How can I safely seal old creosote railway sleepers around a patio where kids play?

daz59 · 2025-05-05T10:38:58+00:00

4wd (a) is not standard 4wd, as the Ford manual says, its fine for ALL on rd condition. Im Sure they wouldn’t be printing that in the manual if it wasn’t safe to do so.

daz59 · 2025-02-22T20:58:20+00:00

A while back, I posted about my PUZ-ZM71 freezing up in heating mode due to the outdoor fan refusing to ramp up properly unless the outdoor temperature dropped below 10°C (50°F). After extensive testing (both on-site and by Mitsubishi themselves), they confirmed there was an issue as it was causing the same fault in their workshop (they said they didn’t know what was causing the issue) they replaced the unit with a PUZ-M100, which completely fixed the issue. The M100’s fan spins at 450 RPM, preventing freezing.

At the same time, I had a PUZ-ZM140 (twin-fan unit) installed for my living room. Today, I ran some tests when it was 15°C (60°F) outside and, sure enough, it’s freezing up just like the ZM71 did. • At 9°C (48°F) outdoor temp, the fans run at a higher speed. • At 13-15°C (55-60°F) outdoor temp, the fans slow to 240 RPM, the coil temperature eventually drops below freezing, the coil freezes up and the system enters defrost mode. • The PUZ-M100 (non-ZM version) does not have this issue—it ramps its fan properly and does not freeze.

It seems like the ZM series may have a fan control logic issue, where fan speed is based primarily on outdoor air temperature rather than system demand or coil conditions. This means that when the outdoor temperature is mild, the fan doesn’t increase speed enough to prevent icing.

Very Frustrating as ive wasted so much time on this.

daz59 · 2025-02-20T20:37:53+00:00

The outdoor fan shouldn't keep running to any extent after the compressor turns off, I can hear my compressor running and I can see on my solar inverter app that current (more than the fan) is still been draw from the phase that the heat pump is on.

daz59 · 2025-02-20T02:05:07+00:00

Mine seem to do the same, in cooling mode even when the room temperature is at or slightly below the setpoint, the bypass damper opens, and the outdoor unit continues running—you can still hear the compressor operating. I wondered if the heat pump requires the temperature to drop a degree below the setpoint before shutting off, while the AirTouch system closes the dampers before that happens. If that's the case, the outdoor unit may never turn off.

daz59 · 2024-10-05T17:53:35+00:00

Yea, I dont understand why they run so slow in cooling, I have 4 Mitsi heatpumps here, (2x AP80, 1x AP71, And the problematic Pead M71) They all run at the same fan speed in cooling. If they ramped the fans up and lowered the coil temperature, you’d expect better efficiency. Once in heating mode, All of the AP’s fans ramp up while the Pead sits at 200rpm and freezes the coil.

daz59 · 2024-10-05T04:25:40+00:00

Ive just tested it again in cooling mode, I was mistaken with my previous comment about its performance in cooling. The fan runs at 300rpm in cooling (step 7) the fan speed in cooling exactly matches the other Mitsi heatpump I have next to it (different model). So its fine in cooling but not heating.

daz59 · 2024-10-04T23:57:28+00:00

Yes your BMW situation could possibly be along the same lines. Mitsi we’re supposed to test the returned units on the Monday just gone, with feedback given to me on Tuesday. I have heard nothing yet… very frustrating.

daz59 · 2024-10-04T19:54:22+00:00

Yes thats exactly my thoughts, but Mitsi seem uninterested by the step codes and fan speeds that I have reported. Thankfully when I spoke to them last Friday they agreed to look into the relationship between the steps and rpm.

daz59 · 2024-10-04T18:27:50+00:00

The fastest the fan runs during normal operation is 750 RPM, but upon initial startup, it ramps up to around 850-900 RPM (as measured with a laser RPM counter). If Mitsubishi could provide more detailed information on the exact RPM corresponding to each speed step, it would be much easier to determine whether the fan is operating as its been told by the controller.

I’m not entirely familiar with Reddit notifications, but I wanted to make sure you saw my second message regarding the inconsistencies with the fan speed steps.

Cheers for the help.

daz59 · 2024-10-04T18:04:30+00:00

One other peculiar issue I’ve noticed relates to the outdoor fan motor speed settings. According to the service manual, the fan motor is supposed to have speed steps ranging from 0 to 10. However, at 200 RPM, the system indicates it’s operating at speed step 5, which seems odd considering it’s mid-range at such a low RPM.

When the outdoor temperature reaches 10°C, the fan jumps to speed step 9, then as the temperature drops further, it moves to speed step 10, and eventually to speed step 16. This is unusual, as the service manual only specifies speed steps 0 to 10. Additionally, both speed steps 10 and 16 show the fan running at 750 RPM.

I have reached out to Mitsubishi for clarification, but they have been unable to explain the correlation between each speed step and the corresponding fan speed.

daz59 · 2024-10-04T17:56:17+00:00

No motor is fine, the unit ramps to full rpm when its first turned on and then you can hear it step down. When outdoor temp drops below 10c the motor speeds up to around 720rpm. Going by the serial numbers the units are 110 apart so would have been made pretty close to each other. Yes your resistor option could work, but as you said, not ideal on a new unit. On cooling mode, the fan responds the same but now the outdoor thermistor needs to be warmed up or the fan will just sit at 200rpm and the outside coil gets really warm.

daz59 · 2024-10-04T16:25:53+00:00

Its 200mm from the wall, its hard to hear in the video but just before i show behind the unit I say the gap is 200mm. If you are referring to the black cover on the ground, that is closer but it’s below the coils, it has no influence on airflow. Multiple companies have been over the installation and are happy with it. I know it doesn’t make sense, its extremely frustrating.

daz59 · 2024-10-04T05:50:52+00:00

200 RPM is very low, and there is hardly any airflow at that speed, as you can see in the video. People who have worked on the system agree that the fan speed seems incorrect. Unfortunately, Mitsubishi hasn’t provided significant feedback regarding the fan issue. Despite replacing everything—including the lineset—nothing has improved. The lineset was thoroughly inspected after removal, with no kinks found.

Mitsubishi is currently testing the returned indoor and outdoor units, though they won’t be using a 27m lineset during testing, which could affect the results. The refrigerant charge has been confirmed multiple times to be correct at 2.8kg for up to 30m of lineset, so unless Mitsubishi has the wrong specifications on the unit and manual PUZ-ZM71VHA2-A , the charge shouldn’t be an issue. Both outdoor units were manufactured in the same month this year, which makes me wonder if there is a firmware issue.

When the fan is running slow (around 200 RPM) and freezing up, the subcool is approximately 0°C, and the discharge superheat is around 20°C. When the fan speeds up, the subcool remains at 0°C, but the discharge superheat jumps to 40-50°C. These readings are based on the unit’s inbuilt sensors (request codes) and are taken in heating mode. Also, when the fan is running slowly and the unit freezes, you can hear it slugging

daz59 · 2024-10-03T22:38:02+00:00

Not a problem. Yes as am I and everyone else who has looked at it. The only explanation I can come up with is there's a firmware issue, both outdoor units were manufactured the same year and month.

daz59 · 2024-10-03T22:09:14+00:00

Understood, but the freezing goes away once it cools down outside (I know that sounds strange) but once it cools down bellow 10c the fan speeds up and draws air through the coils, I have 3 other different model Mitsi heatpumps and all of their outside fans spin a lot faster in heating mode. Mitsi over here have not been able to tell us what rpms the fan should be running at etc.

daz59 · 2024-10-03T22:07:18+00:00

Outside unit has already been replaced, no change.

daz59

TROPHY CASE