Is DIYing a replacement of Electric Furnace and Air conditioner worth it?

Question

My Air conditioner does not produce cold air, however heater part in Furnace works just fine. Air conditoner Unit is at least 20 years old and have no coolent left in the system. I am looking to change air conditioner before coming summer. A HVAC professional suggested to change air handler/electric furnace along with Air conditioner and he quoted $4500 for that. That is out of my budget, there please guide if I can reduce cost by DIYing some aspects of this project.

Here is the some facts:

House: 1200 Sqft Aparment-type condominum where Air conditioner unit is two floor above on roof-top. Electrical wires and Copper pipe lines are all in place on the roof-top and needs no replacement. I am comfortable with Electrical work but not sure about the tuning and installation of central air conditioner unit.

My objective is reliable work with minimum cost. What do knowledged people here thinks? What could be challenges in doing it myself?

Shall I get some help from HVAC professional and do some work myself to save some money? or wait a summer to save money and get this project done next year?

Thank you for any inputs.

Answer 1

The Air Conditioner

Upgrading an A/C is not a DIY job. The cost can be broken down to three components:

1. Buying the new equipment
2. work possibly suitable for DIY --- removing the old, disposing of it, moving the new into place, removing packaging, maybe the electricals if you've built up some skill and knowledge, cleaning up the site.
3. work not suitable for DIY, requiring training, experience and special equipment that you won't have if you're not an A/C pro because you only need to do this once every 25 years.

Trying to do "some of this" as DIY means buying all the equipment yourself, hoping to save a few % on the contractor's markup, AND doing all or most of #2 yourself, hoping to save the contractor some labor cost AND hoping the contractor won't mark up #3 just so they can still make some decent profit.

In return for all that, most contractors will refuse to work with you, and the ones who are willing, will not give you any warranty.

The Heater and Blower

Changing the air handler and electric heater MIGHT be a project for a skilled and experienced DIYer. If the blower is shared with the A/C it's DIY only if the A/C evaporator is a modular component and you can remove and replace the rest of the blower from around it without disrupting the coolant lines.

Condo?

All the above assumes the equipment is in your private space. If any of it is in shared space, notably the A/C compressor on the roof, there may be conditions in your deed/lease/agreement/whatever that require work to be done by licensed professionals, or sometimes even by specific ones or approved ones. Things might be even more complicated depending on what city/state/country you are in.

Answer 2

In the US, and probably many other places, there are very strict rules with respect to handling of refrigerant. That effectively means that beyond self-contained units (window air conditioners) and, I believe, certain types of mini-split units where everything comes pre-charged with refrigerant and ready to connect (and even then, I don't know if it is legal to install your own, just that it may be practical to install your own), an air conditioner normally requires working with refrigerant: capturing the old and charging, leak testing, etc. the new.

In addition, unlike plumbing and electrical where you can start with little stuff and work your way up, HVAC is much more of a "once in a while big job". The consequences (aside from legal) of messing up are significant. Bad water pipe connection and you get a leak, shut off the water and reconnect with minimal replacement parts needed. Bad refrigerant connection and it gets expensive pretty quickly.

That's aside from gas issues if you have a gas furnace, but if your furnace is in good shape, as indicated in the question, you may be able to do just the air conditioner now and leave the furnace (and gasfitting) for another time. But refrigerant is a real issue.

Answer 3

There are a number of issues with doing this replacement yourself. First off, you'll have to purchase and have delivered the new unit. Since the compressor for the AC is on the roof, you'll need a crane to remove the old one and place the new one. I'm sure the condo association will have strict guide lines on who can do what on the roof and require insurance. Your air handler and heating system are probably one unit and really should be replaced because the air handler should match the AC unit and efficiency numbers could vary greatly if you keep the old one. Any work you do would void any warranties on the system so be careful of that. If your heating system is gas, there will be requirements that a professional does the replacement due to the building being a multi occupancy building. Removing the old Freon and recharging your new unit will also require a professional.

I'd be checking professional installers to see if they offer any interest free financing or put off this until you save up the money. I'm all for DIYers but there are a few instances where the pros are needed.

Answer 4

Be sure it is your responsibility to replace the unit not the apartment complex. It is possible your existing system could be repaired, that depends on how long you plan on staying etc. You state "Unit is at least 20 years old and have no coolent left in the system". How do you know this. The coolant is probably freon which does not wear out but it does leak. If you have not had a reliable HVAC person check the system do it now before spending all of that money. The tech can tell you what the real problem is. He can tell you what parts need to be replaced. You have the condensing unit on the roof and the evaporator (air handling) unit and fan in the apartment. It is also possible one of the copper lines has been damaged causing the refrigerant to leak out. Many units made years ago had safety devices to protect the compressor so a leak would have stopped it from cooling. This is a starting point and has many unanswered questions that you need to get answers before a final valid answer can be given. Your best answer will be from an honest reliable and qualified professional that has checked the system out.