[N7WS]

As promised in my earlier thread, "Truth or Fiction" I'm back with a question about a replacement heat pump. To recap I have a 5-ton roof-top packaged Trane that has failed for the fourth time, this time with a second leaking evaporator coil. This was "repaired" with stop leak and a recharge of very expensive R22. I have bids from a contractor who I believe will do a good job and seems trustworthy. He has offered three options, one Rheem, another American Standard and a Bosch. I'm not interested in the Rheem so it's down to a choice between the American Standard, 4WCZ6060B1000A or the Bosch BRB-60HWD1N1-M19. I know we can't discuss prices, but the difference is a push. Three years of service and warranty repair are included in either bid.

As a techie (retired EE) I'm leaning toward the Bosch. There are several contractors on Youtube that seem to push them but one of them just changed his tune after not being able to repair one he installed, for lack of parts (a motor). He's beside himself because Bosch is still turning out units, with the same motor, while claiming a shortage of motors. Is this problem unique to Bosch and/or is it widespread?

One further issue is the inverter driven motor. Generally speaking inverters, solar panel optimizers and the switch-mode power supplies found in everything these days are prolific generators of radio frequency interference (RFI). As a radio amateur (ham) operator I'm concerned about this. I have contacted Bosch about this and they gave me a shrug. I have looked at the schematic of their inverter driver and see a couple of toroids on the line input, so they have seemed to make a nod toward controlling this, but I have no idea how effective this might be. Does anyone have a clue?

I welcome opinions on either option, realizing that opinions are like...

Thanks Wes

 

[pecmsg]

An RTU that's failed 4 times yet still uses R-22? Stop leak was a huge mistake! All manufactures have been having minor issues with condensers and evaporators.

As far as RFI anything is possible.

 

[N7WS]

An RTU that's failed 4 times yet still uses R-22? Stop leak was a huge mistake! All manufactures have been having minor issues with condensers and evaporators.

As far as RFI anything is possible.

The unit is 13 years old. First failure under warranty was a leaking evap coil. Second was a TXV, also under warranty. Third was a shorted winding in the ECM blower. Out of warranty, about two years ago. Repaired it myself. Last was another leaking evap coil. Of course it happened at peak heating season with out of town guests. Repair guy had me over a barrel and alleged that the coil could not legally be replaced. Hence stop leak. It's still working but even before the leak I had plans to replace it between the cooling and heating season, which is a little before now.

 

[pecmsg]

ECM motors generally fail due to high static pressure from poor duct work.
13 years for a RTU is not bad.

 

[N7WS]

ECM motors generally fail due to high static pressure from poor duct work.
13 years for a RTU is not bad.

Duct work is generally fine. Sized for evap cooling in a dual cooling system. Weak link is probably the barometric dampers. That's going away with the new system. I haven't used the evap in ten years. Too much maintenance, water consumption and a 1 hp motor running 24/7 for months. Besides I turned 81 last month. I still can and do climb up to the roof, but it's not my favorite thing to do anymore. Evap coolers are for younger guys

 

[N7WS]

But I still don't have any American Standard v. Bosch comments.

 

[pecmsg]

Duct work is generally fine. Sized for evap cooling in a dual cooling system. Weak link is probably the barometric dampers. That's going away with the new system. I haven't used the evap in ten years. Too much maintenance, water consumption and a 1 hp motor running 24/7 for months. Besides I turned 81 last month. I still can and do climb up to the roof, but it's not my favorite thing to do anymore. Evap coolers are for younger guys

Then the duct work is NOT fine!

 

[N7WS]

Because?

 

[pecmsg]

That RTU requires a different cubic feet per minute of air flow than the evap cooler!