Replies

1. 
   grpphoto | Apr 06, 2007 06:53pm | #1

   > Can they "cap" the outside part with a "screen" or something similar
   > to dryer vent so birds/mices don't enter the pipes?

   I've been told no. Something about the exhaust from natural gas having a lot of moisture, which will form ice and block the screen.

   George Patterson, Patterson Handyman Service

2. 
   THETinman | Apr 06, 2007 10:56pm | #2

   #1
   High efficiency furnace are direclty vented outside with an ABS type pipes.
   Can they "cap" the outside part with a "screen" or something similar to dryer vent so birds/mices don't enter the pipes?

     How far away is the outside wall?  From my own experience it can difficult to keep the venting out of the way if it is a long run. 

   Slope the venting back towards the appliance, and there should be no problem.  If there is no problem with dryers venting through screen, why would there be with a condensing furnace?

   #3
   NOISE:
   High efficiency Furnace and Water heater are equiped with a 'POWER VENT' ; Are these noisy ?
   Overall, the noise of my new high. eff. equipments equipped with power-vents should be lower than the noise of my current furnace?

   * They are more noisy than a pilot.  But a venter motor is nominal.

   #4 High efficiency water heater - is it worth it ?

   * ABSOLUTELY !  Consider that most hot water heaters have a standing pilot, which keeps the appliance within a certain temperature range, what happens to all the excess heat from that?  It goes up the vent pipe.

1. 
   MartinHolladay | Apr 06, 2007 11:14pm | #3

   Tin Man,

   A gas-fired water heater's pilot flame warms the flue gas in the flue.  The flue rises up through the water heater;  therefore the heat from the gas pilot actually helps warm the water.  Power-vented water heaters can be efficient, but they can also be noisy.  In some cases, the cost of the electricity needed to run the power vent blower costs about the same as the gas saved by the higher efficiency of a power-vented water heater compared to an atmospherically vented water heater.

1. 
   THETinman | Apr 07, 2007 10:17pm | #11

   Martin,

   Thanks for the theory refresher.  I'm well aware of how they work.  There is a lot of wasted energy in this process  as you'll probably agree, 50,000-100,000 +/- straight out the flue?.  I strongly disagree that a venter motor's electrical use would offset the benefit of using such an appliance.

     "Instant" hots are an option that one might consider if the hum of a venter motor is too offensive.  I've found most customers to be quite satisfied with them.  The venting for say a Renai can give one a little bit of a shock so ensure that you don't need a large quantity of vent material.

    

3. 
   Rebeccah | Apr 06, 2007 11:52pm | #4

   --- #2
   High efficiency furnace - 2 stages models, apparently required a "dual stage enabled thermostat" in order to get the full potential of the furnace... Some sellers says that you NEED IT, some other said you don't need it since the 'controller' on the furnace take care of that.

   Some other sellers said that you don't need it, but it would be even more efficient to have one - confort wise and for gas consumption $.
   Since the furnace not equipped with the 2 stages thermostat will run for 8 minutes before going on the 2nd stage if required. ---

   My understanding (after doing some research a couple of years ago before getting one myself) is that as opposed to single stage, 2-stage furnaces and their corresponding thermostats are primarily for COMFORT reasons -- the efficiency/ongoing cost differences for heating are minor*, and you don't have the humidity control issues that make such a big difference for air conditioning.

   The idea is that if the house is already near (but not yet at) the thermostat setpoint, you run the furnace at a lower BTU rate for a longer time, keeping the air a more uniform temperature. In contrast, if you just have a single stage furnace, you blast away for a brief period until the return air comes up to temp, and then it shuts down. With the fan running a smaller percentage of the time, the air isn't as well mixed and you get cold spots in the house.

   In contrast, if the house is much colder than the thermostat setpoint (for example, because you have a programmable stat set back at night to a cooler temp, and now it's morning; or because stage one can't keep up with the heat loss on a really cold day), the furnace would come on at full blast to heat the place up quickly.

   To get this effect, you need the two-stage thermostat. My two-stage thermostat is programmable as to how many degrees below setpoint triggers the second stage.

   One can hook up a single-stage thermostat, and as it was explained by my heating contractor, the furnace will automatically start up at stage 1 for a fixed period of time (I forget how long), and then go to stage 2 if it is not up to temp by that point.

