make the heat-pump work harder - http://www.hvacmechanic.com/ Forums
Original message
| Martin J
 |  "make the heat-pump work harder"
, posted Thu 22 May 21:24  
For heating my 1975 cottage in Montreal I have a 36000 Btu heatpump as primairy and oil-furnace for emergency heat.
During the winter months the thermostat is at 70F during the day, 63degF overnight. To prevent the oil-furnace from heating the house when the thermostat is first turned-up in the morning and during defrost cycles of the heat-pump, I installed disable switch for the oil-furnace.
With the oil-furnace disabled I managed to bring the house up to 70 deg within a reasonable time with morning outdoor temperatures down to 27F. With lower morning temperatures below I used the oil- furnace to bring the house up to temperature and disabled it again for the remainder of the day. Using this approach I was able to maintain the house comfortable for outdoor temperatures
down to about 15F.
As a result of this experiment I reduced the heating oil consumption for the 2007-8 winter season by about 35% compared to last year while maintaining the electricity bill about the same by adjusting the the air circulating fan to the "off" position at the thermostat instead of always "on" previous years.
Q: does anyone know of a thermostat on the market that will enable/disable the emergency heat source as a function of the actual outdoor temperature and ideally do all I did manually?
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Replies:
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| Houston204
| "Re(1):make the heat-pump work harder" , posted Sat 24 May 10:00
So you want to run your oil furnace and heatpump simultaneously?
That would create a high head pressure condition in your heat pump.
"Tip of the Day" Remember to remove power first.
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| | Martin J
| "Re(2):make the heat-pump work harder" , posted Sun 25 May 11:18
Not exactly,
Heatpump and aux.heat (oil-furnace) should never heat at the same time.
What I require is a thermostat that will run in "heat-pump only" mode down to 27F outside temp.
When the outside temp. is between 26-20F the aux.heat should come on only when the thermostat is first turned up in the morning. After the house temp reaches 70F the aux.heat will be locked out and the heat-pump will be the sole heating source for the day.
When the outdoor temp drops below 20F the heat-pump is locked-out and the aux.heat will be the sole heat source.
Note: Because the house occupied all day long the thermostat will remain at 70F all day long.
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| | Houston204
| "Re(3):make the heat-pump work harder" , posted Mon 26 May 14:29
Option 360 is for electric heat.
Option 350 is for dual fual applications.
"Tip of the Day" Remember to remove power first.
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| | Martin J
| "Re(4):make the heat-pump work harder" , posted Mon 26 May 20:20
Thank you Houston 204.
It makes sense.
MJ
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