Adding a A/C unit

[Andy T. Bishop]

Hi
I had a call today from a guy looking for an inspection. He was wanting to know if he can add a A/C unit to the HVAC unit. I haven't done the inspection yet but am curious how i would verify that? I know i would have to calculate all the window drafts and size and many factors but i am just looking for a ball park. Like, what size unit would it have to be to be able to condition a 2000 sq ft home? or a 1500 sq ft home?
Appreciate

Andy Bishop
Bishop Home Inspections, LLC
269-686-6485
bishophomeinspection@charter.net

[Russel Ray]

Originally Posted by abishop

Hi
He was wanting to know if he can add a A/C unit to the HVAC unit. I haven't done the inspection yet but am curious how i would verify that?

I haven't run into a furnace yet that couldn't have a cooling condenser added to it.

However, cost is a different story.

If the lineset still has to be run, the cost is going to be greater than if the lineset is already in place.

In South Texas many decades ago, we used to try to get one ton for every 1,000 SF. That was a minimum and rarely worked for the homes with glass walls looking out over the Gulf during the humid heat of summer. Eventually, everyone started using two tons for every 1,000 SF, but that was waaaaaaaay too much for the homes with no windows 10 miles from the coast in the non-humid heat of summer and caused its own problems. As far as size goes, then, I'd let the HVAC tech do those calculations because he should, hopefully, take all that other stuff (siting, roof type, wall insulation, etc.) into consideration.

[Andy T. Bishop]

Sorry for the ignorance but what is the lineset and what should i be looking for?

Andy Bishop
Bishop Home Inspections, LLC
269-686-6485
bishophomeinspection@charter.net

[Paul W. Abernathy]

Dang....guess it is just me but something like that I refer to a HVAC technician...lol...hate to tell a guy one thing and have a tech who is doing it everyday come in and say the HI was wrong...lol

[David A. Andersen]

As Russell indicated there is no way to size an air conditioner in accordance with the square footage of the house. Some contractors can do this based on information which is common knowledge to them such as common type construction for your particular geographical area etc. but there are too many factors involved for you as a home inspector to make that determination.

The issues that you may want to relate to the client is that an air-conditioning coil must be placed on top of the furnace (or down airstream in a horizontal furnace), this requires modifying the existing air ducts for a proper fit. A condensate line to remove water produced by the air conditioner must be routed to a drain or to the exterior of the house. An auxiliary drain pan should also be placed under the furnace as there is unlikely one there for the furnace (if the furnace is located in a finished space or above a finished space). The line set, which is two copper pipes (one that is insulated) must be piped to the outdoor condensing unit. This may require some creative installation as the piping must be installed inside a wall chase or up the side of the building (if on the outside of the building, the refrigerant lines can be installed inside of a false gutter downspout for aesthetics). The outside condensor unit requires a concrete pad, an HVAC disconnect /circuit which must be run from the main electrical panel to the exterior wall where the condensing unit will be located. This requires additional breakers in the main electrical subpanel. The capacity of the unit will be determined by the particular equipment utilized. This is a high amperage circuit requiring substantial current capacity.

The cost of this installation will be affected most by the retrofit requirements running electrical and refrigeration piping to the indoor furnace and main electrical panel.

As posted, any project like this should be referred to the people that will likely be doing the work as there are many variations and unforeseen problems that may be involved in the application. Years ago I could give you an estimate, but today I wouldn't even go there, or try. All the clients want a ballpark estimate but "I won't even attempt a guess".

[Doug Edwards, CMI]

If you are not familiar with what a line set is you are already in way over your head for doing HVAC calculations. I know how and I would still refer this to a licensed HVAC contractor.

[Andy T. Bishop]

I understand this is above and beyond the scope, i just was more curious than anything. I want to learn more and more as you can never know to much.
David...........you told me EXACTLY what i wanted to hear.
Thanks

[David A. Andersen]

Welcome!

[jrupert]

Don’t forget that effective 1-1-2006 units not meeting 10 seer efficiency rating can no longer be manufactured, and 10 seer units may not be available. The new Fed law requires the unit to be at least 13 seer, this translates to quite a $$ dollar increase in customer cost and the size of the equipment is larger for both the indoor evaporator coil and the out door condensing unit. If the house does not have a newer furnace, he may be required to replace what he has to a smaller stature unit to accommodate the larger more efficient evaporator coil.

Refer him to a local HVAC company and avoid looking unprofessional by giving him wrong information

[Russel Ray]

Originally Posted by jrupert

Don’t forget that effective 1-1-2006 units not meeting 10 seer efficiency rating can no longer be manufactured, and 10 seer units may not be available. The new Fed law requires the unit to be at least 13 seer

Can someone post a link to that, or the information itself, so that I can put it in my Interactive Report System Version 2? Thanks.

[Michael R. Boyett]

Here's a short thread I started a few weeks ago on the old board regarding the new requirements. Just fyi...http://www.nachi.org/bbsystem/viewto...highlight=seer

[Russel Ray]

That says:

. . . beginning January 23, 2006. Any less efficient unit made prior to this date can still be sold, installed, and repaired, but no additional ones can be manufactured.

I suspect there is information at the DOE web site. If no one else gets there first, I'll find a link this evening or tomorrow.

[jrupert]

http://www.mindfully.org/Energy/2004...ules3apr04.htm

http://www.howellsac.com/webapp/GetPage?pid=226

http://www.contractingbusiness.com/2...e/False/11710/

Yes the actual date manufactures are required to stop manufacturing is Jan 23rd, but they are currently changing over to the new systems now effective Jan 1.

The lower seer can be sold but not made. Stock here in Ohio should run out in July

[gmartin2]

Say Fellows;

Hows' about a Custom Aire forced air furnace serial# c-5672. Age? (1oo,oooBTU)

Geo

[Russel Ray]

Well, what I can find is that Custom Aire was manufactured by Lear Siegler, which last manufactured in 1975 and is now out of business. So it looks like yours was manufactured in 1972, union week ending May 6 (Saturday).