Line set for new HP system

[troyport]

My current 3 ton AC has just under 15 feet of line, 3/4" suction, 3/8" liquid. The soon-to-be-installed 3 ton heat pump literature suggests a 7/8" suction, buy my installer says since the run is 15 feet the 3/4" is fine. I am not so sure... I figure the manufacturer knows what is best. Opinions? Thanks, Mike.

[wahoo]

Put the correct size line set on unit. If you have to pay extra, then so be it. The new system is rated with the proper size lines!

[beenthere]

You will lose 80 BTUs of capacity. Not enough to even notice.

[bmathews]

I don't really understand suggesting a 7/8" suction line. Either it says you need it or it doesn't. Pretty cut and dry. If it says do it, then it needs to be done and you will need to pay extra for the running of a new lineset. While I have no idea what they are installing and it makes no difference to me, most 3 tons require a 3/4. It really depends on the distance of the run.

[duckman06]

What brand hvac system are they going to be installing? 3/4 and 3/8 is good for 15 foot with any R410a systems that I have seen. Now if you were going to run say 50-100 foot the need for 7/8 and 3/8 might be needed.

Shoot with Trane 3/4 and 3/8 is good for (3.5) tons depending on the length of the line set. Now this is again with r-410a systems. Does your installer have a piping
Program/line set size on his computer? If so then he can run the numbers and see what is needed!

If all else fails and you are concerned about the line set sizing pay them to install the bigger lines. A standard install does not call for line set to be changed as along as sized properly. They will need to flush existing line set with approved methods that the manfactor of the equipment recommed and pull a good vacuum to ensure all old refrigerant and moisture is out of the lines.

[catmanacman]

how hard would it be to run a new one ?

[troyport]

Thanks for the input. Goodman 16 seer 3 ton HP, finishing off a hybrid system with my last year installed 80K modulating furnace. Sorry about the lack of information. The manual I found on line says 7/8" lineset. The installer said due to the length of the run the 3/4 line set already there would be fine. He told me no problem flushing and cleaning the lines. He has no problem changing the lines, he just thinks it would be a waste of money, since the run is pretty short the performance loss would be neglible. Just looking for opinions here, and I thank you for your input.