Mismatched units?

[Ti-Ben]

Hi all, I'm new here.

I installed a YHJF 2,5 ton (York) unit at my brother in law's house. His indoor coil is an almost new Amana 2,5 ton. System is running on 410a. It doesn't have a txv and the orifice was properly sized when I installed it.

I installed the unit last fall and the B-in-L was complaining that the unit was noisy... In heating mode the high pressure was at 450 psi, so I needed to remove some refrigerant from the system to bring it down to a reasonnable pressure (350 if I remember correctly).

He is now telling me the unit is not performing good this summer, so I go there and give a quick look at the pressures: 250 psi head and 150 psi low. Ambient is 90F and indoor 65F WB. I didn't have my probe to look at SH.

I added some refrigerant hoping to see the head go up, it stayed at a solid 250.

I'm thinking maybe the outdoor unit is too big for the indoor unit, but if it was the case the low pressure would be very low, which is not the case. What am I missing there??

Thanks

[gregp]

the indoor coil was "almost new", maybe you should've installed an Amana heat pump for a proper match. Alot of times when units are mis-matched, they just flat out won't work properly. It is also possible the outdoor unit requires a larger (3 ton) indoor coil. Add refrigerant in the summer, take it out in the winter.

[ar_hvac_man]

It is also possible the outdoor unit requires a larger (3 ton) indoor coil.

It does

[Ti-Ben]

It does

That's what I thought...

We didn't install the Amana cause the neighbor took the option when they bought their house and it is incredibly noisy.

[Juan Madera]

HP's are "mismatched" even when factory "matched" as the functions are different in winter and summer. Factory finds the best compromise in design. We mix 'n match and really screw things up.

Might want to explore using tev's to try and salvage the operation. Or better yet, get the correct indoor coil. Might be cheaper in the long run and a lot less angst at family gatherings!

[Tim Race]

you can make it work but you need more refrigerant in there. 410A on a 90F day and only 250? Not knowing the lowside pressure I'd say you aren't close yet. Darn 410A systems are critical charge SOB's. As for the noise, is it right under his bedroom window?

[BaldLoonie]

I'd try a TXV. When you say right orifice, is it right for the York or the Amana or were they both calling for the same size?

I needed to match a Goodman 3 ton HP to a new indoor unit. Goodman called for 3743 coil. I called Jmart and they don't stock, quoted me 3642 coil. I said if Goodman wanted me to use that they would have published that match. He said call tech support. Tech support said no to the 3642, TOO SMALL. I would have run into the same issue as Ben. I advised the Jmart boys they were giving me bum info. They were surprised.

[Tim Race]

my bad. Now that I'm awake and read it again I see NO TXV this time. As Bald Loonie points out the problems with orifice. I'd vote for putting on a TXV. Now I'm going someplace cool, long night followed by a long hot day.