Questions about heat pump for my shop

[JRP3]

Short version: I'm not sure there was ever a pressure issue but it's working now.

Long version:
I did borrow a gauge and checked the pressure, the gauge connections were not low loss, (found out about those after the fact), so I lost some pressure when connecting it but it was about where the 410A pressure chart said it should be for that outdoor temp, 103PSI at 33F. (However one HVAC tech I spoke to said you can't accurately tell charge level by pressure but I don't have the ability to pull the charge and weigh it.)

I added some more anyway up to about 110PSI and turned it on and it started working. Pumped it to about 120PSI while running in cooling mode, then switched it to heat and that worked, except I left the gauge hooked up and in heat mode the low pressure line becomes high pressure and pegged the gauge at 500 PSI. Switched it back to cooling to drop the pressure, then disconnected the gauge, which was a real disaster because the refrigerant came spraying out hard icing up the connector and making it hard to grip with pliers. I thought I lost everything but turned it on again and it's working. Soaped up the valve that had pressure under the cap and watched it for a while, no bubbles at all. (HVAC tech told me the valves could leak a bit when first opened up till the oil lubes the O rings, pressure under the cap could have been left over from initial pressurizing.) MrCool said if it's working with no errors then it's fine. I guess I put in a lot more refrigerant than it needed but lost just the right amount when disconnecting. Total cluster F but I have a working unit, no thanks to MrCool "support".

However, after I went through all that I did find a YouTube comment that said the P4 error might be fixed by disconnecting the compressor to control board plug and plugging it back in, which I had done earlier when checking compressor resistance, but never tried it after plugging it back in because I didn't think I had done anything. So it may have not been a refrigerant problem to begin with.

 

[Highbeam]

Short version: I'm not sure there was ever a pressure issue but it's working now.

Long version:
I did borrow a gauge and checked the pressure, the gauge connections were not low loss, (found out about those after the fact), so I lost some pressure when connecting it but it was about where the 410A pressure chart said it should be for that outdoor temp, 103PSI at 33F. (However one HVAC tech I spoke to said you can't accurately tell charge level by pressure but I don't have the ability to pull the charge and weigh it.)

I added some more anyway up to about 110PSI and turned it on and it started working. Pumped it to about 120PSI while running in cooling mode, then switched it to heat and that worked, except I left the gauge hooked up and in heat mode the low pressure line becomes high pressure and pegged the gauge at 500 PSI. Switched it back to cooling to drop the pressure, then disconnected the gauge, which was a real disaster because the refrigerant came spraying out hard icing up the connector and making it hard to grip with pliers. I thought I lost everything but turned it on again and it's working. Soaped up the valve that had pressure under the cap and watched it for a while, no bubbles at all. (HVAC tech told me the valves could leak a bit when first opened up till the oil lubes the O rings, pressure under the cap could have been left over from initial pressurizing.) MrCool said if it's working with no errors then it's fine. I guess I put in a lot more refrigerant than it needed but lost just the right amount when disconnecting. Total cluster F but I have a working unit, no thanks to MrCool "support".

However, after I went through all that I did find a YouTube comment that said the P4 error might be fixed by disconnecting the compressor to control board plug and plugging it back in, which I had done earlier when checking compressor resistance, but never tried it after plugging it back in because I didn't think I had done anything. So it may have not been a refrigerant problem to begin with.

What an adventure. Happy for you it’s working again. I think these things are far less sensitive than they would like us to think. The guys in third world countries with bare feet and a cigarette hanging out of their mouth manage to get them and keep them working with very little skill or tools.

 

[JRP3]

Unit stopped working again last night with the P4 error, this time I just turned off the circuit breaker for a few minutes and turned it back on, seems to have reset it and it's working again.

 

[JRP3]

Found this on the Midea website, (I think they make MrCool or at least some components). It may explain why I can restart the system after a while.

https://www.midea.es/wp-content/uploads/2020/10/P4-P5_FULL-DC-R32.pdf

 P4 indicates current protection on Phase A of system A.
 P5 indicates current protection on Phase A of system B.
 When the compressor current rises above the protection value 24A, the system displays P4 or P5 protection and all
units stop running. When the current returns to the normal range, P4 or P5 is removed and normal operation
resumes. When P4 or P5 error occurs 3 times in 60 minutes, a manual system restart is required before the system
can resume operation.
 Error code is displayed on main PCB and user interface.
3 Possible causes
 Power supply abnormal.
 Poor condenser heat exchange.
 High pressure side blockage.
 Excess refrigerant.
 System contains air or nitrogen.
 Inverter module damaged.
 Compressor damaged.
 Main PCB damaged.

 

[JRP3]

Now this unit, the one I installed in the garage which has had minimal use, only in the winter, has stopped working. No display showing on the inside unit, all connections showing proper voltage inside and out, blinking red light on outdoor circuit board. Contacted Ingrams about the problem and they said all Mr Cool service is handled directly by Mr Cool now so they forwarded my issue to them. This time it only took a few days to hear back from Mr Cool and they think it's the indoor unit circuit board and should be sending a new one out soon. Hopefully that fixes the issue but needless to say I'm not thrilled with these units.

