My house is a 2 bedroom ranch style build in 1953. It sits on a concrete
slab - no basement or crawl space. The air ducts for the furnace are down in
the slab. The house has a rectangular shape, and the furnace is at one end.
Water is getting into the air ducts. The floor vents for the half of the
house closest to the furnace work and have air coming out. The floor vents
in the half of the house furthest from the furnace have no air coming out,
and when the furnace runs I can hear water gurgling. There is also a damp
scent coming from those vents. Apparently, they are blocked by water. There
was no problem with the HVAC system last night, but there is this morning.
We had rain yesterday and overnight.
What do I do? There is no way to find the place where water is getting in
without demolishing the slab. I suppose new vents could be run over the
ceiling, but I still have to deal with the water. I'm very concerned that
it's going to back up into the house. Even if the old vents are taken out of
commission the leaks still have to be fixed somehow. What do I do? Who do I
call? A furnace company? A general contractor? This sounds like it could
cost a fortune to fix. Any advice will be greatly appreciated. I'm really in
over my head and have no idea what to do. But, I've got to do something soon
before the house floods.
I don't think I'd be to concerned about water coming up, but it seems like a
bizarre way to install the system in the first place. I think you need to
call a HVAC contractor, probably close up and fill with cement the old
ducts, then run new ones overhead. It can't be healthy to have drainage
water flowing into heating ducts. You're right, it's probably gonna cost
I have seen this type of construction. If it was/is common in your area your
local HVAC, concrete, plumbing, and general contractors may already have a
lot of experience with determining the options available to solve your
problem. If the ducts cannot be kept dry and clean for whatever reason I
would certainly look into flexible or formed-in-place liners. There are a
lot of methods available for relining water and sewage lines. It seems a
major and expensive problem and you should get the best professional
on-site evaluation possible before you make a commitment.
Don't forget that there are other systems for heating and cooling homes that
use no ductwork. Don't limit your options. Hope it works out well for you.
This is obviously not good. And possibly expensive. But
whatever the outcome, remain calm.
For starters, I was do a complete walk through and around
the house looking for possible clues. Pay special attention
to gutters, drains, and any septic system. Really, really,
look hard (this is not the time for a casual glimpse).
More often that not, clues are there waiting to be found.
This could be a simple case of a gutter blocked by leaves
dumping water at a critical point where it can flow into
your ducts. Even a backed up drain.
You want to know where that water came from. Even better
if you can determine where and how it entered the ducts.
But with every water problem I've ever known, it's
important to establish the source ASAP.
Look at the water levels around the house -- maybe dig
a small hole/trench in the ground next to house to see
where the water table is.
Approach it calmly and systematically. Post again with
your findings and questions.
| Malcolm Hoar "The more I practice, the luckier I get". |
On Mar 8, 1:47 pm, email@example.com (Malcolm Hoar) wrote:
Never heard of ducts run in the slab. Given the size of ducts and
thickness of slabs, it would seem the duct would be not only in the
slab, but under it too.
I'd probably start by finding a competent home inspector and get an
overall opinion on the whole house including this problem. Then an
HVAC contractor is the next step. Also agree with the advice to look
for obvious sources of how water is getting in, ie water pooling from
downspouts, etc. But if you have ducts in the dirt, this seems like
a design destined to fail.
Not really that unusual when the house is built on slab (as is mine).
This is probably a runoff/drainage or grading issue. The OP might also
want to check the water tank for a leak if it is in fact close to the
furnace. If his furnace is set up like mine the cold air intake is on
top and the hot air is forced down into the ducting
If in fact the leak is due to the water table rising up above the level
of the ducting then one possible solution might be to dig a pit and
place a sump well and pump in a location closest to the flooded area. I
had to do this in my back yard as the area has allot of clay and the
drainage under the backyard does not work fast enough to stop flooding
in the fall. although my house was/is never in any danger of flooding I
did not see boating as a very good use of the back yard.
On Sun, 08 Mar 2009 17:22:59 GMT, "J. Cameron Davis"
Harbor Freight does have two models but they are each 200 dollars.
