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dimming lights from large geothermal heat pump

16K views 65 replies 14 participants last post by  atuel 
#1 ·
Having some light dimming for a second or two (60% of full brightness) when a large geothermal heat pump kicks in (70A max in rush over 4 Cu cable).

I had the utilities monitor my voltage over the past several days and they see drops in voltage of up to 3-5V for a second or two and tell me its with in their legal requirements (even if it is just barely). No phase imbalance detected. Doesnt appear to be loose connections, burns, or over heated breakers either. Though was standing there as it kicked in and may have heard a pop.

Its a 400A service on 4/0 AL cable coming into a single meter and then split from there into two 200A panels with direct connection to the meter with 4/0 AL hots but a smaller gauge neutral cable... maybe 2/0 AL but cant get a good look at it.


So sort of running out of things to check here... I'm wondering there could be an issue with a split 2 panel setup causing issues over a single 400A panel.

Could the smaller neutral be causing some resistance to large in rush currents?

There are a couple visible nails that came in through the exterior siding that dented or puched out one of the knockouts. Nothing visible close to any of the cables but havent pulled the breakers to look underneath.
 
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#47 ·
I was reading thru this one and with POCO underground cable aka lateral run the POCO have it own rules and rating with their underground cable there is not much we can do about it.

The POCO allready know what size lateral conductors will be and they will only genrally sized based on the average load that it.

It will be the same thing with transfomer as well so just like your house and your next door house are on the same transfomer most pad mounted transfomer useally come in 15 or 25 Kva rating which it is the most common size but they do have larger Kva rating as the situation called for which it will be 32.5 is next size larger then 50 Kva ( those are used with larger numbers of house or have the tankless electrique waterheaters )

As far the Géothermal unit it normal to see the lights flicker just once when the unit kick in all it depending on the set up and with soft start kit installed it will reduce the amout of light flicker but not 100% the case.

The last Géothermal unit I did installed in USA side I have see very little light flicker it the simaur to normal heat pump or central A/C unit and to that customer house he have overhead line and he is end of this spur and he did have underground lateral as well but he have 25 Kva transfomer and see it drop real breif during the unit kick in.

And that unit is allready wired for straight 240 volts and sans netual in there

For France side I have a option to wired either on 240 volts single phase (line to netural ) or 415 volts either single phase or triphase {I rather to get on triphase if have it }

And it pretty simauir what the North American verison it will flicker a little during start up but once it running not noticeable even with three phase verison there is no flicker at all.

I know you may ask me about three phase Géothermal unit I will advise ya just don't go there unless the POCO have three phase supply so leave it as it is ( You may end up pay extra to get a three phase supply and most POCO which I know they genrally don't provide any three phase supply to resdentail unless super large service size )

Merci.
Marc
 
#48 ·
I would like to hear from anyone thats had success with hard or soft start kits on large heat pumps. If so, if you know what brand/model what used as there seem be a lot of these avaialbe and some look kind of crappy.

I was reading back and didnt correctly read the post about asking my neighbor... I didnt mean to blow off doing that. Its just my neighbor isnt there right now. Hasnt been since about christmas... visiting family or something i guess. Also, I'm not positive its the same neighbor as I would guess, so when the poco calls me back next wednesday, I'll be able to confirm that and make sure to ask the right neighbor.


I also had one other thought after I discovered that extremely long outlet run. I would normally not think of my living room lights (where this dimmign annnoys me the most) as a long run since the load center is right next to it, but because of the 3 switch locations in the living room and maybe the additional items on that circuit, it ends up being a lot longer than expected.

I'm attaching a diagram that shows the "flow" of electricity. Its not a wiring diagram... just indicates the power needs to get from point A to point B somehow. I know this is accurate because we replaced the normal flip switches with lutron digital fade dimmers so we had to work this all out. Its a little odd because the can lights were added in a remodel. Original had light kits on the fans, but those are no longer there.
 
#50 · (Edited)
I just measured voltage drop at one of the can lights...

At the load center, both phases show 123V immediately before and after checking at the can light.

At the can light, it reads 103V.... at steady state... not during compressor start.

With a "soft" compressor start (ie into a low stage vs into a high stage direct), my instantaneous only multi meter showed a dip down to 97V. Lights only flashed a little bit, but noticible without looking direclty at it as I was looking at my multi meter.

I'm still waiting for the "hard" start that goes straight into high mode where the lights flicker the worst.


So is that all run length or could things like loose connections interfering here?
 
#51 ·
20 volts is pretty big drop on 120 volt circuit unless you did change the battery on the DVM I will use the second voltmeter to verify it.

If that still stay the same then you may have a loose connection.

According to the drawing you provided long run may affected a little in someway.

So I will start with loose connection at switch box or juction boxes where you can able reach it and double check the connection to make sure they are good and tight.

That part do including the load centre as well.

Did you actually read the 240 volt before the unit start and after the unit start up and running ?

Merci,
Marc
 
#52 ·
I did change the battery. I've also verified this is not the case for any other light / outlet in my house outside of the living room/sunroom and office. They all read they same as what is at the panel.

I can reach every connection in these circuits as I have access to the attic over the living room and sunroom as my second story does not cover that part of the house. Could the loose connection be anywhere in the circuit at each and every single connection made?

I havent been able to catch the drop across the 240V. Need to find a way to make my zone controller kick it on when I want. I stood out there for 15 minutes the other day with all zones calling for high stage heat and it still didnt kick on.


