High Efficient Condensing Furnaces
Today’s latest furnaces are much different than the furnaces 30 years ago.
The biggest difference between standard or mid efficient furnaces and the newer
High Efficient furnaces is the fact that they condense flue gases.
A little high school physics refresher. A btu is the amount of energy required to raise a pound of water one degree Fahrenheit.
It then takes another 970 BTU’s to take one pound of boiling water and turn it into steam.
When a pound of water condenses from steam back to water you also recover 970 BTU’s per pound of condensed steam.
This is what makes condensing furnaces so efficient. Also recovered is heat for every degree the condensate drops.
On the old furnaces you would see in the winter steam coming out of the chimney on the roof in colder weather.
One of the biggest byproducts of combustion in a furnace is water vapor.
The newer furnaces recover this wasted heat by condensing the flue gases..
The furnace then exhausts out the side of the house through special plastic piping at a very low temperature.
Because the secondary heat exchanger condenses the flue gases it must be made of stainless steel.
This is because the byproducts of the condensate make it slightly corrosive.
Also this is why you need a drain or a condensate pump to carry the condensate to a drain.
There are other differences to the older furnaces. A furnace must be sized big enough to heat your home at the coldest day of the year.
In Calgary we would figure -40. Some winters it doesn’t even get that cold but it does sometimes, so your furnace has to be big enough to handle that temperature.
Some newer furnaces have a two stage gas valve or a modulating gas valve. With a two stage it operates at lower btu’s most of the time,
usually 70% but can kick in to 100% on the really cold days.
A modulating valve is even more efficient. It runs in increments anywhere from 40% up to 100% depending on the heating requirements.
When replacing an older furnace with a new high efficient the new one will be much lower BTU output. A 100,000 btu 60% efficient furnace basically outputs 60,000 btu.
A new 60,000 btu 95% high efficient furnace outputs basically 57,000 btu’s. This is only 3000 btu’s less. There is a very good chance that this would be enough.
Most furnaces in were oversized back when gas prices were a lot lower. Also over the years a lot of homes have had their insulation, windows and doors upgraded.
This can be determined with a heat loss calculation on your home during the quotation process.
With a modulating valve a 60,000 btu could run as low as only 24,000 BTU’s at 40% when little heat is required.
Compare that to the old furnace running at 100,000 btu’s in the same situation. You do the math.
Now you add a new high tech thermostat into the mix. They are basically a small computer making the furnace even more efficient.
There is a lot of saving in natural gas consumption with new furnaces but there is also electrical savings.
Most of the newer high efficient furnaces go with a variable speed blower.
This is a brushless direct current motor and it is a very efficient user of power.
It also automatically ramps up to what is required to push the air through your ducting system.
If your filter is plugged a little it will compensate.
A lot of people like to have their fan run all the time to make the air more evenly heated in your home. This is where you really realize significant savings.
The Variable speed motor runs at a very low speed so you can’t even hear it. It moves the air around slightly just enough to make the air in your home more evenly heated.
This saves you about 80% in power compared to running an older furnace blower full time.
Last but not least the biggest saving with a 95% plus furnace is the savings you will get back in government rebates. You must have an energy audit done in your home first.
The cost will be around 400. The provincial government will then give 200 towards the grant and another 500 towards the furnace. The federal government steps in with another 790.00 on top of that. (a total of $1490.00 in grants)
Also you are going to see around a 35% saving in your heating bills.
Even if you only plan to stay in your home a few more years you will be able to sell your home much easier.
Consumers are going to be looking for a high efficient furnace in their purchase or take off the amount required to have one installed.
At that time it is going to cost you 1500 more than doing it this year. Plus you will be saving on your heating bill up until that time.
Protech Plumbing Inc. can help you through the process of obtaining your grant. This has to be completed by end of March 2012. After that no such luck.
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