I am thinking about replacing my 13 year old 13 SEER 3.5 ton R-22 single speed AC with a WF 7 split 42 or 50 in order to have better AC and provide a first stage of heat to the house that has a mix of radiators and radiant floor heating. I have a few questions to iron out before inviting contractors in. There is plenty of space for drilling and all the electrical, plumbing and duct work is in place. Whether the duct work can support a 42 or a 50 will have to be determined by contractors should I decide to have some come in for a feasibility analysis and bids. Line set vertical I read the IOMs cover to cover and the main issue I see is the vertical distance of the line set recommendation being 25 feet and maximum length of 80 feet. The vertical would likely be closer to 30 feet and the horizontal maybe 15 feet for this install with the condenser in the basement and the SVH air handler in the conditioned space of the attic where the current horizontal air handler is. Is 30 feet pushing it on the vertical for the line set? Line set reuse The current R-22 line set is 3/8 liquid - 7/8 suction (the size required for the 50. 3/4 suction for the 42). Reusing the line set would be nice, but hopefully a new one could be installed without tearing out too much wall. I read up on chemically cleaning line sets for reuse but I am not sure if anyone really does it, especially for expensive variable speed equipment. Should I accept that a new line set is required and that reusing is too risky? Condenser placement I have the option to place the condenser in either the old basement or a few feet a way on the other side of the old exterior wall in the new basement. The new basement slab sits on and is wrapped in 3/4 inch of insulation. Would that be any better for sound and vibration isolation? To summarize the questions: Is 30 feet pushing it on the vertical for the line set? Should I accept that a new line set is required and that reusing is too risky? Is the insulated basement slab better for noise and vibration? Thanks in advance!
R-410a operates at higher pressure than R-22, so there's some chance the old line set might not handle the pressure, especially at any joints. A different, non-compatible, oil is used in R22, so you need to flush out all the old oil. I believe the main concern with sizing, length, and maximum vertical distance has to do with maintaining a certain velocity so oil will return to the compressor. There could also be capacity loss. I'd recommend contacting Waterfurnace regarding the line set. They might be able to do a calculation to see if your particular line set configuration will work and/or have steps they recommend that would make it work. Can you go with a packaged 7 Series and put it where the current air handler is located?
If the packaged unit could lay in a horizontal left configuration it might work, but I could not envision how that would work the existing duct work that is in a horizontal left with some bracnch ducts running along the back of the unit. The unit is about 1 foot inside a wide set of bi-fold doors. There is not much vertical height due to the roof. It's may be 5 feet that then slopes back behind the unit to the attic floor. I'll will probably have to go with a new line set unless a contractor convinces me otherwise. Thanks for the feedback and suggestion.
The 7 Series can be ordered in a horizontal configuration, with either side or end discharge. Best to have an installer look at what you've got. The nice thing about the packaged unit is it comes pre-charged and nobody should ever need to crack the seal to mess with the refrigerant charge. I wouldn't let a contractor convince me to use the line set, unless I had an OK in writing from Waterfurnace. An out of spec line set could damage the compressor, so I'd expect it to void any warranty claim.
