2-ton comp in a 5-ton RTU!

Dave Yates (GrandPAH) · July 2012

Eugene,

Something we (hopefully) don't see every day: recently responded to a VFW for on-going problems their (previous) HVAC service provider couldn't resolve. Following the compressor's replacement a year ago, they spent more than $4K in attempted repairs to no avail. Upon arrival, we found the evap coil plugged shut, 2-2" filters and 2-1" filters (should have been 2") so filthy that no daylight could be seen holding them up to the sun! In checking the York D3CG060 (5-ton) unit, we discovered the 'new' compressor was a Bristol H22J22 (22,622-Btu capacity). Operating pressures were 100-suction & 120-discharge & this unit has a cap-tube metering system. In addition, our further inspection revealed several linear cracks in the tubular HX.

We replaced the RTU with a new 5-ton (including a 5-ton compressor!) unit. Given that this was a cap-tube system designed for 5-tons, would you believe the system pressures we encountered were what would be expected due to the lower 2-ton flow of refrigerant in a 5-ton cap-tube metering?

We have not (yet) recovered the freon to determine how much R-22 had been installed and are holding the RTU in storage per the VFW's request while they seek reimbursement from the HVAC contractor who had them on a 4x per year maint schedule.

Thanks,

Dave Yates

Empire_2 · July 2012

Now that's something every day.

I'm trying to understand what or why the 2 ton comp. was installed and I think there were problems and what ever it was the other guy's added more and more ref. Was your Super heat high? Since cap tubes work off pressure differential and (assuming) they had weird pressures, they jammed more ref. into the system to at least bring up the head pressure. Anyways, Hard to believe that contractor got away with the shoddy work.

Mike T.

PS; good job and finding problems like this is your job, so disclose your findings to owner of VHW.

Dave Yates (GrandPAH) · July 2012

On cheating vets

I can see making a stupid mistake: Lord knows I've had my fair share of them. But, after they made the bone-headed swap-out, they either couldn't figure out what was wrong or they deliberately decided to deceive the VFW. Hard to believe this was a repeatedly overlooked issue as the outfit that did this has been in the HVAC business for decades. Not my call, however, and we'll see how it plays out. All I can do is report the facts as we know them and let the VFW take whatever action they deem appropriate.

If this has an outcome where they release the RTU to us for recycling, we'll recover and weigh the charge to determine how close to the original charge they were.

Given the lower flow of R22 from a 2- vs a 5-ton compressor, and a fixed orifice (cap tube), I'd be curious if Eugene can weigh in on what pressures we might expect under the circumstances. 87f ambient, 78 return air, 100-psi suction, & 120- to 125-psi discharge with all coils cleaned. I'll need to check with our techs to ask about super heat.

don_9 · July 2012

Good fine

Mr Yates and crew.I bet he only charged 200 a year for four times a year.Lol

With that low of of a differential pressure on the compressor side you would have the same symptoms and reading you would get with a compressor that has decayed as in weak valves.it will cool but has lost its capacity.the superheat would be high and more then likely the subcool low even with an overcharge bc you have so much freon backup in the condenser it unable to transfer any heat.

Techman · July 2012

Now hang on

on a bad day ,that 5 in the comp mn# does look like a 2 upside down after you've just come out of that dark VFW and into the bright sunlight.Compassion.

Empire_2 · July 2012

To say the least

Terry don't forget sliding down that pole can also cause dysfunctional eye sight in addition to your statement.

Mike T.

2-ton comp in a 5-ton RTU!

Comments

Categories