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  1. #1
    Join Date
    Jan 2010
    Location
    Toronto, Ontario CANADA
    Posts
    21

    WaterFurnace needs electric backup heating?

    I had a WaterFurnace installer visit my home today for a quote. I live in toronto, On Canada.

    He said that I would have to install an 60 amp breaker to my electric panel and run a 50 ft line from the box to the furnace room (I have a finished basement, do gonna be a messy job).

    Anyhow, he said I need that electric line for the electric heating unit that will provide supplemental electric heat to assist the Envision furnace on really cold days.

    Is this true???? I see nothing in the WaterFurnace literature saying it requires additional electric heat. This would completely defeat the purpose of installing a geothermal unit in my opinion.

    It could turn out that my electric bills will be considerably higher if the weather stays cold for prolonged periods. Shame on WaterFurance if this is the case. or, shame on the WF dealer who came to my house today and is misleading me.

    Can someone please clarify if this electric heater is required??

    TIA

  2. #2
    Join Date
    Mar 2008
    Location
    northern Indiana
    Posts
    114
    Welcome to Geothermal or GSHP.
    Heat pumps work by "moving heat" from one place to another, from a loop to your house. When sizing a GSHP a load is figured for your house in your location. It is based on bin data collected over many years of average temperatures including high and low temps. Design temperature is the coldest day of the year based on the bin data, this happens for a short period once a year
    If you size the GSHP to handle 100% of the heat load you have to increase the unit and loop size accordingly. That costs more money up front and cost more to operate annually. It's a matter of economics a larger unit costs more to operate when the weather is not as cold. So a unit may be sized to handle say 90% of the load and back up heat is used for the for coldest days.
    You have a choice of back up heat like fireplace or wood burner but electric strip is often used and does not cost much.

    Electric heat is not a Water Furnace idea and is used by all Geothermal manufacturers.

    It you research geothermal you will find this to be common practice especially in Canada.

  3. #3
    Join Date
    Mar 2007
    Location
    Cedar Rapids, Iowa
    Posts
    121

    Balancing act

    Designing a ground source heat pump, in a northern climate, is a balancing act between heating, cooling and economics. Your home requires about twice the amount of Btu's to heat, at design temperature, as compared to cooling at design temperature. If you were to install a system to provide 100% of the heating Btu's required at design temperature you would, more than likely, be over-sized for the cooling load. Your system would also be over-sized for 90% of the heating season. If you've ever been in a home with too much cooling, you know it right away. The home is cold and "clammy" because the system cools the home quickly and shuts down before having a chance to dehumidify.

    Think about this... A 5 ton unit provides 100% of the heating and 4 ton unit provides 94% of the heating, with electric strips making up the 6% difference. The 5 ton unit costs more and the added loop field costs more. These costs can easily run several thousand dollars, or more, depending on many factors. The electric strip has to run a very long time to make up several thousand dollars.

    Ah!! But you think it would be better if the larger unit heated quickly and did not have to run a long time like the smaller unit would. Well... If you get in your car and blast down the highway to get there fast, do you use more, or less, gas than you would by slowing down and enjoying the sights?

    So you see, there is a balancing act for every Geo install. What works in your neighbors home won't, necessarily, work in yours.

    Bergy

  4. #4
    Join Date
    Dec 2006
    Location
    Middle Tennessee
    Posts
    11,347

    *

    Quote Originally Posted by teeball57 View Post
    If you size the GSHP to handle 100% of the heat load you have to increase the unit and loop size accordingly. That costs more money up front and cost more to operate annually
    a GSHP set-up to handle 100% of the load would cost less to run annually, if set up properly

    but in general to answer the question

    a backup/emergency heat source should always be installed, in case the heat pump part of the system breaks down



    .

  5. #5
    Join Date
    Mar 2007
    Location
    Cedar Rapids, Iowa
    Posts
    121

    Not true...

    At least in a heating dominate climate. A unit covering 100% of the load at design conditions will NOT cost less to run annually.

    Bergy

  6. #6
    Join Date
    Oct 2008
    Location
    OFFICES IN : ARIZONA - NEVADA - TEXAS
    Posts
    258
    If you use the correct thermostat with the electric aux. heat , one that you can easily adjust the 2nd stage the electrical consumption would be considerably lower than what you think.. Do you have a fireplace ?
    "Rock-n-Roll " Ain't noise pollution..

  7. #7
    Join Date
    Jan 2010
    Location
    Toronto, Ontario CANADA
    Posts
    21
    i have a NG fireplace inert that I would like to replace one day with a more efficient wood/pellet burning unit.

  8. #8
    Join Date
    Aug 2009
    Location
    Dell Rapids, SD
    Posts
    44
    Have you considered a split system geo? That is what I decided would be best for me. My back up heat is my NG furnace.


  9. #9
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,319
    Heat pumps break down. Having the backup assures heat if/when something goes wrong with the refrigeration system.

  10. #10
    Join Date
    Mar 2009
    Location
    Russell ON Canada
    Posts
    24

    WF Strip Heating

    My old WF had 15KW of 3'rd stage strip heating which came in pretty handy when the WF died in Jan 2009. The 15KW was enough to heat the house for the rest of the winter until I replaced the 15 yr old WF. Just look at the electric heat as a handy backup in case something bad happens.

    If memory serves me the 15KW is 3 strips and needs a 100 amp breaker and the proper guage wiring. The heater comes in 5, 10, 15 & 20KW sizes. Make sure your installer gets all this right by having the job inspected afterwards.

  11. #11
    Join Date
    Feb 2004
    Location
    Pacific NW
    Posts
    568
    RE:
    At least in a heating dominate climate. A unit covering 100% of the load at design conditions will NOT cost less to run annually.

    Simply not true for a professionally designed system, esp in a heating dominate area where summer humidity control or cooling is seldom needed.

    Darth: get your woodburner installed, then you dont need that 60A feeder, plus the woodburner will cover those power outage / ice storm days when there is no juice to flow in the 60 A feeder !

  12. #12
    Join Date
    Feb 2006
    Posts
    468
    I disagree - a unit sized to meet worst case demand in a heating-dominated climate will run with much shorter cycles than one allowing for occasional strip use. Those shorter cycles decrease efficiency

  13. #13
    Join Date
    Jan 2010
    Location
    Fort Wayne, Indiana
    Posts
    97
    DarthBane,

    Your geothermal unit will provide the largest majority of your heating. The amount of heat provided by the auxiliary heater will vary from house to house depending on factors like climate, unit sizing, heating load, and economics.

    Economically, there is a point (outdoor air temperature) where it makes sense for the geothermal unit to work in conjunction with the auxiliary heat. When considering both the cost of installation and the cost of operation, it often makes sense to size the geothermal unit to provide something less than 100%of the total heating requirement. Generally, sizing the unit in a northern climate to provide 100% of the heating does not make sense economically because the added initial cost of the larger unit and earth loop may not be recovered in energy savings over a reasonable period of time.

    The other reason for the auxiliary heater is to provide heating in the event of a compressor failure. Switching to Emergency Heat mode on your thermostat will provide the home with a source of heat until the compressor is replaced.

    WaterFurnace International, Inc.

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