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-   -   Heat Pump Aux Heat Sizing (http://www.diychatroom.com/f17/heat-pump-aux-heat-sizing-163301/)

digitalplumber 11-14-2012 08:16 AM

Heat Pump Aux Heat Sizing
 
How is the aux heating determined in a heatpump system?

Done That 11-14-2012 02:07 PM

You could use kW to BTU/h conversion of 1kW = 3401 BTU/h, so a 20kW kit would be ~68,000 BTU/h as an example and size that way.

Then I guess you have to decide how much "risk" you want to have in terms of covering yourself in the event of no other heat source. Guess in your neck of the woods you could be a little more risk tolerant and size to the smaller end of available options, where I'm at not nearly as much.

digitalplumber 11-14-2012 03:57 PM

Quote:

Originally Posted by Done That (Post 1052062)
You could use kW to BTU/h conversion of 1kW = 3401 BTU/h, so a 20kW kit would be ~68,000 BTU/h as an example and size that way.

Then I guess you have to decide how much "risk" you want to have in terms of covering yourself in the event of no other heat source. Guess in your neck of the woods you could be a little more risk tolerant and size to the smaller end of available options, where I'm at not nearly as much.


This is one of those, just curious things! I am not doing this.

So if I understand you, the heat strip needs to be equal to the amount of heating BTU'S that you need in the evemnt that your heat pump fails?

Done That 11-14-2012 04:03 PM

Yes, as a homeowner that is how I approached it. I sized mine based on a load calc just like sizing for a gas furnace etc. and assumed I might want to be comfortable for days or weeks at a time should the pump fail and not be able to be serviced.

Technow 11-14-2012 05:00 PM

I do it different and here is why:

1. Your heatpump quits and you don't notice. The strips cover the load for a month and a half......you finally notice when you get the bill.
2. I do a load calc on every house, so I know what your heating load is and what the heatpump will put out at design conditions....so I know the minimum heater size to carry the load.....
3. You will NEVER need a strip to carry the entire load until you have a heatpump problem, so if the house only needs to maintain 60 degrees until you get it fixed......

I always put heater sizes in between. So you will know when you have a problem and don't have to have a bunch of controls to save you from running 15KW when you only need 5kw


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