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condensing unit changeout

If I may ask..who has the liability if the hx goes out in acouple of are customer?

York used to make a flat coil.Its like the n coil you see now but a bunch of them put together.Its only about 12 inces in height.

Its always best to match a new coil to the condenser so one would have a match system and know what type of capacity and efficency it can produce.

As for the r22 issue..sure the coils will still be around
along with r22 or a drop in soon to follow then it not a issue.Price may be but,hell its his money let him spend it the way he chooses too.

Sure, you can put a 3 ton coil on a 2 1/2 ton condenser.your metering device and airflow will dictate rather its working properly.

I would asked the owner if he would be willin to spwnd the money to have a few test ran so you and he could make the right decension.

Start off with offering to do a heatgain and loss on the home.You might be surpise find that the furnace he has now
is to big.Then it become a easy sell for a new furnace.
Also you may discover that the ac is to small or to big.
then that to become more ammno to offer newer equipment.

If you were to measure total external static pressure on the system he has now you made be supise to find that he does not have the needed cfm that he needs to support a new ac system.Heck it might even show that he distribution system is leaking big time.

When you have the math to backup what you are tellin them it makes for a easy sell.The hard part his getting them to pay you to do the testing.

Good luck..hope this helps.


  • ddenny
    ddenny Member Posts: 75
    condensing unit changeout

    someone wants me to change out an old condensing unit and an "A" coil. the oil fired furnace the coil sits on is a high boy over 20 years old but he doesn't want to go for a new furnace yet. the a/c he has now is an r-22 system. I don't think it's a good idea to put a new a coil on top of an old furnace. what if the heat exchanger goes in a couple years. I've only got 15 inches between the furnace and ductwork and don't think I can squeeze an "A" coil in there. the shortest rheem "a" coil I could find needs more than 20 inches height. I think it's a better idea to change just the condensing unit. then when he wants to get a new furnace, that's when I'll put the "A" coil in.
    question is will I be able to get an "A" coil that works with r-22. will they be available a few years from now? don't think I can put a 410a condensing unit with a coil that is now using r-22.
    one other question. the system he has now is 3 tons. the "A" cioil has a tx valve. I think the unit is over sized. can I put a 2 1/2 ton condensing unit with a 3 ton coil.
    would appreciate some feedback. thankyou
  • ddenny
    ddenny Member Posts: 75
    condensing unit changeout

    hello don
    thanks for your answer.
    I did a heat load heat gain calculation already. nice software from it's an oufit in canada. the job I'm looking at has a highboy oil furnace. I didn't look at the btu rating but I'm pretty sure it's oversized. the heat load according to the software was less than 40'000 and the heat gain called for 1 1/2 tons. the condensing unit is very old; can't find any model number on it or the air coil. there was the number 3 stamped on the tx valve so I'm assuming it's a 3 ton air conditioning system. so that's oversized too. I'd be scared to install less than 2 tons though. the smallest oil fired rheem furnace is 50+ thousand and I would be comfortable with that.
    the ductwork is old but it looks like thick gauge and very sturdy. I have a magnahelic gauge but not sure how to use it or what I'm looking for with static pressure. do I drill a small hole in the supply and return ducts then stick the probes in each side? what am I looking for?
  • don_185
    don_185 Member Posts: 312

    You would want to make sure you have a static pressure test tube first.

    Then you would drill you a hole at the return after the filter and before the furnace.Thats your negative reading.Then drill another hole before the coil and after the furnace.that your postive reading.
    Add the two together and you will get your tesp.

    Sorry Dennis,I had to edit. I almost had you leaving your filter out of the equation.Oppps.

  • tim smith
    tim smith Member Posts: 2,397
    Improve his energy costs!

    Go with a heat pump. Do your heat loads, figure total air flow and put in a properly sized heat pump using the oil furnace as backup. If you do a good job he will thank you. At today's oil rates it would be crazy not to use alternate energy to oil. Good luck, tim
  • Mitch_4
    Mitch_4 Member Posts: 955

    Get him to find a way to finance the entire job.(line of credit, home loan, many manufacturers offer it as well) Replace the entire system, use an air to air heat pump, and a oil furnace with ECM, 2 stage stat, have him figure out his heating and cooling costs, and put any savings into the payment, his ROI is likely 3 years if the old unit is WAY oversized. same with the A/C. I know by right sizing and using this strategy (high eff gas instead of oil thought) my gas bill dropped an average of 138.00/mo and the electricity 75. I am saving an average of 213.00/MONTH!

    (FYI..old system 125,000 gas furnace, maybe 60% efficient, 2.5 ton 5 SEER A/C, new system is an Olsen G95V 60k 95% 2 stage gas36k low fire) with a 2 ton heat pump 13 SEER, 2 stage stat, with the 2 stage furnace operating on timer delay of 10 minutes, giving 3 stage heating..)

    With this strategy, it'll cost him more up front, but you can tout the advantages of savings, comfort, and a system that is designed to operate together for max comfort. rather than a patchwork, that may not be the best, and he has a totally new system.

    I charge X for furnace, Y for Cooling system, but offer a nice discount if I do both same time..point out the charges if done seperately, you gotta SELL the comfort...

  • Eugene Silberstein_2
    Eugene Silberstein_2 Member Posts: 349

    You have a number of options. As far as the R-410A concern goes, you would need to check the test pressure of the existing evaporator coil. If the coil has a test pressure above 235 psig, you can use the coil with a 410A condensing unit.

    The replacing of the existing evaporator coil should not be affected by the condition of the existing furnace if the customer has his/her heart set on replacing only the cooling portion of the system. If you are not willing to replace the components the customer wants, it will not be difficiult for him to find someone who will do what he wants.

    Ideally, replacing the furnace along with the cooling equipment is desirable, but you will have to do your homework in determining an estimated payback period to seal the deal. If the heating system is as old as you mentioned, this should not be a difficult task.

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