to coil or not to coil

[tunacan]

I am replacing an upright 75,000 btu furnace. Every contractor has advised me to replace the coil whilst replacing the furnace (no problems with the 25 year old a/c, coil, outside condenser, etc. - the furnace has a cracked heat exchanger). Should I replace the coil when I replace the furnace?

[ammoniadog]

It depends on how much money you want to spend. If you have lots of money, have the installers re install your old air conditioner coil into the new furnace plenum and keep trying to milk out your inefficient dinosour air conditioner to see how long you can make it last. You might get a few more months or years out of it. If you would like to save money, get a complete new higher efficiency air conditioner installed at the same time as the furnace.

[AvantGarde]

I am replacing an upright 75,000 btu furnace. Every contractor has advised me to replace the coil whilst replacing the furnace (no problems with the 25 year old a/c, coil, outside condenser, etc. - the furnace has a cracked heat exchanger). Should I replace the coil when I replace the furnace?

I'm in the same boat w/cracked HEx. Unless your family's in a financial bind, do the right thing and replace it all. I'm just dippin' my toe into this HVAC ocean, these guys on here are dog gone good and will help circum-navigate the sharks and pitfalls.

God Bless
AG

[tunacan]

i think i get your point. I should mention that this is a rental (don't really care about efficiency) and I have been advised by one contractor to "not open the system, keep the existing coil - the outside condenser could last another 10 years"

[ammoniadog]

-- the outside condenser could last another 10 years"

It might be able to make it 10 more years, but the odds are not good, especially when you say it's for the rental property. You usually will get a better deal by buying and having everything installed at the same time.

[beenthere]

Unless your changing the outdoor unit at the same time.
Don't replace the indoor coil.

The coil is part of the A/C, not the furnace.

[Kevin O'Neill]

Unless your changing the outdoor unit at the same time.
Don't replace the indoor coil.

The coil is part of the A/C, not the furnace.

What beenthere said.

[tunacan]

Thank you 'beenthere' and 'KO' ... you seem to support what the contractor who made the best impression told me: "opening the system (coil/condenser) creates more problems than it solves". The others recommended replacing the coil now in case it failed later. So ... I guess this is a case of "if it ain't broke, don't fix it"?

[heaterman]

What beenthere said.

I'm of the same opinion. Inspect and clean the old coil and leave it be.

[catmanacman]

it is possible that the old coil is so clogged it will need to be removed and cleaned (WHY DID THE HEAT EXCHANGER CRACK) if this is the case i would replace it, ask about a builder grade complete system

[tunacan]

Catmanacman, could you elaborate? You ask "why did the heat exchanger crack" as if there is a relationship with or affect on the coil ...?

[clintkennon]

I would. 25 yrs old!

[catmanacman]

if the coil is clogged it can cause the furnace to exceed the rated tempature rise or overheat and cause the hx to fail or crack

[tunacan]

Catmanacman, I'm confused now (and I guess that is why this forum allows the homeowner in). As I understand it, the coil is part of the a/c - it is a heat exchanger where refrigerant picks up heat from the house. How can this affect the furnace heat chamber?

[pecmsg]

Rental property or not 25 years old it had a good life. Has any one performed a heat load / loss calculation yet? If not get it done.

[BaldLoonie]

The coil is part of the A/C but it is in the airstream of the furnace and uses the furnace's blower to move air over it to cool the house. If it is dirty, it can restrict airflow causing the furnace to run hotter and cause the heat exchanger to crack. The installer should check it once the furnace is out and see if it needs to be cleaned. It would have to be very plugged not to be able to be cleaned in place with a stiff brush or possibly some evap cleaner spray.

[tunacan]

BaldLoonie, thany you. Yes, that is how I understand the system, but didn't realize it could affect the hx (clogged=overheat). I have heard stories of people not using or replacing filters and the coil getting dirty and needing to be cleaned ... It sounds as if you are in the camp that recommends keeping the existing coil if it is clean, etc.

[catmanacman]

[QUOTE=tunacan;2086525]I am replacing an upright 75,000 btu furnace. Every contractor has advised me to replace the coil whilst replacing the furnace we cant see it from here mabey they are seeing a rusted drain pan or other things as to the reason they think it needs replaced other than just old ,25 years ago drain pans were made of metal and they do rust though and leak water into the furnace

[tunacan]

Catmanacman, you raise an interesting point ... the furnace - the burners, the hx - has a lot of rust. None of the contractors mentioned that it may have come from the coil or drip pan. Rather, they all said it is "condensation" and I think explained to me that it is natural for a furnace to "rust", or to produce condensation that causes rust ... So, is this another way of saying the coil has caused the rust? I should also add that each contractor merely stated that it was cost effective to replace the coil NOW because of the cost of labor later ... i.e. convenient - the point being that none of them said outright that the coil was a problem or caused the rust.

