Backup electric strip heat question

[jrcase]

Is there a set amount of KW back up electric strip heat per ton of Heat Pump? Is 15 KW strip heat enough for a 3 ton heat pump? (5 KW per ton)

[Jultzya]

Load Calc

[amickracing]

There's a possibilty that's right.... could be way off too.

Go with the above answer.

[ddog1]

plenty...be sure and check available power at panel... 15k is a lot of amp draw w/heatpump

[beenthere]

Do a load cal, and find out if thats enough to heat your house without the heat pump.

You might need 17 kw without the HP running.

[dan sw fl]

Originally posted by jrcase
Is there a set amount of KW back up electric strip heat per ton of Heat Pump? Is 15 KW strip heat enough for a 3 ton heat pump? (5 KW per ton)

Generally,
kW needed =
Total Heat Load - the reduced Heat Pump capacity at dsign temp ( 0'F to 35'F) depending on North or South U.S.

3 Ton ... ~36,000 BTUh Total
_______.. ~36,000 BTUh at 47'F
_______.. ~20,000 BTUh at 17'F
_______.. ~14,000 BTUh at 10'F ( ??)

For example, IF heating load for 2,000 S.F. residence is 50,000 BTUh at 10'F design temperature, a heat strip would need to provide 36,000 BTUh (50K -14K)
or 10kW ( 1 kw = 3,412 BTUh)

If your winter design temperature is 30'F (several Southern U.S. states), the heat pump would provide
~28,000 BTUh and residence may only need 37,000 BTUh
total heating capacity. Therefore, a 5 kW ( 17,000 BTU) heat strip would be MORE THAN sufficient to meet the 9,000 BTUh demand.

[beenthere]

Size the strip to carry the full load, incase the OD unit goes out when its near design, if your design is below 30.

[jrcase]

Thanks a million for all the replies. One more question. Do the heat strips only come in 5K increments? (5KW, 10KW, 15KW, ect.)Say I only need 7.5 KW, do I have to step up to 10KW or can I get 7.5KW?

[Jultzya]

Originally posted by jrcase
Say I only need 7.5 KW, do I have to step up to 10KW or can I get 7.5KW?

Check with your distributor for each manufactures available options:

5, 7.5 and 10 nominal KW models available with lug terminals

5, 7.5, 10, 15, 20, 25 and 30 nominal KW models available
with Circuit Breakers