 

[begreen]

Now this unit, the one I installed in the garage which has had minimal use, only in the winter, has stopped working. No display showing on the inside unit, all connections showing proper voltage inside and out, blinking red light on outdoor circuit board. Contacted Ingrams about the problem and they said all Mr Cool service is handled directly by Mr Cool now so they forwarded my issue to them. This time it only took a few days to hear back from Mr Cool and they think it's the indoor unit circuit board and should be sending a new one out soon. Hopefully that fixes the issue but needless to say I'm not thrilled with these units.

A voltage spike can fry a circuit board if there is no surge protection on that circuit. If you live in an area where voltage fluctuations happen often then it would be good to add this. We live in a rural area and they happen here at least a couple times a year. A friend had a circuit board on a high-end Fujitsu system due to a surge. This can be due to lightning strikes, a car hitting a pole, a transformer blowup, etc.

 

[JRP3]

A voltage spike can fry a circuit board if there is no surge protection on that circuit. If you live in an area where voltage fluctuations happen often then it would be good to add this. We live in a rural area and they happen here at least a couple times a year. A friend had a circuit board on a high-end Fujitsu system due to a surge. This can be due to lightning strikes, a car hitting a pole, a transformer blowup, etc.

It did happen after a power outage so that makes some sense, though it wasn't running at the time. Would that still affect it? You'd think they'd have built in surge protection to save themselves warranty issues.

 

[begreen]

It did happen after a power outage so that makes some sense, though it wasn't running at the time. Would that still affect it? You'd think they'd have built in surge protection to save themselves warranty issues.

It doesn't have to be running as long as there is voltage to the circuit. I lost a control board in a pellet stove during the summer due to a voltage surge. Learned this the hard way.

 

[woodgeek]

My HPWH had a control board go south about a month after a surge that led to arcing across the 120V outlets in my house.

The unit was 4 years old then, and has worked for another 7 with a new (free) board.

And that was WITH a surge suppressor on my breaker box. It gave its all, and left a little char mark inside the door. It got replaced too.

 

[begreen]

It's why I put the pellet stove on a UPS. All our computers and video equipment are on UPS now too.

 

[JRP3]

Would something like this work? Amazon product ASIN B008DIYAPM

 

[begreen]

Maybe. It depends on what panel is installed.

 

[JRP3]

Yeah I just meant something like that in general. I have a Square D, I think it's Homeline but I'll have to check.

 

[begreen]

That's the right idea. I think Square D makes a different model for the Homeline panel. Best to check. Our panel takes Eaton. Another option in some cases is to install one on the bottom of a surface-mounted panel.

 

[JRP3]

That's the one for Homeline, and I checked both my panels, (house and garage), are Homeline.

 

[JRP3]

I might go for this universal unit instead, 50kA rated, (not sure why link says 25kA),

https://www.lowes.com/pd/Square-D-SurgeArrest-25-KA-Indoor-Outdoor-Surge-Protective-Device/1000217397

 

[woodgeek]

Mine took up two breaker slots, but the universal one is slick too.

 

[JRP3]

What I don't understand is the universal can be hooked up directly to the main bus bars with no breaker or through a circuit breaker, but they specify a maximum 30 amp breaker. Why limit the max breaker if it can be hooked up with no breaker? Not a big deal but a bit confusing.

(broken link removed)

 

[EbS-P]

This is what I will be installing, lugged to the main bus bar. I’ll pay an electrician to do it.

Your friend has shared a link to a Home Depot product they think you would be interested in seeing.



(broken link removed)

 

[gthomas785]

Why limit the max breaker if it can be hooked up with no breaker? Not a big deal but a bit confusing.

I'm guessing it has to do with compatibility of the SPD leads to the terminal lugs on the breaker. The larger breakers probably only accept larger conductors.

 

[JRP3]

That makes sense.

 

[begreen]

This is what I will be installing, lugged to the main bus bar. I’ll pay an electrician to do it.

Your friend has shared a link to a Home Depot product they think you would be interested in seeing.



(broken link removed)

It should go through a breaker that is sized to the wire gauge of the surge protector.

 

[JRP3]

It should go through a breaker that is sized to the wire gauge of the surge protector.

The instructions I linked state that it can be wired directly to the mains with no breaker.

7. For a single-phase, 120/240 three-
wire application, connect one of the
two HEPD50 / HEPD80 black wires to
the line one (L1) phase bus mounting
screw, connect the other black wire to
the line two (L2) phase bus mounting
screw and secure them with keps nuts
(1/4-20). Connect the white wire to the
neutral bar, and the green wire to the
ground bar. For torque values, refer to
the panel electrical connection
requirements.
See Figures 4 through 6.

 

[gthomas785]

The instructions I linked state that it can be wired directly to the mains with no breaker.

Yes. better to connect as close to the source as possible. Under an extreme surge the SPD may suck down enough current to trip the main breaker and reduce the damage. But power surges don't follow any rules

 

[EbS-P]

It should go through a breaker that is sized to the wire gauge of the surge protector.

This one can go directly on the lugs on the bus bars. It saves two slots in a full panel. I will pay an electric as the main panel will be hot.

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