   To my way of thinking, if you have a wide variation in your heating load (for example, a poorly insulated house with really cold winters and milder but still chilly transition seasons), you'll want the two-stage furnace *and* thermostat. On those really cold days, you don't want to have to wait 8 minutes for stage 2 to come on, and on the milder but still chilly days, depending on your air flow patterns around and in and out of the house, you can minimize cold spots by keeping the air circulating on stage 1. From experience I can tell you, keeping the fan on to keep the air mixed when the heat is off just makes unpleasant drafts.

   If your winters are mild or you have a really well-insulated and sealed house, then it probably doesn't matter much.

   Rebeccah

   *Regarding gas consumption: Yes, there may be less gas consumption at stage 1, but keeping the fan on for a longer time increases the electricity usage, and on my bills it seems to be kind of a wash.

4. 
   reinvent | Apr 07, 2007 01:00am | #5

   Not to disregard the good advice here but you should also post your Q at

   http://www.heatinghelp.com at their Q & A section called the 'Wall'.
   Those guys love to give there 2c on this stuff. Also you may find a heating contractor on that site who could come out and give you some good advice/quote.

1. 
   Bencrx91 | Apr 07, 2007 02:31am | #6

   Thank you all for your answers !

5. 
   danski0224 | Apr 07, 2007 04:03am | #7

   First, make sure the installing contractor does a load calc.

   Next, the brand is not as important as the installation. Installing a 90+% furnace without an intake pipe is pointless- might as well stick with an 80%.

   You do understand that a properly sized 92% furnace will save you only 12% over a properly sized 80%, right? An 80% with combustion air piped into the room eliminates new required PVC flue ventwork, helps to eliminate drafts and has a  lower equipment cost. They make 80% variable speed drive 2 stage units.

   Two stage and variable speed is a good choice- best bang for the buck. 

   A two stage thermostat will allow the best operation of your equipment. You will need a minimum of 5 wires for 2 stage heat, but some thermostats can use just 3 wires and an additional module at the furnace. Almost everyone has a built in timer on the control board now.

   The big names like to use proprietary parts in their cabinets. Makes getting parts quite difficult for the DIY repairman.

   Goodman is much more generic. Goodman is also manufactured to meet a price point- there is quite a savings potential compared to a big name brand. Make sure you know what you are giving up to get the lower price.  

   Variable speed ECM motors are quite expensive to replace, and they are not generic like regular AC motors. The part that goes bad is the brain box- the controller. Some manufacturers have replacement controllers, some do not. It is usually possible to replace an ECM motor with a standard AC motor for emergencies or long term (the "frame size" is the same). Better manufacturers include a "motor test" feature on the furnace control board to eliminate costly misdiagnosis and reduce their warranty costs. The motor itself is quite durable.

   If you go ECM, then make sure you add surge protection to the AC circuit feeding the furnace.

   An out-of-warranty ECM replacement service call will set you back over $1000.00 USD.

   Reading the energy guide label on the water heaters will answer your questions there.

1. 
   Bencrx91 | Apr 07, 2007 05:47pm | #8

   Thanks for the info, what kind of equipment is required as far as "surge protection" for the furnace circuit ?

   Thanks again,

   Ben

1. 
   danski0224 | Apr 07, 2007 07:38pm | #9

   Something like a Supco SCMPLUS 120v surge protector. Cheap insurance.

   Supco offers plenty of stuff and their catalog is online in pdf format.

6. 
   MrBill | Apr 07, 2007 08:02pm | #10

   Ben,

   #3
   NOISE:
   High efficiency Furnace and Water heater are equiped with a 'POWER VENT' ; Are these noisy ?
   Overall, the noise of my new high. eff. equipments equipped with power-vents should be lower than the noise of my current furnace?

   I replaced an oil burning furnace with a high efficiency gas about 5 years ago. I have been very disappointed in the noise level of the power draft blower :( It is almost as noisy as the old oil burner was. Our furnace is located in a "closet" in our living area so you can really hear it, in a basement it may not be as bad. Ours is right behind the wall that our couch is against in the rec room and I usually have to turn the TV up a notch when it fires up. Not bad up in the bedrooms though.

   If you are concerned with the noise level, I would definitely ask to listen to some of the furnaces you are considering in an actual installation. Having to do it all over again, I would have sacrificed the efficiency to have an old style gas furnace without the power draft blower. 

   Just my opinion,

    

    

   Bill Koustenis

   Advanced Automotive Machine

   Waldorf Md