Ducting Questions

[jeb_64]

First let me say this is a great site and I wish there were many more like it in the construction fields.

I apologize for the lengthy post I am writing

My post is about the house I'm renting/care taking. the house is 100-110 yrs old. 2 story brick. Basement very rough not heated. The furnace is located in the basement and was replaced about a year ago. The house has the old 12x12 registers. The ducting was not changed out and they runs of 14" to 10" and so on. There is no returns on the second floor and they are poorly laid out on the main floor. As my rent is so cheap I am also doing some repairs to the place and it needs allot of them. I am responsible for paying the heat which is why I am here. If there is something I can do to reduce heating costs please help. I would like to see the furnace running up to its potential. Should the dusting have been replaced. The new furnace is a carrier. Seems like a good unit. I know nothing of furnace brands or quality. I am capable of doing the repairs I just need a starting point. What can I do with the returns for the up stairs without tearing open walls. I did read a post for trying to run it through the floor to the stairwell where there is actually a return located at the bottom of the stairwell. There is about a 1" to 1.25" gap under bedroom doors. There are also some sort of small round 5" diameter registers in the baseboard. I am wondering what these might be some sort of possible return air?

Thanks for any input
Jeb

[luskys a/c]

Hopefully the hvac contractors that put in the carrier unit made sure the exsisting duct work isn't oversized and why they didn't situate the return in this old house while they had the chance. I have been doing alot of rehab houses in the St. Louis area and they are also 2500sqft or more. It is alot of work and if your house is around this sqft then your house needs two units to carry the load because I will bet there is not much or no insulation only plaster walls??? Windows- are they new - single -double paned. Did you say if the ductwork downstairs was old or new?

[jeb_64]

The house is brick actually. Plaster on brick. I am sure the home owner is on a budget and just wanted the new furnace in. The duct work is old. Like I stated there are 14" down to about 6"-8". I have no idea how to calculate what should be there. I am also just a renter trying to do improvements. Part of the issue is probably the asbestos on the duct work. No problem there as I have extensive knowledge on asbestos removal and access to all the equipment necessary to do the proper removal.

[glennac]

There is no problem with free air return provided that you have a path for it to go threw the house back to the furnance. Your upstairs doors have a gap of 1 to 1.25 inches. This should be enough for an adverage size room. I don't believe that you need to do anything on the return aspect of your house. Just make sure the supply duct is sealed up good. :D :D

[gonekuku]

If you have good airflow, but poor register placement, the furnace may be performing to it's potential even if the bills are high and some of the living areas are cold.

To analyze the airflow, you may need to bring in an HVAC contractor - at least to tell you where the trouble spots are. Get an IR thermometer, and you may be able to tell yourself.

Just like stated above, are the windows single pane? Do you have any insulation in the walls? Take off a few switch plates on the exterior walls, try to peek in the wall cavity and look for insulation. (I used to live in a 1906 house and the walls were insulated with Russian newspaper from the 1950's - Retrofit obviously).

Do you have attic insulation? What's the temperature in the basement this time of year? Is the floor insulated?

[jeb_64]

There is no insulation in the walls. No insulation in the floors. There is insulation in the attic but it could definatley be improved upon. The lack of insulation on the duct work is one of my concerns. I haven't actually had a thermometer in the basement but it has to be around 45-50 f. The register placement is what I question. I have several rooms in the upstairs which are closed off for the winter and there is no central air. I know that some air is probably wasted being supplied to the upstair so if I reduced those lines to the upstairs for rooms not being heated maybe the rest of the house would heat better reducing energy costs? Thanks for the replys.

[gonekuku]

By the sounds of it, improving on your duct insulation may only improve the temperature of the air 5-8F before it enters the uninsulated structure you are renting.

Move.

[luskys a/c]

The supply vents are fine unless you are redoing the floor then I would use normal size vents maybe like the 4by10. If you remove the asbestos off the duct work you need to install some duct insulation where you removed the asbestos. Honestly the house will never be at its best potential comfortbility with out the attic being reinsulated and the walls striped of plaster and insulated and drywalled and the budget in a new airhandler for the upstairs rooms. Then work on the windows and hope the floors are thick. This should be more of a in the budget kind of project.?? or maybe not.....