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john-hvac-new
11-09-2009, 04:04 PM
Starting from a call for heat:

1. With factory-set blower CFM, roughly how long should it take for the high side pressure on a 3.3 ton split heat pump system to get to say 90% of its eventual maximum - in heat mode? Indoor temperature is 79F. Outdoor temperature is 55F.

2. All else being equal, how much quicker (if any) would the high side pressure get to that 90% level - if the blower was, instead, set to a lower but 'approved', optional speed?

Assume there are no obstructions in the system, the coil, filters, etc. are clean, the system, including all duct work, was properly designed and installed, everything is working properly.
beenthere
11-09-2009, 04:14 PM
That would depend what the factory set CFM is.

Not all brands use the same size air handlers/blowers.
john-hvac-new
11-09-2009, 04:47 PM
That would depend what the factory set CFM is.

Not all brands use the same size air handlers/blowers.

I can't decipher the manual, so I can't give exact numbers. But, suppose the lower setting on the blower was 2/3 of the factory setting.

I'm just trying to get an idea of how 'influential' blower CFM is on the early pressure buildup phase - as in, say, the first 30 seconds.
beenthere
11-09-2009, 05:09 PM
Can't say for sure.

If everything is proper. Not too much.

Problem is your system, probably doesn't have everything proper.
john-hvac-new
11-09-2009, 05:59 PM
Can't say for sure.

If everything is proper. Not too much.

Problem is your system, probably doesn't have everything proper.

Good point. Thanks.

That answers a nagging question - whether an "approved" but non-factory blower setting - by itself - would be causing the strong line-set/indoor coil vibration I'm getting within 30 seconds of the call for heat.

It has to be more than that.

I'm still waiting for the new contractor and the Goodman rep to come out. I talked with the new contractor again today. He says the request for some of the rep's time has been placed and we are just waiting for the rep to become available.

In the meantime, I continue to wonder about the what-ifs that I know are in the mix.
beenthere
11-09-2009, 07:08 PM
Good point. Thanks.



In the meantime, I continue to wonder about the what-ifs that I know are in the mix.

Try not to give yourself an ulcer while waiting though.
john-hvac-new
11-09-2009, 11:23 PM
Try not to give yourself an ulcer while waiting though.

:eek2::toetap::limb: