Haha. That is probably true.


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