fyrmnk Posted December 16, 2010 Report Share Posted December 16, 2010 Hi all, just want to make sure I am reading this right. Had 2004 Lennox Heat Pump Model #10HPB48-11P, which I take is a 4T unit? It had a C33-60D-2F-1 A-coil which I take as a 5T coil if I read Lennox's website correctly. Can anyone confirm this? I'm calling it out since it's a heat pump, I believe they should be exact. Thanks, Kevin Quote Link to comment Share on other sites More sharing options...
Marc Posted December 16, 2010 Report Share Posted December 16, 2010 Some coils will accept a variety of pistons for downsizing the tonnage to whatever condenser capacity you've got outside. An oversized indoor coil, for a heat pump in cool mode, will likely result in bubbles in the liquid line as well as reduced cooling and other issues. With practice, you can feel the bubbles in the line, if there's no sight gauge installed. Marc Quote Link to comment Share on other sites More sharing options...
fyrmnk Posted December 16, 2010 Author Report Share Posted December 16, 2010 Hmm, I know in my area they frequently mismatch sizes, but thought heat pumps always had to be the same size? Quote Link to comment Share on other sites More sharing options...
Marc Posted December 16, 2010 Report Share Posted December 16, 2010 Hmm, I know in my area they frequently mismatch sizes, but thought heat pumps always had to be the same size? That's what I think too. To do otherwise is to meddle with the system's design. Marc Quote Link to comment Share on other sites More sharing options...
Terence McCann Posted December 16, 2010 Report Share Posted December 16, 2010 An oversized indoor coil, for a heat pump in cool mode, will likely result in bubbles in the liquid line It won't affect the liquid line however the superheat will most likely be to high. It was wise to recommend calling a contractor to take a look at it. You'd really need gauges and temperature probes to see how it functions in the real world. Quote Link to comment Share on other sites More sharing options...
fyrmnk Posted December 16, 2010 Author Report Share Posted December 16, 2010 Just noticed I placed this in the wrong forum, loooong day. Thanks for the feedback. Quote Link to comment Share on other sites More sharing options...
hausdok Posted December 16, 2010 Report Share Posted December 16, 2010 Just noticed I placed this in the wrong forum, loooong day. Thanks for the feedback. Hi, There's no need to make a second post. Just PM me and I'll move it. I have. The other one is gone now. ONE TEAM - ONE FIGHT!!! Mike Quote Link to comment Share on other sites More sharing options...
fyrmnk Posted December 16, 2010 Author Report Share Posted December 16, 2010 Just noticed I placed this in the wrong forum, loooong day. Thanks for the feedback. Hi, There's no need to make a second post. Just PM me and I'll move it. I have. The other one is gone now. ONE TEAM - ONE FIGHT!!! Mike Sorry about that, thanks for the move! Quote Link to comment Share on other sites More sharing options...
Bain Posted December 16, 2010 Report Share Posted December 16, 2010 An oversized indoor coil, for a heat pump in cool mode, will likely result in bubbles in the liquid line It won't affect the liquid line however the superheat will most likely be to high. It was wise to recommend calling a contractor to take a look at it. You'd really need gauges and temperature probes to see how it functions in the real world. Totally in agreement, but wouldn't the condenser have to be overcharged to make a system like that function correctly? Quote Link to comment Share on other sites More sharing options...
Terence McCann Posted December 16, 2010 Report Share Posted December 16, 2010 An oversized indoor coil, for a heat pump in cool mode, will likely result in bubbles in the liquid line It won't affect the liquid line however the superheat will most likely be to high. It was wise to recommend calling a contractor to take a look at it. You'd really need gauges and temperature probes to see how it functions in the real world. Totally in agreement, but wouldn't the condenser have to be overcharged to make a system like that function correctly? Playing it out - you would think but to how much I couldn't guess. If your superheat was in line then the head pressure would be too high and the sub-cooling to low (over-charged). If the head pressure was ok, and the sub-cooling was ok then the superheat would be high (under-charged). An evap that is 1 ton bigger than the rest of the system is really stretching it. If, as Marc said, you changed the piston/TXV (you could split the difference) then you maybe able to dial it in where it would be passable however very unorthodox and not recommended. Seeing as so many new techs cut their teeth in the residential market it would surely throw them for a loop either way. Quote Link to comment Share on other sites More sharing options...
