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Piwoslaw · 10-02-11, 04:25 AM

OK, I searched for pictures of the insides of boilers to see the difference in hardware between open and closed combustion chambers. Here is a good comparison:

Notice the closed model on the right: The combustion chamber itself is not sealed, but instead is inside a sealed box, with the rest of the plumbing, motor, electronics outside the box. I think this is the way to go: seal the upper half of what is inside the boiler.

While searching I also noticed that all models had intake and exhaust in a concentric tube set-up (with the exhaust inside the intake), I didn't see any which would have the intake come in from a different side than the exhaust. Other than safety, maybe this to pre-warm the intake air?

This concentric intake/exhaust tube can either go vertically up a chimney, or horizontally out through a wall.

Also, all models had a fan for ventilating the combustion chamber. This fan could also act as a damper to hinder airflow when the burner is off, though with a totally sealed chamber this shouldn't be a problem.
I believe (though I am not sure) that a Rheem model has two fans: one for the intake and one for the exhaust

Now, once the combustion chamber is closed up it will be very temping to take the next step and convert the boiler to a condensering model increasing the efficiency by up to 15%. The problem for a DIY'er would be a good, acid resistant condensing heat exchanger. The commercial HXs are made of 409 stainless steel, from what I've read.

But 'condensifying' the boiler is worth its own thread.

S-F, I'm very interested in what your Buderus friend has to say.

10-02-11, 04:25 AM	#22
Piwoslaw Super Moderator Join Date: May 2009 Location: Warsaw, Poland Posts: 961 Thanks: 188 Thanked 110 Times in 86 Posts	OK, I searched for pictures of the insides of boilers to see the difference in hardware between open and closed combustion chambers. Here is a good comparison: Notice the closed model on the right: The combustion chamber itself is not sealed, but instead is inside a sealed box, with the rest of the plumbing, motor, electronics outside the box. I think this is the way to go: seal the upper half of what is inside the boiler. While searching I also noticed that all models had intake and exhaust in a concentric tube set-up (with the exhaust inside the intake), I didn't see any which would have the intake come in from a different side than the exhaust. Other than safety, maybe this to pre-warm the intake air? This concentric intake/exhaust tube can either go vertically up a chimney, or horizontally out through a wall. Also, all models had a fan for ventilating the combustion chamber. This fan could also act as a damper to hinder airflow when the burner is off, though with a totally sealed chamber this shouldn't be a problem. I believe (though I am not sure) that a Rheem model has two fans: one for the intake and one for the exhaust Now, once the combustion chamber is closed up it will be very temping to take the next step and convert the boiler to a condensering model increasing the efficiency by up to 15%. The problem for a DIY'er would be a good, acid resistant condensing heat exchanger. The commercial HXs are made of 409 stainless steel, from what I've read. But 'condensifying' the boiler is worth its own thread. S-F, I'm very interested in what your Buderus friend has to say. Attached Images __________________ Ecorenovation - the bottomless piggy bank that tries to tame the energy hog. Last edited by Piwoslaw; 10-02-11 at 04:40 AM..