One is 36 inches and the other 24. Not enough, although you can
look in each vent and you might get lucky if the leak is within 3 feet
of one of them. It might be useful at some stage for keeping an eye
You know you might be able to see the water just by looking in the
vent if the vent is in the floor, with a flashlight and your eye. I
would start where you say no air comes out.
I don't understand all the difference or why they are the same price.
Mayvbe you can find longer or better for 300 dollars. Maybe you need
one for other purposes too?
Amazon has one for 250 for 36 inches. You'll hae to pump out the
water before using one of these.
Proabaly a lot more money http://www.provision100.com/products_b.html
has two that are 96", one with an obedient scope and one with a
non-obedient flexible scope, whatever they are. No price given.
Although NOrthern Tool and Equipement sells their 36 inch model for
barely anymore than harbor freight wants for a no-name brand. I'm
assuming becuase of Provision's long list of models and accessories
that it is a quality brand.
I googled on fiber optic scope and fiber optic scope shipping
I use the word shipping to find only places that will ship (and sell
First thing I would try to do is inspect the outside of the slab to see
if you an identify the entry point, beginning at the end that has most
water - perhaps that end is a tad lower and the water is collecting
there first. It would seem very odd for water collecting in ducts to be
coming from OUTSIDE the house, unless the foundation is cracked. Check
for plumbing leaks, see if the water meter is turning when everything is
shut off. Ground frozen? Downspout near the "wet" end of house that
empties close to the house or onto a low spot of ground?
Ouch. Been there. Unlike the others, have had the exact same thing happen.
Long message and ready for any questions. No other repliers I have noted,
have this construction or have had this happen. I have.
The problem is not the HVAC system, but the repair may involve re-routing
it. It's ok to contact them first but your chances of them really knowing
what is going on are 'unlikely'. You may luck up with one who has
knowledge, but they arent really who to contact.
First thing is do not panic.
This is the first time right? Take it systematically like our solution did.
Your solution may not be that expensive depending on what caused it.
1. Can you see any water at the 'gurgling' end? Or just hear it? This
gives a feel for how much seepage you have and I bet you, seepage is the
problem. (Ours was so bad we needed a wet/dry vac to drain it in any rain
2. Do follow what the others said and make a good inspection of the outside
of the house, including drainage. It may not be there though (was not in
our case exactly that). Consider getting a general contract on the phone
and explain what is happening then ask them for an inspection. Be prepared
to pay about 100$ for this, more if they have camera gear to run under the
house through the vents.
- This is your best bet. Do NOT let them high pressure you. I had 3
inspectors and 2 of them were very high pressure with added work that was
NOT needed for the job and they kept tossing the 'mold' keyword every 2-3
3. If this is a first occurance (best as you know) and it *only* happens in
rain, it is most likely from my experience to be an exterior drainage issue
and possibly a need for a reinforced footer on the outside on part of the
house (cheaper to do it all at once if you can afford it). It may just be a
bad gutter placement but keep in mind there is something wrong with the slab
too. It just need not be terminally bad.
- It will get worse over time until dealt with
- Mold may develop in the sub-floor channels but once fixed, it will go
4. In our case what was 'broke' was not at all obvious and it involved 2
separate breaks. The house drain pipe corroded under the slab and it
happened to lay right along one of those HVAC channels. It *also* degraded
in the yard so that when water (rain) got deep, it backflowed up that way to
under the house. There was nothing visible in the yard to see this.
5. The fix in our case due to the dual break, was to first fix the yard
pipe out to the city sewer line (your household insurance may pay for this,
area dependant. Your water company probably wont if it well in your yard as
ours was). Then, unfortunately as the main underslab duct from the HVAC was
where the other break was, we had it backfilled with cement which had to be
professionally 'blown in' to make sure it got all the way through the system
(not just at the outlet ends).
- alternatives do exist but cost a heck of a lot more in our case with no
guarantee they will work.
- the main drain under the house had to be re-routed which fortunately was
easy to do from the garage and down the other side of the house.
