Looking for info on Lennox heat pump system

Problems related to residential installations.

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fastartcee
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Looking for info on Lennox heat pump system

Post by fastartcee » Fri Mar 22, 2013 5:09 pm

Hi,

We've purchased a home on Vancouver Island, BC, Canada, that has a Lennox heat pump (Model XP15 048 230 01; air source); and a Lennox electric furnace (Model CBX32M 048 230 6 04). There were no info or manuals left in the home about the heat pump system, and we have not owned a heat pump before. (I have downloaded the XP15's installation and operating manual.)

Everything about both the outside & inside units looks and sounds - no blockages; no unusual noises; new filter; good line insulation. The system has seemed to function well all winter, but our electric bills have been higher than expected. (During our winter, temperatures usually range between plus 10 C and minus 3 C; our lowest overnight temperature this winter was minus 8.)

Looking at the inside unit, there appears to be two electric heaters, one (15 kW) fused at 60 amps, and one (20 kW) at 50 amps. I presume these are the 'Auxiliary' and 'Emergency' heat sources.

Our programmable thermostat was set to 16 degrees C overnight, and 20 during the day. If the thermostat schedule has a jump of 4 degrees, would the auxiliary heat source cut in automatically? (This might be why our hydro bills have been so high, but I'm trying to confirm that idea through posting this plea for information.)

I have changed our thermostat to 16 C overnight, with two 2 degree steps in the morning. I'm in the process of checking (using our smart meter) whether that reduces our power usage. (- With a heat pump, would it be best to simply leave the thermostat at the same temperature setting, day & night.)

One last - if the auxiliary heater is off, about what power should the rest of the system draw (compressor, outside fan, & inside fan)?

Thanks for any replies that enlighten me on heat pump basics!

PS. I don't know why my post looks okay on my machine, but is littered with * symbols, with words missing, when I use a question mark or a dash.

Freon
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- Looking for info on Lennox heat pump system

Post by Freon » Sat Mar 23, 2013 1:29 pm

You are right about the Aux electric heat being used when the thermostat goes from night to day setting. You might check with the thermostat to see if you can adjust the temperature differential between the thermostat set temperature and house temperature before it (thermostat) activates the Aux (electric) heat. You might find it's a 2 degree differential so you may want to have it set to stage the morning warmup over 2 hours thereby reducing the electric heat usage.

All of the data for the power calculations are on the outdoor condenser unit (voltage and Run Amps, not start amps) as well as on the indoor equipment (voltage and amps for the electric heat).

fastartcee
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- Looking for info on Lennox heat pump system

Post by fastartcee » Sat Mar 23, 2013 3:36 pm

Freon -
> You are right about the Aux electric heat being used when the thermostat
> goes from night to day setting. You might check with the thermostat to see
> if you can adjust the temperature differential between the thermostat set
> temperature and house temperature before it (thermostat) activates the Aux
> (electric) heat. You might find it's a 2 degree differential so you may
> want to have it set to stage the morning warmup over 2 hours thereby
> reducing the electric heat usage.
>
> All of the data for the power calculations are on the outdoor condenser
> unit (voltage and Run Amps, not start amps) as well as on the indoor
> equipment (voltage and amps for the electric heat).

Thanks for the reply, Freon.

I had to look up a few abbreviations (I'm not an electrician), but I now see that the compressor draws 21.8 run load amps; the outside fan, 1.1 full load amps; and the inside fan, 2.4 full load amps.

By the way, I have edited my post, which contained errors and was littered with asterisks and deletions. It seems this forum text processor has problems with posts from Canada which contain question marks or dash marks!

fastartcee
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- Looking for info on Lennox heat pump system

Post by fastartcee » Sat Mar 23, 2013 4:47 pm

Freon, a follow up -

When I take the total amps for compressor plus outside fan plus inside fan, at 240 V, I get a power draw of about 6 kW per hour. Does that seem about right?

Thanks.

Freon
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- Looking for info on Lennox heat pump system

Post by Freon » Sun Mar 24, 2013 2:28 pm

The text processor has trouble with all posts due to trying to stop spammers. You have learned quickly.

Your calculation is correct for approximation purposes.

fastartcee
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- Looking for info on Lennox heat pump system

Post by fastartcee » Sun Mar 24, 2013 4:18 pm

Thanks, Freon.

I think I now have sufficient general knowledge about our heat pump.

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