Adding Air Conditioning to an Old House

[Dherbert53]

We just purchased an 100 plus year old house with forced air heat and a

1970's era furnace to use as a rental property.

My brother in law insists that the existing non-insulated ductwork cannot be used with Air Conditioning as it will cause moisture problems. We already have tenants scheduled to move in...they have allergies and are very upset about this new revelation.

My HVAC guy disagrees and claims that the existing duct is fine.

Which one is correct and what should I do?

Thanks

Dean in Cincy

[Shopdog]

First of all, whats your brother in Law do for a living?

and if I am getting this straight, you asked him AND an HVAC pro the same thing?

Unless your B.I.L. is an HVAC designer or and engineer for heat/ac systems, I'd go with the HVAC guy.

We DID NOT have insulated duct work and my house was built in 1980. The only place that had the insulated ductwork, was for the fireplace. We had a run of 15 ft for filtered room air to go to hit the heater box in a fireplace, so pops used the insulated. Only, I believe because it travelled through a crawlspace that was open to the elements VIA a 10X15? vent at both ends. Hey I was a kid I'm lucky to remember all that. But the bottom line is, that we never had an issue with moisture.

Searcher

[buffalobill]

from a buffalo ny landlord who has asthma and is allergic to house dust: both answers are correct subject to the insulation, vapor barriers, design of the house, and the temperature and humidity at the moment of giving the answer. upset tenants won't pay rent, let them out of the lease before they move in and tell them they should have any dwelling inspected before they move anywhere to be considerate of their medical requirements. depending on the seasonality and severity of allergies they could be allergic to a piece of new carpet or even peanuts in the bird feeder. buy out your brother-in law. rental home ownership cannot survive a partnership except with your wife. here, people move in summertime. i know how extreme it gets inland in ohio, i've visited there summer and winter. re-advertise that air conditioned house, new tenants will be more than happy to move into a 1970 home with ice cold air conditioning available to them. wonderful info and technical stuff at:

[hallerb]

dont need insulated ductwork....

most homes dont have it..

brand new homes built super tight are more likely to need it.

100 year old house forget about it........

[Shopdog]

I agree with Buffalo, If your prospective tenants are already complaining, it sounds like it might be more of a headache then its worth. I too would release them from the lease citing medical concerns. Then relist the rental property, you don't know how the house was built, you can only assume it was done correctly in regard to vapor barriers, ETC;.. The house my wife and I just bought looked great at the time we looked at it, it looked great when we did our walk through and even our inpsector said the problems he found were only minor. Well, things happen, our furnace died, a whole electrical circuit is not correct and the garage was a mess with errant electrical wiring. Seems the guy that had the house before ran wires whereever the hell he wanted without regard. You will never know all the problems a house poses prior to buying it, you have to live with it before it lets out all its secrets. Then you have to hope you have the knowledge to do the repairs or have the money to have them done.

Searcher

[m Ransley]

BIL is wrong, tens millions of houses don`t have insulated ducts, actualy few old ones did .

[Anthona]

Here in NYC, I got a notice of a new way of installing air conditioning without duct work into an old house. According to the notice, they say they will drill small holes in various part of the house, and its regulated with an outdoor product which feeds the cool air..not having to install new ducts or use old ones. You might want to check it out.

[Joseph Meehan]

I suspect many people would be put off from a home that lacked A/C As for medical concerns, you may want to contact an attorney before trying to use that one as a reason to cancel a lease as the lessee may well have rights.

Besides that, I think the situation needs a professional evaluation of adding A/C. Unless the brother in law is a trained professional, I suspect strongly that he has it wrong.

[Edwin Pawlowski]

Do not, under any circumstances, consult your brother in law for medical problem.

[Frank Boettcher]

Basic physics. If your metal duct carrying refrigerated air travels through warmer, humid environments (attic, crawl space) it will condense a tremendous amount of water on the surface of an unisulated duct. In an attic this will be disastrous as it leaks on the ceiling below. In a crawl space it is just the matter of efficiency as long as the ground below can drain properly.

Frank

[Stormin Mormon]

I was going to suggest that he go to the BIL for a minor surgery or two.

[Don Wiss]

I also have an 100 plus year old house with forced air heat. The house originally had hot air heat, but not forced (electricity arrived in my neighborhood after the house was built). The problem with this scenario is the ductwork is all wrong, especially the return. For heat only the returns are only on the lower floors. For A/C you want the returns on the top floors. For supply the returns get smaller as you go up, but for cooling they need more on the top floors. So I have two A/Cs. The top two floors are cooled by a packaged unit on the roof feeding through closets. The A/C through the original ductwork sort of does the bottom two floors.

Don (e-mail link at home page bottom).

[ds549]

i used uninsulated pipes in my 100year old home and they dont sweat at all. my basement is pretty well sealed up from the humid summer air. lucas

[Deano]

Thanks for all the Great Replies!! No, the house has not been rented yet so the prospective renters' allergies are not the issue. The ductwork is aluminum...and the HVAC people I have spoken to feel that my brother in laws needs to get a life in regards to the "moisture in the walls" problem. The air return may be more of an issue. There are three vertical shafts extending into the upstairs floor; one exposed in the kitchen: one hidden in a dining room closet and one inside a wall next to the front chimney in the parlor. The only return appears to be in the foyer on the first floor. Our other rental house came with A/C but also does not have an upstairs return...the A/C seems to work OK with ceiling fans on upstairs. Both houses are circa 1890. Any more suggestions?

In other news...sister and BIL put in two windows yesterday...one an inch lower than the other.

They're leaving today. :-)

Deano

[trader4]

Is anyone else curious how the prospective tenents managed to find out your brother in laws dumb opinion?