Upgrade PR for Booster

[USN-LPD7]

I have been mulling over what Dave had said regarding the upgrade of
the booster compressor with the UMSR50 and I am still not convinced
that doing so would provide a negative benefit.

To begin with and this is my own personal opinion the PR's that
Hallowell initially installed were of less than adequate quality.
After inspecting my 2 relays I noticed that pitting had started to
occur on the contacts thus reducing the amount of actual contact area
for the energy to flow and that the metal element on which the active
contact was placed was weak either from wear or design.

I know that the booster is not utilized as much as the other
compressors but that actual booster utilization is subject to the
climate and/or location in which it is installed and subject to
defective control boards or sensors so in effect ones booster may
cycle considerably more than another located in another part of the
country.

Would the retrofit for the booster be similar to that of the primary?

Any technical/operational objections to making the change?

I will be updating my 4 ton start capacitor (metal can) to the 189mf
listed in the updated FOW by the fall if and would like to perform the
upgrade of the booster PR if no adverse reactions would be anticipated.

[David Friedman]

My position is that the UMSR is a better part - but is not a critical FWO (necessary to obtain satisfactory operation)

 

I probably will write up a discretionary FWO to use the USMR for the booster - and probably we can also reduce the cap - but failures of booster have not been a problem.  It clearly makes sense overall to use the same part for both compressors but it is not mandatory.

 

The install is very similar with the potential relay and its wires removed - and the UMSR put in its place and wired to the start and run caps exactly as in the case of the primary. (r to s)

 

David

[USN-LPD7]

I have been mulling this over and wondered if the only reason why we
have not seen any booster failures is because the main compressor
failed before the booster or the booster just hasnt run enough to have
the problem pop up. I will probably do the swap in the fall when I
install the upgraded board just so I have some peace of mind, I will
run my install steps by the group just to make sure I dont blow
anything up.

[David Friedman]

The reason from my analysis is that the booster is a single direction motor and doesn't have the dual relay circuit.  The three wire start used is virtually identical to that used for the older t-89 used in the ACHP which didn't tend to fail.

 

When there is only one direction of spin only one contactor is used and a single potential relay works perfectly.  The only reason to use the USMR is to get uniform parts - but reliability should be the same.

 

David