- Once properly sealed, the HVAC had to be re-worked and added vents in the
attic made. Chances are good with minimal adaption, your *existing* HVAC
can be reworked, especially if you have ceiling vents as well as floor ones
right now. The re-work of the HVAC itself is fairly simple but the ducting
can cost a bit depending on how close to current code yours is now. (we were
lucky, it was codespec and beyond with larger ducts than normal suitable for
immediate expansion with no need to remove the old).
Slab construction like this is not common in a good part of the USA which is
why some of the repliers think it 'odd' or 'cant be'. They just don't live
where I do and you apparently must be in a similar area if not Norfolk.
(BTW, if you are in Hampton Roads area, I may be able to find the names of
who did some of our work but it was over 10 years ago).
Cost would be your main question I bet? Sadly it was so long ago all I can
do is my best 'guess' as I didnt keep good records. If 'guess' is ok? Keep
in mind this was about 1998-1999 (and no problems at all since).
-HVAC adjustment for upper flow: about 200$?
-HVAC duct work (6 added ones if i recall, may have been 7-8): about 1,000$
-Filling bottom (includes re-route of house drain but not the yard portion):
-Digging out yard and replacing line from new outlet: 2,000$
So, all I really recall is it was a bit under 4,000$ and house insurance
covered about 1/2 of it.
I do distinctly recall the 2 high pressure sales guys wanted 20,000$ and
35,000$ respectively. One of them even said we needed to have the house
lifted and a new slab poured. Rest at ease. You do not have to have the
house lifted and a new slab poured.
This house was probably never intended to last this long. There used
to be a lot of them where I lived in Southern Georgia and they were
called Florida Homes. They werre usually built of concrete block on a
slab. They were cheap and never intended to last more than about 20
years. I would bet you also have galvanized pipe buried under the slab
too that has about seen its day. I hope you got the house cheap
because you are about to spend some money now. my parents bought one
and fixed it up wanting a smaller home after they retired. They had to
put in an outdoor gas pack HVAC unit, run duct work through the
ceiling. Along with the HVAC and water they also had to redo the
electrical. None of this was that bad considering the roof including
the rafters had to be torn off to repair termite damage. The on thing
going for them was that they bought the house very cheaply $15K and
spent about another $30K on renovations. For less than $50K they got a
house that was worth $80k upon completion in 1990 and about $110K
All sounds dire, but what turned out to be wrong with the ducts in the
slab? There was water in them? Where was it coming from.
Although your parents had all these problems, he only has the water so
far and might be able to learn something from you or your parents to
help him fix it.
You don't want to call a city/county inspector
because you could be ordered to evacuate your
home by people with guns. It's for your own
safety. I hope you can get a competent private
home inspection service to look at your problem
but first make sure that they won't rat you out
to the MAN if they find a health problem.
Stranger things have happened when people call
a government agency for help.
What the hell makes you think it's a troll?
I witnessed incidents where people I know
said the wrong thing to the wrong person and
had government types show up and demand all
sorts of insanely expensive remediation. I
know of several people who bought property
and had no idea that there were buried oil
or vehicle fuel tanks on the property. When
they contacted government officials about it
guess what happened to them. I know another
guy who bought a small piece of business
property for a food stand. The place had been
a taxi stand before and the taxi owner changed
his own oil and spilled a little on the ground.
Guess what would have become of the new owner if
some government busybody had gotten involved. I
sincerely hope that the fellow with the water
problem can get some help without being snake
bit by government bureaucrats.
It's pretty frickin obvious.
This is at worst case, water under the slab due to poor footer likely. Read
his actual post before you reply.
The guy is getting advice from sump pump (not applicable to his
construction) and how to seal his basement (doenst have one obviously) to
you telling him if he asks for help someone will tell him to evacuate his
Go away troll. He doesnt need that.
It was tongue and cheek, Christ, you actually think every
post is meant to be serious. You obviously haven't been
around Usenet very long not to recognize humor or sarcasm.
A few more years of reading posts will likely lead you to
better understand human behavior in Usenet newsgroups. You
may have noticed a lack of name calling and foul language
on my part. Trolls don't usually respond with coherency
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