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New hvac system setup suggestions

Posted by audiomixer (My Page) on
Mon, Feb 4, 13 at 20:03

I have a new Trane dual fuel system: XV95@60K btu + XL15i H.P. and a Honeywell Prestige tstat. In the NW around Portland my rates are: Electricity-$0.10/kwh, NG-$1.10/therm (and dropping).

I would like to know the optium set points and setup for the tstat and system ?

Thanks

This post was edited by audiomixer on Tue, Feb 5, 13 at 1:50


Follow-Up Postings:

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RE: New hvac system setup suggestions

Audio

What size is your HP condenser?

What size is your home?

While I don't know your COP, I used 2.8 which may be on the low side. With that said, on a BTU basis alone, there is a marginal cost advantage of HP heating over nat gas less than 10%. Numbers below.



Cost per 100,000 btu of useable heat

Electric baseboard: $2.64
Heat pump: $1.05
Natural gas: $1.12

I probably would set the changeover at 32-35 degrees and adjust as necessary to the temp that provides good comfort for you and your family.
The changeover could go lower but you have a nice furnace and it should be used

It is my understanding that Portland has relatively mild winter temp averaging around freezing. Yes, I know they can go lower. I personally think the XV95 furnace was overkill and the XV80 a better choice.

Pay attention to your nat gas rate. When it gets close to $1.00/therm, you would basically be close to a wash with electric HP heat.

IMO
Good Luck


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RE: New hvac system setup suggestions

Electric baseboard: $2.64 "

IN my neck of the woods, I pay $0.20 per KWHH which translates to $5.85 per 100000 BTU for electricity.

Depends on where the OP lives before making the calculation


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RE: New hvac system setup suggestions

Sorry, just noticed he posted his rates.


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RE: New hvac system setup suggestions

Heatpump is 3 ton sized for cooling
House is 2800 sqft, single level
Load 40k heat, 25k cool

Tigerdunes....I know you like the 80s, but the xv95 cost was minimal in difference.

joeplumb....weather is mild, but 2 months a year are below 30 at night, 2 months a year are above 90 in the day. Hudimity is 50 or more, fog, rain is common with freezing fog.


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RE: New hvac system setup suggestions

Audio

Can't blame you then for going with the XV95.

A heck of a nice system.

Did you add a filter cabinet?

I hope I answered your question about settings-I assume you meant the outdoor temp to change from electric to nat gas heat and vice versa. On defrost calls, I would only want low stage of nat gas heat to temper air. I would ask installing dealer about that. Not certain that can be accomplished. Not a big deal though.

IMO


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RE: New hvac system setup suggestions

I've been noticing my (oil) furnace running even when above the crossover set point that I have selected. (25 Deg.)

Yesterday I discovered what was going on - I have 2 year old Carrier equipment with a Carrier Edge Thermostat - there is a setting that calls for the furnace to continue operating until the thermostat temperature setting is reached after the furnace has run during a defrost cycle. By default this feature was enabled. (it overrides the crossover temperature setting.)

While I do have small setbacks, I have them sized and timed based on the assumption that the heat pump alone will operate above the set crossover temperature.

I disabled this feature yesterday and I am now seeing what I desire. I unnecessarily used about 75 gallons of oil in January. @#$%^&


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RE: New hvac system setup suggestions

Did you add a filter cabinet?

Yes, it's a 4 inch one....20x20. It seems the 4 inch, or for that matter, the 5 inch filters aren't true to size.....more like 4 3/16 or a bit under for the 4.

Any suggestions on brand that can be purchased from HD or Lowes ?

Thanks Tigerdunes, your comments and knowledge are great.

This post was edited by audiomixer on Tue, Feb 5, 13 at 17:41


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RE: New hvac system setup suggestions

Audio

What brand air filter media cabinet was installed?

And you should identify the MERV rating on the filter that was installed for future reference.

IMO


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RE: New hvac system setup suggestions

>>What brand air filter media cabinet was installed?

Not sure yet. I believe it will be custom made. I specified gaskets, hinged door with gasket...etc. It will be attached to the return air at the top of the furnace in a downflow setup.

>>And you should identify the MERV rating on the filter that was installed for future reference.

Yes, I will. Looking at what is available in the "box stores", I'm thinking somewhere between 10 and 12 ?


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RE: New hvac system setup suggestions

Audio

Being a Trane system, I would want their Perfect Fit Media cabinet. The name alone explains why. The cabinet fits to the furnace like a hand fits a glove. It has gaskets that seal the door nicely. Very easy to open and close when replacing filters. Filters while proprietary size can be purchased at Internet filter houses, both OEM and generics.

IMO


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