HeatPump - amp draw

Curious Geroge

Sorta sticky on what is the amp draw on your HeatPump (Make/Model - amp draw on startup and running). Thanks for sharing

MENACE2010

Hi
we have thermia Atec Plus (Airsource) (2phase), 24A running , 11 at startup

soundskin

Your starting amps should be 2-3 times your running amps.

Running amps for a 12kW output compressor would be between 14-19 amps, varies with output/flow temps.

Faulty run capacitors (60 micro farads for 12kW output compressor usually) can have an affect on your running amps. All this varies from heat pump to heat pump, condition of compressor windings, local voltage supply also will affect your amps. Low voltage will give higher amps.

It's good to check your amps as gives you good indication of power consumption. If your heat pump tells you your running hours then you can work out costs. Amps will give you kWs, by hours gives kWhrs, then by your unit costs per kWhr your cost to date. If you want to go all out then if you know how long your heat pump is installed and the size of your house then you can figure out kWh/m2/yr which will show you your BER rating (probably more accurate than any assessment).

2011

soundskin wrote: »

Your starting amps should be 2-3 times your running amps.

This will depend on the type of starter that you have. Some motors have a "soft" starter that significantly reduces starting current. DOL starters (Direct On Line) are typically 3 to 5 times the full load current of the motor.

Running amps for a 12kW output compressor would be between 14-19 amps, varies with output/flow temps.

A 12kW load will draw a minimum of 52 A (this would be for a purely resistive load, a motor has an inductive component increasing the magnitude of the current) at 230VAC.
How much larger the current will be will depend on the power factor.

Current = Power / (Power Factor x Voltage)

For a purely resistive load the Power Factor = 1
The inductive component of electrical motors will mean that the power factor will be < 1

0.9 would be a typical power factor for an electric motor.
In Ireland single phase supplies to domestic installations are at 230V.

I assume that when someone talks about a 12kW heat pump they are referring to the heat output, not the electrical input (which would be less).

Low voltage will give higher amps.

Generally as the voltage reduces the current decreases, see Ohm's Law.
Although I accept that things work a little differently when the load is an electric motor.

I don't mean to be pedantic, but Amp is short for "Ampere" which is the SI unit for measuring electrical current.

2011

On the topic of how volt drop decreases the current drawn by an AC motor page 2 of this document has a very interesting graph:

http://www.dreisilker.com/Documents/Ctrl_Hyperlink/ac_motor_guide_uid2162010222362.pdf