All house lights flicker when heatpump compressor comes on

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Batman

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#119473 2-Jun-2013 19:47

I am going to be very basic as I'm not very sure what's going on or if it's ok or bad -

There is a giant heat pump, every time its compressor turns on to give out hot air the whole house lights flickers. The TV modem etc doesn't turn off or anything.

This is quite annoying, but apart from annoying is it bad? What's going on?

Thanks

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#829769 2-Jun-2013 20:42

Same thing used to happen with my household water pressure system when I lived in Rural Residential Dunedin and on tank water supply.
The 1hp pump motor would draw heavy current for about a second til it got up to speed and the start circuit dropped out.
Turned out there were too many households in our street on one phase from the street supply and when I checked the voltage it was dropping drastically (like to about 160 -180V) at switch-on. Must have affected our neighbours too as the local Power Company came round one day and changed our supply to one of the other two phases and the problem almost disappeared.
Might be an idea to get you power company to check the setup.

timmmay

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#829792 2-Jun-2013 21:11

I have to say I have two heat pumps, 8kw and 10kw, neither causes any power problems when they're turned on.

mattwnz

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#829793 2-Jun-2013 21:14

joker97: I am going to be very basic as I'm not very sure what's going on or if it's ok or bad -

There is a giant heat pump, every time its compressor turns on to give out hot air the whole house lights flickers. The TV modem etc doesn't turn off or anything.

This is quite annoying, but apart from annoying is it bad? What's going on?

Thanks

Do you get the same problem turning on a 2400watt fan heater, or turning on the oven?
What wattage and amp is you heat pump?

Niel

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#829830 2-Jun-2013 22:25

It is very common. Change to LED lamps and you will not notice the power dip. These days it is unlikely to have entertainment products with a power supply that is not universal (i.e. will also run on 110V, even when labelled 240V), so the dip will not really matter.

That said, there are specifications as to how much the power can dip so you might want to look at getting a higher rated power feed or at least get it checked out. There could be a weak connection which could get hot (or it might just be an unusually high start-up current).

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#829856 3-Jun-2013 00:24

I guess there are a number of things ... I will look into the power connection to see if it has its own fuse ... my guess is it doesn't have its own fuse because it was installed rather long ago, when standards were non existent, hence wired with the rest of the lights :(

is it a bad thing though? will it cause major problems?

TinyTim

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#829901 3-Jun-2013 05:25

All electric motors take a fair amount of power to get started. That's why (for example) you can't run things like fridges on inverters.

gregmcc

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#829905 3-Jun-2013 05:57

this could be anyone of a number of things.

Are you living in a rural or urban area? how far are you away from your point of supply? how old is the wiring in the house?

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Batman

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#829907 3-Jun-2013 07:20

Thanks,

Urban, about 30m, 1971

Niel

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#829922 3-Jun-2013 08:17

If you have fuses, then that is the start of the problem. Resistance in the fuse will cause a voltage drop and the board wiring will not be very good. At that age I'd suggest getting the board rewired and updated, our 1960's house had fuse holders disintegrate and started melting from age and it was not designed to run heaters, kettles, microwaves, etc. In those days the fuse would rarely see it's rated current. (And yes, we used the correct fuse rating.)

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#829930 3-Jun-2013 08:47

Well i dont know where its connected to the mainboard, there are no labels to guide ... Will investigate ...

gregmcc

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#829935 3-Jun-2013 08:57

Niel: If you have fuses, then that is the start of the problem. Resistance in the fuse will cause a voltage drop and the board wiring will not be very good. At that age I'd suggest getting the board rewired and updated, our 1960's house had fuse holders disintegrate and started melting from age and it was not designed to run heaters, kettles, microwaves, etc. In those days the fuse would rarely see it's rated current. (And yes, we used the correct fuse rating.)

the biggest load of bs I've ever heard, more than likely once the 40 year old wiring was replaced and the 4mm mains of the 1960's replaced with 16mm the problem went away. nothing to do with fuses.

as for the OP, get you mains upgraded, this will also mean that the fuseboard will have to be upgraded. if you an overhead power line, get the power company to check out the pole fuse, the wire may be loose.

got to remember that an electric motor starting uder load can draw up to 6 times it's full load rated current, so if the motor is rated to draw 10 amps, this gives a starting current of up to 60amps, with a dodgy pole fuse and smalls mains this will result in the power dipping for a second or 2 as the motor gets up to full speed.

gregmcc

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#829936 3-Jun-2013 08:57

Niel: If you have fuses, then that is the start of the problem. Resistance in the fuse will cause a voltage drop and the board wiring will not be very good. At that age I'd suggest getting the board rewired and updated, our 1960's house had fuse holders disintegrate and started melting from age and it was not designed to run heaters, kettles, microwaves, etc. In those days the fuse would rarely see it's rated current. (And yes, we used the correct fuse rating.)

Skolink

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#829966 3-Jun-2013 11:13

Sounds like your heatpump is an older non-inverter type. As others have said it is due to the voltage drop on your incoming wiring because A/C induction motors draw about 7x normal (full load) current when connected 'direct on line'.
A modern inverter heatpump will not cause your lights to flicker because the motor (DC or AC) has a box of electronics between it and mains.
We see a slight flick on the lights when we switch on our insinkerator.

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#830170 3-Jun-2013 18:53

I see ... Hmmm might get a new inverter heatpump then? Is it a lot more efficient?

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#830171 3-Jun-2013 18:54

It's a giant mitsubishi mr slim by the way

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