fyrmnk Posted December 16, 2010 Author Report Share Posted December 16, 2010 I did finally reach someone at Lennox, they confirmed it is not allowed and the A coil and Heat Pump have to be sized the same, at least on that one. Thanks Kevin Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted December 17, 2010 Report Share Posted December 17, 2010 I did finally reach someone at Lennox, they confirmed it is not allowed and the A coil and Heat Pump have to be sized the same, at least on that one. Thanks Kevin Also, be sure to check the actual coil. I've seen Lennox installations where the outer coil housing was labeled 5 ton and the actual coil inside the housing was, in fact, 4-ton. - Jim Katen, Oregon Quote Link to comment Share on other sites More sharing options...
davidlord Posted December 17, 2010 Report Share Posted December 17, 2010 I just had a new Trane 15 seer heat pump system installed with a 4 ton condenser and a 5 ton variable speed evap. Quote Link to comment Share on other sites More sharing options...
fyrmnk Posted December 17, 2010 Author Report Share Posted December 17, 2010 I did finally reach someone at Lennox, they confirmed it is not allowed and the A coil and Heat Pump have to be sized the same, at least on that one. Thanks Kevin Also, be sure to check the actual coil. I've seen Lennox installations where the outer coil housing was labeled 5 ton and the actual coil inside the housing was, in fact, 4-ton. - Jim Katen, Oregon Just curious, how do you determine that without disassembly? Even with disassembly, is there another label on the coil itself? Thanks, Kevin Quote Link to comment Share on other sites More sharing options...
Jim Katen Posted December 17, 2010 Report Share Posted December 17, 2010 I did finally reach someone at Lennox, they confirmed it is not allowed and the A coil and Heat Pump have to be sized the same, at least on that one. Thanks Kevin Also, be sure to check the actual coil. I've seen Lennox installations where the outer coil housing was labeled 5 ton and the actual coil inside the housing was, in fact, 4-ton. - Jim Katen, Oregon Just curious, how do you determine that without disassembly? Even with disassembly, is there another label on the coil itself? Thanks, Kevin That's the problem. You can't tell unless you disassemble it. Sometimes that's easy to do in the context of a home inspection and sometimes it's nearly impossible. Just be aware of the possibility when you write your recommendation. I got caught on that years ago. Now, when I write up a situation like that, when I can't get to the actual coil, I say so. - Jim Katen, Oregon Quote Link to comment Share on other sites More sharing options...
fyrmnk Posted December 17, 2010 Author Report Share Posted December 17, 2010 I did finally reach someone at Lennox, they confirmed it is not allowed and the A coil and Heat Pump have to be sized the same, at least on that one. Thanks Kevin Also, be sure to check the actual coil. I've seen Lennox installations where the outer coil housing was labeled 5 ton and the actual coil inside the housing was, in fact, 4-ton. - Jim Katen, Oregon Just curious, how do you determine that without disassembly? Even with disassembly, is there another label on the coil itself? Thanks, Kevin That's the problem. You can't tell unless you disassemble it. Sometimes that's easy to do in the context of a home inspection and sometimes it's nearly impossible. Just be aware of the possibility when you write your recommendation. I got caught on that years ago. Now, when I write up a situation like that, when I can't get to the actual coil, I say so. - Jim Katen, Oregon That makes sense, thanks for the clarification. I just advised what the sizes appeared to be based on the manufacturer's spec plates. I also emailed them also about what the rep at Lennox told me the next day. Thanks again. Kevin Quote Link to comment Share on other sites More sharing options...
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