I'm not sure if its related, but I have these Lutron Maestro digital fade dimmers on all the lights in the living room and office. I have noticed even when fully on, they seem to drop my ~120V line down to 110V, so seems they dim even when fully on. Not sure what effect that has on the voltage drop when the heat pump kicks on, but these things seem unable to control CFL and LED, so I'm thinking of changing them out. Know any good dimmer that can control CFL/LED with multi-location ability? I belive I do have neutral in every switch location (no switch legs), so that should not be a problem.

I was looking at these ICON dimmers as I saw this post: http://forums.x10.com/index.php?topic=21819.0 referring to "2876DB Icon Wall Switch Dimmer". They seem to work even though they dont seem to claim it in their specs.
 
#53 ·
Well crap... seems its user error here on the voltage drop at the can lights. I thought it was turned all the way up, but apparently theres a few more higher settings even though the top LED indicator was on.

So its actually reading 111V and can drop as low as 107-108V when the heat pump kicks on in low mode. That'd be about the same 4V drop the poco measured before during the soft starts they caught the previous week. I havent caught a start directly into high yet.

I was reading on another forum though that these scroll type compressors have a high in rush particularly when its cold. Its something about the oils inside them having a much high viscosity when its cold.

Prior to reading that, I had my crawl space entry (inside the non-heated garage) open (mostly from being lazy), so my crawl space was 30-40F when it was 20F or below outside. With my new HVAC, we sealed the crawl space with insulation on the walls and liner on the ground. We also installed some air inducers there so its semi-conditioned. Essentially, its within 10-15 degrees of the inside temp of the house. Since I've done this, it has not have a case of the very significant dimming in the past 2 days.
 
#54 ·
I caught the voltage drop when it kicks into its first state operation... it went form 250V to 242V. This was taken at the terminals inside the heat pump. Normal?

Theres a small 2 slot load center with a 70A breaker in it acting as the disconnect at the heat pump end. Its a squareD QO thats rated at 70A on the mains. I'm used to simple physical cut offs instead of this breaker setup. Any issue with this?

I also verified while I had the door open that is already had a hard start capacitor on it that was included from the factory.
 
#56 ·
Why are you checking the voltage at the pump? It has nothing to do with the dimming lights. You need to find out how much voltage drop you have and the main connection to your circuit breaker panel that serves your house.
In my previous job in Corporate America, I was a top gun troubleshooter and got involved all kinds of problems. One of the most difficult printer to fix was the one that wasn't broken..... It would be working as designed but the customer would want the print output to have a different appearance.
 
#58 ·
We'll know for sure when we get the data back from the poco monitor, but yes, I dont think there is anything major wrong. That will confirm the power draw and hopefully make sure that 400V reading I saw was a fluke due to low battery.

I did correct some possible issues with some looseness in the line to the heat pump with the stranded thhn working itself loose as the strands smashed out.

And by sealing the crawl space door, it went from 20-30F in there to more like 60F, so that seems to decrease the draw since theres less resistance in the compressor start up due to lower viscosity in the oil. Its been pretty cold here the last few days that I've done this and I've not seen any major flickering in the lights.
 
#59 ·
So poco left a voicemail..... 123V to 117V drop.

They also said they saw current draw of 190A... i think he said on each leg which would make sense as the voltage was being measured on each leg individually.

He stated that theres no problem, but then he went into a bunch of questions about the geothermal system and who had installed it like there was some concern about it.

I havent been able to catch him when I call back, but anything odd about those numbers?

Is the 190A on each leg a total of 380A out of the 400A service or when they say 400A service, will it do that much on both legs?
 
#61 ·
Is the 190A on each leg a total of 380A out of the 400A service or when they say 400A service, will it do that much on both legs?
Yes. It is 400A @ 240V.

In simple terms, what you have is 190A out of 400A available.
 
#62 ·
Its not 190A continuous... it hit that high for a few seconds. I dont have the actual data, but I suspect it was probably something like 120A and then had about 70A inrush when the heat pump kicked on and then dropped back down to 140 give or take.

And I doubt that was sustained all day long. My elec bill has been in the $200-250 range (I think high, but its a small town coop, so its high even for the area in general). When they first came to hook up the monitor, we had a late start day and were still sleeping when they got here with nothing on in the house. They knocked to ask if we had anything on as they didnt see hardly anything at that time.

So guessing I might have a high usage when I'm actually home and awake, but when at work or sleeping, I guess I dont use much of anything. Wish I had a branch monitor to tell me where and what...
 
#66 · (Edited)
Ratings from the mfg:


Code:
---------------------------------------------------------------  HWG     Ext    Fan    Total    Min    Max
Model    Rated            Voltage    ------Compressor------      Pump   Loop  Motor   Unit    Circ    Fuse/
Model    Voltage          Min/Max    MCC  RLA   LRA    LRA**     FLA     FLA   FLA      FLA    Amp    HACR

 064     208-230/60/1  197/254    40.0   25.6  118.0  41.0       0.4      5.4    7.0     38.4   44.8     70

NOTES:
* With optional 1 HP ECM2 motor
** With optional IntelliStartTM
Rated voltage of 208/230/60/1
Min/Max voltage on 197/254
All fuses Class RK-5
HACR circuit breaker in USA only

Page 16 if you want the original table: http://www.waterfurnace.com/literature/envision/IM1000AN.pdf
 
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