Posts Tagged ‘Burnham’

Boilers Part 17 – Restrictive Heat Exchanger = High Pumping Costs

November 30, 2010

The second disadvantage of most Direct Vent Condensing Boilers is their restrictive heat exchangers. Not all DVCB have this disadvantage however so you must make sure to ask your contractor about this. Let’s say that you have a 3,000 square foot home with an 80,000 BTUH boiler. You would probably need about 8-10 GPM or 8-10 gallons of water passing through your boiler per minute. Most boilers would have a pressure drop through your boiler of 8 feet of head. The best boilers have a pressure drop as low as 5 feet of head. This means that with the right boiler your pump will work half as hard. Pumping water around your house uses quite a bit of electricity. With a non restrictive heat exchanger, you will be able to keep this cost to a minimum.

Make sure that your contractor understands pump and boiler flow curves so that your system will be designed to run as efficiently as possible.


Boilers Part 15 – Turndown

November 25, 2010

Hi Again, Turndown is the ability of a boiler to reduce its input to match the load. Imagine a home with 3 floors and a separate thermostat and heating zone for each floor. When all three floors require heat, the demand might be 80,000 BTUH. This would require an 80,000 BTUH boiler. If only the basement needed heat, the load might only be 20,000 BTUH. Firing an 80,000 BTUH boiler would be overkill and horribly inefficient. All DVCB have a turndown that allows the boiler to fire at the required rate for that time so the boiler would fire just at the 20,000BTUH that you need. Efficiency is enhanced once again.

Now that it is crystal clear that the best option for a boiler is the DVCB, Direct Vent Condensing Boiler, I would like to discuss the problems with these boilers and how to avoid them.

Boilers Part 8 – Combustion Efficiency

November 9, 2010

Today I will discuss Combustion Efficiency.

Combustion Efficiency is the percentage of heat you get from your fuel. For instance, if your boiler has a combustion efficiency of 70%, you are getting 70 cents of heat for every dollar of gas that you are paying for. The rest of the heat is going right up the chimney. This is why you can burn your hand when you touch the hot chimney of a 70% efficient appliance. You are feeling the heat that is being wasted right up the chimney.

If you think about it, you are getting burnt even if you don’t touch the chimney because you are losing/wasting so much energy.

Compare this to a DVCB which has a 95% combustion efficiency and you will see that you are getting 95 cents for every dollar in fuel used. This is a great savings of almost 30%. If you feel the vent of a condensing appliance, it is just a bit warm because you are extracting 95% of the heat from the flu gases before you send them out the vent.

With today’s high energy prices and our concern for the environment, it is a crime not to invest in a DVCB.

Boilers Part 4 – Power Vented Boilers

November 1, 2010

Proud of a great furnace install.


Today I will discuss the Power Vented Boiler.  Power vented boilers can reach up to 85% efficiency which is a bit more than the old workhorse atmospheric. They are relatively reliable and are easy replacements for the old atmospheric. They look like the atmospheric with one difference, the atmospheric has the mushroom-shaped draft hood on top while the power vented boiler has an induced draft blower on the side of the boiler. Please see the picture below.

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These boilers have a blower that forces the flu products out of your home, so they are a little bit safer than atmospheric boilers. However, since they rely on air from inside your home for combustion air, they still present some dangers and their installation are also restricted by the TSSA as follows.

1. A dedicated and properly sized combustion air duct directly from the outside must be installed in the boiler room.

2. Carbon monoxide detectors must be installed in or adjacent to every sleeping area in the home.

See the Safety Advisory below. Again, when I hear that these boilers require such extensive carbon monoxide monitoring, I would not consider installing these types of boilers in my home and jeopardizing the safety of my family. To me it is like throwing my child overboard in rough seas with a life jacket.

In my home, I would only install a direct vented boiler that we will discuss in my next post. These boilers have no restrictions on their installation because they are inherently safer than the 2 boilers we just discussed.

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