Missed match system

[koolerdude]

I just replaced a new 13 seer 3tons condensing unit today to an existing evap coil and I got some weird data.
pressure was off. low side was at 62 n high side was 250 during the 90deg out side temp. I heard other said that if u match 13seer condensor to a 10 seer evap, u get about an 8seer cooling capacity. wat are ur experience with the pre-installed mis-matched system?

[BaldLoonie]

Sounds about right. Smaller evap looking for higher head pressures so you have to overcharge the outdoor unit to get the suction up.

I hope you inspected the old coil for cleanliness before reusing?

[SBKold]

At least use the right piston # or install a TXV.

In florida they stopped allowing these 13seer condensors on 10seer handlers for this very reason.

[Home&Marine]

Where can a HO or DIY come to get some advice on their Hacked Mis-Matched System? Goooood 'Ol HVAC Talk!

[HJ Controls]

Ditto. Piston/txv. for the 10000000000 time. if you want a correct anwere we need subcooling and superheat. for the 100000000000000000000000000 time. and is it txv or piston your using. your head pressure is way low.

[SBKold]

Ditto. Piston/txv. for the 10000000000 time. if you want a correct anwere we need subcooling and superheat. for the 100000000000000000000000000 time. and is it txv or piston your using. your head pressure is way low.

Head pressure way low? No. way high.

[dandyme]

Ditto. Piston/txv. for the 10000000000 time. if you want a correct anwere we need subcooling and superheat. for the 100000000000000000000000000 time. and is it txv or piston your using.

whatjutryintosayWillis?

Head pressure way low? No. way high.

did i miss what flavor frexone is running in this thing?

[koolerdude]

Where can a HO or DIY come to get some advice on their Hacked Mis-Matched System? Goooood 'Ol HVAC Talk!

I went thru and finished training at an Hvac-r trade school. I started working for an Hvac company after school end in June. My boss did the selling, proposal and pricing. His clients want cheap, so the solution is to just replace old condensing unit with newer one. Now 13 seer is the min. so that's what we got for the installs. He didnt tell me about the loss capacitor of the mis-matched system. I over heard from other technicians. I brought it up here just to see wat kinds of info. being discuss here.


Thanks for those who put out good discussion.

[HJ Controls]

my bad i was thinking 410a.

[jpsmith1cm]

There is a thread going in AOP Residential right now on this very topic.

http://hvac-talk.com/vbb/showthread.php?t=926552

Towards the end of the thread, there is some good information to present to your boss and your customers.

You are doing them NO FAVORS by mis-matching equipment like this. In fact, you are actually costing them money rather than saving it for them.

[Paul Bee]

koolerdude, get your post count up to 15 and apply for pro membership! A lot of good training in the educational forums. Also check out www.rses.org

[walterc]

Some systems can be downsized if the home is in need of updating such as insulation in the attic which is cheap, sealing infiltration or even fixing windows etc. Some homes have already had this done and the load calc may show for example a 2 ton system will work instead of the present 2.5 or 3 ton system. In this case a 13seer with a reduced tonnage can be installed on a present 10 seer coil with acceptable operation.
This falls in the category of people who just don't have the money at the time for a complete change out. A more common occurrence now days.
I don't favor using any R22 systems replacements unless it can be converted to R410 in the future. In fact I have turned away quite a few jobs because it was just wrong and let the other contractor do it. I have gotten calls to fix such wrong applications after I had turned them down and they had mr xx do it. I sadly say to them- they are stuck unless they allow me to redo all that been done and it is costly.

I NEVER mix match heat pumps.

[koolerdude]

koolerdude, get your post count up to 15 and apply for pro membership! A lot of good training in the educational forums. Also check out www.rses.org

I'll do that. Thanks.