heat duct problems

[kevfish1]

What are some options here? The lower level of my house is heated with a furnace. the duct work is under a cement slab and is made of cement and tin. There are several problems that have developed and I am getting alot of sand in the duct work, This causes dust to get over everything when the furnace runs. I had it cleaned out but more sand just comes in. I have thought about just sealing the system off and going with electrical heaters. Or is there anyone that can spray or coat the existing pipes so they wont leak?? Or go with a gas fireplace?? It is one big room.???

[CAMAN]

I would seal off the floor ducts and run a duct along the ceiling.

Also depending on the size of the existing ductwork you might be able to get some flexible ducting to line it.

[Tom7227]

Just an idea - i think there's some products that are self-leveling material for floors. Sounds like you have cracks and I wonder if you could at least clear up any on the bottom of the duct with this type of a product.

[upnorthvoice]

I think Caman's idea is what you should look into. If you are getting dust from the duct work you might also have a humidity problem now or in the future. One more thing to look into is radiant heating, there some products you can use over the slab and pour over it and only raises the floor 1 to 1 1/2 inches. Camans plan should be the least expense to you. A gas fireplace wood look great in a family room but you might have cold spots from poor circulation the fireplace gives. If the budget works do the duct work along the ceiling and boxed in now and plan for the fireplace in the future, or the fireplace first etc.

[Surface Tension]

Ideally you want the heat registers low.

If it were me I'd snake a camera into the run to see what it looks like. I'd keep the furnace myself.

We really don't have enough information to say what is the best solution. How many of these underground runs are there? Lengths and straight runs? Is it possible to scrap those runs and get new ones in low?

Where is the cold air return? Got any pictures.

A flexible liner if possible might be best. Even then you might need to add another run because you lost cubic inches with a liner. If you had to run that one in the ceiling it wouldn't be the end of the world.

[kevfish1]

The furnace heats one big open room. Living room , dining room, kitchen.

Had a camera down last weak and one area is either caved in or the cap is damaged. That section i think is now capped off as we put a ballon type device in and capped it off. I just took the furnace out to look under it. It is a down flow furnace. A small tin pit sits under the furnace. this pit is rusted and has some small holes in it. Thered are then 3 ducts that run into the pit. these ducts are also tin and are not in good shape rusty and joints are not good.

Now somewhere these ducts turn to cement as the ducts in the registers are all cement. we did not view under the furnace with the camera. I will need to get a camera again to do this and then decide. I think flexible duct or a spray type duct liner would work if there is such a thing and if it can work around corners.

to go with new duct at the ceiling I do not think would work beacause of the stairwell opening back door etc. I could get a upflow furnace and shoot heat out the return air duct but I would have just one heat duct then.

I am checking with my homeowners insurance to see if it would cover this. Adjuster came and looked and said he would have to do some research cause he has never seen this before

any ideas?????????????????????????

[CAMAN]

That sounds like the perfect situation for a high velocity HVAC system retrofit. Basically its a furnace and AC system that uses 2" diameter tubular ducts that can be installed pretty much everywhere. And you will get the same amount or better airflow as your current system.

Its used in a lot of remodels of older houses and buildings that don't have room for the larger ducts to be run.