[catmanacman]

Catmanacman, you raise an interesting point ... the furnace - the burners, the hx - has a lot of rust. None of the contractors mentioned that it may have come from the coil or drip pan. Rather, they all said it is "condensation" and I think explained to me that it is natural for a furnace to "rust", or to produce condensation that causes rust ... So, is this another way of saying the coil has caused the rust?

no, just saying that the coil can have other problems that are not visable unless opened and looked at, if you do not want to replace the coil then dont but do not blame the contractor if later on it causes problems with your brand new furnace such as leaking water onto the motor or circuit board and is not coverd by warranty all im saying is the contractors have come to your house and looked at it and for some reason they think it should be replaced if you dont trust them call someone else

[tunacan]

Catmanacman, I appreciate your point and good advice. I had several bids and all suggested replacing the coil now and all made a favorable impression. IF I may push my luck, do you have any problem with following these recommendations to replace the furnace and coil, but not the condenser (in consideration of the upcoming refrigerant change)?

[biglew1973]

Catmanacman, I appreciate your point and good advice. I had several bids and all suggested replacing the coil now and all made a favorable impression. IF I may push my luck, do you have any problem with following these recommendations to replace the furnace and coil, but not the condenser (in consideration of the upcoming refrigerant change)?
tunacan, I have been in the trade for 12 yrs, I have been in alot rental houses, talked with alot of land lords. D o you have a regular contractor you use? Or do you go through a phone book for the cheapest guy everytime? You know what your used to doing when it comes to your property. If your usual contractor says replace the 25 yr old coil then replace it. My recomendation would be since it is a rental, and I wouldnt want to be bothered with an HVAC problem when the cooling season comes around, just put a contractor grade system in and be done with it. Its time to bite the bullet!!!!!

[tunacan]

Biglew1973, are you talking about the outside condenser as well, or just what has been recommended by all the bidders: replacing the furnace and the coil and keeping the condenser?

[biglew1973]

I would for what its worth replace the outside unit, A-coil and furnace.

[Kevin O'Neill]

The evaporator coil and the condenser are a matched set. If you replace the coil, for whatever reason, replace the condenser at the same time with a unit that matches the coil.

[tunacan]

KO, at the risk of belaboring this already trodden dog, what about the idea of buying a new condenser now when the new refrigerant models are coming out soon? Thanks, tc

[biglew1973]

it doesnt matter its a rental house!!!

[hvacrmedic]

I'm not sure what you're looking for, but IMO you'd likely be money ahead to replace the entire system with an R410a system. Sure you "might get 10 more years out of the existing AC system" but it's a long shot. Odds say that it's more likely that it won't make it through the next summer. 25 years is old!

If on the other hand you replaced the coil right now, without replacing the condensing unit, then you run the risk of having to replace the coil all over again when you finally do replace the condensing unit, because it's likely that the coil you just put in won't be compatable with the new condensing unit. We've already been through this with the switch to 13 SEER, and now we'll go through it again with the switch to 410a. In just a couple of years you won't be able to get a new R-22 condensing unit of any SEER, and certainly not a 10SEER R-22 condensing unit. What evap coil are you going to install right now that will be compatible with both the existing condensing unit, and with the new condensing unit that you'll likely be installing within the next couple of years?

Either replace the whole system, or just the furnace, but do not replace the coil without replacing the condensing unit as well.

[tunacan]

hvacrmedic ... thank you. Should I (can I) get the new 410A equipment?

edit: oops, sorry. I see where you recommend the R410A system. Thanks.

[Kevin O'Neill]

KO, at the risk of belaboring this already trodden dog, what about the idea of buying a new condenser now when the new refrigerant models are coming out soon? Thanks, tc

The new models with the new refrigerant have been out for years. Didn't any of the contractors mention that?

[tunacan]

KO, no, but I will inquire. Thank you for your help ... you and all posters are greatly appreciated. Isn't the internet a wonderful tool ... yes!

[STANCILHVAC]

ONLY you know what your rental property is worth---if its a dump that dont make much money and gets torn apart about everytime its rented ,then i would do no more than needed---if its a decent place that brings fair money and has fairly decent renters and i planned on keeping it ---then of course you need to replace everything after 25 years and hopefully be done with it for a long time---if you dont --then in the long run its gonna cost more---i had a place that i rented out for awhile(learned my lesson there) i would fix everything to grade a before renting and it was a nice place but everytime i would get stuck on dead beat payers and they would pretty much trash the place in return everytime leaving me lucky to break even.Guy i know who has about 40 rental properties told me that the only way to make money was to go in and just paint everything in site with the cheapest paint,cheapest flooring etc.--get them in and when there done trashing it---slap another quick cheap paint job up and throw someone else in---anyway only you know what you have and if its worth putting out anymore than needed---thanks

[tunacan]

Stancilhvac ... thanks. Actually, this is a nice rental and I have had good luck (I live next door!). I am leaning toward replacing the entire system. I am curious, though, about the life span of these units. I have a Ruud unit in my house, installed in 1979 after I first bought this property. I think I have had only one service call in all these years, possibly to re-charge the lines. After the advice I have received on this site, I fear I am on borrowed time and am thinking about replacing my entire system as well. Your comments are welcome. Thanks!

[DOGBOY]

one thing i can think of. how old is your car? do you expect it to last for 25+ years? not too many daily drivers of that age out there now. older equipment was made to last but it will fail. and when it does will you be prepared to make a good decision under no heat or no cooling circumstances?

dogboy